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Env Sci > Renewable Energy Alternatives > Flashcards

Renewable Energy Alternatives Flashcards

1
Q

Which country produces the most solar power per person (despite receiving less sunlight than Alaska) and allocates more public money to renewable energy than any other?

A

Germany

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2
Q

Feed-in tariff system

A

an economic incentive for renewable energy that requires utilities to buy power at premium prices (more than market price) with a long-term contract from anyone that generates it from renewable energy sources (+ feeds it into the electrical grid); encourages businesses and homeowners who can sell excess solar power, etc. to utilities; Germany served as a model of the system to 100+ countries

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3
Q

Renewable Energy Sources Act of 2000 (Germany)

A

strengthened feed-in tariffs law/renewable energy use and production + enhanced energy supply security, lowered carbon emissions and lowered external costs of fossil fuels; gave renewable sources their own payment rates, decreased them over time to increase efficiency, and led to the government slashing solar tariff rates later on to lower the burden on ratepayers (which sparked an increase in photovoltaic module sales)

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4
Q

What issues have arisen in Germany in regards to renewable energy use?

A

use of coal still spiked after the closing of power plants following Chernobyl; increasing energy means that the power grid is occasionally flooded with excess energy; difficult to increase renewable energy use while keeping the supply steady and predictable

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5
Q

What new energy policy was introduced in Germany in 2016?

A

an auction system applying to large-scale producers - the government decides the new capacity for each renewable energy type per year, then auctions permits for developing it to the lowest bidders (small-scale photovoltaic solar installation is still eligible for tariffs so regular homeowners were unaffected)

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6
Q

What were the reactions to Germany’s 2016 energy policy?

A

some thought it would decrease energy costs for ratepayers, strengthen the industry with competition and give the power grid time to expand considering sources would be mixed; others thought it favored powerful firms over small ones and created risk and uncertainty that would decrease private investment/progress

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7
Q

Net metering

A

an economic incentive for renewable energy where utilities credit customers who produce renewable energy and feed it into the power grid; the value of the power is subtracted from the homeowner’s utility bill

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8
Q

Some renewable energy sources (especially water for hydropower and biomass for bioenergy) can be overharvested.

A

true (especially locally)

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9
Q

Perpetually renewable energy

A

sources of renewable energy that cannot run out in any imaginable amount of time (i.e., from the sun, wind, Earth’s geothermal heat and ocean water); AKA “new renewables” since just starting to be used widely

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10
Q

Renewable energy is currently used more for ___ than ___ .

A

electricity generation; transport

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11
Q

What is sometimes a major technical issue with renewable energy?

A

the infrastructure to transfer huge volumes of power inexpensively and on a large scale has not been developed enough

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12
Q

What factors will increase renewable energy use?

A

better technology, lower prices, decreased fossil fuel use, higher demand for clean energy

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13
Q

What are the main benefits of renewable energy?

A

provide long-term security, help the economy in several ways (diversify energy sources + make prices less volatile + decrease reliance on imported fuel), may generate income/property tax in rural communities and help people in developed regions to produce their own energy, decrease air pollution and serve as the main way to decrease greenhouse gas emissions

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14
Q

Green-collar jobs

A

jobs in the environmental sector, many of which are created by renewable energy (needs people to design, install, manage and maintain technology + rebuild and operate energy infrastructure)

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15
Q

About cost and availability of renewable energy

A

most still more expensive than fossil fuels but prices are falling quickly and cost-competitive in many places; political support lowers prices and increases spread; governments are setting goals/mandates to obtain a certain percentage of energy from renewables + investing in research/new businesses and offering tax credits/rebates to those who produce and buy it (affects private sector as well)

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16
Q

Criticism of public renewable energy subsidies

A

some believe taxpayer money supporting particular energy sources is inefficient and skews the market, so it is better for sources to compete freely; subsidies on fossil fuels enhance the economy + national security + international influence by supporting a global industry dominated by U.S. firms

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17
Q

Support of public renewable energy subsidies

A

fossil fuels and nuclear power are always subsidized far more anyway so the market is never truly free (worldwide, $1 of taxpayer money going towards renewables means $4 going towards fossil fuels); being a global leader in the renewable energy transition can have the same benefits as subsidizing fossil fuels

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18
Q

Renewable energy study by Mark Jacobson and Mark Delucchi

A

considered future energy demand, the outputs and limits of renewable energy, the costs to manufacture the technology needed and how solar/wind energy can vary throughout a given day (and compensating with a balance of sources so supply is reliable); created infrastructure plans for each state in the U.S.

