AP Environmental Unit 6 (Energy)
Geothermal energy
-earth's internal heat produces geothermal energy -using the heat from natural radioactive decay of elements deep within Earth as well as heat coming from Earth. -Heat from magma warms groundwater, which can be used as a direct heat source or as a means to generate electricity. -The heat source is non-depletable, but the groundwater it heats is nonrenewable if not used sustainably. -Ground source heat pumps can be used to heat and cool residential and commercial buildings.
Gigajoule (GJ)
= 1 billion (1 x 109) joules or about 8 gallons of gasoline
Exajoule (EJ)
= 1 billion GJ
U.S. government reports energy consumption as the quad
= 1.055 EJ
Best approach to minimize energy use
-Although renewable energy is more sustainable than nonrenewable, using any form of energy has impact on environment -Best approach is to minimize use through conservation and efficiency
joule (J)
-Basic unit of energy
Energy efficiency
-By quantifying the energy expended to obtain and process the fuel, and convert it into work -Dictated by 2nd law of thermodynamics
Benefits of Conservation and Efficiency
-Conservation and efficiency efforts save energy that can be used later. -Demand for energy varies with day, season, weather, etc. -Energy companies must provide enough energy to meet peak demand. -Many energy companies have an extra backup source of energy = natural gas-fired generators -Consider the losses: the amount of energy we save is the sum of energy not used and energy that would be lost in converting energy into its consumer product (2nd law)
Advantages of Natural Gas
-Contains fewer impurities and therefore emits almost no sulfur dioxide or particulates -Emits only 60% as much carbon dioxide as coal
Subsistence energy sources
- those gathered by individuals for their own use such as wood, charcoal and animal waste. -Much greater use in the developing world
Commercial energy sources
- those that are bought and sold, such as coal, oil and natural gas.
U.S. Coal Mines
-1,450 coal mines according to U.S.D.o.E -Produce 1 billion metric tons of coal -After burning, 3-20% remains as coal ash
Major Oil related Disasters/Events
-1989 Exxon Valdez -Crashed in Prince William Sound, AK spilling 11 million gallons of oil, killing hundreds of thousands of birds and marine mammals -1991 Persian Gulf War -240 million gallons of oil in Kuwait -2010 BP Deepwater Horizon -206 million gallons of oil spilled -85% of oil in marine -ecosystems comes from runoff ANWR
Fossil fuels
-Derived from organic material fossilized millions of years ago -Immense heat and pressure -Coal, oil and natural gas -Access ancient solar energy by burning and releasing energy stored in bonds -Provide majority of energy for developed & undeveloped countries -Extracted from 50-350 million year old organic matter deposits (swamps, deltas, ocean floors)
Nuclear fuels
-Derived from radioactive materials that give off energy
-Consider energy use as system of inputs and outputs
-Domestic and foreign inputs (oil, hydroelectric, etc) -Work (transportation or industry) and waste (heat, CO2, and other pollutants) are the outputs
Petroleum Extraction and Refining
-Drilled or pumped -Transported in pipelines or supertankers to refineries -Contains natural gas -Gas flares or extracted as fuel -Liquid petroleum is crude oil -Refined into tar, gasoline, asphalt, diesel, kerosene, etc. -About 150 oil refineries in U.S. -Petroleum is also raw material for plastics, lubricants, solvents and pharmaceuticals -Countries with the most petroleum are Saudi Arabia, Russia, the United States, Iran, China, Canada, and Mexico -Account for ½ the world's production
Natural Capital
-Ecologically minded economists describe resources as "natural capital". If properly managed, renewable and replenishable resources are forms of wealth that can produce "natural income" indefinitely in the form of valuable goods and services. -This income may consist of marketable commodities such as timber and grain (goods) or may be in the form of ecological services such as the flood and erosion protection provided by forests (services). Similarly, non-renewable resources can be considered in parallel to those forms of economic capital that cannot generate wealth without liquidation of the estate.
