Renewable Energy Alternatives

Question 1

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?

Answer 1

Germany

Question 2

Feed-in tariff system

Answer 2

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

Question 3

Renewable Energy Sources Act of 2000 (Germany)

Answer 3

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)

Question 4

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

Answer 4

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

Question 5

What new energy policy was introduced in Germany in 2016?

Answer 5

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)

Question 6

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

Answer 6

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

Question 7

Net metering

Answer 7

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

Question 8

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

Answer 8

true (especially locally)

Question 9

Perpetually renewable energy

Answer 9

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

Question 10

Renewable energy is currently used more for ___ than ___ .

Answer 10

electricity generation; transport

Question 11

What is sometimes a major technical issue with renewable energy?

Answer 11

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

Question 12

What factors will increase renewable energy use?

Answer 12

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

Question 13

What are the main benefits of renewable energy?

Answer 13

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

Question 14

Green-collar jobs

Answer 14

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)

Question 15

About cost and availability of renewable energy

Answer 15

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)

Question 16

Criticism of public renewable energy subsidies

Answer 16

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

Question 17

Support of public renewable energy subsidies

Answer 17

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

Question 18

Renewable energy study by Mark Jacobson and Mark Delucchi

Answer 18

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.

Question 19

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

Answer 19

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

Question 20

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

Answer 20

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

Question 22

How does the sun release energy?

Answer 22

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

Question 23

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

Answer 23

25

Question 24

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

Answer 24

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

Question 25

Passive solar energy collection

Answer 25

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

Question 26

Active solar energy collection

Answer 26

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

Question 27

Flat plate solar collectors

Answer 27

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

Question 28

Solar cookers

Answer 28

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

Question 29

Concentrated solar power (CSP)

Answer 29

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

Question 30

Photovoltaic (PV) cells

Answer 30

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

Question 31

Thin-film solar cells

Answer 31

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

Question 32

Benefits of solar technology

Answer 32

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

Question 33

Disadvantages of solar technology

Answer 33

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

Question 34

How are the disadvantages of solar energy being mitigated?

Answer 34

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)

Question 35

What is the fastest growing power source?

Answer 35

photovoltaic cells

Question 36

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

Answer 36

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

Question 37

Wind power

Answer 37

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

Question 38

Wind turbines

Answer 38

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

Question 39

How do wind turbines work?

Answer 39

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

Question 40

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

Answer 40

Texas

Question 41

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

Answer 41

true

Question 42

Why are offshore wind turbines an appealing idea?

Answer 42

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

Question 43

When and where was the first offshore wind turbine constructed?

Answer 43

1991, Denmark

Question 44

What are the benefits of wind power?

Answer 44

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

Question 45

What are the drawbacks of wind power?

Answer 45

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

Question 46

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

Answer 46

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

Question 47

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

Answer 47

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

Question 48

For whom can wind turbines be dangerous?

Answer 48

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

Question 49

Geothermal energy

Answer 49

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

Question 50

How is geothermal energy accessed?

Answer 50

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

Question 51

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

Answer 51

Iceland

Question 52

Benefits of geothermal energy

Answer 52

inexpensive and efficient; all forms decrease greenhouse gas emissions substantially

Question 53

Drawbacks of geothermal energy

Answer 53

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

Question 54

How do geothermal power plants work?

Answer 54

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

Question 55

What is the largest geothermal power plant in the world?

Answer 55

The Geysers (in California)

Question 56

Ground-source heat pumps (GSHPs)

Answer 56

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

Question 57

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

Answer 57

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

Question 58

Enhanced geothermal system (EGS)

Answer 58

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

Question 59

What kinds of energy can be harnessed from the ocean?

Answer 59

kinetic and thermal energy

Question 60

How is tidal energy harnessed?

Answer 60

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

Question 61

Where is the most tidal energy harvested?

Answer 61

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

Question 62

What is the largest tidal energy station?

Answer 62

Sihwa Lake facility (South Korea)

Question 63

What is the oldest tidal energy station?

Answer 63

La Rance facility (France)

Question 64

Main benefit of tidal energy

Answer 64

little to no pollutant emissions

Question 65

Main drawback of tidal energy

Answer 65

can affect the ecology of estuaries and tidal basins

Question 66

Wave energy

Answer 66

energy from the motion of ocean waves

Question 67

What are some ways that wave energy may be harnessed?

