Understand Energy Final Exam Prep

Rankine vs Brayton cycle

The difference between Brayton and Rankine cycles is that the Brayton cycle operates entirely on gases that are fed into it, while the Rankine cycle uses a liquid as one of its working fluids. The Brayton cycle is a gas turbine cycle, while the Rankine cycle is a steam turbine cycle.

What are concerns behind the duck curve?

The duck curve shows steep ramping needs and overgeneration risk. - A large amount of electric capacity needs to be (1) built, leading to expensive overbuild / low capacity factors, and (2) ramped up quickly when people get up or come home, resulting in a tremendous stress on the electricity grid. - The potential for oversupply increases as more renewable energy is added to the grid but demand for electricity does not increase (unless significant demand response measures are implemented). - The belly of the duck can go low enough to require hard to adjust baseloads like nuclear to ramp down / shut off.

Nuclear fusion vs nuclear fission

The main difference between these two processes is that fission is the splitting of an atom into two or more smaller ones while fusion is the fusing of two or more smaller atoms into a larger one. Fusion on the other hand does not create any long-lived radioactive nuclear waste.

Porosity

The volume of pore space in a rock as a percentage of the total volume the rock occupies

Cut-out speed

The wind speed, usually around 55 to 65 miles per hour, at which some wind turbines automatically stop the blades from turning and rotates out of the wind to avoid damage to the turbine.

Energy currency

These are secondary sources. They are modified by primary sources to exist in a form that can be effectively used for an energy service. They are often energy carriers. Examples include electricity, biofuels, hydrogen, gasoline, etc.

How much more efficient are heat pumps?

They are approximately 50% more efficiency than electric resistant heating such as furnaces and baseboard heaters

How can companies buying RECs claim they are 100% renewable?

They are paying the solar project owners for these RECs, meaning they are purchasing the renewable energy produced by this solar farm, and others cannot claim they are renewable by using that energy production. This contributes to the development of a new renewable energy projects overall. In the course of a year, this project will generate an amount of energy equal to their annual consumption. However, this is somewhat misleading because time of use is not considered. For instance, companies use baseload energy at night (for data centers, especially) when there is no renewable energy production.

Energy service

They are the work that is eventually accomplished by the energy resource, often carried out by the energy currency. Examples include an internal combustion engine, a generator, a heat engine, etc.

Types of ocean energy

Tidal - most going on here - most capacity installed Ocean current - -very little here Wave - lots of R&D activity here, waves everywhere Thermal - basically uses the ocean as a solar collector, temperature gradients, Hawaii more soon Not a big potential in any category really, except OTEC, but could be important locally, maybe, if someone can make it work economically? Really really small portion of global energy use today Very site specific and a bunch of environmental issues Tides - most commercial Thermal - most potential

Capacity factor equation

To calculate the capacity factor, take the total amount of energy the plant produced during a period of time and divide by the amount of energy the plant would have produced at full capacity.

Importance of transmission for wind energy

Transmission is particularly important for wind power due to the locational dependence of wind resources, the relatively low capacity factor of wind plants, and the mismatch between the short lead time to build a new wind project and the longer lead time often needed to plan, permit, and construct transmission.

Transportation as a percentage of energy use

Transportation is the second largest energy use sector

What factors impact cost of biomass?

Transportation, type of biomass, final end use sector

US and world electricity mix breakdown

US is NG, then nuclear, then coal, then renewables (wind) World is coal, then NG, then hydroelectric, then nuclear

US and world energy mix breakdown

US is Oil (35%), then NG (34%), then coal (10%), then nuclear (9%), then hydro (3%), then other renewables (other 7%) World is oil, then coal, then NG, then hydro, then nuclear, then other renewables

Semi-renewable energy definition and examples

Use of the resource can be renewable if carefully managed such that production does not result in depletion Example: Hydro, geothermal, biomass

Types of retail structures

Volumetric - Price is fixed per kWh (cost therefore increases based on use) - Simple, good incentives for wind and solar, but poorly aligned with utility costs and has no flexible load incentives Tiered - Increasing rates based on differing levels of energy use - Great at incentivizing efficiency and solar and progressive, but cannot incentivized flexible loads, really poorly aligned with utility costs Time-differentiated - Higher costs associated with higher use during peak hours - Better aligned with utility costs and can incentivize flexible loads, but can remove existing incentives for efficiency and solar Fixed/demand charge & retail time pricing - Price varies based on short time intervals (real time based on supply and demand!) - Most economically efficient, best at incentivizing flexible loads and provides fair allocation of costs to customers, but it is complicated and has poor solar and wind incentives

What are pros and cons of hydraulic fracturing?

Pros: - Greater energy independence - Cheap natural gas driving coal out of business - Reducing economic power of OPEC - Incentivizing domestic manufacturing in the US Cons: - Environmental impacts (global warming, noise pollution), environmental justice (Standing Rock pipeline), potential dangerous oil transportation (derailing trains, etc)

How is the power extracted from a wind turbine calculated?

Pturbine = ½ ρAv^3C ρ = air density A = swept area of blade (pi r squared) v = wind velocity C = wind turbine power coefficient, which is a measure of wind turbine efficiency often used by the wind power industry

Implications/importance of alternative modes of transportation - rideshare, public transit, transportation network companies (uber, lyft)

Public transit - very energy efficient, an example of public transit is the Caltrain. Transportation network companies such as uber ave pros and cons such as: Pros: - Increased utilization of vehicles - Reduction in car ownership - Increased ridesharing - Support for public transit - Less drunk driving Cons: - Induced demand - Substitute for public transit - Contributes to congestion

How is wind power calculated? (important as shit)

Pw = ½ ρAv^3 Pw = wind power ρ = density of the air A = swept area of blades (given by pi(r^2)) v = wind velocity

What is solar energy?

Radiant heat and light energy from the sun (a fusion reactor)

Energy efficiency definition and examples

Reduces the need for energy resource use in the first place (e.g. a negawatt, a Rosenfeld). Energy efficiency should be prioritized before renewable energy. Examples: heat pumps, LED lights

Types of natural gas power plants (2)

Simple cycle gas plants - Consists of a gas turbine connected to a generator - Less efficient than a combined cycle at 20-35% - Able to dispatch faster (good for peaking power) Combined cycle gas plants - Consists of another external combustion engine, operating on the Rankine cycle - More efficient because it makes use of the hot exhaust gases that could otherwise be dispelled from the system - These exhaust gases are used to boil water into steam, which can then spin the turbine and generate more electricity - The thermal efficiency of the combined cycle can be up to 60% - They produce much less waste because of the efficiency

Environmental and social impacts of transportation

Social impacts - Around 33,000 deaths per year from transport in the US alone. - In the US, car crashes are the leading cause of death up to age 30. - Stress from car congestion. Environmental impacts - Air pollution - NOx and SOx from exhaust in cars lead to acid rain, ozone and particulate matter lead to smog - Oil based internal combustion engine carbon dioxide - Land and Water Pollution - Lead, Oil from cars leaking, and fuel from roads, creating vehicles is environmentally damaging (tires, scrap metal that is not recycled) - Resource Use - Land has been used up for parking and highways, materials to make cars are being used up such as metal, oil, and plastics. This is all depleting non renewable resources.

Sweet vs sour NG

Sweet = low sulfur/CO2 content Sour = high sulfur/CO2 content

Energy conversion technology

Technologies that convert one form of energy to another, such as chemical to mechanical or mechanical to electrical. Examples include a generator, wind turbine, solar panel, heat engine, internal combustion engine.

What was the shale revolution?

The "Shale Revolution" refers to the combination of hydraulic fracturing and horizontal drilling that enabled the United States to significantly increase its production of oil and natural gas, particularly from tight oil formations, which now account for 36% of total U.S. crude oil production.

Explanation of carnot efficiency

The Carnot Efficiency is the theoretical maximum efficiency one can get when the heat engine is operating between two temperatures: The temperature at which the high temperature reservoir operates ( THot ). The temperature at which the low temperature reservoir operates ( TCold ).

Clean Air Act definition

The Clean Air Act is the law that defines EPA's responsibilities for protecting and improving the nation's air quality and the stratospheric ozone layer. It was enacted in 1970 and major revisions were made in 1987 and 1990

Why did coal mining shift from the East Coast to West Virginia (and the West Coast generally) in the 1970s?

The Clean Air Act put limits on sulfur emissions, which meant that coal mining switched away from the Appalachians to low sulfur deposits in the western U.S., especially Wyoming. It was cheaper to switch to mining lower-sulfur coal than to add sulfur scrubbers to existing coal plants.

Brayton cycle

the operating cycle of a gas turbine engine consisting of the following 4 simultaneous events: intake, compression, combustion, exhaust

What is well-to-wheel analysis?

Well to wheels looks at the entire fuel cycle from recovery & processing to vehicle motion. It does not include embodied energy.

Wet vs dry NG

Wet = less than 90% methane composition Dry = more than 90% methane composition

Whole systems thinking for energy efficiency

Whole systems thinking allows you to see the big-picture of the social, environmental, and technical systems that a product is a part of. This can help you identify new possibilities for innovation.

Rated wind speed

wind speed at which the 100% rated power (maximum power) is first achieved

Permeability

A measure of the ease with which fluids or gases can move through the interconnected pores of rock

Energy use intensity (EUI)

A metric that expresses a building's energy use as a function of its size

IOUs v. POUs v. FOUs v. Power Marketers, IPPs,

IOUs: investor owned utilities POU: public owned utilities FOU: federally owned utilities Power marketers: are intermediaries who buy and sell power IPPs: wholesale generators

Top energy end uses by sector

Residential sector: 1) space heating 2) water heating 3) water cooling Commercial sector: 1) cooling (refrigeration and space cooling) is pretty dominant. Mostly used by office buildings Industrial sector: 1) chemical production and oil refining dominate Transportation sector: fuel duh

What is an oscillating water column system?

Rising and falling water column drives air past a turbine, generating electricity

Hydrogen long term energy storage

- Hydrogen energy storage is a process wherein the surplus of energy created by renewables during low energy demand periods is used to power electrolysis, a process in which an electrical current is passed through a chemical solution in order to separate hydrogen - Hydrogen can be stored physically as either a gas or a liquid. Storage of hydrogen as a gas typically requires high-pressure tanks (350-700 bar [5,000-10,000 psi] tank pressure). Storage of hydrogen as a liquid requires cryogenic temperatures because the boiling point of hydrogen at one atmosphere pressure is −252.8°C. Hydrogen can also be stored on the surfaces of solids (by adsorption) or within solids (by absorption).

Potential applications for hydrogen fuel

- Hydrogen gas for backup power for data centers - ZeroAvia's hydrogen fuel cell plane - Yanmar/Toyota hydrogen fuel cell boat - Hydrogen gas for steel production, ironmaking and other hard-to-decarbonize sectors

Why is hydrogen gas hard to transport?

- Hydrogen is 14.5 times lighter than air - It is flammable and potentially explosive - Melting temperature is -259.2 celsius - Boiling temperature is -252.76 celsius - Hydrogen dissolves well in metals as it can easily diffuse through their thickness

Pondage definition

the storage capacity of a pond or reservoir.

How were ISOs and RTOs established?

- ISOs and RTOs were established in the 1990s (FERC orders) to help promote competition in electricity markets - ISOs and RTOs administer competitive wholesale power markets and provide equal access to the grid for all potential competitors - In the absence of ISOs and RTOs, direct competition between energy resources over time and across territories was limited - Without ISOs and RTOs, each utilities in the US, in order to provide electricity to customers in their individual service territories, either own and operate their own large power plants, or enter into long-term contracts with power plants. - Note that RTOs and ISOs also serve as the balancing authorities for their region, thus helping the balance supply and demand and provide reliability planning for the bulk electricity system. - However, other regions without RTOs and ISOs also have balancing authorities

Production tax credits (PTC) vs investment tax credits (ITC) for wind energy

- ITC rewards individuals for building the project, while PTC rewards how well individuals manage the project and its productivity - The PTC provides a tax credit of 1¢-2¢ per kilowatt-hour for the first 10 years of electricity generation for utility-scale wind - The alternative Investment Tax Credit (ITC) provides a credit for 12%-30% of investment costs at the start of the project - ITC is better for capital intensive projects

How has the shale revolution (NG) impacted coal?