Depleting & Regenerating Energy Sources Over Time
-Energy sources have evolved from primarily biomass (wood and animal manure, etc.) to fossil fuels and nuclear power -Energy sources formed over millions of years. -Depleted much faster than they can be replenished. -Regenerate rapidly -Renewable as long as we do not consume them faster than they can be replenished -Biomass must be used sustainably -Cannot be depleted, no matter how much we use
Energy intensity
-Energy use per unit of GDP -has been decreasing due to developments in energy efficiency
Advantages of Coal
-Energy-dense -plentiful -easy to exploit by surface mining -technological demands are small -economic costs are low -easy to handle and transport -needs little refining
Nonrenewable Energy
-Every energy choice has positive and negative effects -In U.S., each person averages 10,000 W of energy use continuously -Majority comes from nonrenewable energy resources - fossil fuels (coal, oil, natural gas) and nuclear fuels
EROEI
-Every energy source requires an expenditure to obtain it -Converting coal to electricity is 35% efficient -Calculate the energy return on energy investment -EROEI = Energy obtained from the fuel/ Energy invested to obtain the fuel -Larger EROEI value suggests a more efficient and desirable process
Energy conservation
-Finding ways to use less energy -Incentives -Government programs -Tiered rate system -Efficiency -Obtaining same work from using a smaller amount of energy -Technology (e.g. Energy Star appliances, CFLs, etc.)
Why do we need to make a global shift from nonrenewable resources like petroleum, natural gas, coal, and uranium, to renewable resources?
-Global energy demand is growing -Limited supply -Cut down on CO2 emissions and other pollutants
The Future of Fossil Fuel Use
-If current global use continues, we will run out of conventional oil in less than 40 years. -Coal supplies will last for at least 200 years, and probably much longer.
Sustainable Designed Houses/Homes
-Improving the efficiency of the buildings and communities in which we live and work -Build residential communites close to businesses and workplaces to reduce fossil fuel use and pollution -Build sustainably designed homes
hydrogen fuel cell
-In a hydrogen fuel cell, electricity is generated by the reaction of hydrogen with water: 2H2 + O2 → 2 H2O -Hydrogen fuel cells have many potential applications
carbon neutral
-In theory, biomass is the better choice because the net change in atmospheric CO2 concentrations should be zero
Hydroelectricity
-Kinetic energy of water can generate electricity -Hydroelectricity is generated by the kinetic energy of moving water. -Second most common form of renewable energy in the world. -7% of electricity generation in US -> ½ of hydroelectric generated in U.S. comes from WA, CA, and OR
Biodiesel
-Liquid Biomass -Biodiesel is direct replacement of petroleum-based diesel fuel -Produce less emissions than petro-diesel -Commonly made from vegetable oils or animal fats -Usually more expensive and typically diluted to "B-20" -Any diesel vehicle can be converted to 100% straight vegetable oil (SVO) -Waste product obtained from restaurants with deep fryers -Algae produces 15-300 times more fuel per area than conventional crops
Disadvantages of Coal
-contains impurities -release impurities into air when burned -trace metals like mercury, lead, and arsenic are found in coal -combustion leads to increased levels of sulfur dioxide and other air pollutants into the atmosphere -ash is left behind -carbon is released into the atmosphere which contributes to climate change
Advantages of Petroleum
-convenient to transport and use -relatively energy-dense -cleaner-burning than coal -releases sulfur, mercury, lead, and arsenic into the atmosphere when burned
Some figures regarding economic and environmental issues:
-Mass yields from a Casamance kiln and a well-managed traditional mound kiln are about 25 percent. In other words, 1 ton of wood will give 250 kg of charcoal. With poorer techniques, however, yields often do not exceed 15 to 20 percent, in other words about 150 to 200 kg from 1 ton of wood. Many charcoal makers, for example, use green wood, and the energy needed to dry it is provided by part of the load, reducing yields to 15 percent. -The carbon content of wood and charcoal is 50 and 90 percent respectively, giving the following carbon equivalents: 1,000 kg of wood → 500 kg of carbon; 250 kg of charcoal → 225 kg of carbon; 150 kg of charcoal → 135 kg of carbon. -When a ton of wood is carbonized, 365 kg are released into the atmosphere with a poorly managed technique and 275 kg with improved methods. Improved technique thus prevents the emission of 90 kg of carbon per ton of carbonized wood, equivalent to 300 kg of carbon or 1.1 tons of CO2 per ton of charcoal consumed. -For the city of, Abidjan, Côte d'Ivoire, which consumes about 300,000 tons of charcoal per year, the annual savings amount to: 330,000 tons of CO2 emission avoided; 800,000 tons of wood not consumed as a result of the increased yield.
Energy Efficiency of coal
-Most coal burning power plants are about 35% efficient.
Overall Fuel Efficiency of U.S. Automobiles
-Nearly 30% of energy used in U.S. is for transportation
The challenge of Renewable Energy
-New energy sources may be the key to energy independence. -This largely depends on the willingness of governments to commit to the development of renewable energy technologies. -In the US, wind and solar only account for less than 1% of energy produced. -The creation of a Smart Grid and decentralized "energy parks" will help to meet the ever increasing energy demands of US citizens. -Research facilities like the Schatz Energy Research Center at Humboldt State University are leading the way to develop new applicable green energy solutions.
