© 2011 Pearson Education, Inc. CHAPTER 16 Renewable Energy.

© 2011 Pearson Education, Inc.

CHAPTER 16

Renewable Energy


An introduction to renewable energy• Coastal locations are known for constant, cooling

wind• Drawing tourists and residents

• Vacationers increase the population and stress the energy infrastructure• A proposed wind farm off Nantucket Sound could

supply 75% of the area’s electricity• There would be 130 turbines, each 417 feet tall

• People opposed to the wind farm filed lawsuits• Visual pollution• Threats to tourism, navigation, fishing, and birds


Wind farms are controversial• Proponents of wind farms view concerns as a case

of NIMBY (Not In My Backyard)• Opinion polls show strong support for wind farms• Every state and federal agency has approved• The wind farm may be operable by 2011

• Wind farms are appearing all over the U.S. and other countries• In 2008, wind power provided energy to 6.5 million

U.S. homes


Solar, too• Solar energy provides hot water and electricity

globally• Building design, insulation, and solar collection

devices can reduce energy bills by 75%• “Farms” with trough-shaped mirrors boil water or

synthetic oil and drive turbogenerators• A renewable-energy future is absolutely essential• It can replace limited, polluting fossil fuels and nuclear• Solar and wind energy are becoming cost competitive

• Renewables provide 6.7% of U.S. and 18% of world energy


Rooftop hot water


Solar thermal power in southern California


Renewable-energy use in the United States


Putting solar energy to work• Solar energy originates from the Sun’s thermonuclear

fusion• Solar constant: radiant (solar) energy reaching Earth• Energy ranges from ultraviolet to visible to infrared (heat)• 50% of the energy makes it to Earth, 30% is reflected,

20% is absorbed by the atmosphere• The amount of sunlight reaching Earth is almost

unbelievable• Full sunlight delivers 700 watts/m2 to Earth’s surface• 700 MW of power (equals a large power plant) delivered

to 390 mi2

• The Sun delivers 10,000 times the energy used by humans


The solar-energy spectrum


Using solar energy• Using solar energy does not change the biosphere’s

energy balance• Energy absorbed by water or land, in photosynthesis, or

used by humans is ultimately lost as heat

• Solar energy is abundant but diffuse• Varies with season, latitude, and atmospheric conditions

• Using solar energy requires turning a diffuse, intermittent source into a form (fuel, electricity) that can be used

• Collection, conversion, and storage of solar energy are difficult and must be cost effective


Solar heating of water• Flat-plate collector: a thin, broad box• The black bottom absorbs sunlight and heats up• Water in tubes absorbs the heat• The glass top prevents heat loss

• Active systems: use pumps to move the heated water

• Passive systems: use gravity and convection to move water• The collector is lower than the tank• Heated water from the collector rises through

convection


The principle of a flat-plate solar collector


Solar energy is used worldwide• The U.S. has over 1 million residential and 200,000

commercial solar hot-water systems• This is only a small fraction of hot-water heaters• The initial cost is 5–10 times higher than gas or

electric heaters• Over time, the solar system is cheaper to use

• In the U.S., solar thermal collection systems heat pools

• China leads the world in using solar thermal systems• 10% of people get hot water from these systems


Solar space heating• Flat-plate collectors can be used for space heating• They are less expensive and can be homemade• It is necessary only to have air circulate through the

collector box

• Efficiency is gained if collectors are mounted to allow convection to circulate the heated air into areas to be heated


Passive hot-air solar heating


Building = collector• A building can act as a collector for solar space

heating• Windows should face the Sun• Insulated drapes or shades can trap heat inside

• The building should have appropriate insulation, doors, and windows to store heat• Tanks of water or rocks do not store heat economically

• Awnings or shades shield windows from summer heat• Deciduous vegetation blocks summer but not winter

heat• Evergreen hedges on the shady side protect from the

cold


Solar building siting


Earth-sheltered housing• Combines insulation and solar heating• Earth insulates the building• The building is oriented for passive solar energy

• Earth (berms) can be built up against a conventional house• Or the building can be covered with earth• The building has south-facing windows

• Walls and floors store heat during the day• Release it during the night to warm the house

• Moisture must be controlled with dehumidifiers


Earth hall


Energy Stars• A well-designed solar-energy building can reduce

bills• With added construction costs of only 5–10%

• 25% of our energy use is for space and water heating• Solar design can save oil, natural gas, and coal

