EGR 240 Final
What is the unit of LCOE?
$/MWh
What is levelized cost of electricity (LCOE)?
(annualizing factor x capital cost) + fixed O&M)/(annual expected generation hours) + variable O&M + fuel
According to the "Solutions Project" in the mix of 100% renewable energy sources considered for Kentucky in 2050, what is the approx. contribution expected from offshore wind turbines?
0%
How much is the energy efficiency improved on an HEV as comparted with a conventional internal combustion vehicle?
0.1 more efficient
Wind potential as a fraction of total surface (desert) solar potential?
1%
How much total power is available on the earth's surface?
1,366W/m^2
What is the typical capacity factor for a solar PV installation? Is 20% a realistic number?
15%; this number depends on if it were operating at its peak output 24 hours a day
What percent of the world's electricity is provided by hydro?
16%
How much solar power does the earth (in total) receive from the sun?
174 petawatts; only 50% gets to the surface
How much solar power and energy is available?
188W/m^2 average or 95,700TW reaches Earth's surface. 7% of Arizona with PV cells could supply all energy requirements of the US.
What is the energy payback for solar PV panels (in years)?
2 years; but it depends on where to install them. Desert has shorter payback but places with less solar potential like Germany have a longer payback period.
What is generating capacity of Three Gorges Dam, China?
22.5GW
What is the surface area and the capacity (rated power) of the largest PV power plant currently operational in KY?
45 acreas; 10MW; E.W. Brown Solar PV plant
After how many months (or years) is a wind turbine carbon neutral?
7 months
What is the US avg height, rotor diameter, and rated power for wind turbines?
80 meters in height; 100 meter diameter; 2MW capacity
How does this compare to the amount the average power used by people?
89 petawatts (89,000 terawatts) useable on surface; people use 17 terawatts; over 5000x more power available
What is a wind speed graph, and how is it used?
A wind speed graph shows how the wind speed varies over time in a location. This helps determine what levels of power output can be expected by a turbine in that location.
Briefly describe the physical mechanism of acid rain and provide one example of regulatory follow up response.
Acid falling back to earth; US regulated power plants with emphasis on SO2 sulfur dioxide; Clean Air Act
How can the variability of solar electricity generation be mitigated?
Adding energy storage
List and describe two major advantages and perceived disadvantages of wind turbines.
Advantages: sustainability, water and carbon emissions Disadvantages: bird kills, noise, aesthetics
List two examples of CSP power plants discussed in class and their main characteristics.
CSP plant in Arizona- 280MW with 6 hours storage; Tower CSP plant in NV 110MW and 16hrs of storage
Briefly describe one CSP power plant example - location and remarkable characteristics
CSP trough power plant in Arizona: almost 300MW
According to NREL, which of the states listed below have the highest potential of rooftop solar PV generation as percentage of the state total electricity sales at more than 55% (check ALL that apply)?
California, Florida, Vermont, Maine
What is capacity factor? What are typical values for capacity factor?
Capacity factor is total energy produced over a year divided by energy that would have been produced if running at full capacity. (avg power output / max power output). Typical values for a wind turbine is 24% for onshore, 41% offshore.
Which countries lead in total installed wind energy generation capacity?
China, US, Germany
Briefly describe the physical mechanism of smog and provide couple examples of tragic events.
Cool smoky air that decreases visibility; ex. London Smog
Which country has the highest wind penetration (% of total electricity)?
Denmark
List three countries that are in the top 10 in terms of installed wind power capacity.
Denmark, Ireland, Portugal
Which countries have the highest fraction of their electricity generation from wind?
Denmark, Spain, Portugal
List two major challenges (other than cost) to larger scale renewable energy deployment
Energy storage, getting higher capacity factor
What are the different categories of regulations, and what are examples of these?
Environmental regulation: 1970 Clean Air act, 1990 federal clean air act
Largest geothermal plant in the world
Geysers
Briefly describe the green house effect and provide two examples of potential effects.
Greenhouse gases stick in the ozone layer causing temperature changes across the world. Additionally, pollution causes acid rain.