Advantages of Nuclear Energy
-No air pollution is produced -Countries can limit their need for imported oil
Nuclear Power Plants
-Nuclear power plants use uranium-235 as fuel source -Nuclear power plants work by using heat from nuclear fission to heat water. This water produces the steam to turn the turbine, which turns a generator.
The Sun's energy can be captured directly with:
-Passive solar energy -Sustainable building design -Solar cookers -Active solar energy
Disadvantages of Nuclear Energy
-Possibility of accidents -Disposal of the radioactive waste
Disadvantages of Petroleum
-Releases carbon dioxide into atmosphere -possibility of leaks when extracted and transported
Three broad classes of natural capital:
-Renewable natural capital, such as living species and ecosystems, is self-producing and self-maintaining and uses solar energy and photosynthesis. This natural capital can yield marketable goods such as wood fiber, but may also provide unaccounted essential services when left in place, for example, climate regulation. -Replenishable natural capital, such as groundwater and the ozone layer, is nonliving but is also often dependent on the solar "engine" for renewal. -Non-renewable (except on a geological timescale) forms of natural capital, such as fossil fuel and minerals, are analogous to inventories: any use implies liquidating part of the stock.
Coal
-Solid fuel formed primarily from the remains of trees, ferns, and other plant materials that were preserved 280-360 million years ago. -Four types of coal ranked from lesser to greater age, exposure to pressure, and energy content. -lignite, sub-bituminous, bituminous, and anthracite -The largest coal reserves are in the United States, Russia, China, and India
Charcoal Production
-Sustainable production and use of charcoal through proper management and planning of supply sources, together with rational trade and marketing infrastructures and efficient use, can have a significant positive impact by helping to conserve resources, reducing migration from rural or forested areas and improving people's incomes. -In places where high charcoal consumption and weak supply sources put strong pressure on existing trees resources (because of high population density, low income and/or severe climate conditions), deforestation and devegetation problems are still of great concern.
Modern Carbon vs. Fossil Carbon
-The (modern) carbon found in biomass was in the atmosphere as carbon dioxide, taken in by the tree, and by burning it we put it back into the atmosphere -As long as the biomass is harvested and processed sustainably -Burning coal is (fossil) carbon that has been buried for millions of years and was out of circulation until we began to use it. This results in a rapid increase in the concentration of carbon dioxide in the atmosphere.
Biomass is Energy from the Sun
-The Sun is the ultimate source of almost all types of energy -examples: All fossil fuel & all renewable energy -Solid fuels: wood and charcoal, animal products and manure, plant remains, and municipal solid waste -Liquid fuels: ethanol and biodiesel -not source of energy for only tidal, nuclear fission, nuclear fusion, geothermal
Electricity Generation in a Power Plant
-The burning fuel from coal transfers energy to water, which becomes steam. -The kinetic energy contained within the steam is transferred to the blades of a turbine, a large device that resembles a fan. -As the energy in the steam turns the turbine, the shaft in the center of the turbine turns the generator. -This mechanical motion generates energy. -Energy generated is transferred to users via network of transmission lines called an electric grid
Control rods
-cylindrical devices that can be inserted between the fuel rods to absorb excess neutrons, thus slowing or stopping the fission reaction. -Prevent melt downs
Sustainable Development
-The term "sustainable development" was first used in 1987 in Our Common Future (The Brundtland Report) and was defined as "development that meets current needs without compromising the ability of future generations to meet their own needs." The value of this approach is a matter of considerable debate and there is now no single definition for sustainable development. For example, some economists may view sustainable development as a stable annual return on investment regardless of the environmental impact, whereas some environmentalists may view it as a stable return without environmental degradation. -Consider the development of changing attitudes to sustainability and economic growth, since the Rio Earth Summit (1992) leading to Agenda 21. Int: International summits on sustainable development have highlighted the issues involved in economic development across the globe, yet the viewpoints of environmentalists and economists may be very different.