• In 2001, the EPA extended its Energy Star Program to buildings using at least 40% less energy and meeting other criteria• By 2008, 4,100 buildings had saved $1.5 billion/yr


Criticizing solar heating misses the point• Solar heating is criticized for needing a backup

heating system• Good insulation minimizes this need• Backup can come from a small wood stove or gas

heater

• This criticism misses the point: • The objective of solar heating is to reduce

dependency on conventional fuels• Fuel demand is reduced, and the economic and

environmental costs are also reduced


Solar production of electricity• Solar energy can produce electrical power• Providing an alternative to coal and nuclear power

• Photovoltaic (PV) cells: a wafer of material• One wire is attached to the top, one to the bottom• Sunlight striking the wafer puts out 1 watt of power• 40 linked PV cells produce enough energy to light a

lightbulb

• PV cells are highly sophisticated• Light hitting the wafer causes an electron to go from

the lower layer to the upper layer


Photovoltaic cell


Solar cells do not wear out• Solar cells convert light energy directly to electrical

power• With 15–30% efficiency

• Cells have no moving parts and last about 20 years• Silicon, one of the most abundant elements, is the

main material used in solar cells• The cell’s cost lies mostly in its design and construction• Cells are used in calculators, watches, toys, rural

homes, pumps, traffic signals, transmitters, lighthouses, satellites

• Net metering: rooftop electricity is subtracted from power use from the power grid


Cost• The cost of PV power = 25 cents per kilowatt-hour• Other sources = 6–12 cents per kilowatt-hour

• More efficient cells and less expensive technologies• Dramatically reduce costs• Provide incentives for more applications, sales, and

markets

• This industry is the fastest growing energy technology• In 2008: existing PV panels turned sunlight into

16,000 MW


The market for PV panels


Inverters: complicated yet necessary• Act as an interface between the solar PV modules

and the electric grid or batteries• Convert incoming direct current (DC) to alternating

current (AC) from the grid or for powering the devices

• Also act as a control that detects and responds to fluctuations in voltage or current

• Must be robust enough to withstand the heat of attics for rooftop PV systems

• Costs have declined, but are still substantial• But they are eligible for subsidies


PV system inverter


Utilities• Utility companies are moving toward large-scale PV use• 53 plants worldwide (2008) generating 10 MW• The largest U.S. plant is in Nevada

• The most promising future for PV power: rooftop panels• Unused space (e.g., warehouse and factory roofs)

• California, New York, New Jersey, Connecticut give incentives for home use• A 2 kW system gives half the energy needed for 1 year

• The 2008 Emergency Economic Stabilization Act gives tax credits for 30% of system costs


PV power plant


New PV technologies• Costs must decline to compete with other electricity

sources• New technologies are in production or close to it

• Thin-film PV cells: amorphous silicon or cadmium telluride• Instead of expensive silicon• The film is applied to roofing tiles or glass

• Silicon crystals are sliced to make SLIVERs• Uses 10% of the silicon in normal cells

• Light-absorbing dyes transmit energy to solar cells on the edge of the glass• Light passes through to conventional solar panels


Concentrated solar power (CSP)• Technologies convert solar energy into electricity • Reflectors (concentrators) focus sunlight on a

receiver, which transfers the heat to a conventional turbogenerator

• CSP works well in sunny, remote areas• Solar troughs: reflect sunlight onto a center pipe• Heat-absorbing liquid is heated to high temperatures,

boiling water to produce steam for a turbogenerator• Energy can be stored for release at night• The Mojave Desert generates one-third the capacity

of a nuclear power plant at a cost equal to coal-fired facilities


CSP technologies• Power towers: Sun-tracking mirrors focus sunlight

onto a receiver mounted on a tower at the center of the area• Heated liquid flows to a heat exchanger to drive a

turbogenerator or a tank to store the heat• A California facility generates electricity for 10,000

homes

• Dish-engine system: parabolic concentrators focus sunlight onto a receiver• Fluid is transferred to an engine that directly

generates electricity at 30% efficiency


Power tower Solar Two


Solar dish-engine system


The future of solar energy• Solar energy: a $20 billion industry and is growing

rapidly • It is hard to keep up with demand

• But solar energy does have disadvantages• Technologies are more expensive than traditional

energy sources (but subsidies help decrease costs)• A backup energy source, storage battery, or thermal

storage for nighttime power is needed• Many areas are not sunny in winter

• But other energies also have disadvantages • Mining, greenhouse gas emissions, nuclear waste, etc.