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19
Q

Findings of the renewable energy study by Mark Jacobson and Mark Delucchi

A

it is possible to replace the three more damaging energy sources (biofuels, nuclear energy and fossil fuels) with the three lower-impact energy sources (wind, solar and water); excess energy could produce hydrogen fuel; most barriers are social/political, not technological/economical; also found the land needed for the infrastructure (0.41% more than the 0.74% currently occupied, + 1.18% for spacing unless some was over water); suggested demand and use can be decreased with reliance on electricity over combustion and improvements to efficiency + jobs would be created + early deaths from pollution would greatly decrease + money would be saved without having to fight the impacts of climate change

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20
Q

Criticisms of the renewable energy study by Mark Jacobson and Mark Delucchi

A

rare-earth metals in the equipment and materials for the technology are limited and would need to be recycled; may underestimate costs, overestimate efficiency, and does not provide quantitative evidence that intermittency in supply will be overcome (though simulations later showed hydropower and an energy storage system would work); one team felt that the proposals were very unrealistic and while the economy will eventually be dominated by renewables, the world will still have to use nuclear energy and fossil fuels to a degree

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21
Q
A
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22
Q

How does the sun release energy?

A

by converting hydrogen to helium through nuclear fusion (only a tiny amount of energy reaches Earth but sustains life)

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23
Q

Each day, the Earth receives enough solar energy to power human consumption for ___ years.

A

25

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24
Q

A typical home has enough roof area to meet its power needs using solar panels.

A

true (average 1 square meter gets 1 kilowatt solar energy)

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25
Q

Passive solar energy collection

A

refers to designing buildings to maximize energy absorption from the sun in the winter and minimize it in the summer; south-facing windows for winter provide low-angle light, overhangs on windows for summer provide overhead sunlight and vegetation prevents temperature swings; thermal mass for floors/roofs/walls or portable blocks absorb, store and slowly release heat

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26
Q

Active solar energy collection

A

refers to the use of technology to focus, move or store solar energy; flat plate solar collectors, solar cookers, etc.

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27
Q

Flat plate solar collectors

A

technology featuring metal in flat glass boxes on rooftops that absorb heat for a building’s air or water tank; water, air or antifreeze runs through tubes in collectors to transfer heat; China is the leading producer of the technology; used in rural and developing areas; controller senses when enough heat is transferred and a boiler (in water tank) heats water as needed when sunlight is not available

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28
Q

Solar cookers

A

portable ovens powered by solar energy that intensify it by gathering it from a wide area and focusing it on a single point; used in the developing world

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29
Q

Concentrated solar power (CSP)

A

used on larger scales than solar cookers; utilities generate electricity at facilities and transmit it to homes and businesses via an electrical grid; especially used in sunny, arid regions; may have curved mirrors that focus sunlight on synthetic oil that is piped to the facility or hundreds of mirrors that focus sunlight on a central receiver atop a power tower (where air or fluids carry heat through pipes to a steam-driven generator); significant environmental impact due to land use required + the clearing/grading of said land that destroys habitat + water to maintain it, especially when water is scarce in dry climates

30
Q

Photovoltaic (PV) cells

A

convert sunlight to electrical energy when light strikes a pair of mostly silicon (semiconductor) plates, causing one plate to release electrons that are attracted to the other plate; wires connecting them allow the electrons to flow back and generate a direct electrical current that can be converted to an alternating current and used for residential or commercial power; small cells can power small devices; all types can be connected to batteries to store accumulated charge until it is needed