- In the US, natural gas surpassed coal in 2016 as the number one energy resource for electricity generation after coal reigned in the electricity sector for over 100 years - The abundance of natural gas, which has pushed down natural gas prices, has also caused lower electricity prices, increased competition for other generating resources, and caused retirements of coal and nuclear power plants

How did the shale revolution impact the US petrochemical & manufacturing industry?

- Industrial use of natural gas grew 27% between 2008 and 2018, driven primarily by the petrochemical industry, in particular methanol, fertilizer and ethylene production - Many US shale plays are producing increasing amounts of natural gas liquids (NGLs) such as propane, butane and ethane. - These NGLs are used to make plastics, antifreeze and some gasoline components - The availability of low-cost feedstock also helped lower prices of fertilizer production, and lead to 24 new fertilizer plants in the last few years. - In 2016, the fUS also shipped its first waterborne exports of ethane

Energy policy: Renewable energy certificate (RECs)

- A renewable energy certificate (REC) is a tradeable, market-based instrument that represents the legal property rights to the "renewable-ness"—or all non-power attributes—of renewable electricity generation. - A REC can be sold separately from the actual electricity (kilowatt-hour, or kWh). - The REC owner has exclusive rights to make claims about "using" or "being powered with" the renewable electricity associated with that REC. - A REC is issued for every megawatt-hour (MWh) of electricity generated and delivered to the electric grid from a renewable energy resource. - Renewable Energy Certificates (RECs) are a market-based instrument that certifies the bearer owns one megawatt-hour (MWh) of electricity generated from a renewable energy resource. - Once the power provider has fed the energy into the grid, the REC received can then be sold on the open market as an energy commodity. - RECs can benefit your business as well, helping you achieve emissions goals and helping promote your commitment to renewables.

What is an impoundment hydropower system?

- A reservoir with elevation is created by a dam by putting a barrier in the channel - Localizes elevation difference between the water surface right by a powerhouse - Water is taken out of the reservoir and delivered to a powerhouse through penstocks where it is converted to electricity

What is a run of the river (with pondage) system?

- Instead of using a waterfall, a dam is built which alters the flow of the water - The dam creates a very small reservoir upstream which allows for a little bit of time shifting by altering the flow - It has considerably less storage than the reservoirs or large dams and conventional hydroelectric station which can store water for long periods such as a dry season or year

Solar thermal electric technologies: parabolic trough

- A type of thermal collector that is straight in one dimension and curved as a parabola in the other two, lined with a polished metal mirror - The sunlight which enters the mirror parallel to its plane of symmetry is focused along a focal line, where objects are positioned that are intended to be heated - To generate electricity, a tube containing a fluid runs the length of the trough at its focal line; the fluid is heated and run to a heat engine which generates electricity - Total efficiency is ~15%, similar to PV

Oil API and what factors determine in

- API determines the performance of a given oil - Generally, lighter oil is more valuable because it requires less refining to become high demand products like gasoline

Innovation in wind energy

- Advanced power control systems & software updates (optimizes power produces, minimizes fatigue from wind damage, allows virtual monitoring) - Modern blades (lighter, stronger, more aerodynamic) - Flexible rotor hub designs (increase efficiency) - Innovation in direct-drive, low-speed generators and power train designs (increase efficiency, eliminate/reduce gearboxes) - Improved tower designs and construction materials (increase cut out speed)

Cons of biomass

- Air pollution - Biodiversity impacts - Soil degradation (deforestation or growing crops) - Competition with food sources (e.g. ethanol sources from corn) - Lifecycle carbon emissions - Water intensity - Fertilizer use/dead zones - Large land-use requirements - Can require lots of water usage - Reduced efficiency because its not as carbon or energy-dense as coal (lower T-hot)

Ground source vs air source heat pump

- Air source heat pump is described in the heat pump explainer above - Ground source heat pump uses geothermal heat from the ground. - They are 44% more energy efficient than air source heat pumps and 70% more efficient than conventional air conditioners with electric resistance heating - They move 3-8 kWh of heat for every kWh of electricity used.

Allam cycle

- Allam Cycle is a process for converting gaseous fuels into thermal energy, while capturing the generated carbon dioxide and water. - It is a novel natural gas power plant design that can theoretically capture 100 percent of emissions while being cost- and efficiency-competitive with advanced natural gas plants that have no carbon capture capability. - The cycle captures all CO2 emissions and diverts a pure output stream into a pipeline for sale or storage, while avoiding most or all water costs and using a fraction of the space of standard natural gas plants

Trends, barrier and solution to energy access in the developing world (China and India in particular)

- Almost 97% of households are connected to the grid but electricity is not consistent and there are a lot of outages (in India) - Also, India considers access as 10% of households in a village or grid connection within 5km, and India has 3 grids with different reliabilities - Global grid extension has been responsible for 97% of electricity access since 2000 but off grid options are growing (but it's expensive)

Why is geothermal seen as semi renewable?

- Although geothermal heat is continuous, it is a finite source. There is a limited capacity of geothermal heat in a reservoir. - Geothermal power plants release small amounts of carbon dioxide, nitrogen oxides and particulate matter. - They are not emitted during combustion, though— these gases are naturally emitted from the geothermal reservoirs themselves. - Some argue that these should not be considered emissions because they would eventually vent to the surface and into the atmosphere, but this process is expedited due to geothermal power production.

Pros of biomass

- Available almost everywhere (almost) that people live (but not always in sufficient quantity) - Easy to store wood (you can make a pile) but have to do more relative to fossil fuels - Limited transportability due to low energy density - Have to worry about bugs/rain, etc - Waste as a fuel (landfill, industry, municipal, etc) - Renewable (ish) - Diverse sources with different characteristics - Can replace fossil fuels - Biomass waste can be used as a fertilizer (byproduct)

Though they might have a high up-front cost, why can wind and solar still have competitive LCOEs on an unsubsidized basis?

- Because their fuel cost is essentially free so their fuel costs are much lower - Also because they have lower operating costs (low maintenance)

Why is LCOE a useful metric?

- Because we need a metric that will allow us to compare energy resource generation over lifetime - For instance, if some resources have high capital cost but low O&M cost, they should be evaluated for those costs equally to a resource with low capital cost but high O&M cost

What is the difference between biomass and biofuels?

- Biofuels are fuels derived from biomass - Biomass is organic matter converted to fuel

What is the carbon neutrality of biofuels?

- Biomass is only carbon neutral on long time scales - Burning wood immediately releases carbon, and it takes a decade or even a century for a replacement tree to absorb the same amount of carbon - In the meantime, that atmospheric carbon continues to drive climate change - Forests need proper management to remain carbon neutral - Planting trees/plantations do not store the same amount of carbon as natural forests - Carbon emissions don't just come from burning; a large amount is stored in the soil which you're releasing as you harvest the trees - However, the EPA named burning of forest biomass as carbon neutral in 2018, putting it in the same category as wind and solar

Characteristics of biomass

- Biomass is organic material that comes from plants and animals - Biomass is semi-renewable, so it must be used wisely and be carefully managed in order to be sustainable - Constitutes 12% of global energy consumption and 5% of US energy consumption - There are two broad categories of biomass: organic materials (plants & animals) and waste material (garbage, sewage and agricultural waste)

What are trends in solar, hydro, biomass and energy efficiency (global and domestic)?

- Biomass is the primary energy resource used worldwide. It is used for cookstoves, but it has the social issue of causing adverse health effects (respiratory issues) for 10% of the world's population - Wind and solar energy are growing rapidly as they are now the cheapest energy source for 2/3 of the world - Hydropower is growing rapidly in developing nations as it requires available materials, relatively simple construction methods and accessible geography (flowing water). - Energy intensity (amount of energy used to produce a given amount of output) has improved by 1.5% each year - Globally, renewable energy sources are the fastest growing, as there are shifts to invest in renewable energy sources

What is carbon capture and storage?

- CCUS involves the capture of CO2 from large point sources, including power generation or industrial facilities that use either fossil fuels or biomass for fuel. - The CO2 can also be captured directly from the atmosphere. - If not being used on-site, the captured CO2 is compressed and transported by pipeline, ship, rail or truck to be used in a range of applications, or injected into deep geological formations (including depleted oil and gas reservoirs or saline formations) which trap the CO2 for permanent storage.

Direct use solar thermal vs. solar thermal electric (CSP)

- CSP systems convert the sun's energy using various mirror configurations that drive a heat engine and produce electrical power. - Direct use solar thermal (photovoltaic solar panels), on the other hand, use the sun's light, rather than its energy. Unlike CSP, PV converts light into electricity directly - Biggest difference is that CSP is dispatch-able through thermal storage (fluids) while PV does not have battery storage at scale yet

Why is NG such a good fit for electric power generation?

- Can meet baseload and peak demand - Scalable from 10s to 1,000 of MW - Low NIMBY issues versus other resources - Cost competitive - Highest conversion efficiency of fossil fuels - Low air emissions and low water use: "blue bridge to a green future"

Environmental impacts of wind turbines

- Causes 450,000-888,000 bird deaths annually - However, wind turbines cause substantially less deaths than cats, buildings, power lines, etc - Avian death has dropped in the US because bigger turbines rotate slower - Other solutions include using computer vision to recognize raptors when they get close and slow down/stop turbines

Which countries consume and produce the most bioenergy?

- China has the largest capacity, followed by US, Brazil and India

What is Building Integrated PV (BIPV)?

- Consists of replacing conventional building materials used in walls or windows or roofs directly with PV materials - Install on or in building during remodeling or new construction - DC power generated by the PV modules is converted to AC by the inverter and fed into a distribution panels where it is typically consumed by lighting, HVAC and plug loads within the building - If excess power is generated, it's fed back into the external electrical grid, creating a credit for the owners - Currently represents less than 1% of worldwide market but has growth potential

Conventional reservoir vs unconventional reservoir

- Conventional: oil can be produced naturally from geologic formations or with pumping - Unconventional: heavy oil, tight oil, oil shale, tar sands. Essentially any resource that cannot be produced naturally from geologic formations or with pumping

Economics of solar PV

- Cost has fallen by 90% from 2010 to 2020 - Module cost accounted for 80% of installed price reductions - They now stand at ~$30 per MWh - Residential rooftop PV is 5-6x more expensive than utility scale (high costs, not as much output, less economies of scale, worse location)

What are factors that are not considered in LCOE?

- Cost of carbon (relevant in Canada and California) - Potential revenue streams (like CCHT can operate in flexible power markets while the coal-fired power plants can't) - Subsidies - Transmission or congestion costs - Permitting or regulation compliance costs - Social or environmental externalities

Drivers of OTEC technology

- Could be viable for baseload power (can run all the time, no need for auxiliary storage - OTEC could produce up to five liters of freshwater for every 1000 liters of cold seawater in open-cycle systems. - It produces desalinized fresh water because the vapourized surface seawater leaves all the salts and contaminants in the low-pressure container. Since the vapour is pure, it generates desalinized fresh water on condensation - Almost zero emissions

Solar PV efficiency

- Current efficiency is between 15-18% - Maximum possible efficiency of a solar PV cell is 33.7%

What is the current state of nuclear fusion?

- Currently in R&D phase - Lots of government support

DC vs. AC - What are they? What are they typically used for? What are the pros and cons of each? Why did AC prevail over DC in The War of Currents and how have things changed since then?