Matching demand• 70% of electrical demand is during the day – we can use

solar• We can rely on conventional sources at night• Air-conditioning, the second largest power user (after

refrigeration), is well-matched to energy from PV cells

• Solar and wind can replace coal and nuclear electrical power• Can be planned and built in months, not years• Can be installed in small increments• Have less financial risk for utility companies• Are less vulnerable to terrorist attacks • Can provide energy for the 1.6 billion in poor nations


Indirect solar energy• Energy from the Sun is the driving force behind

dams, firewood, windmills, sails• The force of falling water can turn paddle wheels• To grind grain, saw logs, do other tasks

• Hydropower: hydroelectric dams use water under high pressure to drive turbogenerators

• In the U.S., it generates 6% of electrical power• 300 large dams mainly in the Northwest and

Southeast

• Worldwide, dams generate 19% of electrical power• It is the most common form of renewable energy


Hoover dam


Trade-offs: benefits of dams• Dams, especially large ones, have benefits and

serious consequences• Benefits• They eliminate the cost and environmental impacts of

fossil fuels and nuclear power• Dams provide flood control and irrigation water• Reservoirs provide recreational and tourist

opportunities• Pumped-storage power dams can pump water to a

higher reservoir for later use during peak times


Trade-offs: disadvantages of dams• Reservoirs drown farmland, wildlife habitats, towns• Land of historical, archaeological, or cultural value

• Reservoirs displace rural populations• In the last 50 years, 40–80 million have been

displaced

• Dams impede or prevent migration of fish• Even if ladders are provided• Fish habitats are suffering

• Dams wreak havoc downstream• Decreased sediment reaches the river’s mouth


More dams?• The U.S. and other developed nations have brought

their hydropower to maximum capacity• The U.S. has 75,000 dams 6 feet or higher• Two million smaller dams• The Wild and Scenic Rivers Act (1968) protects most

of the last 2% free-flowing rivers• Many dams that impede river flow are being removed

• Worldwide, dams are controversial• The projected benefits may not justify the ecological

and sociological effects


The Nam Theun 2 Dam• A 50-m-tall dam being completed on the Mekong

River in Laos• Is projected to help Laos develop• The project has displaced 6,200 people• It will damage or destroy 174 square miles of

sensitive environments

• It is being built to sell power to Thailand• Critics say the government cannot manage this

project• Money will not be used to help the poor


Dam report• The Three Gorges Dam on the Yangtze River in China• Was completed in 2006• Is the world’s largest dam (1.4 miles long)• Displaced 1.2 million people• Will generate electricity and control floods• Produces electricity equal to 12 coal-fired plants

• The World Commission on Dams 2000 report found dams are a mixed blessing• They should be built only as a last option

• Many more dams will be built in China, Brazil, India, etc.


Wind power• The Horse Hollow Wind Energy Center in Texas• The world’s largest wind farm• 304 turbines on 47,000 acres produce electricity for

260,000 homes

• The U.S. is the world leader in wind energy• Germany is second

• Wind capacity has increased 28%/yr• It is economically competitive• It could provide 12% of the world’s electricity by 2020


Horse Hollow Wind Energy Center


Wind energy in the U.S.


Design• The most practical design is using wind-driven

propellers• The propeller shaft is geared directly to a generator• Wind turbine: a wind-driven generator

• Reliability and efficiency have reduced electric costs• Wind farms: arrays up to several thousand turbines• Produce pollution-free power competitive with

traditional sources

• The amount of wind that can be tapped is immense• Wind farms in the Midwest could meet U.S. needs• Farmers are paid well to put turbines on their land


Drawbacks• Wind is intermittent, so backup or batteries are

needed• Wind farms can be visually unappealing• Turbines can be hazardous to birds• When placed on migratory routes or in critical habitat• But far fewer die than from cars, traffic, and windows

• Offshore wind farms use dependable, strong winds• They have less of a visual impact• Land does not need to be bought

• New turbines in 2008 displaced emissions from 40 coal plants


Biomass energy• Burning firewood for heat: the oldest form of energy• Renamed “utilizing biomass energy”

• Biomass energy: energy derived from present-day photosynthesis• Leads hydropower in U.S. renewable energy• Most is used for heat