What are plug in hybrid electric vehicles (PHEV)?
HEVs with a large battery pack of stored energy
Where in the US are there good wind resources? Which states or regions have the most wind farms, and which have the least?
Higher areas in the US, like the middle of the country of the Great Plains. There are the most wind farms in Texas, and no wind farms in southeast US.
What country has the highest percentage of electricity from geothermal?
Iceland
What is solar insolation? What is the avg solar insolation on Earth's surface? What are factors affecting insolation?
Insolation/irradiation is the average energy/area over time period (day or year). The average solar insolation is 208W/m^2. Higher places are deserts, with few clouds. Locations closer to poles have lower insolation, and places that are have altitude have more insolation.
Early steam engines for boats and railways
James Watt 1769
What are capital costs?
Land, equipment, facilities
Enumerate and briefly describe the functions of main wind turbine components.
Mechanical power: rotor, gearbox, generator Electrical power: generator, converter, transformer. output to the power grid
What area of Europe has the most offshore wind resources? Which country has been leading in capacity installation of offshore wind in recent years?
North Atlantic and North Sea, United Kingdom; leading country was UK
How does off-shore wind compare to on-shore wind?
Offshore wind produces more power and has a higher capacity factor
What are the DOE SunShot objectives for reducing cost of PV?
PV module cost reduced by 2/3 Power electronics needs cost reduction by 1/2 Installation cost reduced by 2/3
What do the acronyms PV, NZE, and VPP stand for?
PV: photovoltaic NZE: Net Zero Energy VPP: virtual power plant
Planned offshore wind turbine developments in USA
Pacific region, North Atlantic, Great Lakes
What are the two major technologies by which we generate electricity from solar power, and in what situations is one better than the other?
Photovoltaic and concentrating solar power (CSP) "solar thermal". Advantages of thermal is it is established technology and thermal storage; however, it requires very direct sunlight and utility scale systems. PV does not require direct sunlight and is suitable for all scales of implementation (residential, commercial, utility).
What are the types of electric utilities?
Regulated power grids where utilities are granted monopoly to generate and deliver power. Deregulated power grids have competing utilities and the consumer chooses based on price, etc.
List the main advantages of regulated and deregulated power grids, respectively.
Regulated: costs built into the rate structure, but consumers have no choice in power Deregulated: consumers chooses, but prices vary
Which type of solar power potential, PV or CSP, is higher for the SW desert states (CA, NV, AZ, NM) and which one is better for Midwest and neighboring regions (IL, IA, KY, NC)?
SW: CSP midwest: Solar PV
Enumerate and briefly describe two advantages and disadvantages of solar PV?
Solar PV is unable to generate electricity when we need it when the sun is not out. Additionally, it cannot respond quickly when power demands change. PV panels do have low CO2 and other emissions as well as produces little waste.
What energy sources are directly powered by solar energy, and which are indirectly powered by solar energy (possibly over different periods)?
Solar directly powers photovoltaics, waves, wind, hydro, tidal, ocean thermal, solar thermal *CSP), and biomass fuels. Indirectly powered are chemical, heat other than geothermal, mechanical work, electricity, fossil fuels (solar inheritance).
Which US states has the highest installed capacity of wind generation?
Texas
What is a wind turbine power output curve? What is its shape? What do the terms "cut-in/out-speed", "rated output speed/power" mean?
The power output curve shows how the power varies with steady wind speed. Cut in speed is when no energy is produced below a certain wind speed. Cut out speed applies brakes to reduce damage in turbine during high speed wind. Rated output speed means full power doesn't begin until that speed. Rated output power is the amount expected from the turbine.
Early steam engine for removal of water from mines
Thomas Newcomen 1709
In what country was the modern PV cell technology invented?
USA (Bell Labs in 1954)
What country leads in geothermal electric capacity?
United States
List two examples of large two wind turbines, incl. their maximum power rating and rotor diameter.
Vestas wind turbine: 165m rotor, 9MW GE's wind turbine: 220m rotor, 12MW
What is wind? What is major cause of wind?