- DC: current flows in a constant direction - AC: current flows back and forth (the one that is used because it enable central generation and efficient long distance power transmission - Long distance is good because spreading transmission over more customers brings down the cost - However, now DC can be more cost effective bc there are fewer cables, and are used for very long distances, underwater or underground lines, and for grid stabilization to mitigate cascading blackouts

The rationale and impact of utility decoupling

- Decoupling refers to policies designed to decouple utility profits from total electric or gas sales so utilities are not incentivized to sell more energy - Decoupling modifies traditional rate practices to adjust rates frequently to ensure that utility revenue is neither more nor less than what is needed to cover costs and a fair return - If this happens, they are much more likely to promote energy efficiency, renewable energy programs and energy storage as revenue streams

How does nuclear fusion work?

- Deuterium-tritium is heated to high temperature and changes from a gas to a plasma (electrons are separated from the nuclei) - When plasma is hot enough (generally >100 million celsius) nuclei overcome electrostatic forces - Nuclei get close enough together that attractive nuclear forces take over and fuse nuclei together, releasing energy (E = MC^2)

Direct use geothermal technologies: heating, ground-source heat pumps

- Direct or non-electric use of geothermal energy refers to the immediate use of the energy for both heating and cooling applications - Direct use geothermal heat meets a tiny portion of energy needs (0.04% of world energy use, 0.2% of world heat production) - Must be a shallow reservoir - China uses most of direct use, growth is also seen in Europe

Direct vs diffuse solar energy

- Direct radiation is used to describe solar radiation traveling on a straight line from the sun down to the surface of the earth - Diffuse radiation is sunlight that has been scattered by molecules and particles in the atmosphere but has still made it down to the surface of the earth - When the sky is clear and the sun is high in the sky, direct radiation is ~85% of total insolation and diffuse radiation is ~15%

Key challenges of BIPV

- Durability/lifespan - Low efficiency (8-9.5%) - High costs compared to conventional PV - Limited portion of building stock has good enough solar access (because of trees, neighboring buildings, etc)

What are the greatest challenges to stabilizing greenhouse gases and mitigating climate change?

- Economic costs - Tragedy of the commons - Difficulty garnering collective action among countries due to equity issues and the prisoner's dilemma - The lack of a silver bullet solution - Challenges to policy (short term election driven decisions) - Public perception - Changing consumer decision-making

Relative transportation efficiencies

- Efficiency is very low in cars, around 80% in losses. - Less than 1% of a car's fuel moves the driver. - Cars and planes are the least efficient transportation for passengers. - Bicycles and walking are the most efficient forms of transportation.

How electric vehicles work

- Electric cars function by plugging into a charge point and taking electricity from the grid. - They store the electricity in rechargeable batteries that power an electric motor, which turns the wheels. - Pros: No oil changes, little maintenance, silent, no pollution, no emissions, fill up at work or at home, way more efficient - Cons: Lower range of EV's because of high cost and weight of battery, need to figure out recycling, and optimize charging on the grid.

Sustainable business models for big countries in developing worlds

- Electricity and energy access is only useful as it is appropriately designed and supported to serve social and sustainable needs - Electricity access as a metric is basic and controversial. Electricity use can impact income generating potential in very different ways - Direct impact research can serve both educational and community needs - Request: push for the integration of underserved voices and needs in policy, technology and service development and education - True multi disciplinary work is complex and messy but it is a key approach to a more sustainable and equity future

Potential roles for hydrogen gas

- Electricity: storage and carrier - Transportation: fuel cell - Industry: steelmaking, heating, etc - Residential: heating, etc

Electrolysis

- Electrolysis is the process of using electricity to split water into its component parts of hydrogen and oxygen. - That hydrogen can then be stored for later use as fuel in a fuel cell vehicle, to power a stationary fuel cell system, or for power-to-gas applications

What defines a green building? How can this be measured?

- Energy use, water use, indoor environmental quality, material section and the building's effects on its site - Life cycle assessment. - Siting and structure design efficiency. - Energy efficiency. - Water efficiency. - Materials efficiency. - Indoor environmental quality enhancement. - Operations and maintenance optimization. - Waste reduction.

Types of ethanol content

- Ethanol is a grain alcohol that can be blended with gasoline and used in regular motor vehicles at a concentration of up to ten percent. - E10, E15, E85

How to address concerns with a grid dependent on renewable energy

- Expand the market (make it a regional market) to add flexibility of supply and demand - Build more transmission capacity (similar to above) - Add other flexible generation resources like natural gas - Have more demand response bid into the market as a flexible resource - Add electricity storage as a flexible resource

Pros and cons for nuclear power plants (environmental, financial/economic, safety concerns, value added to the grid, etc.)

- Expensive to build, safety accidents, water use, takes time, waste storage - High energy density, No carbon emissions

Tidal power systems summary

- Extract energy from tidal motion of oceans or seas (non-depletable) - Very predictable, but not dispatchable and hard to match to load patterns - Two types are tidal barrage systems and tidal current systems - Because water is more dense than air, tidal turbines produce 4x the energy of wind turbines of the same size - Tidal energy potential is about 3% of US electricity and only 10% of that is extractable - Tidal currents are predictable and reliable, giving them the advantage over wind and solar

Challenges of nuclear fusion

- Extreme heat is necessary - Extreme pressure is necessary - Difficult to control the reaction - Need to develop materials strong enough to withstand heat and pressure. - Very high cost right now - Must produce more energy than is inputted, not the case right now

Energy efficiency

The percentage of energy put into a system that does useful work Examples - Switching from incandescent to fluorescent to LED light bulbs - Switching from traditional HVAC to heat pumps - Installing a programmable thermostat - Installing variable frequency drives (VFDs) instead of variable speed drives (VSDs)

Growth in solar energy

- Fastest growing electricity resource worldwide - Power generation from solar PV in 2020 is estimated to have increased by a record 156 TWh, marking 23% growth from 2019. - Solar PV accounted for 3.1% of global electricity generation, and it remains the third-largest renewable electricity technology behind hydropower and onshore wind after overtaking bioenergy in 2019. - Over the last 10 years, solar PV cost has dropped by 90% making it the cheapest resource in most of the world

Flaring vs venting of natural gas and its environmental impacts

- Flaring is controlled burning of natural gas - Venting is the direct release of natural gas into the atmosphere - Flaring is better than venting

Solar thermal electric technologies: linear fresnel

- Flat cylindrical lenses that condense or diffuse light in a linear direction - Light is focused onto one or more linear receivers positioned above the mirrors

List of biomass energy resources

- Forest wood and wood wastes such as lumber, wood chips, charcoal - Energy crops/fuelwood plantations such as corn, palm oil, logs, soybeans and switchgrass - Agricultural residues such as rice hulls, corn husks, brewer/distiller waste Domestic farm wastes such as dung and sewage - Aquatic biomass such as seaweed and algae - Municipal solid waste, landfill gas and tires

Disparaties in energy consumption, usage and development rights

- Generally, we see that a person living in a developed nation, which has a highly developed economy, will consume more energy than a person living a developing country that is non-industrialized and poor - Developing countries currently emit 63% of the world's CO2 emissions - Of increased global energy consumption over the next 25 years, >80% are from developing nations - Lack of access to consistent and good quality electricity comes from economic and structural issues

What consumes the most electricity globally?

- Heating - Electric motors - Electronics - Lighting

Drivers and barriers of CSP

- High up front costs, most cost effective with large projects of >100 MW - Can act as dispatchable source as thermal storage is available - Generates AC current so easy to distribute - CSP is harder to build and more expensive than PV - They require more space than PV - CSP is really competing with natural gas as a flexible, dispatchable resource

What is hot dry rock (aka EGS) geothermal?

- Hot rocks but no water - low to no permeability, no water cycle. - Enhanced, or Engineered, Geothermal Systems (EGS) inject water into hot rocks - Three requirements for EGS to become viable (not commercial today): - Commercial level of fluid production with acceptable flow impedance through the reservoir (uses lots of water!). - Establish modularity and repeatability over a range of sites. - Lower development costs for deep and moderate temperature EGS systems. - Huge potential for EGS resource for electricity, but it's expensive

How hybrid electric vehicles work (also pros and cons)

- Hybrid electric vehicles are powered by an internal combustion engine and one or more electric motors, which uses energy stored in batteries. - A hybrid electric vehicle cannot be plugged in to charge the battery. Instead, the battery is charged through regenerative braking and by the internal combustion engine. - Pros: No charging, combustion engine operates at its most efficient mode, either powering wheels or emotor or battery - heat engine operates at its most efficient mode. Improves fuel economy and operates like a traditional ICE. - Plug in hybrid EV's are the same as hybrid but with a bigger battery

Carnot Efficiency equation

(Thot-Tcold)/(Thot) = 1- (Tcold/Thot)

How does hydraulic fracturing work?

- Hydraulic fracturing involves drilling into a reservoir and injecting a fluid in order to maintain a downhole pressure greater than the fracture gradient of the rock, causing the rocks to crack, or fracture - Once fractures extend throughout the formation, a "proppant" such as sand is injected to hold the cracks open and permit the gas or oil within to flow towards an extraction well - This is necessary to access reservoirs with very low permeability, usually both a source rock and a reservoir rock

Hydrogen gas as a storage medium

- Hydrogen can be stored physically as either a gas or a liquid. - Storage of hydrogen as a gas typically requires high-pressure tanks (350-700 bar [5,000-10,000 psi] tank pressure). - Storage of hydrogen as a liquid requires cryogenic temperatures because the boiling point of hydrogen at one atmosphere pressure is −252.8°C.

Current applications of hydrogen fuel cells in the US

- Hydrogen cars are now commercially available (265 - 312 mile range, almost 10,000 sold and leased - Onboard storage in trucks (300 mile range at full load weight of 80,000 lbs, super light) - 450 liquid hydrogen gas storage sites in the US - Small-scale pilot of liequified hydrogen ship debuted in 2019

Current state of carbon capture utilization and storage

- 27 operating projects - 39 million tonnes per year of co2 captured - Capture sources include gas cleanup, ammonia production, steel manufacturing, ethanol production and power plants

Built environment energy demand in the US (global CO2 emissions from building operations and building energy consumption from fossil fuels)

- 39% of global CO2 emissions from building operations and building materials and construction (28% operations and 11% construction) - Building energy consumption: Residential: 52% fossil fuels, Commercial: 34% fossil fuels

Production and capacity of hydropower

- 6.3% of US electricity generation in 2020 - Hydro produces 16.3% of electricity generation worldwide - Massive individual scale: 9 out of the top 10 power facilities in the world are hydropower

Solar thermal electric technologies: power towers

- A large number of flat, sun-tracking mirrors known as heliostats focus sunlight onto a receiver at the top of a tall tower - A heat-transfer fluid heated in the receiver is used to heat a working fluid, which, in turn, is used in a conventional turbine generator to produce electricity

What are photovoltaics?

- A method of converting sunlight to electricity using layer of materials that exhibit the photoelectric effect: they that either readily give up or absorb electrons. - These semiconductor materials absorb the photos emitted by the sun and generate a flow of electrons - Solar PV panels generate direct current (DC) electricity, and our grid runs on AC so you have to convert it

Solar thermal electric technologies: dishes

- A mirror array formed into the shape of a dish used to focus the suns rays onto a receiver which converts the energy into electricity at a high efficiency (80-90%) - Form of concentrated solar power

Energy policy: PPA

- A power purchase agreement (PPA) is a contractual agreement between energy buyers and sellers. - They come together and agree to buy and sell an amount of energy which is or will be generated by a renewable asset. - PPAs are usually signed for a long-term period between 10-20 years. - Helps ensure financing over long period of time

Share of primary energy carriers in global hydrogen gas production

68% gas, 16% oil, 11% coal, only 5% electricity Only <0.7% of hydrogen gas is from renewables or from fossil fuel plants with carbon capture. Currently, hydrogen production contributes 830 million tons of Co2/year. As a result, producing low carbon or carbon free hydrogen is costly at the moment

How much of US annual energy consumption could potentially be provided by biomass domestically?

