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Biosphere CH 12- > Chapter 16 > Flashcards

Chapter 16 Flashcards

1
Q

U.S. renewable energy consumption

A

9% of the energy consumed in the U.S. comes from renewable sources; of this amount most derives from bioenergy and hydropower. Of electricity generated in the U.S. 13% comes from renewable energy sources, predominantly hydropower and wind

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2
Q

Economic Diversity

A

diversify an economy’s energy mix, reducing both price volatility and reliance on imported fuels. some renewable sources can generate income and property tax for rural communities and some help people in developing regions of the world to produce their own energy. Unlike fossil fuels, most renewable sources are inexhaustible on time scales relevant to society

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3
Q

Green-collar jobs

A

jobs resulting from new employment opportunities in a more sustainably oriented economy such as jobs in renewable energy

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4
Q

Reduced greenhouse gas emissions

A

renewable energy sources release far fewer greenhouse gas emissions than fossil fuels

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5
Q

Current market prices

A

most renewable energy sources have market prices higher than those for nonrenewable sources but some are competitive

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6
Q

Subsidies

A

Fossil fuels and nuclear power have received far more in U.S. governmental subsidies (mostly tax breaks) than have renewable energy sources

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7
Q

German feed-in tariff system

A

financial incentives for businesses and individuals that spread the use of renewable energy quicker

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8
Q

U.S. net-metering

A

governments set goals or mandate that certain percentages of power come from renewable sources; targets for renewable energy use

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9
Q

Market volatility

A

technologies evolve quickly and policies vary from place to place and can change unpredictably; results in steep price fluctuations, bursts of rapid growth and bankruptcies of promising companies

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10
Q

Ranking alternative energy sources

A

Wind power most desirable and ethanol least desirable (Science behind the story: figure 2)

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11
Q

Passive solar energy

A

buildings are designed to maximize absorption of sunlight in winter yet to keep the interior cool in the summer

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12
Q

Active solar energy

A

makes use of devices to focus, move or store solar energy

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13
Q

Building design

A

south-facing windows maximize the capture of winter sunlight and overhangs shade windows in the summer when the sun is high and cooling is desired; planting vegetation around a building buffers it from temp swings; along use materials that absorb heat, store it and release it later; all these approaches can conserve energy and reduce costs

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14
Q

Solar collectors

A

fig 16.7; flat plate solar collectors (solar panels) heat water and air for homes and businesses; dark heat-absorbing metal plates mounted on rooftops in flat glass-covered boxes. Water, air or antifreeze runs through tubes that pass through the collectors transferring heat from them to the building or its water tank

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15
Q

Solar cookers

A

.

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16
Q

Concentrated solar power plants

A

fig 16.8; utilities concentrate solar power to generate electricity at large scales; requires vast areas of land and water but impacts are still less than those exerted by fossil fuels

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17
Q

Photovoltaic (PV) cells

A

fig 16.9; converts sunlight to electrical energy; sunlight hits the silicon layers of the cell, electrons are knocked loose from some of the silicon atoms and tend to move from the boron-enriched “p-type” layer toward the phosphorous enriched “n-type” layer; imbalance connected by wiring remedies this imbalance; direct current converted to alternating current to produce usable electricity

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18
Q

Thin-film solar cells

A

photovoltaic materials compressed into ultra-thin sheets; less efficient in converting sunlight to electricity but are cheaper to produce

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19
Q

Production and pricing of solar energy

A

production of PV cells has grown exponentially and prices have fallen rapidly

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20
Q

Benefits and limitations of solar

A

harnessing solar energy is more profitable in sunny regions such as the southwestern U.S. than in cloudier regions like Alaska

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21
Q

Function of a wind turbine

A

convert kinetic energy (energy of motion) to electrical energy; wind blowing into a turbine turns the blades of the rotor, which rotate machinery inside a compartment called a nacelle which sits atop a tower. Inside the nacelle is a gearbox, generator, and equipment to monitor and control the turbine’s activity; turbines rotate in response to changes in wind direction and they turned at specified wind speeds to harness energy efficiently

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22
Q

Production and pricing of wind energy

A

production of wind power has been doubling every 3 yrs in recent years and prices have fallen; most of the world’s wind power capacity has been developed in China, the U.S. and Germany

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23
Q

Offshore wind farm

A

offshore winds tend to be stronger yet less turbulent; more wind farms being developed offshore

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24
Q

NIMBY syndrome

A

not in my backyard syndrome; characterization of opposition by residents to a proposal for a new development because it is close to them (or, in some cases, because the development involves controversial or dangerous technology) often with the connotation that such residents believe that the developments are needed in society but should be further away

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25
Q

Benefits and limitations of wind energy

A

wind speeds vary from place to place and time to time; most populations in the U.S. don’t live near highest wind speeds located in the Great Plains and mtn ranges so the electricity would need a way to reach populated areas; pose a hazard to birds and bats which get killed by the turbines

26
Q

Geothermal energy

A

thermal energy that arises from beneath Earth’s surface; radioactive decay of elements amid high pressures deep in the interior of the Earth generates heat that rises to the surface in molten rock and through cracks and fissures

27
Q

Geothermal power plants

A

harness naturally heated water and steam to generate electricity; brings groundwater to the surface and converts it to steam by lowering the pressure in specialized compartments; the steam turns turbines to generate electricity