Wind is air movements driven primarily by thermal differences. Warmer air expands and rises, creating low pressure area. Cooler air is high pressure and moves in.
Why is wind attractive in comparison to (as a compliment to) solar power?
Wind is available in climates where sun is not and times when sun is not.
Wind is an intermittent energy source. What does this mean?
Wind varies in speed and direction, over the day/year, and geographically. It is not continuous.
examples of upcoming designs and pre-commercial floating wind turbines
WindFloat wind farm
Briefly describe the concept of distributed generation and microgrids.
a network of integrated microgrids that can monitor and heal itself
According to the study published by Scientific American and briefly discussed in the lecture, in order for California to rely on 100% renewable energy in 2020, which of the following sources of energy was NOT considered as part of the mix?
biofuel
What are common objections to wind power?
bird/bat kills, aesthetics, noise concerns
What are three of the main functionalities of the new smart grid?
bring more communications and controls onto the grid, communication allows two way info exchange, power flows to and from consumer, sensing
What are costs of electricity generation?
capital, operation and maintenance, fuel, and transmission
What is an electric vehicle (EV)?
car powered by electric
Typical efficiency for commercial and research PV cells
commerical: 20%; research 40%
What is CSP
concentrated solar power
What is annualizing factor?
considers life of project, weighted average cost of capital, tax burden, etc.
What is DR?
demand response
What is run-of-river?
diversion; no large created reservoir
What is the greatest engineering achievement of the 20th century according to NAE?
electrification
What is the "Solutions Project"?
energy roadmaps for all 50 US states to reach 100% clean energy
What are the main subsystems of the power system?
generation, transformation, transmission, distribution
Natural gas-based power plants employ
less personnel than coal old units
How many operational power plants are in the US?
more than 7,000
How are the carbon emissions from natural gas compared with those from coal?
natural gas is less than coal
What is marine hydro?
ocean based tidal, currents, wave
What are the major pollutants from fossil fuels?
particulate matter and gasses, sulfur, nitrogen oxides, mercury, carbon monoxide, carbon dioxide
What is flash steam geothermal plant?
pressurized water comes from well, then vaporizes and drives the turbine; most common today
What is the Porter Hypothesis?
properly designed regulatory standards stimulate innovation and business opportunities that offset any costs incurred in complying with those same regulations
What is curtailment in the context of wind energy?
purposeful reduction in wind power output by the utilities due to inadequate transmission capacity or power demand.
What was novel about the 1990 Clean Air act and its regulation of SO2 and NOx?
set permanent cap on total amount of SO2 that can be emitted by power plants; reduced emissions below the capped levels
According to the "Solutions Project" in the mix of 100% renewable energy sources considered for California in 2050, which is projected to have the highest contribution?
solar PV plants
main types of floating wind turbines
spar: stable through weight below its tank semisubmersible: static stability by distributing buoyancy TLP: has submerged buoyancy tank
What is a dry steam geothermal plant?
steam directly drives turbine, ex. Geysers in California
What factors contributed to the dramatic reduction in new wind farms in the US in 2013?
the US tax incentives changed in 2013 which made projects not happen
What is the Betz limit (for a wind turbine rotor)?
the maximum rotor efficiency
What type of energy storage is employed for CSP power plants?
thermal energy storage
Why are regulations sometimes needed?
to acknowledge and account for externalities to permit better decisions regarding aggregate well-being of larger society
how large will the offshore wind turbine get?
twice as big as land-bsed, but not limits to further growth
What is a hybrid electric vehicle (HEV)?
use an internal combustion engine and an electric machine; have advantages for higher efficiency and reduction of fuel consumption
geothermal heat pumps
use of ground as an energy sink/source
What is direct geothermal?
use of heat in ground directly for heating
What is the binary cycle geothermal plant?
uses heat exchanger and secondary fluid; suitable for lower temperature reservoirs
What is impoundment?
using dam to create large reservoir
What are operation and maintenance costs?
variable like repairs, fixed (maintenance)
What are externalities?
when decisions made by one firm or person affect another firm or person without its permission or compensation
Is there enough renewable energy potential to cover the world's consumption needs?
yes