8%

Four main methods to harness the solar resource

1) Indirect: daylight, warmth 2) Direct: hot water, warm pools, space heating/cooling, cooking - Typically ~50% efficient - Growing at ~10% per year globally, dominated by china - In the US, dominated by pool heating (over 70%) - Costs are similar to alternatives, but mostly up-front costs - Few (but not zero) environmental issues 3) Solar photovoltaic (PV): Generates electricity directly from sunlight via an electronic process that occurs naturally in certain types of materials when hit by photons, called semiconductors - ~15-21% efficient - High growth (~30%/year globally and in the US) - Two main categories: 1) utility-scale and 2) distributed/behind the meter 4) Solar thermal electricity: from concentrating the sun's rays, known as Concentrating Solar Power (CSP) - Expensive and slow growth - Land use, wildlife habitat and water use are main environmental issues - Thermal storage and natural gas backup adds value

Components of the solar system

1) PV cell: composed of semiconductor material (commonly silicon), small (4 inches across), produces 1-2 watts of power 2) PV module: the web that captures solar power to transform it to sustainable energy (makes up the solar panels) 3) PV array: the complete power generating unit, consisting of the array and panels 4) Balance of systems: the components and equipment that move DC energy produced by solar panels through the conversion system which in turn produces AC energy 5) Tracking system: maximizes PV production by moving the panels to follow the sun throughout the day (optimizes angle)

Government support for solar PV in US

- Investment Tax Credit (ITC) The ITC is a 26% tax credit for solar systems on residential and commercial properties - Accelerated depreciation (MACRS) The government has an accelerated depreciation schedule for solar PVs of 5 years, reducing the amount of taxes a company or business pays via tax deductions - Renewable Portfolio Standards (RPS) and RECs RPS (also known as Renewable Energy Standards, REC) require that a specified percentage of the electric utilities sell comes from renewable resources - Net energy metering for residential solar PV A policy that compensates customer rooftop solar. Under this policy, an owner of rooftop solar can sell excess generation back to the utility at a retail rate during times of excess production - Other state/local incentives

Irradiance (solar energy)

- Irradiance (W/m^2) is the power per unit area received from the sun in the form of electromagnetic radiation, measured wen the sun is at a 90 degree angle to the earth. - Irradiance may be measured in space or at the Earth's surface after atmospheric absorption and scattering - Irradiance is also expressed as "suns." One sun = 1000 W/m^2, which is the irradiance of the sun on the outer atmosphere at a distance of 1 astronomical unit

Insolation (solar energy)

- Isolation (W/m^2/day) is the power received on Earth per unit area per unit of time (e.g. a minute or day) on a horizontal surface. - It depends on the height of the Sun above the horizon. - Solar irradiance over time is called solar irradiation, solar exposure or insolation

Why is NEM considered controversial?

- It has the potential to create a cost-shift to non-solar customers because the retail rate does not equal the "value of solar" - Fixed cost of the distribution and transmission system are included in volumetric retail rates for residential customers - Utility holds many contracts that may be more expensive than the marginal cost of energy such as renewable contracts - Since a regulated utility is allowed to recover its cost, if it loses revenue from one set of customers i.e. solar customers, it must raise rates on other customers in order to recover its costs -- this is known as a cost-shift

Economics of wind energy

- LCOE for offshore wind is super low, at $30-$40 per MWh - Capital costs are low ($1,200-$1,600 per kW), and 2x that for offshore because of balance of system Factors that influence wind project returns include: - Wind turbine technology (old vs new) - Wind speeds - Downtime for maintenance - Curtailment

Design tools for building decarbonization/efficiency

- LEDs vs incandescents - More efficient computers that have lower wattage ratings - Variable speed drives and aI based control for HVAC - Equipment substitutes: furnace to ductless heat pumps, gas cooking to induction cooking

Wind energy global potential

- Largest non-hydro renewable electricity resource and is one of the fastest growing resources worldwide - Global potential is 3-85 TW which is 0.5-12x the world electricity capacity (stands at 7 TW right now)

Geothermal proportion of world energy mix

- Less than 1% of energy mix globally - Double production compared to 10 years ago though - 2% of renewable energy generation in US

Biofuel concerns (similar to biomass cons but has examples)

- Lifecycle carbon emissions - Low energy intensity - Competition with food production - Biofuels are by far the most water intensive of all major energy carriers - Land use / deforestation (corn for ethanol) - In the US: expansion of agricultural land, reduction of conservation easements, more fertilizer in water ways, more flooding - Lower fuel economy / energy performance - Fertilizer use / dead zones - Fertilizer causes algae blooms which starve fish of oxygen - Air pollution from burning ethanol (better than diesel though)

Barriers of OTEC technology

- Low efficiency and large parasitic pumping requirements renders net efficiency in the 2-4% range - Potentially harmful temperature and salinity changes to surrounding marine environment - Carbon dioxide released that was sequestered in deep sea water, but it is likely small compared to fossil fuel plants - Highly capital intensive, with costs of $4,200-$12,000 per kW for a 100 MW plant, depending on distance to shore

What are the environmental benefits of natural gas?

- Lower carbon intensity than coal - NG uses less than half the water of coal during electricity generation (gas turbines don't use water cooling, CCGT use much less water per MWh) - Natural gas has no SOx (sulfur removed at well site) or mercury emissions, and has a third of the NOx (nitrous oxide) emissions of coal during electricity generation

How to improve efficiency in vehicles (ie. light-weighting, electric propulsion, etc)

- Making vehicles lighter - a cause for concern because this means they are not as safe. This can be overcome by using different materials like carbon fiber which is light and safe. - Electrification- helps improve the efficiency of a car because the way it works is by using the electric motor to brake instead of using friction to brake. By turning off the motor to stop, you are conserving energy and having dramatic improvements to the fuel economy of the vehicle. - The electric motor contains no gasoline, no heat engine and no oil changes. > Gasoline fueled cars.

Environmental impacts of solar PV (cons)

- Manufacturing (involves chemicals, hazardous materials, manufacturing waste, silicon waste, embodied energy/energy use - Installation & use (3.5-10 acres per MW for utility scale PV, habit degradation and visual NIMBY) - End of life (some contain hazardous materials such has cadmium, lead and arsenic)

Electric pyrolysis

- Methane pyrolysis is a fundamentally new process technology that splits natural gas or biomethane directly into the components hydrogen and solid carbon. - This process requires relatively little energy. And if it uses electricity from renewable sources, there are actually no greenhouse gas emissions.

Different types of solar panels (monocrystalline, polycrystalline, thin film)

- Monocrystalline solar cells are more efficient because they are cut from a single source of silicon. - Polycrystalline solar cells are blended from multiple silicon sources and are slightly less efficient. - Thin-film technology costs less than mono or poly panels, but is also less efficient

Economics of geothermal energy

- More expensive than wind and solar - ~$55-100 per MWh - Geothermal is cheaper than natural gas

Facts about hydrogen

- Most abundant element in the universe (75% of mass) - Hydrogen atom fusion to helium is the primary energy source for sunlight on earth - Hydrogen mostly exists as water and organic compounds - Oxidation of hydrogen gas produces water which is carbon free - Hydrogen gas 3x more energy dense than gasoline or diesel - Much lighter than air

What is NERC? How is it different than NERC?

- NERC is the North American Electric Reliability Corporation - It is a subsidiary of FERC - Its goal is developing and promoting voluntary compliance with rules and protocols for the reliable operation of the bulk power electric transmission systems of North America.

Why now for hydrogen gas?

- Need renewable energy with lower cost in electricity mix - Need energy storage for intermittent energy - Need energy carrier for transporting renewable energy over long distance

Why is a condenser and a cooling system needed for a Rankine cycle?

- Need the cold sink to drive steam energy through the turbine, heat engine needs both hot source and cold sink, otherwise not a driving force for the steam through the turbines - That's why steam cycle plants are more efficient in winter (colder water used)

Environmental impacts of solar PV (pros)

- No water, emissions or noise - No moving parts, low maintenance, long life - Land co use: also used for parking lots, rooftops, substations, airports, etc - Site agnostic: can be deployed on brownfield or greenfield site, arable or arid land

Solar PV applications: utility and small scale/rooftop solar

- On grid applications are utility-scale (1 MW or more) and small-scale production (less than 1 MW) - Utility scale solar projects have a lot of advantages over rooftop solar. The power generated is cheaper due to the scale of the projects, they're located in prime solar locations to maximise generation, they have better reliability, and are generally financed at attractive rates. - Utility scale solar has larger generating capacity nationwide, but small scale solar is growing at a faster pace in states with large incentives (net metering policy, federal tax credit) like California has experienced larger growth in small scale PV - Rooftop solar has savings in transmission and distribution cost

Why is waste to energy to important?

- One ton of garbage produces 150-200 cubic meters of landfill gas - This gas consists of 50% methane and 45% carbon dioxide - Landfills are the third largest anthropogenic methane emission source accounting for 12% of methane emissions

Off-grid solar products

- PV panel portable power bank used to charge phones and computers - Other off-grid PV uses: supply electricity to a few LED light bulbs, used to power a small hospital in Nepal

Solar thermal electric technologies: chimneys

- Passive solar heating and cooling system that can regulate the temperature of a building as well as provide ventilation - Chimney is painted black, solar radiation hits chimney and column of air inside chimney is heated. Heated air is forced back into the living space if top exterior vents are closed - When the the exterior vents are open, the heat is allowed to escape, cooling the house

Hydro role in the energy system

- Really dynamic resource. Can be used for base load because it has massive capacity. - However, it is also extremely flexible (can turn off and on at real time) - It can also be used as a black start source because it requires very little energy to boot up - With pumped storage, it can be used as a dispatchable source as well - Really great for developing nations because it is an accessible option

Why are renewable energy producers excited about battery technology?

- Reduces variability and intermittency concerns of a renewable energy dependent grid - Limits the use of fossil peaker generation to meet steep peaks

What role does each renewable energy technology play in the energy system?

- Renewable energy currently powers 21% of US electricity generation, 12% of US energy consumption, and 13% of the world's energy consumption - Renewable energy sector is used to generate electricity and heat, and less so in the transportation power

What are strategies to store nuclear waste from plants?

- Reprocessing: collect the nuclear waste and re-enrich it, lowering the demand for new mining (used by France) - Long Term Storage: Storing all the country's nuclear waste in one long term storage facility (such as Yucca Mountain) - On-site long term storage: keep the nuclear waste near the reactor for the end of time in dry casks - Reactors that run on lower grade uranium/decay products: use the waste from traditional reactors to produce energy in new type of reactors

Types of hydropower faciliaties

- Run of the river (no pondage) - Run of the river (with pondage) - Micro hydro facility - Hydro storage facility - Hydroelectric dam - Pumped storage

What are challenges with on-site long term storage of nuclear waste?

- Security risk - Would require 24/7 security - Would be a consistent O&M cost over lifetime of power plant

Wave power systems summary

- Seeks to directly harness the kinetic energy in waves to generate electricity - Huge potential: theoretically up to 10% of world electricity use - Three types of systems: 1) Wave surge or focusing 2) Oscillating water column 3) Floats or pitching devices

Major requirements of Clean Air Act

- Sets air quality standards for six common "criteria pollutants": particulate matter, ozone, sulfur dioxide, nitrogen dioxide, carbon monoxide and lead - Calls for new stationary sources (e.g. power plants and factories) to use the best available technology and allows less stringent standards for existing sources

Disadvantages of wind energy

- Site-specific resource (good locations are often far from cities where needed) - Intermittent resource - NIMBY/BANANA (visual pollution) - Impacts to birds and bats - Noise - Transmission needs to be built

Describe the origins and processes that form smog

- Smog is formed by the combination of ozone and particulate matter - Particulate matter comes from burning hydrocarbons - Ozone is formed from a combinations of VOCs, NOx and sunlight

Energy efficiency's past in reducing US carbon/energy intensity

- Strict energy efficiency regulations in California has led per capita electricity consumption to stay nearly flat over the past 40 years - If the US lowered energy consumption like did from CA from 1975-2016, US GHGs would be 25% lower - Energy efficiency has reduced carbon intensity of US economy over the past 40 years much more than decarbonization efforts have

What causes oil prices to go up or down in today's economy?