31
Q

Thin-film solar cells

A

a variation of photovoltaic cells that have the materials compressed into ultra-thin sheets for use in many surfaces; less efficient but cheaper

32
Q

Benefits of solar technology

A

use no fuel, have no moving parts, are quiet and safe, can last for 20-30 years, allow local and decentralized power control (where users don’t have to be near a plant or connected to a grid), emits no air pollution or greenhouse gases aside from during the production of equipment

33
Q

Disadvantages of solar technology

A

1) not all regions get the same amount of sunlight and those that get less may have trouble meeting needs and making profits; 2) intermittent, so daily or seasonal variations in sunlight can limit energy supply without other sources or sufficient storage in batteries/fuel cells/grids; 3) upfront costs are high

34
Q

How are the disadvantages of solar energy being mitigated?

A

reliance upon solar energy is possible in cloudy and dark areas with the right technology and many leaders in solar energy receive less sunlight; the use of nonrenewable energy or pumped-storage hydropower can compensate when sunlight is less available, plus battery storage is becoming more efficient and affordable; prices are dropping and efficiency is increasing for solar power as a whole and the technology can pay for itself in less than 10 years (then virtually free for as long as equipment lasts)

35
Q

What is the fastest growing power source?

A

photovoltaic cells

36
Q

What issues have occurred with China’s supply of solar power?

A

supply exceeded demand, leading to highly subsidized firms selling solar products abroad at prices so low they often lost money; drove manufacturers elsewhere out of business who then placed tariffs on Chinese imports in retaliation; both sides ended up filing complaints with the World Trade Organization

37
Q

Wind power

A

the generation of electricity from the energy created as sunlight heats the atmosphere and causes air to move (causes wind)

38
Q

Wind turbines

A

mechanical assembles that convert kinetic energy to electrical energy; often several in a group as a wind farm

39
Q

How do wind turbines work?

A

wind turns blades that turn a shaft in the nacelle and a gearbox in the nacelle converts the speed into higher speeds that are strong enough to power a generator; motor faces the wind at all times as rotation occurs in response to changes in direction; greater heights means lower turbulence and damage plus higher wind speed (average is 80 m); turn at specific wind speeds to effectively harness energy

40
Q

Which U.S. state generates the most wind power in the country (1/4)?

A

Texas

41
Q

At favorable locations, wind power can generate electricity at lower prices than fossil fuels.

A

true

42
Q

Why are offshore wind turbines an appealing idea?

A

wind speeds are an average 20% faster over water than land and the air is less turbulent/unsteady; likely more profitable even if construction and maintenance costs are higher

43
Q

When and where was the first offshore wind turbine constructed?

A

1991, Denmark

44
Q

What are the benefits of wind power?

A

produces no emissions once manufactured and installed; very efficient in optimal conditions (produces around 20x more energy than consumed, which is better than most energy sources); helps make small areas more self-sufficient; gives farmers and ranchers a way to make money by leasing land; increases property tax income in rural communities; provides many job opportunities

45
Q

What are the drawbacks of wind power?

A

intermittent and output varies from place to place; alleviated with multiple sources of energy, pumped-storage hydropower, batteries or hydrogen fuel as storage, and studying wind patterns before planning a wind farm

46
Q

What areas in the U.S. are best for wind farms?

A

mountainous regions, offshore and parts of the Great Plains; have higher wind speeds

47
Q

What makes supplying electricity from wind farms difficult in the U.S.?

A

population is largely concentrated on the coasts (offshore farms are few in number) and far from ideal areas; continent-wide transmission networks must be enhanced or more offshore farms are needed; offshore farms are often opposed for aesthetic reasons

48
Q

For whom can wind turbines be dangerous?

A

birds (especially large raptors) and bats, who can be killed if they fly into them; important to select sites away from migratory flyways or priming the surrounding habitat for affected species

49
Q

Geothermal energy

A

thermal energy that arises from beneath the Earth’s surface; radioactive decay under high pressure generates the heat that travels via molten rock or through cracks and fissures; may erupt as steam or water if it heats groundwater (geysers, submarine hydrothermal vents); may also be heated by magma

50
Q

How is geothermal energy accessed?