Answer 67

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

Question 68

What are the three ways to harness marine kinetic energy?

Answer 68

tides, waves, and currents

Question 69

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

Answer 69

250 billion

Question 70

Ocean thermal energy conversion (OTEC)

Answer 70

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

Question 71

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

Answer 71

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

Question 72

Hydroelectric power (hydropower)

Answer 72

the generation of electricity using the kinetic energy of flowing river water

Question 73

How much of the world's electricity is supplied by hydropower?

Answer 73

about 1/6

Question 74

How is most hydropower generated and stored?

Answer 74

using concrete dams to trap water in reservoirs; allow water to pass through as needed

Question 75

How does hydropower work?

Answer 75

water turns turbines as it flows, generating electricity that travels through transmission lines and supplies the electrical grid; the turbine turns a rotor (a series of magnets) past a stator (the stationary part of a generator made of copper wire coils); provides a steady and predictable supply even when flow is low

Question 76

Run-of-river technique

Answer 76

diverts part of a river's flow through a pipe and a powerhouse, then returns it to the river; doesn't greatly disrupt flow and is useful in areas that are remote or lacking in the resources to construct larger sources of hydropower (i.e., dams); doesn't guarantee reliable water flow in all seasons but lowers storage impacts

Question 77

Pumped storage

Answer 77

a way to better control the timing of flow for hydropower; pumps water from a lower reservoir to a higher one when demand is weak and prices are low + from a higher reservoir to a lower one when demand is high and prices are high; needs energy input but profitable, helps to balance a region's power supply, and compensates for intermittency

Question 78

What are the advantages of hydropower?

Answer 78

renewable as long as precipitation fills rivers and reservoirs; more efficient than any other modern energy source with an EROI of 80:1; essentially emits no pollutants (fossil fuels are used to construct and maintain components + large reservoirs may release methane from anaerobic decay in deep water, but small contribution); a keystone of development and wealth in countries with many rivers and the needed resources

Question 79

What are the disadvantages of hydropower?

Answer 79

damming rivers destroys habitat as (ecologically rich) riparian areas above the sites are submerged and areas below are starved of water; disrupts natural flooding and floodplains don't receive nutrient-laden sediment as often due to regulated water discharge (instead sediment is trapped in the reservoir); modifies water temperature and blocks the passage of aquatic organisms, leading to decreased biodiversity

Question 80

What is the biggest hydropower project (in terms of generating capacity)?

Answer 80

Three Gorges Dam (China)

Question 81

Why might hydropower not expand much further?

Answer 81

most of the largest rivers in the world have already been dammed, plus opposition exists due to ecological impacts (some dams are no longer functional and are being dismantled which allows the ecosystem to recover)

Question 82

Wild and Scenic Rivers Act

Answer 82

protects some of the rivers in the U.S. (2%) from development (such as for hydropower)

Question 83

Bioenergy

Answer 83

energy from biomass; may involve burning it for heating, using it to generate electricity or processing it to create liquid fuel for transportation

Question 84

Biomass

Answer 84

organic material from living or recently living organisms that contains chemical energy from sunlight (with photosynthetic origins)

Question 85

What forms of biomass are used for heating?

Answer 85

fuelwood, charcoal, manure

Question 86

What forms of biomass are used for electricity (biopower)?

Answer 86

crop residues, forestry residues, processed wastes (from sawmills, pulp mills, paper mills, etc.), landfill gas, livestock waste used for anaerobic digesters to generate gas

Question 87

What forms of biomass are used for liquid fuel (biofuel)?

Answer 87

corn (for ethanol), bagasse/sugarcane residue (for ethanol), soybeans or rapeseed (for biodiesel), used cooking oil (for biodiesel), algae, plant matter treated with enzymes (for cellulosic ethanol)

Question 88

How many people use wood as their principal energy source?

Answer 88

more than 1 billion, especially in rural and developing areas (for cooking, heating, lighting)

Question 89

Wood, charcoal, and manure make up how much of all renewable energy worldwide?

Answer 89

about 1/2

Question 90

Bioenergy is always renewable.