• Produced by burning wood or municipal waste, generating methane, or producing alcohol


Burning firewood• With enough forests, burning firewood (fuelwood)

can be a sustainable energy resource• The primary cooking and heating source for 2.6 billion

• Five million U.S. homes use only wood stoves for heat• Another 20 million use them for some heating

• Pellet stoves use compressed pellets made from wood wastes• They need little attention and they burn efficiently


Pellet stove


Fuelwood crisis?• Consumptive fuelwood use: people get wood from forests

for their daily needs• Productive use: people convert wood into charcoal to sell• Both can degrade local forests and woodlands• Global fuelwood use peaked in the 1990s and is declining• With development, people switch to fossil fuels

• The Millennium Ecosystem Assessment judged that fuelwood demand is not a significant cause of deforestation• But it could be if fossil fuel costs continue to increase• There are also local areas of concern


Burning wastes• Facilities can generate electricity from burning• Municipal wastes (waste-to-energy)• Wood wastes: sawmills, woodworking companies• Cane wastes: sugar refineries• Olive oil wastes: provides electricity to 100,000

homes in Spain

• The power may meet only a small percent of electrical needs• But it is a productive, inexpensive way to dispose of

biological wastes


Producing methane• Biogas: anaerobic digestion of sewage sludge to

produce methane• Nutrient-rich sludge for fertilizer

• Animal manure can also be digested• Millions of Chinese farmers have digesters:

underground fermentation chambers with a dome on top to store gas• Fermented agriculture wastes (pig manure, cattle dung)• Biogas is used for cooking, heating, lighting• The residual slurry is used for fertilizer

• India and China provide subsidies for home biogas plants


Biogas power


Renewable energy for transportation• The most critical need for a sustainable energy

future: a new way to fuel vehicles• Biofuels: complex organic matter (plant and animal

waste)• Ethanol and biodiesel

• Biofuels produce only 1% of global transportation fuels• But they are expanding rapidly• High oil prices, new technologies, farmer support,

subsidies, environmental concerns• Sources come from agricultural and food commodities


Ethanol• Produced by the fermentation of starches or sugar• Using corn, sugarcane, sugar beets, or other grains

• Production costs make it more expensive than oil• Until oil sells for more than $55/barrel

• Gasohol: 10% ethanol, 90% gasoline• Widely used in the U.S. Midwest• Provides another corn market to help local economies

• The U.S. uses 10 billion gallons (240 million barrels)/yr• Equal to 160 million barrels of oil (ethanol contains

two-thirds the energy of regular gasoline)


Farm production• 25% of U.S. corn is dedicated to ethanol• Ethanol facilities also produce corn oil and livestock

feed

• Future production will reach 12.6 billion gallons/yr• The 45 cent/gallon tax credit helps it compete with oil

• A renewable fuel standard (RFS)• Requires renewable fuel in gasoline • Mandated 9 billion gallons of renewable fuels in 2008• Increasing to 15 billion gallons by 2015• The 2002 36 billion gallon target will also use other

sources


Can ethanol reduce oil imports and emissions?• Ethanol equals 5% of U.S. gasoline consumption• It could rise to 15% if all corn were used (impossible)• No more farmland is available for expansion• It may have contributed to recent increases in food

costs• Producing (fertilizer, pesticides, machines),

transporting, and operating ethanol plants use fossil fuels

• Replacing oil with ethanol reduces greenhouse gases 13%

• The primary strategy for ethanol? • Reducing reliance on imported oil


Second-generation biofuel• Made from cellulosic feedstocks• Crop residues, grasses (switchgrass), logging

residues, fast-growing trees, fuelwood

• Miscanthus: a giant perennial grass • Grows in poor soils• Outproduces corn and other grasses

• Cellulosic technology uses enzymes to break cellulose• Cheaper and more energy efficient• 11 plants are being constructed in the U.S.• A $1.01 tax credit helps increase this industry


Miscanthus x giganteus


Air quality• Ethanol substitutes for methyl tertiary butyl ether

(MTBE)• A fuel additive that makes cleaner-burning gasoline• Reformulated gasoline: contains additives to improve

air quality

• MTBE is carcinogenic in animals• It is showing up in water supplies

• The Energy Policy Act refused to grant the oil industry liability protection against MTBE• The industry is turning toward ethanol