A

directly harness from geysers or (more commonly) drill wells to reach heated groundwater and pipe it upwards to heat buildings or for industrial processes

51
Q

Which country heats about 90% of its homes using geothermal energy?

A

Iceland

52
Q

Benefits of geothermal energy

A

inexpensive and efficient; all forms decrease greenhouse gas emissions substantially

53
Q

Drawbacks of geothermal energy

A

only feasible to use it where it is readily accessible, e.g., above a divergent plate boundary, and geothermal activity patterns do change; renewable but power plants cannot necessarily work indefinitely as water use that is too rapid for aquifers to recharge means a lack of energy (The Geysers tried to resolve this by injecting municipal wastewater to use instead); some hot groundwater has salts and minerals that corrode equipment and pollute the air, leading to equipment lasting for less time and higher maintenance costs

54
Q

How do geothermal power plants work?

A

use groundwater at 150-370 degrees Celsius and turn it to steam by decreasing the pressure in the compartments that hold it; steam turns turbines to generate electricity; steam is cooled, condensed and returned to its aquifer to maintain pressure

55
Q

What is the largest geothermal power plant in the world?

A

The Geysers (in California)

56
Q

Ground-source heat pumps (GSHPs)

A

provide heating by transferring heat from the ground to buildings and cooling by transferring heat from buildings to the ground using a network of plastic underground pipes that circulate water and antifreeze; take advantage of the fact that soil temperature varies less from season to season than air temperature anywhere in the world; has cool air in ducts or radiant cooling system and warm air in ducts, water tank, or radiant heating system under floor

57
Q

How do ground-source heat pumps compare with conventional heating/cooling systems?

A

heating is 50-70% more efficient, cooling is 25-60% more efficient, emissions decrease up to 70%

58
Q

Enhanced geothermal system (EGS)

A

involves drilling deep into dry rock, fracturing it, pumping in cold water, and drawing it back up when it is heated (as a means of creating geothermal energy sources where they are lacking); has been made profitable with tariffs (ex. in Germany) but may trigger minor earthquakes

59
Q

What kinds of energy can be harnessed from the ocean?

A

kinetic and thermal energy

60
Q

How is tidal energy harnessed?

A

by building dams across the outlets of tidal basins such that as tides rise, water passes through them, enters an enclosed basin, and turns turbines; possible because tides rise and fall twice a day and move large amounts of water

61
Q

Where is the most tidal energy harvested?

A

in long, narrow bays where the difference in height between low and high tides is the greatest

62
Q

What is the largest tidal energy station?

A

Sihwa Lake facility (South Korea)

63
Q

What is the oldest tidal energy station?

A

La Rance facility (France)

64
Q

Main benefit of tidal energy

A

little to no pollutant emissions

65
Q

Main drawback of tidal energy

A

can affect the ecology of estuaries and tidal basins

66
Q

Wave energy

A

energy from the motion of ocean waves

67
Q

What are some ways that wave energy may be harnessed?

A

through offshore floating devices that move up and down with waves, onshore funneling of waves into narrow channels and elevated reservoirs to generate electricity as they flow out, or using rising and falling on the coast to push air into and out of chambers to spin turbines

68
Q

What are the three ways to harness marine kinetic energy?

A

tides, waves, and currents

69
Q

Each day the ocean absorbs an amount of heat from the sun equivalent to ___ oil barrels.

A

250 billion

70
Q

Ocean thermal energy conversion (OTEC)

A

a way of utilizing the ocean’s thermal energy that relies upon the temperature gradient between surface and deep water

71
Q

What are some proposed ways of using OTEC to generate electricity?

A

piping warm surface water to a facility to evaporate chemicals with low boiling points (such as ammonia) and spin turbines, then condensing the gas with cold deep water to reuse it; evaporating warm surface water in a vacuum and using the steam to turn turbines, then condensing it with cold deep water

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