- Sudden decrease in supply from oil producing countries due to natural disasters or civil unrest - Controlled supply decreases, such as OPEC production curtailment - Negative/positive reports about industrial activity in the global economy (expectations about the future) - US dollar appreciation/depreciation - Increasing impact of electric vehicles - Sanctions caused by geopolitical friction - New sources of oil coming online - New technology developments for oil

Name at least 3 of the components within natural gas that must be removed before it can be converted into a liquid

- Sulfur - Mercury - Water Vapor - CO2 - Hydrogen Sulfide - Propane - Butane

What is FERC?

- The Federal Energy Regulatory Commission - The stated mission of the commission is to regulate and oversee energy industries in the economic, environmental, and safety interests of the American public. - They have jurisdiction over all wholesale electricity sales (except texas) - They ensure reliability - The FERC is an independent agency that is part of the DOE but is free of oversight.

Energy policy: ITC

- The ITC is a dollar-for-dollar credit for expenses invested in renewable energy properties, most often solar developments - The Consolidated Appropriations Act of 2016 extended the ITC through 2019 as a 30 percent credit for qualified expenditures. - It is one of the most important federal policy mechanisms to support the growth of solar energy in the United States

PURPA (explanation and significance)

- The Public Utility Regulatory Policies Act of 1978 (PURPA) was implemented to encourage, among other things, The conservation of electric energy. Increased efficiency in the use of facilities and resources by electric utilities. - Encouraged energy resources such as natural gas, hydro, nuclear, and wind, led the electricity industry down the road to deregulation

How is hydrogen used for fuel?

A power source (preferably excess wind or solar) is used to power the electrolysis process, where electricity is run through water, separating out the hydrogen as either a liquid or gas. The process is then run in reverse order to create electricity, with a round trip efficiency of 50%.

How is the US mineral rights structure different than the rest of the world? What are the positive and negative consequences of this?

- The US has private mineral rights, which means that it is automatically included in the purchase of land unless and until the ownership gets separated at some point by the owner/seller - Positive consequences are lots of oil wells in the US (more than Saudi Arabia) because of private ownership, allows for competition (and small companies to compete with large companies), less federal corruption from oil money, incentivizes innovation in oil and gas - Negative consequences are that shifting away from oil and gas become harder due to more fragmented industry and private profit motives

Types of thermal energy

1) Sensible heat storage Sensible heat storage means shifting the temperature of a storage medium without phase change. It is cheap and accessible. 2) Latent heat storage Latent heat storage stores heat in a storage medium in the form of potential energy between the particles of the substance. The conversion between the heat and the potential energy within the substance involves a phase change - thus heat storage occurs without significant temperature changes in the storage medium. 3) Thermo-chemical heat storage Thermochemical heat storage (TCS) is based on storing chemical energy making use of reversible chemical reactions (eq 4). In the simplest case, a reactant A is transformed in the products B and C in an endothermic reaction during the charging step

Three approaches to waste-to-energy conversion

1) Solid waste to energy recycling facility - Biomass carbonization plant is a waste recycling plant that can alter almost anything organic into charcoal (called biochar) through pyrolysis. Processable ingredients include sludge, human waste, chicken manure, scrap wood, agricultural residue, food waste and water hyacinth among others 2) Power generation from landfill gas - Landfill gas (LFG) is a natural byproduct of the decomposition of organic material in landfill 3) Gasification - Converts biomass or MSW into other forms of energy without actually burning it. Instead, gasification converts the solid and liquid waste materials into a gas through a chemical reaction.

What are the 3 types of biomass?

1) Traditional biomass: wood fuels, agricultural by-products and dung. Very inefficient (~90% losses). 2.8 billion people burn traditional biofuels for cooking, heating & light. 2) Commercial biomass: electricity and heat for industrial and residential consumption 3) Biofuels: fuels derived from plant or algae material or animal waste. Used for transportation.

How does hydro work?

1) Water is collected at the top of a dam 2) The water flows into a penstock that carries the water down to a turbine 3) The penstock is a pressure-pipe, which means that it is 100% full of water and as it moves downwards the water pressure inside the pipe increases as the head increases 4) Water then strikes the blades of the turbine, producing torque and causing the shaft to rotate 5) The turbine is connected to a generator and spins a generator rotor, which converts mechanical energy into electricity 6) The generator rotor spins electromagnets attached the rotor, producing electricity 7) This electricity is sent across transmission lines to the grid for use 8) The falling water then exits the generating station where it rejoins the body of water

Ethanol profiles in developed and developing countries and the world

- The United States (56%) and Brazil (28%) produce 84% of the world's ethanol. - The U.S. produced 60 billion liters of the ethanol, Brazil produced 28.5 billion litres - 90% of ethanol production is used within the US (E10 fuel) - The vast majority of U.S. ethanol is produced from corn, while Brazil primarily uses sugarcane - The most common ethanol fuel production type in Brazil is hydrous ethanol, which is the highest concentration grade of ethanol achieved through distillation. - Brazil is the third largest markets for biofuels worldwide, with specifically designed flexible-fuel vehicles available that run on fuels with a greater ethanol content than regular motor vehicles. - As a result, the adoption rate of fuel ethanol has been a lot higher compared with other countries, with flexible-fuel vehicles the most widely produced car in Brazil. - Brazil uses E80-85 fuel!

Open vs closed cycle OTEC, difference in byproducts

- The basic difference between them is the circulation of the working fluid. In the closed cycle gas turbine the same working fluid is circulated again and again within the turbine but in the open cycle gas turbine the working fluid i.e. air is replaced again and again while flowing through the gas turbine - Both produce energy, open cycle also produces fresh water

What is a run of the river (no pondage) system?

- The extraction occurs as the water is available without any significant intervention in the flow - Takes advantage of a location where water has two very different energies - Without any extraction of energy, the water loses this energy as it falls through the turbine so that, when it reaches the bottom of the falls, it is at a lower energy and lower elevation - A small portion of the flow is diverted out of the river above the waterfall and it is put into a powerhouse where it is extracted

Drivers of nuclear fusion tech

- The fuel is abundant (and nearly inexaustible) - No radioactive waste, byproduct is helium - No air emissions (GHGs, others) - Insanely energy dense: net energy production is about 4 times larger than fission

Explanation behind wind power formula (how do wind speed, swept area, air density, and turbine height interact?)

- The higher off the ground a wind turbine is, the faster the wind speeds get. That is really important because v^3 (wind velocity). So, we want bigger and taller wind turbines - Dense air exerts more pressure on the roots, which results in higher output. Air density decreases with increased height, so it has an inverse effect - Larger blades allow the turbines to capture more of the kinetic energy of the wind by moving more air through the rotors. However, larger blades require more space and higher wind speeds to operate.

How internal combustion engines work

- The ignition and combustion of the fuel occurs within the engine itself - The engine then partially converts the energy from the combustion to work - Pistons are used in internal combustion engines to transmit force to the connecting rod and crankshaft thus generating engine torque. Pistons convert the gas pressure from the combustion chamber into mechanical force - Today's gasoline engines are only around 30 to 35 percent efficient

What are the grid concerns about an electric grid dependent on renewable energy? (from the perspective of ISOs and RTOs)

- The limited dispatchability of wind and solar PV resources - The intermittency of wind resources - The technical feasibility of achieving such rapid deployment - The difficulty of ensuring adequate transmission access to all the new generation coming on line (curtailment) - The difficulty of forecasting renewable energy generation from wind and solar - Insufficient reserve capacity (lack of storage) - Dealing with the duck curve

Energy policy: PTC

- The renewable electricity production tax credit (PTC) is a per kilowatt-hour (kWh) federal tax credit included under Section 45 of the U.S. tax code for electricity generated by qualified renewable energy resources. - Electricity from wind, closed-loop biomass and geothermal resources receive as much as 2.5 cents/kWh

How do wind turbines work?

- The turbine catches the wind due to asymmetric blade surface, causing it to spin - A nacelle is mounted on the tower, which houses the generator and gearbox, and supports the rotor which connects the blades and the hub - The gearbox converts the turning speed of the blades into faster rpm needed by the generator - The generator converts the kinetic and mechanical from the wind, and therefore the rotational energy from the blades & gearbox, to electricity

Types of PV tracking technologies

- There are two main solar tracking systems types that depend on the movement degree of freedom are single axis solar tracking system and dual axis solar tracking system. - As the name implies, single-axis trackers move on only one axis of movement while dual-axis trackers move on two axes. This means that solar panels with a single-axis tracker can only move from East to West. Having a dual-axis tracker means that the solar panel can move from East to West AND from North to South.

Uncertainty about wind energy PTC moving forward

- There are uncertainty about PTC renewals which could rapidly reduce wind energy installations - PTC is currently ramping down and is slated to be phased out completely for projects starting after 2021 - Biden's Build Back Better plans to extend PTC by 5 years (but its dead now) - Wind energy can be competitive without PTC, but many argue that PTC is important for valuing positive social externalities and setting a level playing field with other energy resources that also receive subsidies

Energy efficiency's potential role in reducing US carbon/energy intensity

- There is massive efficiency potential eft to capture as approximately 70% of energy produced by humanity gets lost as heat - New research shows that energy efficiency can slash US energy use and greenhouse gas emissions by 50% by 2050 and get the United States halfway toward its climate goal - Building operations are responsible for 27% of global GHGs annually

What are energy crops (fuelwood plantations)?

- They are high-yield, fast growing trees that are easy to grow and harvest -- they are used for closed-loop biomass - They are planted at high density on three-five year rotation schedules - They can be grown on a variety of land - Examples include cottonwood, silver maple, sweetgum and sycamore - Social costs of fuelwood plantations include deforestation, water use, fuel and fertilizer use and competition with food crops

Tidal current/stream vs tidal barrage systems

- Tidal barrage is similar to hydro power, but it is direction agnostic (depends on the tides) - Tidal stream energy differs from tidal barrage technology because the electrical generators are installed directly into the tidal stream. - This design means that there is no requirement for a wall to obstruct the flow and for this reason they have, as already said, a much smaller impact on the environment.

Resource and site characteristics of ocean technology

- Tidal turbines function well where costal currents run at 2-2.5 meters / second (slower tides are uneconomical, faster ones put stress on equipment) - Near demand centers - Used to match base load

What is the typical recovery rate of primary oil recovery (natural pressure and pump jacks)? What are other secondary and tertiary methods to recover more oil?

- Typical recovery rate is 12-15% of origin oil in place through primary methods - Secondary methods include injecting water or natural gas produced at the well (inject at a well nearby, push the oil out at an adjacent well) - Tertiary recovery (also known as enhanced oil recovery) involves injecting heat, additional liquids, or gases (CO2) at a nearby well, push the oil out an adjacent well. What is the p

Environmental impacts of coal

- Upstream: topographical changes, can be dangerous, legacy - Midstream: transportation related impacts (dust, energy use, train emissions) downstream impacts: solid waste, air pollution, high water consumption, emissions of mercury, lead, sulfur dioxide, nitrogen oxides, particulates, and various other heavy metals - Very low efficiency given impacts

How are agricultural residues and byproducts used as biofuels?

- Used for open-loop biomass production - Bagasse is residue from sugar cane processing; it is -burned to generate electricity - Other examples include rice hulls and olive waste

How fuel cell vehicles work

- Uses hydrogen to power a fuel cell that will power the entire vehicle. - Hydrogen comes from hydrocarbon fuels (natural gas), water (electrolysis or thermo/thermochemical processes), and/or single celled algae.

What is Ocean Thermal Energy Conversion (OTEC)?

- Uses the ocean as the world's largest solar collector - OTEC systems use the ocean's natural thermal gradient— the fact that the ocean's layers of water have different temperatures— to drive a power-producing cycle - Byproducts can include fresh water, nutrient-rich deep ocean water, and cooling water OTEC uses the ocean's warm surface water with a temperature of around 25°C to vaporize a working fluid, which has a low-boiling point, such as ammonia. The vapor expands and spins a turbine coupled to a generator to produce electricity.

How can you get paid for a wind project?