Biodiesel• Biodiesel: made largely from soybean oil• But can come from any natural oil or fat• Even from recycled vegetable oil from frying

• Competitive with petroleum diesel fuel• $1/gallon tax credit

• Equals 1% of U.S. diesel fuel transportation use • Offbeat technologies can produce biodiesel• One Missouri plant uses turkey wastes• Converts 250 tons/day of wastes into 20,000 gallons

at a profit, plus fertilizer from wastes


Hydrogen: highway to the future?• Conventional cars can be adapted to run on hydrogen

gas• Hydrogen is not a fuel but an energy carrier – like

electricity• It must be generated using another form of energy

• The only major by-product of burning H2 is water

• 2H2 + O2 → 2H2O + energy

• There is almost no hydrogen gas on Earth• Atmospheric gas is ignited by lightning to form water• Soil bacteria produce hydrogen, which other bacteria use• Elemental hydrogen is combined with other elements


Hydrogen can be extracted from water• Electrolysis: extracting hydrogen from water• Requires an input of energy

• Hydrogen can be derived from hydrocarbon fuels • Such as methane, petroleum oil, methyl alcohol• More energy is put into the process than is in

hydrogen• It is better to use the hydrocarbons directly

• Using hydrogen requires an cheap, abundant, nonpolluting energy source• Solar energy


Plants do it• Photosynthesis splits water into hydrogen and

oxygen• Using light energy

• One method can mimic this process: a catalyst of cobalt and phosphorus can be used to split water• The electricity could come from solar cells• It operates in neutral water and ambient temperature

and pressure

• Another process uses electrolysis to pass an electric current through water• Hydrogen gas is collected, compressed, and stored


Electrolysis has drawbacks• It is hard to store enough hydrogen to allow a vehicle

to travel long distances• Compressing hydrogen requires energy• Reducing the energy efficiency involved

• Hydrogen can be combined with metal hydrides to absorb the gas and release it when needed• Most hydrides are too heavy to use


Solar energy to hydrogen• Arrays of solar-trough or PV generating facilities

would produce electricity• In deserts of the southwestern U.S.

• The electrical power would produce hydrogen by electrolysis

• Hydrogen would be moved through underground pipes• They already exist• Additional pipes would be expensive


The Model U• Ford’s concept car• Its internal combustion engine runs on hydrogen• It has a range of 300 miles

• But there must be a hydrogen-fueling infrastructure• Cars like the Model U would be replaced by fuel cells

• Fuel cells: devices that chemically combine hydrogen or some other fuel with oxygen• Produces an electrical potential, instead of burning• Emissions are water and heat


Fuel cells are being used• Fuel cells are 45–60% efficient (combustion engines =

20%)• Vehicles have hundreds of fuel cells in a fuel-cell stack• Along with a hydrogen storage device, a cooling

system, and a device to force oxygen into the fuel cell• Fuel cells power buses all over the world• GM’s Hy-wire and Sequel have no engine

compartments• By-wire systems: electronically controlled units that

replace steering, braking, and other mechanisms• All major car manufacturers are developing concept

cars


Hydrogen-oxygen fuel cell


FreedomCAR• Obstacles to fuel-cell-driven vehicles are their high

cost and lack of infrastructure for refueling• President Bush’s FreedomCAR and Fuel Partnership

(2003)• A government-industry partnership to promote research

• The National Research Council recommended shifting to developing plug-in hybrid electric vehicles (PHEVs)• Still support some fuel-cell vehicle research

• The American Recovery and Reinvestment Act (2009)• Gives $2.4 billion to help meet President Obama’s goal

of 1 million PHEV vehicles by 2015


The hydrogen economy• Will emerge when hydrogen infrastructure is in place• Vehicles powered by fuel cells are available

• With a hydrogen economy, we will no longer be tied to nonrenewable, polluting energy sources

• A hydrogen economy is still decades away• There are other renewable-energy options available


Geothermal energy• Around the world, springs yield hot, almost boiling,

water• These areas also have natural steam vents and other

thermal features

• These features occur where the hot molten rock of Earth’s interior is close enough to heat groundwater• Near volcanic regions

• Geothermal energy: using naturally heated water or steam to heat buildings or produce electricity

• In 2008, geothermal energy provided electricity equal to 10 large nuclear or coal-fired power plants


Geothermal energy


The U.S.: world leader in geothermal energy• The Geysers, 70 miles north of San Francisco• The largest electrical generating geothermal facility