28
Q

Enhanced geothermal systems

A

drill deeply into dry rock, fracture the rock and pump in cold water. the water becomes heated deep underground and is then drawn back up and used to generate power

29
Q

Ground source heat pumps

A

provide an efficient way to heat and cool air and water in a home; transfers heat from the ground into buildings and they provide cooling in the summer by transferring heat from buildings into the ground

30
Q

Benefits and limitations of geothermal energy

A

reduce emissions relative to fossil fuel combustion; renewable; power plants can’t operate indefinitely b/c plant could use heated water more quickly than groundwater is recharged so it will eventually run out of water; geothermal activity of Earth’s crust can shift overtime; hot groundwater can be laced with salts and minerals that corrode equipment and pollute the air

31
Q

Tidal Energy

A

erecting dams across the outlets of tidal basins; as tidal currents pass through the dam, water turns turbines to generate electricity

32
Q

Wave Energy

A

energy harnessed from the motion of waves; many designs for machinery to harness wave energy have been invented, but few have been adequately tested

33
Q

Ocean Thermal Energy Conversion (OTEC)

A

a potential energy source that involves harnessing the solar radiation absorbed by tropical ocean water

34
Q

Benefits and limitations of ocean energy

A

tons of energy that is constant (24/7); reliable and will always be there; hasn’t been adequately tested and infrastructure isnt in place for it yet

35
Q

Hydroelectric power (hydropower)

A

uses the kinetic energy of a flowing river water to turn turbines and generate electricity

36
Q

Storage

A

water is stored behind dams so as reservoir water passes through a dam it turns the blades of turbines which cause a generator to generate electricity; electricity generated in the powerhouse is transmitted to the grid by transmission lines

37
Q

Run-of-the-river

A

generates electricity without greatly disrupting a river’s flow; one method is to divert a portion of a river’s flow through a pipe or channel, passing it through a powerhouse and returning it to the river

38
Q

Pumped storage

A

better controls timing of flow; water is pumped from a lower reservoir to a higher reservoir at times when demand for power is weak and prices are low; when demand is strong and prices are high water is sent downhill through a turbine generating electricity

39
Q

Hydropower producers

A

China, Brazil, Canada, U.S., Russia

40
Q

Benefits and Limitations of hydropower energy

A

dependable, low operating cost, green; expensive to build, drought

41
Q

Sources and Uses of Bioenergy

A

for direct combustion for heating; for generating electricity (biopower); for powering vehicles (table 16.2)

42
Q

Biomass for heating and cooking

A

wood from trees; in theory trees are renewable but not is they are overharvested

43
Q

Biopower

A

biomass for electricity generation; burned in power plants to produce heat

44
Q

Waste products

A

waste products can be combusted for biopower; woody debris from logging, liquid waste from pulp mills, organic waste from landfills or feedlots and residue from crops (cornstalks or husks)

45
Q

Crops

A

growing certain plants as crops specifically to generate biopower; these include fast-growing grasses such as bamboo, fescue and switchgrass as well as trees like willow and poplars

46
Q

Biodigesters

A

use livestock manure to generate electricity; provide portable and decentralized energy production for remote rural areas

47
Q

Co-firing

A

wood chips, wood pellets or other biomass is introduced with coal into a high-efficiency boiler at some coal-fired power plants; minor equipment modification

48
Q

Gasification

A

biomass is vaporized at high temperatures in the absence of oxygen, creating hydrogen, carbon monoxide, carbon dioxide and methane; this mixture generates electricity when used to turn a gas turbine to propel a generator in a power plant

49
Q

Pyrolysis

A

heating biomass in the absence of oxygen that produces a liquid fuel that can be burned to generate electricity

50
Q

Benefits and limitations of bioenergy

A

widely available, low cost inputs, requires water to grow, not entirely clean when burned, may compete with food production, land utilization; no net gain

51
Q

Biofuels

A

liquid fuels used primarily to power automobiles

52
Q

Ethanol

A

the alcohol in beer, wine and liquor; produced as a biofuel by fermenting biomass from carbohydrate rich crops

53
Q

Flexible-fuel vehicle

A

run on a mix of 85% ethanol and 15% gasoline

54
Q

Corn and sugarcane

A

40% of U.S. corn crop is used to make ethanol

55
Q

Biodiesel

A

produced from vegetable oil, used cooking grease or animal fat

56
Q

Algae

A

one promising next-generation biofuel that does not exert heavy impacts on land; produce large amounts of lipids that can be converted to biodiesel

57
Q

Cellulosic ethanol

A

uses enzymes to produce ethanol from cellulose, the substance that gives structure to all plant material

58
Q

Benefits and limitations of biofuels

A

cheaper than gasoline; can be grown locally

59
Q

Electrolysis

A

electricity is input to split hydrogen atoms from the oxygen atoms of water molecules; produces pure hydrogen and it does so without emitting carbon or nitrogen based pollutants of fossil fuel production

60
Q

Function of hydrogen fuel cell

A

.

61
Q

Benefits and limitations to switching to a hydrogen economy

A

lack of infrastructure, would require massive and costly development of facilities; concern of leakage of hydrogen

Biosphere CH 12- (5 decks)

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