- Utility buys and rate-bases it - Obtain a PPA with a utility or other customer - Sell the RECs - Operate it as a merchant power plant - Receive production tax credit - Receive investor tax credit - MACRs - Zero emissions tax credit

Environmental impacts of CSP

- Water issues (high water usage) Concentrated solar energy plants require large amounts of direct sunlight and hence are best constructed in arid or semi-arid regions, globally known as the Sun Belt. - However, Concentrating Solar Power plants are often designed to use water for cooling at the back-end of the thermal cycle, typically in a wet cooling tower. - High land use and visual disruption

What is pumped storage?

- When there is excess energy form the grid, that energy can be used to invert the turbine rotation and pump the water up to the reservoir for later energy production - This acts as a large scale storage, as it currently accounts for 93% of all utility-scale energy storage in the United States. - New pumped hydro tech involve storing water in aquifers, in the ground or inverse (?)

What are challenges with reprocessing nuclear waste?

- Will need to have a national/regional collection which could be difficult and states do not want it to cross borders - Could be expensive to set up and would need to compare costs to mining - Could be a concern for weapons proliferation

Sources of wind energy

- Wind is a form of solar energy - Winds are caused by heating the atmosphere by the sun, the rotation of the Earth, and the Earth's surface irregularities - Wind power usually uses wind turbines to generate electricity

What is the total annual potential for each energy resource relative to each other?

- Wind is the most abundant renewable resource (can meet US electricity demand 8x over), coal is the most abundant stock resource - Tides are the least abundant renewable resource, natural gas is the least abundant stock resource - Ethanol, hydropower and coal consumes the most freshwater of all energy sources - Wind and solar energy are growing rapidly compared to other forms of renewable energy generation. Hydropower is at a steady rate of electricity generation, while wood, waste and geothermal energy remain at a low electricity generation rate in the US.

Advantages of wind energy

- Wind power is cost effective (1-2 cents / kWh after PTC) - Wind creates jobs (potential to support 600,000 jobs) - Wind enables U.S. industry growth and U.S. domestic production (domestic clean energy economy) - It's clean, no GHGs - Wind turbines can be build on existing farms or ranches (dual land use) - Abundant resource - Complementary to solar (wind blows more at night) - No water use or pollution - Not depletable - Quick to install - Modular (flexibility in repair)

Factors for productive wind energy location

- Wind speed - Weather patterns - Local geography

Vehicle fleet characteristics

- World Vehicle fleet is continuously growing, as it DOUBLED from 1999-2017. - In the US, there is about one vehicle per PERSON, compared to the world's average being 0.18 vehicles per person.

What are challenges with Yucca Mountain nuclear waste management?

- Would require national collection which would be hard because states do not want it crossing borders - One site would be easier to defend but also higher risk - How do you protect something for thousands of years?

What are challenges with reactors that run on lower grade uranium/decay products as nuclear waste management strategies?

- Would take long term R&D investment - Could be expensive/economically infeasible to run on lower grade fuel

Potential for 1 GtCO2/year sequestration scale?

1 GtCO2/yr is about 35 million barrels per day of injection (the world used about 100 million barrels per day of fuels, US ~ 18 million barrels/day, in 2020 (25 yr low)

What is the Watt to J/sec equation?

1 W = 1 J/sec

Four elements of a geothermal reservoir

1) A heat source (flows upwards from earth crust) 2) A fractured rock reservoir to store heated water and permit flow (permeability) (water is necessary to carry heat to the surface) 3) A water convection or recharging system 4) A seal to contain the heat and water flow (optional)

Policy tools for transportation decarbonization/efficiency

1) CAFE - Corporate Average Fuel Economy - A cap and trade system in which automakers save, sell and buy credit to cover vehicles they are selling to meet their average fuel economy - Tesla sold all their credits because they are entirely electric - Right now there is an excess of credits to automakers can easily meet standards - Need more make it more efficient 2) GHG regulations would also help out with this

Challenges to implementing energy efficiency mesaures

1) Challenges specific to behavior change energy efficiency measures High level challenges involve the scale of implementation, since there is a large diversity and number of end users 2) Market barriers (e.g. split incentives) Split incentives are when the person making energy efficient decisions are not aligned with those who benefit (e.g. Commonly, building owners pay for retrofits while tenants enjoy the decreased utility costs) 3) Measurement and verification (M&V) There are performance uncertainties in produces due to a lack of research. Also, there is a lack of funding to measure adoption of energy efficiency

Policies for energy efficiency

1) Energy efficiency standards (such as lighting performance standards in California) 2) Utility efficiency programs (utilities invest in energy efficiency on behalf of their customer in order to overcome barriers to customer investment in energy efficient technology)

Ethanol production practices

1) Fermentation (commercial) - Commonly produced by fermenting crops high in starch and sugars, such as sugarcane and corn - It is more land efficient to make ethanol from sugarcane than corn though 2) Cellulosic (labratory) - Breaks down the cell wall to release the starch or sugars in the plants leaves and stems. These simpler compounds are then fermented into ethanol. - Commercial production is small/nonexistent though

Components of a hydro plant

1) Forebay - basin where water is temporarily stored before going into the intake chamber 2) Intake structure - collects the water from the forebay and directs it into the penstock 3) Penstock - large pipes that carry the water from the intake structure (or reservoir) to the turbines 4) Surge chamber - a cylindrical tank which controls the pressure in the penstock 5) Hydraulic turbines - converts hydraulic energy to mechanical energy which is used by the generator to produce electricity. two types are impulse turbine and reaction turbine 6) Power house - building that protects the hydraulic and electrical equipment 7) Tailrace - flow of water from the turbines to the stream

Types of turbines

1) Impulse turbine vs reaction turbine - Impulse turbines are most efficient for use in cases where the flow is low and the inlet pressure is high. Reaction turbines develop torque by reacting to the gas or fluid's pressure or mass. - The pressure of the gas or fluid changes as it passes through the turbine rotor blades 2) Free flow turbines - For hydrokinetic

Pros of carbon capture

1. CCS Can Reduce Emissions at the Source - The International Energy Agency estimates that CCS could be responsible for removing as much as 20% of total CO2 emissions from industrial and energy production facilities 2. CO2 Is Easier to Remove at Point Sources - One of the major disadvantages of removing CO2 from the air—through technologies like direct air capture—is that the concentration of the gas in the atmosphere is relatively low 3. Other Pollutants Can Be Removed at the Same Time - During oxyfuel combustion, high concentrations of oxygen used for combustion leads to a significant reduction of nitrogen oxide (NOx) and sulfur dioxide gases. 4. CCS Could Reduce the Social Cost of Carbon - A benefit might be the increase in overall productivity in the agricultural sector. - By removing CO2 directly from the source, net damages to society could be decreased.

Steps to CCUS

1. Capture - Carbon dioxide is captured after the fuel has been burned 2. Compression - Carbon dioxide is either compressed to the desired pressure using a gas compressor or is liquefied at lower pressures by using refrigeration systems and then pumped to the desired pressure. 3. Pipeline Transport - Pipeline transportation is well establish and costs are understood. Truck transportation is only viable for pilot scale 4. Storage - CO2 is injected at depth of about 1 mile or deeper into rocks with tiny pore spaces - Trapping beneath seals of low permeability rocks

Energy resource

An energy resource is a form of primary energy that can be captured by humans and converted to do work. They are generally categorized as flow resources and stock resources. Stock resources store energy in the form of nuclear, coal, oil, etc. Flow resources have kinetic energy that can be converted to work or heat such as solar, wind, hydro, etc

Anaerobic digestion

Anaerobic digestion is a series of biological processes in which microorganisms break down biodegradable material in the absence of oxygen. One of the end products is biogas, which is combusted to generate electricity and heat, or can be processed into renewable natural gas and transportation fuels.

Utility death spiral

As grid maintenance costs go up and the capital cost of renewable energy moves down, more customers will be encouraged to leave the grid. In turn, that pushes grid costs even higher for the remainder of customers, who then have even more incentive to become self-sufficient. Meanwhile, utilities are stuck with a growing pile of stranded assets.

Associated vs non associated NG

Associated NG = found with oil Non associated NG = not found with oil

CCS vs CCUS

CCUS utilizes the captured carbon dioxide, while CCS permanently stores it

How does our everyday actions contribute to air pollution, and how does this relate to the tragedy of the commons?

Clean air is one of our natural resources, although it is a public good. It is non-excludable and non-rivalrous. However, people act in independently and rationally in their own self interest, which has a negative impact on this shared resource. Our use of fossil fuels in cars, cooking, industries and manufacturing have negative consequences such as environmental impacts such as global warming and health impacts such as particulate matter and lead production.

What is the difference between closed-loop and open-loop biomass?

Closed-loop biomass: plants grown exclusively for electricity production (energy crops), i.e. switchgrass Open-loop biomass: material not originally intended as a fuel source, i.e. wood chips, manure, waste

Cost of various hydrogen gas production methods

Coal gasification is with 90% carbon capture and storage is the lowest cost and highest emissions Electrolysis with wind or nuclear is highest cost but zero emissions

Major energy end uses in buildings (commercial, residential)

Commercial buildings - Heating - Cooling - Office equipment - Lighting Residential - AC - Space heating - Water heating - Fridges - Lighting

Difference between heat pumps and heat engines

Heat engine: uses a working fluid to produce work from heat flowing from a hot source to a cold sink Heat pump: uses a work fluid to move heat from a cold source to a hot sink by adding work (through electricity or gas) A heat pump is a refrigerator while a heat engine is a steam cycle

Non energy benefits of hydro

Hydropower provides benefits beyond electricity generation by providing flood control, irrigation support, and clean drinking water. Hydropower is affordable. Hydropower provides low-cost electricity and durability over time compared to other sources of energy.

How to calculate Power = I*V, V=I*R, Power Loss = (I2)*R

I = Current V = Voltage R = Resistance

What are PTC and ITC

ITC: renewable energy investment tax credits (ITCs) PTC: production tax credits (PTCs)

What are the steps in utility-scale renewable energy project development?

Important factors in the development phase are.. - Site selection: safety clearance, resource availability, proximity to demand, sufficient spacing, climate risks, costs, and wildlife impacts - Solar can be implemented everywhere, while wind requires a large amount of land and experiences high winds which is not available in all of the US. Florida has no wind, while Texas is the wind capital of the world. - Wind also has to consider bird migration while solar energy has to consider flat terrain for solar PV panels

5 steps/categories to oil refining, with explanations

Distillation: separation of crude "fractions" by boiling point range Cracking: breaking large molecules into smaller molecules, often in the presence of hydrogen to populate the chemical bonds Reforming: chemically changing low-octane molecules into higher octane molecules Blending: combining different hydrocarbon streams into a prescribed "recipe" as a final product Hydrofining/hydrotreating: removing sulfur with hydrogen

Types of geothermal power plants

Dry steam - Provides 25% of the world capacity - Steam goes directly through a pipe to a turbine to spin a generator that produces electricity - First type of geothermal system Flash steam - Flash steam provides the highest percentage of current world capacity of geothermal power at 58%. - Flash steam plants pump high temperature fluids under high pressure into a tank at the surface held at a much lower temperature, causing some fluid to rapidly vaporize and drive a turbine and generator. Binary cycle - Binary cycle is the fastest growing type of geothermal power plant. It currently provides 16% of world capacity. - Binary cycle power plants pass heated geothermal fluid along with a working fluid with a lower boiling point than water through a heat exchanger. - The heat causes the secondary fluid to flash to vapor, which drives a turbine and eventually a generator. - The cooled water vapor is then released back into underground reservoirs so that system can begin again. - No gas is emitted so it is a closed system.

General trends in transportation

Electrification, automation and servitization - Massive potential in efficiency improvement. This is being driven by 1) Fuel prices - fuel is more expensive (higher taxes), diesel engines are more efficient but also more expensive - worth it in Europe and 2)Air pollution standards - much stricter here, diesel can't meet it, VW scandal!!