U.S. Patterns of Energy Use
-Today, oil, coal and natural gas provide majority of energy. -2008 energy input, ~1.05 x 1018 J per year -84% fossil fuel -9% nuclear -7% renewable
The Two Types of Nonrenewable Energy
-Two primary categories: -Fossil fuels -Nuclear fuels
Combined cycle natural gas-fired power plant - gas combustion turns turbine and heat boils water for 2nd turbine
-Up to 60% efficient
Disadvantages of Natural Gas
-When unburned, methane escapes into the atmosphere -Exploration of natural gas has the potential of contaminating groundwater
Pros of Wind Energy
-Wind energy is a green energy source and does not cause pollution. -The potential of wind power is enormous - 20 times more than what the entire human population needs. -Wind power is renewable and there is no way we can run out of it (since wind energy originates from the sun). -Wind turbines are incredible space-efficient. The largest of them generate enough electricity to power 600 U.S. homes. -Wind power only accounts for about 2.5% of total worldwide electricity production, but is growing at a promising rate of 25% per year (2010). -Prices have decreased over 80% since 1980 and are expected to keep decreasing. -The operational costs associated with wind power are low. -Good domestic potential: Residential wind turbines yields energy savings and protects homeowners from power outages
Cons of Wind Energy
-Wind is a fluctuating (intermittent) source of energy and is not suited to meet the base load energy demand unless some form of energy storage is utilized (e.g. batteries, pumped hydro). -The manufacturing and installation of wind turbines requires heavy upfront investments - both in commercial and residential applications. -Wind turbines can be a threat to wildlife (e.g. birds, bats). -Noise is regularly reported as a problem by neighboring homes. -How wind turbines look (aesthetics) is a legitimate concern for some people.
Solid Biomass
-Wood, Charcoal and Manure- used to heat homes throughout the world. -Globally, 2-3 billion people use wood for heating and cooking; in the U.S., ~3 million homes rely on wood for heating -In addition, particulate matter, CO, and NOx are released
Passive solar design
-a Sustainable Design -can lower your electricity bill without the need for pumps or other mechanical devices. -Building the house with windows along a south-facing wall which allows the Sun's rays to warm the house. -Using materials with a high thermal inertia -Double-paned windows -Window shades
Green Roofs
-a Sustainable Design -put green vegetation on roof -Cool and shade the buildings and the surrounding environment -Improves air quality
Fuel cell
-a device that operates like a common battery where electricity is generated by a reaction between two chemicals.
Hubbert curve
-a graph that shows the point at which world oil production would reach a maximum and the point at which we would run out of oil.
Fission
-a nuclear reaction in which a neutron strikes a relatively large atomic nucleus, which then splits into two or more parts. -Releases more neutrons and heat
Run-of-the-river systems
-a type of hydroelectric power system -Water is held behind a low dam and runs through a channel before returning to the river -Does not store water in a reservoir -Advantages: little flooding upstream and seasonal changes in river flow are not disrupted -Disadvantages: generation is intermittent, water can't be stored, and can't generate in dry, hot weather
Tidal systems
-a type of hydroelectric power system -the movement of water is driven by the gravitational pull of the Moon.
Water impoundment
-a type of hydroelectric power system -tores water in a reservoir behind a dam -Gates of the dam are opened and closed controlling the flow of water (ex. Glen Canyon Dam in AZ, White Salmon River dam in WA)
Siltation
-accumulation of sediments on reservoir bottom
Bitumen (tar or pitch)
-another type of fossil fuel -a degraded type of petroleum that forms when a petroleum migrates close to the surface, where bacteria metabolize some of the light hydrocarbons and others evaporate. -Much more energy-intensive than conventional oil -For every L of bitumen obtained, 2-3 L of water is contaminated -Overall system has lower energy efficiency and releases a greater amount of CO2 than conventional oil
Oil sands
-another type of fossil fuel -low-flowing, viscous deposits of bitumen mixed with sand, water, and clay.
Sustainability
-any society that supports itself in part by depleting essential forms of natural capital is unsustainable. If human well-being is dependent on the goods and services provided by certain forms of natural capital, then longterm harvest (or pollution) rates should not exceed rates of capital renewal. Sustainability means living, within the means of nature, on the "interest" or sustainable income generated by natural capital.
Photovoltaic systems
-captures light energy and convert to electricity -Use thin, ultra-clean layers of semiconductors -12-20% efficient
Active solar energy
-capturing the energy of sunlight with the use of a pump or photovoltaic cell and generating electricity.
Solar Water Heating Systems
-cold water is heated as it passes through a solar collector, then into an insulated reservoir.