• Homes and buildings are also directly heated • Especially in Japan and China

• Enhanced geothermal systems (EGS): produce electricity• Holes are drilled into granite that holds high

temperatures• Water is injected into one hole and turns to steam• The steam flows up another hole to a power plant

• The U.S. has widespread underground heat• $1 billion should be invested in EGS technology


Heat pumps• Earth can be used as part of a heat exchange

system• Far more abundant than large geothermal power

plants

• The ground extracts heat in winter and absorbs it in the summer• Eliminates separate heating and air-conditioning

systems

• A geothermal heat pump (GHP) system: uses loops of buried pipes filled with antifreeze solution• Air is moved through the pump and the house

• High costs are offset by being trouble-free and long-term savings


Geothermal heat pump system


Tidal and wave power• The twice-daily rise and fall of ocean tides have a

phenomenal amount of energy• Tidal barrage: a dam is built across the mouth of a

bay• Incoming and outgoing tides turn the turbines• 30 locations have tides high enough for this use• North America has one location: the Bay of Fundy

• Adverse environmental impacts • Traps sediments, impedes fish migration, prevents

navigation, and changes water circulation patterns


Ocean waves• It may be possible to harness energy in waves• But the technology is challenging

• The ideal location must:• Receive the wave’s force before it hits the sea floor• Be close to shore to hook up with transmission cables• Be deep enough not to crash to the floor during

storms

• The U.S.’s Pacific Northwest region qualifies• This technology is still in the early research and

development stage


Ocean thermal-energy conversion (OTEC)• Most oceans have a thermal gradient between warm

upper surface water and cool, deep water• OTEC uses this temperature difference to produce

power• Warm surface water heats and vaporizes ammonia to

drive a turbogenerator• Cool water recondenses the ammonia

• There is little interest, due to its low economic promise• Unless it can be coupled with other operations (e.g.,

cooling buildings)


Policies for a sustainable energy future• Global issues are clear:• Oil and gas will not last long• Fossil fuels produce pollution and greenhouse gases

• Renewable energy means sustainable energy• Global targets need to stabilize levels of greenhouse

gases• They must have a sustainable-energy development-

and-consumption pattern based on renewable energy

• Energy conservation and efficiency: focus on consumption by increasing mileage standards and energy efficiency


National energy policy• The U.S. has a serious oil-transportation problem• $500,000 leaves the U.S. each minute for imported oil

• The U.S. has a serious energy security problem• We are vulnerable to terrorism and whims of others

• Policy responses for U.S. energy include• The 2005 Energy Policy Act• The 2007 Energy Independence and Security Act

• The 2009 American Recovery and Reinvestment Act• Gave $43 billion to renewable energy and conservation• Intends to double energy from renewables by 2012


Supply-side policies for renewables• An RFS for ethanol and biodiesel to 15 billion gallons

by 2015, 35 billion gallons by 2022 • Anything over 15 billion gallons must come from second-

generation (non-corn) sources

• Continue funding for research and development of renewable energy (solar and biomass)

• Extend tax credits for electricity from wind, hydropower, geothermal, and biomass

• Tax credits for heat pumps, solar heating, biofuels, PV • Enable geothermal energy to compete with fossil fuels


Demand-side policies• Focus on energy conservation and efficiency• Increase CAFE standards to 39 mpg for cars by 2016• Extend the Energy Star Program to schools, homes,

etc.• Tax credits for increasing energy efficiency in homes• Require 30% increase in lightbulb efficiency• Already met by fluorescent lightbulbs (CFLs)

• The EPA will encourage waste-energy recovery• Efficiency standards and tax credits for most

appliances• Funding and tax credits for the FreedomCAR, hybrids,

and PHEVs


Policies can do more• Recent policies did not establish a federal renewable

portfolio standard (RPS)• Requiring utilities to provide increasing power from

nonhydroelectric renewable energy sources

• 16 states have set their own RPS• 10–20% renewable energy by 2010–2025

• Policies did not take direct action on global warming• But did expand DOE’s research on carbon capture

and sequestration• Efficiency and renewable energy will reduce

emissions


Final thoughts• The U.S. is making a serious effort to develop

renewable energy sources and increase efficiency• We are also trying to move to a hydrogen economy