Energy conservation

Energy conservation is finding and implementing ways to use less energy. Examples -Improving availability of public transportation. -Taxing use of electricity. Higher taxes discourage use. -Offer rebates or tax credits for upgrading homes to operate on less energy. -Use a "tiered rate system." Customers pay a low rate if they use less electricity. More they use, the higher their rate.

Energy vs power

Energy is the capacity to produce heat or work, power is the change/rate of production of heat or work

Heat rate to efficiency conversion equation

For example if using Btu/kWh, use a conversion factor of 3,412 Btu per kWh to calculate the efficiency factor. For example, if the heat rate is 10,500 Btu/kWh, the efficiency is 32.5% (since 3,412 Btu / 10,500 Btu = 32.5%).

Working fluid

For fluid power, a working fluid is a gas or liquid that primarily transfers force, motion, or mechanical energy

What is a float or pitching device system?

Generate electricity from the bobbing or pitching action of a floating object mounted on a floating raft or fixed for the ocean floor

Environmental and social impacts of hydropower

Generation - Downstream fish passage (mortality and injury): when fix go through turbines they get smushed - Hydropower generation alters flow patterns and channel structures, which alters the ecosystem and their associated flora/fauna Dams and Reservoirs (these puppies are real bad) - Alters and eliminates fish migratory pathways - Inundates river valley scenery with cultural/historical/environmental value - Submerged vegetation causes greenhouse gas emissions (carbon dioxide and methane) - Human displacement and subsequent relocation from construction in valleys (Three Gorges Dam is expected to displace 1.1 mil people) - Reservoir can cause earthquakes (Three Gorges Dam has been linked as the cause of hundreds of earthquakes in the area) - Water quality impacted by change in temperature and dissolved gases

Types of geothermal energy

Geothermal electricity - Less than 1% of world and US electricity; value is baseload, steam cycle Geothermal direct use - Not a lot of growth or potential, very site specific Ground source heat pumps - Greatest potential (to save energy); can be used almost everywhere; growing slowly - Biggest challenge is lack of conformed market and substantive industry players; expensive relative to other incentives and "pricing"; drilling is expensive

Name at least one externality of air pollution

Increased risk of cardiovascular disease, increased risk of respiratory illness, decreased visibility (also accepted: increased healthcare costs due to the noted health problems)

Renewable energy definition and examples

Inexhaustible and naturally replenishing. Use of the resource has no significant bearing upon future availability of the resources. Examples: Wind, solar, ocean energy

How does an Allam Cycle power plant operate?

Instead of steam, supercritical CO2 (high temperatures and high pressures above critical point, where distinct liquid and gas phases do not exist) is used to produce power via a turbine and generator. Natural gas (or any other fossil fuel) is combusted with oxygen from the air and the recirculated CO2, and the resulting CO2 + water working fluid, is what spins the turbine. Excess CO2 from combustion of the fossil fuel is capture and transported offsite

Solar resource characteristics

Irradiance, insolation, suns, direct vs. diffuse

What does the rotten egg smell mean for the quality of oil?

It contains sulfur, which will need to be removed from the oil when making refined products like gasoline and diesel, making it lower quality

How much more efficient are LED light bulbs?

LEDs are about 90% more efficient than incandescent light bulbs, and about 50% more efficient than fluorescent bulbs

LED, heat pumps, energy star, behavior change for efficiency information

LEDs: use at least 75% less energy, and last up to 25 times longer than incandescent lighting. Heat pumps: Ductless heat pumps provide ~70% savings compared to baseboard electric heat. This is because under ideal conditions, a heat pump can transfer 300% more energy than it consumes. Energy star: ENERGY STAR certified homes are at least 10% more energy efficient than homes built to code and achieve a 20% improvement on average while providing homeowners with better quality, performance, and comfort. Behavior change (e.g., normative messaging)- Education (e.g., school programs, targeted community trainings), financial incentives, social interactions/pressure (community challenges)

Levelized Cost of Energy definition

Levelized cost of energy (LCOE) is a measure of the average net present cost of electricity for a generating plant over its lifetime. In more simple terms, the LCOE represents the average revenue per unit of electricity generated that would be required to recover the costs of building and operating a generating plant during an assumed financial life and duty cycle In even more simple terms, how much does electricity have to cost for the energy plant to make a profit?

Lifecycle thinking for energy efficiency

Lifecycle thinking allows you to quantify environmental impacts so that you can prioritize, set metrics around, and most effectively reduce them. This process is not just about making things "less bad." It can help unlock your creativity and lead to game-changing innovations.

What are the drivers for renewable energy technologies?

Main drivers of renewable energy are: - Innovation (improved productivity) and scale creating cost competitiveness - Strong policy support - Lower environmental impacts

Lithium ion batteries: role in energy system, raw materials, recycling, applications, cost, environmental impacts

Material: cathode (biggest cost component made of NCM and nickel and cobalt) Found in developing countries Recycling is more desirable than from raw ores

Types of energy storage technologies: mechanical, electromechanical, electric, thermal, chemical

Mechanical: mostly pumped hydro Electrochemical = li-ion battery (highest growth) Electric ( capacitors, superconducting magnetic coil) Thermal: molten salts, ice storage/chillers Chemical: hydrogen fuel cells, methane

One example of how we can make climate change impact personally, professionally, politically and socially

Personally - Invest in energy efficient home appliances such as LEDs, heat pumps, etc Professionally - Work at a company that has a strong ESG policy or a company helping solve the climate crisis directly Politically - Vote politicians into power who have strong climate plans Socially - Educate friends and family about climate change and how they can best make an impact

Geothermal exploration and discovery process

Phase 1: Geology, geophysics and geochemistry a) Exploration by geophysicists and geologists to determine ideal location for test well Phase 2: Drilling a) Drilling of a test well to access the reservoir and evaluate geologic features b) Typical 4,000-8,000 feet depth c) Added challenge compared to oil & NG drilling due to high heat conditions Phase 3: Testing a) Testing of the well for reservoir qualities, flow capacity and thermal characteristics Phase 4: Assessment a) Potential of the new resource to provide geothermal power

Pros and cons of nuclear energy

Points in favour of nuclear energy: 1. Extremely energy dense. Generates an exponentially lesser quantity of waste compared to coal. Nuclear waste is local, concentrated, controlled and monitored whereas the CO2 emissions from burning (fossil fuel resources are released into the atmosphere. 2. Nuclear energy can be used to generate base load power since it is consistent (constant) and scalable 3. Takes much lesser land footprint compared to wind/solar energies. Points against nuclear energy: 1. Enhances Nuclear weapons proliferation. One major nuclear weapon usage incident would have extremely devastating effect and cause major life loss. 2. CO2e emissions from the lifecycle of nuclear energy are higher than the CO2e emissions from renewable (wind and concentrated solar) energies. 3. Takes a long time to setup (and to meet the electricity demand in this long gap we need to rely on available energy sources like fossil fuels) and this adds to the total footprint of nuclear energy power generation

What percentage of wind is offshore

- ~5% of global wind capacity is offshore - 70% is located in Europe, the rest in China

Potential risks of CCUS

1. Worker safety 2. Groundwater quality degradation 3. Induced seismicity (felt events) 4. Resource damage 5. Ecosystem degradation 6. Public safety 7. Release to atmosphere

Cons of hydrogen fuel

1. Hydrogen Extraction - Hydrogen does not exist on its own so needs to be extracted from water via electrolysis or separated from carbon fossil fuels. - Both of these processes require a significant amount of energy to achieve. - This energy can be more than that gained from the hydrogen itself as well as being expensive. 2. Investment is Required - Hydrogen fuel cells need investment to be developed to the point where they become a genuinely viable energy source 3. Cost of Raw Materials - Precious metals such as platinum and iridium are typically required as catalysts in fuel cells and some types of water electrolyser, which means that the initial cost of fuel cells (and electrolysers) can be high 4. Regulatory Issues - There are also barriers around regulatory issues concerning the framework that defines commercial deployment models. - Without clear regulatory frameworks to allow commercial projects to understand their cost and revenue basis, commercial projects can struggle to reach a financial investment decision (FID). 5. Overall Cost - The cost for a unit of power from hydrogen fuel cells is currently greater than other energy sources, including solar panels. 6. Hydrogen Storage - Storage and transportation of hydrogen is more complex than that required for fossil fuels. 7. Infrastructure - Large scale adoption of hydrogen fuel cell technology for automotive applications will require new refueling infrastructure to support it, although for long-range applications such as those for HGVs and delivery truck is it likely the start-to-end refueling will be used. 8. Highly Flammable - Hydrogen is a highly flammable fuel source, which brings understandable safety concerns. Hydrogen gas burns in air at concentrations ranging from 4 to 75%.

How a heat engine works

1. It gains heat from a reservoir of higher temperature, increasing the engine's internal energy. 2. Converts some of this energy into mechanical work through a piston or turbine 3. Expels the remaining energy as heat to some lower-temperature reservoir, usually called a sink.

Big questions with hydrogen gas

1. Producing low-carbon or carbon-free hydrogen is costly at the moment. How do we reduce this? 2. Hydrogen is light, diffusive and reactive. How do we move and store a large quantity of hydrogen cost-effectively and safely? 3. How do we use hydrogen gas cost-effectively and safely?

Why carbon capture and storage?

1. Reduce hard-to-eliminate emissions from the industrial, commercial, and electricity sectors 2. Enable carbon dioxide removal from the atmosphere to offset emissions from air transport and heavy duty transportation 3. Reduce costs for decarbonization 4. Accelerate decarbonization by tackling all sectors at the same time

Pros of hydrogen fuel

1. Renewable and Readily Available - Hydrogen is the most abundant element in the Universe 2. Hydrogen is a Clean and Flexible Energy Source to support Zero-Carbon Energy Strategies - Hydrogen fuel cells provide an inherently clean source of energy, with no adverse environmental impact during operation as the byproducts are simply heat and water. - Unlike biofuel or hydropower, hydrogen doesn't require large areas of land to produce 3. More Powerful and Energy Efficient than Fossil Fuels - Hydrogen has the highest energy content of any common fuel by weight (around 120MJ/kg) 4. Highly Efficient when Compared to Other Energy Sources - For example, a conventional combustion based power plant generates electricity at 33-35% efficiency compared to up to 65% for hydrogen fuel cells. 5. Almost Zero Emissions 6. Reduces Carbon Footprints 7. Fast Charging Times - Where electric vehicles require between 30 minutes and several hours to charge, hydrogen fuel cells can be recharged in under five minutes 8. Long Usage Times - A hydrogen vehicle has the same range as those that use fossil fuels (around 300 miles). 9. Ideal for Use in Remote Areas - Where local conditions allow, the availability of hydrogen through local generation and storage could prove to be an alternative to diesel-based power and heating in remote areas. 10. Versatility of Use 11. Democratisation of Power Supply

Types of solar thermal collectors: Evacuated tube

1. Sunlight: sunlight hits a heat conducting cylinder, efficiently heating it from any angle 2. Heat reflection: a clear glass or plastic casing traps heat that would otherwise radiate out. This is similar to how a greenhouse traps heat. 3. Convection: a copper tube running through each cylinder absorbs the cylinder's stored heat, causing fluid inside the tube to heat up and rise to the top of the cylinder. 4. Circulation: cold water circulates through the tops of the cylinders, absorbing heat

Types of solar thermal collectors: unglazed solar collectors

1. Sunlight: sunlight hits the heat conducting material (usually dark metal) which heats up. 2. Circulation: cool fluid (water) or air circulates through the collector, absorbing heat 3. Use: the warmer fluid is used for applications such as pool heating

Types of solar thermal collectors: glazed flat-plate

1. Sunlight: sunlight travels through the glass and hits the heat conducting material (usually dark metal) which heats up 2. Heat reflection: a clear glass or plastic casing traps the heat that would otherwise radiate out. This is similar to the way a greenhouse traps heat inside 3. Circulation: cold water or another fluid circulates through the collector, absorbing heat.

