Wind
Geothermal
Biomass
Grab-bag
100
True or false: Slight changes in the wind speed cause large changes in power output for a wind farm.
True - Power production increases as a function of the cube of wind speed
100
True or False: Electricity generated by harnessing geothermal energy is always carbon-neutral.
False, although they emit very small amounts of carbon
100
What is biomass? Give 3 examples.
organic material derived from living / recently living organisms, also includes waste materials • Forest waste / wood • Agricultural residue • Energy crops • Municipal wastes • Aquatic biomass • Peat
100
organic materials are the largest component in the US waste stream. What are the two ways this waste can be converted to energy?
• Landfill gas • Put it in a digester to make gas
200
These two resources are the fastest-growing resources worldwide. (Put them in rank order.)
Photovoltaics (35.1%) and wind (25.3%)
200
This is the primary difference between a “dry steam” or “direct steam” power plant, and a “flash steam” power plant
Dry steam generation system is used when the geothermal resource produces steam directly from the well. Flash steam is used when the geothermal resource produces how water or a combination of hot water and steam
200
Is biomass combustion a carbon neutral energy resource?
resulting CO2 was previously absorbed by the plants from the atmosphere – net zero emissions as long as extraction does not exceed regeneration
200
what is the fuel of the future for ethanol? Why aren’t we using that now?
• Cellulosic ethanol, more difficult to break down into glucose than crops used today, has up to three times the energy yields of current ethanol crops
300
What are two drivers and one barrier to offshore wind development?
Driver 1) Higher offshore winds = higher power production Driver 2) Some aesthetic concerns / siting issues might not be as much of a problem Barriers: Cost- 40-100% increase
300
In -_______________ zones, the lithosphere folds downward, plunges under the adjacent lithosphere and descends to very hot deep zones. These regions are characterized by intense seismicity and high terrestrial heat flow
What are subduction zones
300
About how much of the world’s population depends on biomass as a primary energy source?
2.5 billion people, 37% of total population. Concentrated in Africa, south east Asia and Latin America – 3/4 of world biomass production is consumed in developing countries
300
True or False: Currently, electricity generated by harnessing geothermal energy is significantly more expensive than electricity generated by natural gas; however, technological advancements will hopefully bring down the cost in the future.
False A California Energy Commission study estimates geothermal electricity costs are around 4.5 – 7 cents, which are competitive with natural gas.
400
Why are wind and natural gas a winning combination?
They have many complementary characteristics. Wind = low operating cost, high capital cost, non-dispatchable, no fuel supply risk, no emissions Natural gas = high operating cost, low capital cost, dispatchable, fuel supply risk, emissions
400
These are two techniques that would qualify as “Enhanced Geothermal Systems”, as described in the reading
What are hydrofracturing and recharging existing wells with wastewater
400
We have a lot of livestock in the United States. True or False: waste from cows and pigs could be used to provide 1% of our total energy needs?
False: harnessing power from all of the livestock in the United States would produce ~1/2 a coal plant
400
What are two different types of government incentive schemes that have been used to incent wind development in the US
Investment Tax Credit (ITC) or Production Tax Credit (PTC)
500
What are two examples of turbine improvements that can improve efficiency?
New rotor hubs are more flexible Better construction materials = taller towers
500
This use of geothermal energy has the most installed capacity worldwide
What are ground source heat pumps
500
how do CO2 emissions from corn based ethanol size up to emissions from other transportation fuels? What factors contribute to its carbon total?
• Can be more or less carbon intensive than gasoline depending on the type of plant that is used to produce it, either way not that different. • Cultivation – fertilizers, land use changes; transportation, production
500
In this type of geothermal power plant, a secondary working fluid, such as isopentane or isobutene, drives the turbine.
Binary Cycle Power Cycle
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