Natural gas
-exists as a component of petroleum in the ground as well as in gaseous deposits separate from petroleum -Contains 80 to 95 percent methane and 5 to 20 percent ethane, propane, and butane -Two largest uses in U.S. are electricity and industrial processes -Also used to make fertilizer, as vehicle fuel, and for residential cooking and heating -Liquid petroleum gas (LPG) can be transported easily and is used in BBQ's and heaters -Natural gas and LPG supply 24% of energy needs
Total worldwide energy consumption
-fossil fuels=81% -oil=34% -natural gas=21% -coal/peat=26% -Renewable energy=13% -Nuclear Fuels=6% -Total=495 exajoules (496 quadrillion Btu, or "quads") per year -Total energy use continues to increase worldwide although energy use per person has leveled off
California Academy of Sciences in San Francisco Building
-it uses passive solar, radiant heating, solar panels that produce 213,000 kWh/year, green roofs that capture 13.6 million of liters of rainwater/year, skylights fill 90% of office space with natural light
Ethanol
-liquid biomass - used as substitutes for gasoline and diesel fuel. -Ethanol is made by converting starches and sugars from plants into alcohol and CO2 -In U.S., 90% comes from corn and corn by-products, and is heavily subsidized -Brazil uses sugarcane, which unlike corn needs to be replanted every year, is replanted every 6 years and harvested by hand -Flex-fuel vehicles can run on gasoline or E-85
Petroleum
-liquid mixture of hydrocarbons, water, and sulfur that occurs in underground deposits. -Oil and gasoline are ideal for mobile combustion =Formed from the remains of 50-150 million year old ocean-dwelling phytoplankton
Sustainable yield (SY)
-may be calculated as the rate of increase in natural capital, that is, that which can be exploited without depleting the original stock or its potential for replenishment. For example, the annual sustainable yield for a given crop may be estimated simply as the annual gain in biomass or energy through growth and recruitment. See figures 1 and 2.
Secondary source of energy
-obtained from the conversion of a primary source (coal, gas, wind) -It is an energy carrier, in that it moves and delivers energy in a convenient usable form to end users. -Clean at the point of use (home) -About 40% of energy in U.S. is used to generate electricity. -Only 13% is available to end users because of conversion loss.
Peak oil
-oil extraction and use will increase until half the supply has been used up
Radioactive waste
-once the nuclear fuel can not produce enough heat (spent fuel rods) to be used in a power plant but it continues to emit radioactivity. -this waste must be stored in special, highly secure locations because of the danger to living organisms. -Uranium-235 has a half life of 704 million years
Keystone XL pipeline
-the 4th extension pipeline of the keystone pipeline system from Canada to the Gulf of Mexico that would carry tar sand oil between Canada and the U.S. -the tar sand oil would be mined, refined, transported, and used among both Canada and U.S. -first rejected by President Obama but is now accepted under President Trump -pros: -more jobs -reduced demand for oil in unstable countries -cons: -This extension would run through many natural environments & Indian lands -tar sand oil releases more toxins into atmosphere compared to other oils (worst than other oils)
Fuel rods
-the cylindrical tubes that house the nuclear fuel used in a nuclear power plant.
Wind Energy
-the most rapidly growing source of electricity -Winds are the result of uneven heating of the Earth's surface by the sun -using a wind turbine to convert kinetic energy into electrical energy. -U.S. has largest wind generating capacity in the world; yet, we obtain <1% of electricity from wind
Nuclear fusion
-the reaction that powers the Sun and other stars. This occurs when lighter nuclei are forced together to produce heavier nuclei and heat is released. -Fusion is a promising, unlimited source of energy in the future, but so far scientists have had difficulty cotaining the heat that is produced.
Concentrated solar thermal electricity generation
-use lenses or mirrors to focus sunlight into a small beam to evaporate water and produce steam that turns a turbine -capable of generating 35 MW, but use large amounts of land
Cogeneration
-using a fuel to generate electricity and to produce heat. -Ex:steam is used for industrial purposes or to heat buildings it is diverted to turn a turbine first. -Efficiency is as high as 90%.
Variable price structure
-utility customers can pay less to use energy when demand is lowest and more during peak demand
Is Hydroelectric Sustainable?
-while hydroelectric projects generate a large amount of electricity without direct air pollution, waste products or CO2 emissions, and provide recreational and economic opportunities there are negative environmental consequences: -Free-flowing river is held back and floods 100's-1000's of hectares -Submerges ancient cultural and archeological sites -Displaces people -Impounded water holds more heat and contains less DO -Destroys downriver ecosystems (ex: canyon cottonwoods, salmon, trout, shellfish, etc.) -siltation -In recent years, some dams are removed due to environmental concerns or heavy siltation