Cons of CCUS

1. The Cost of CCS Is High - One report from researchers at the University of Utah cites estimates of a 50% to 80% increase in the cost of electricity in order to pay for the implementation of CCS technology. 2. Using CCS for Oil Recovery Could Defeat Its Purpose - Unless the amount of CO2 captured during CCS also accounts for the CO2 released by the oil that was made available, CCS will simply be contributing to a larger amount of the greenhouse gas in the atmosphere. 3. Long-Term Storage Capacity for CO2 Is Uncertain - The EPA estimates that not all countries will have enough CO2 storage capacity to properly implement CCS 4. CO2 Transport and Storage Sites Could Be Dangerous - While accident rates during the transport of CO2 are relatively low, the potential for a dangerous leak still exists. - According to the Intergovernmental Panel on Climate Change, if CO2 were to leak from a pipeline, a concentration between 7% and 10% in the ambient air could pose an immediate threat to human life. 5. Public Perception of Placing CO2 Near Them Is Negative - Storing carbon from CCS has several perceived risks that are not popular among the public.

What is a net zero building?

A building with zero net energy consumption, meaning the total amount of energy used by the building on an annual basis is roughly equal to the amount of renewable energy created on the site

Key terms for electricity generation (baseload, peaking generation, dispatchability, ramp rate, net demand)

Baseload: minimum level of demand over 24 hours Peaking generation: power plants that can come online quickly and fill peaks in demand, expensive to run Ramp rate: how fast a power plant can increase/decrease output Dispatchability: ability to turn electricity generation on/off Net demand: actual demand - renewable variable generation resources

Why is PTC better than ITC for incentivizing wind energy production?

Because ITC depends on investment, so people would want to build wind turbines even if they don't produce power. This will cause people to build them where it is easy to build and not necessarily in the highest producing area. PTC depends on only how much energy on investment creates. This means that investors are incentivized to produce more energy, not just build turbines.

Why is achieving 100% carnot efficiency impossible?

Because the Second Law requires that waste heat be produced in a thermodynamic process where work is done by a heat source. Such a process is given by the equation

Offshore wind benefits and challenges

Benefits: - Big resource: high winds, low turbulence - Not constrained by land availability or NIMY/BANANA - Ørsted offshore wind story (was primarily a coal producer in mid 1990s, strategically shifted to offshore wind, now Denmark gets almost 50% of its power from it) Challenges: - Greater regulation/permitting hurdles - 2-3x LCOE vs onshore wind, along with higher transmission costs - Requires shallow water (innovation in floating platforms will require installment in >50m depth) - NIMBY concerns for visible projects - Installation and O&M in harsh conditions

Which country produces the most coal globally?

China

Pros/cons of oil sands and oil shale

Extraction & Production - Open mit mining, in-situ (heat is injected into sands to recover) Environmental Impacts - High energy, water, land requirements - Produce more GHG than conventional oil sources - Why many protest the keystone XL

Mitigation strategies for environmental and social impacts of hydropower

Fish passage - Monitoring fish through various tagging technologies - Using screens to divert fish - "Fish friendly turbines" -- Alden turbine has a spiral turbine that works at high efficiency in high head hydro systems and has a fish survival rate of 90% - Redirecting fish through volitional fish passage Dams and Reservoirs - These impacts are more inevitable, but thoughtful design and operation can help mitigate

Gray vs green vs blue hydrogen

Gray hydrogen: produced by reforming natural gas, CO2 emissions ● Pro: relatively cheap compared to blue and green hydrogen. Can be used as a "bridging fuel" ● Con: CO2 emissions, contributes to climate change Blue hydrogen: same as gray hydrogen except the CO2 produced in the process is not released to the atmosphere - it is captured and stored using CCS ● Pro: less carbon emissions than gray hydrogen ● Cons: CCS process is complex and expensive, still relies on fossil fuels to create the hydrogen Green hydrogen: uses electrolysis powered by renewable energy to produce hydrogen. ● Pro: no carbon emissions, most sustainable option, does not require fossil fuels. ● Con: very costly, not yet practical to produce green hydrogen on a large scale, renewable energy output varies - can't produce green hydrogen at any time.

How a heat pump works (review this)

Heat pump in cooling mode Step 1) A liquid refrigerant is pumped through an expansion device at the indoor coil, which is functioning as the evaporator. The hot air from inside the house is blown across the coils, where heat energy is absorbed by the refrigerant. The resulting cool air is blown through the home's ducts. The process of absorbing the heat energy causes the liquid refrigerant to heat up and evaporate into gas form. Step 2) The vaporized refrigerant now passes through a compressor, which pressurizes the gas. The process of pressurizing the gas causes it to heat up. The hot, pressurized refrigerant moves through the system to the coil in the outdoor unit Step 3) A fan in the outdoor unit moves outside air across the coils, which are serving as condenser coils in cooling mode. Because the air outside the home is cooler than the hot compressed gas refrigerant in the coil, heat is transferred from the refrigerant to the outside air. During this process the refrigerant condenses back to a liquid as it cools. The warm liquid refrigerant is pumped through the system to the expansion valve at the indoor units. Step 4) The expansion valve reduces the pressure of the warm liquid refrigerant, which cools it significantly. At this point, the refrigerant is in a cool, liquid state and ready to be pumped back to the evaporator coil in the indoor unit to begin the cycle again. Heat pump in heating mode The steps are simply reversed, so the heating source becomes the outside air (even when outdoor temperatures are low) and the heat energy is released inside the home. The outside coil now functions as the evaporator, and the indoor coil is the condenser

Relationship between energy and human development index (HDI)

Higher energy per capita and higher HDI index have a positive correlation

What are the capital costs vs operating costs of each energy resource?

Hydroelectric and nuclear have the highest capital costs ($1,200-$5,000 per kW), while combustion turbines (NG and/or coal) have the lowest capital costs ($500-$1000 per kW). Solar PV and wind power have drastically decreased in capital costs; they now cost $800-900 per kW and $1500-2000 per kW (depending on onshore or offshore), respectively Solar, hydro and wind turbines have the lowest O&M costs (less than $0.01 per kW). Oil-fired generation has the highest O&M costs, followed by coal, natural gas, biomass and nuclear. They sit at $0.05-0.1 per kW. Renewable sources have lower O&M costs because they have no fuel costs, low operations cost and negligible waste.

Types of hydropower technology

Hydroelectric vs hydrokinetic facilities This technology differs from traditional hydropower plants, which rely on the elevation difference (head) between the intake and outlet. Hydrokinetic devices are placed directly in the stream of flowing water and energy is extracted with turbines similar to those used in tidal plants or in the ocean.

What was the geopolitical context behind the 1970s oil price increase?

In 1973 Arab nations imposed an embargo on Israel and supporting nations (US, EU) following the Yom Kippur War, in what was called The Arab Oil Embargo. This decreased supply to the embargoed countries and caused prices to increase (partly real decreased supply, partly panic-caused price increase).

Private Costs vs Social Costs

Private costs only account for what the consumer pays for a product or service, whereas social costs include all the impacts of that product or service on society as a whole.

What is deregulation/restructuring of the electricity grid?

Refers to the shift from a vertically integrated monopoly to multiple companies competing at the wholesale / retail levels with open access to transmission

Who pays for the difference between rooftop solar PV cost (which is greater than utility scale solar PV)

Remember that the LCOE numbers are unsubsidized. PG&E and its ratepayers pay for the difference through net metering based on the retail price of electricity. US taxpayers more broadly also help pay for the difference given that the 30% ITC provides more subsidy in absolute terms to rooftop solar on a per MW basis given the higher capital costs associated with it.

Basic similarities and differences with oil/natural gas development

Similarities is that its a pretty damn similar process. The difference is that the geological features are quite different. Geothermal has harder rocks and higher temperatures

What is a wave surge or focusing system?

Shore-mounted or floating structure channels and concentrates waves into a reservoir, from which electricity is generated

Pros/cons of offshore oil drilling

Significance - Less widespread than onshore - challenging and expensive, Equipment - Most common is the jackup, Environmental Impacts - Oil spills, accidents

Steam methane reforming (SMR)

Steam methane reforming (SMR) is a process in which methane from natural gas is heated, with steam, usually with a catalyst, to produce a mixture of carbon monoxide and hydrogen used in organic synthesis and as a fuelIn energy, SMR is the most widely used process for the generation of hydrogen

How a heat pump works in cooling mode

Step 1) A liquid refrigerant is pumped through an expansion device at the indoor coil, which is functioning as the evaporator. The hot air from inside the house is blown across the coils, where heat energy is absorbed by the refrigerant. The resulting cool air is blown through the home's ducts. The process of absorbing the heat energy causes the liquid refrigerant to heat up and evaporate into gas form. Step 2) The vaporized refrigerant now passes through a compressor, which pressurizes the gas. The process of pressurizing the gas causes it to heat up. The hot, pressurized refrigerant moves through the system to the coil in the outdoor unit Step 3) A fan in the outdoor unit moves outside air across the coils, which are serving as condenser coils in cooling mode. Because the air outside the home is cooler than the hot compressed gas refrigerant in the coil, heat is transferred from the refrigerant to the outside air. During this process the refrigerant condenses back to a liquid as it cools. The warm liquid refrigerant is pumped through the system to the expansion valve at the indoor units. Step 4) The expansion valve reduces the pressure of the warm liquid refrigerant, which cools it significantly. At this point, the refrigerant is in a cool, liquid state and ready to be pumped back to the evaporator coil in the indoor unit to begin the cycle again.

How has PURPA impacted the US electricity industry?

The Public Utilities Regulatory Policies Act (PURPA) deregulated energy companies by allowing non-utilities to produce energy (independent power producers), which increased energy production/supply in the US. PURPA also encouraged hydroelectric power and energy efficiency, reducing demand in the US and added early support for renewable energy developers.

What is flow (hydro)

The flow rate is the quantity of water flowing past a point in a given time. This is usually measured in litres per second.

What is head (hydro)

The height difference where the water enters into the hydro system and where it leaves it, measured in meters. It provides the greatest range of opportunities The more head you have the higher the water pressure across the hydro turbine and the more power it will generate.

Cut-in speed

The speed below which power is not generated

Passive solar building design

Windows, walls, and floors are designed to collect, store and distribute solar energy in the winter and reject it in the summer • Doesn't involve mechanical devices or system • Used for space and/or water heating • Energy is collected through properly oriented south facing windows • Storage of energy is in "thermal mass," building materials with high heat capacity such as concrete slabs, brick walls, or tile floors

What is biomass used for?

Worldwide: - 61% traditional heating - 17% industrial heat (Brazil is the largest user of industrial heat) - 11% building heat - 7% transport - 3% electricity It also produces 40% of US renewable energy

Is coal a prevalent resource globally?

Yes! It is the second most used resource in the world, right after oil. China has been driving coal use in the world as it continues to industrialize, and global coal use is growing.

Challenges of CCUS

• Costs: some combination of regulatory requirements, a price on carbon, subsidies, and government participation in projects will be required to provide the incentives for capital-intensive projects to move forward. • Financing and cost recovery: we need better ways to understand and manage climate risks, associated investment risks, and risks associated with transition pathways (IEA estimate $9.7 trillion will be required to meet Paris goals). • Systems integration: hubs to gather and transport CO2, clusters of industrial facilities that handle CO2 (power, refining, metals, H2, fertilizer, ...) to spread risk, create flexibility. Commitment and coordination across industries required (who will lead?). • Project permitting and regulatory requirements: careful planning, siting, operations are essential - a coordinated regulatory environment will be needed. • Pace and urgency: the current pace of economy-wide decarbonization (not just CCUS) will not meet 2050 goals. • Public acceptance: transparent project siting and design, with emphasis on safety, will be essential. Coalition building with labor unions, NGOs, partners, will be needed.

Why CCUS?

• Reduce hard-to-eliminate emissions from the industrial, commercial, and electricity sectors • Enable carbon dioxide removal from the atmosphere to offset emissions from air transport and heavy-duty transportation • Reduce costs for decarbonization • Accelerate decarbonization by tackling all sectors at the same time