• Current policy also promotes further use and development of fossil fuels• U.S. oil prices have been extremely low• Rising prices make consumers buy efficient or hybrid

cars

• A carbon tax levied on fuels based on their carbon emissions would encourage non-taxed renewable energies


CHAPTER 16

Renewable Energy

Active Lecture Questions


In 2001, the Environmental Protection Agency extended its ______ program to buildings and began awarding its label to energy-efficient buildings.

a. solar power

b. building collector

c. Earth-sheltered

d. Energy Star

Review Question-1


In 2001, the Environmental Protection Agency extended its ______ program to buildings and began awarding its label to energy-efficient buildings.

a. solar power

b. building collector

c. Earth-sheltered

d. Energy Star

Review Question-1 Answer


The inverter on a photovoltaic cell must change the incoming ______ current from the photovoltaic cell to ______ current compatible with the electricity coming from the grid.

a. direct; indirect

b. direct; alternating

c. alternating; direct

d. indirect; direct

Review Question-2


The inverter on a photovoltaic cell must change the incoming ______ current from the photovoltaic cell to ______ current compatible with the electricity coming from the grid.

a. direct; indirect

b. direct; alternating

c. alternating; direct

d. indirect; direct



Which of the following are considered disadvantages of building and using dams?

a. The reservoir created drowns the area behind

the dam.b. Dams can displace large populations of

humans.c. Dams can impede the migration of some fish.d. all of the above

Review Question-3


Which of the following are considered disadvantages of building and using dams?

a. The reservoir created drowns the area behind

the dam.b. Dams can displace large populations of

humans.c. Dams can impede the migration of some fish.d. all of the above



All of the following are forms of biomass energy except

a. burning firewood.

b. burning animal wastes.

c. producing methane.

d. harnessing the wind.

Review Question-4


All of the following are forms of biomass energy except

a. burning firewood.

b. burning animal wastes.

c. producing methane.

d. harnessing the wind.



______ are devices in which hydrogen or some other fuel is chemically recombined with oxygen in a matter that produces an electrical potential rather than initiating burning.

a. Hybrid engines

b. Fuel cells

c. Electrolysis cells

d. Photovoltaic cells

Review Question-5


______ are devices in which hydrogen or some other fuel is chemically recombined with oxygen in a matter that produces an electrical potential rather than initiating burning.

a. Hybrid engines

b. Fuel cells

c. Electrolysis cells

d. Photovoltaic cells



According to Fig. 16-3, which of the following is the greatest source of renewable energy in the United States?

a. oil

b. biomass energy

c. hydropower

d. natural gas

Interpreting Graphs and Data-1


According to Fig. 16-3, which of the following is the greatest source of renewable energy in the United States?

a. oil

b. biomass energy

c. hydropower

d. natural gas

Interpreting Graphs and Data-1 Answer


According to Fig. 16-18, the cost of wind energy in the United States

a. decreased dramatically from 1980 to 2000.

b. increased dramaticallyfrom 1980 to 2000.

c. remained the same between 1980 and 2000.

Interpreting Graphs and Data-2


According to Fig. 16-18, the cost of wind energy in the United States

a. decreased dramatically from 1980 to 2000.

b. increased dramaticallyfrom 1980 to 2000.

c. remained the same between 1980 and 2000.

Interpreting Graphs and Data-2 Answer


In about 30 locations around the world, tides of 20 feet or more are produced to generate

a. geothermal energy.

b. tidal and wave power.

c. oceanic pumps.

d. dams.

Thinking Environmentally-1


In about 30 locations around the world, tides of 20 feet or more are produced to generate

a. geothermal energy.

b. tidal and wave power.

c. oceanic pumps.

d. dams.

Thinking Environmentally-1 Answer


How can hydrogen gas be produced using solar energy?

a. with catalysts that allow us to mimic the process of photosynthesis

b. by connecting photovoltaic cells to water

c. by combining helium and oxygen

d. by using solar power to drive hydrogen turbines

Thinking Environmentally-2


How can hydrogen gas be produced using solar energy?

a. with catalysts that allow us to mimic the

process of photosynthesis

b. by connecting photovoltaic cells to water

c. by combining helium and oxygen

d. by using solar power to drive hydrogen turbines

Thinking Environmentally-2 Answer

© 2011 Pearson Education, Inc. CHAPTER 16 Renewable Energy.

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Transcript of © 2011 Pearson Education, Inc. CHAPTER 16 Renewable Energy.