Answer 90

false (regionally, overharvesting can occur)

Question 91

How can bioenergy be harmful?

Answer 91

overharvesting of resources involves deforestation and causes erosion and desertification; burning wood, etc. indoors has health hazards and pollutes the air; does deprive soil of the nutrients and organic matter it would have otherwise received (unless these are supplied manually by other means)

Question 92

What kinds of crops are best to use for biopower?

Answer 92

fast-growing crops (grasses like bamboo, fescue, and switchgrass + trees like specially bred willows and poplars)

Question 93

Small-scale options for biopower

Answer 93

farmers/ranchers/villagers can use manure for small-scale modular systems; rural or remote households can use small biodigesters for portable and decentralized energy

Question 94

Large-scale options for biopower

Answer 94

power plants that have been built or retrofitted to burn biomass may utilize 1) co-firing, where wood chips/pellets are combined with coal at coal power plants in a high-efficiency boiler; 2) gasification, where biomass is vaporized at high temperatures without oxygen to spin turbines and propel a generator; or 3) pyrolysis, where biomass is heated without oxygen but to produce liquid fuel for electricity

Question 95

What are the benefits of bioenergy (especially biopower)?

Answer 95

conserves resources and decreases greenhouse gas emissions by increasing efficiency and using waste products; replaces some coal which decreases sulfur dioxide emissions

Question 96

Biogas

Answer 96

a mixture of methane and other gases from breaking down organic matter without oxygen present; can be used for electricity, heating and vehicle fuel

Question 97

Where might biogas be collected?

Answer 97

biogas plants, landfills, wastewater treatment plants

Question 98

What are the two main biofuels?

Answer 98

ethanol for gas engines and biodiesel for diesel engines

Question 99

Ethanol

Answer 99

alcohol in liquor that is produced as a biofuel by fermenting biomass, often carbohydrate-rich crops, into sugar and then alcohol; primarily made using corn; widely added to gasoline in the U.S. to decrease emissions and conserve oil (a change that has been mandated and subsidized)

Question 100

Any gas engine can run on a blend of up to ___ % ethanol.

Answer 100

10

Question 101

Flexible-fuel vehicles can run on ___ % ethanol and ___ % gasoline, also known as E-85.

Answer 101

85; 15

Question 102

Why do some scientists oppose ethanol as a biofuel (even though policymakers often support it)?

Answer 102

growing corn takes up millions of acres of land and increases the use of fertilizers, pesticides and water; requires a large fossil fuel input for farm equipment, petroleum-based fertilizers/pesticides, transportation to processing plants, and heating water in refineries to distill ethanol; yields are modest compared to energy input (EROI is about 1.3:1)

Question 103

Biodiesel

Answer 103

fuel from vegetable oil, used cooking grease or animal fat mixed with small amounts of ethanol/methanol and a catalyst

Question 104

To produce biodiesel, Europe often uses ___ while the U.S. often uses ___ .

Answer 104

rapeseed oil; soybean oil

Question 105

B20 mix

Answer 105

a common mix of 20% biodiesel and 80% diesel for diesel vehicles (although they may run on 100% biodiesel)

Question 106

What are the benefits of biodiesel?

Answer 106

lowers greenhouse gas emissions, provides a fuel economy nearly as good as regular diesel, nontoxic and biodegradable, made more sustainable if produced from waste oils

Question 107

What are the drawbacks of biodiesel?

Answer 107

slightly more expensive than regular diesel, made from plants grown specifically for it and thus increases rainforest loss in tropical areas, etc. (as with ethanol)

Question 108

What potentially makes algae a good crop for biofuel?

Answer 108

major crops have big environmental impacts (reliance on any monocultural crop may not be sustainable); many species produce lipids that ca be converted to biodiesel and carbs and then to ethanol if desired; can produce a variety of fuels; may be grown outside in open, circulating ponds or in labs within closed tanks or tubes; grows faster and produces more oil than standard crops; can be grown in saltwater, saline water or nutrient-rich wastewater from sewage treatment plants

Question 109

Cellulosic ethanol

Answer 109

ethanol produced from cellulose (a material that gives plants their structure) using enzymes

Question 110

Benefits of cellulosic ethanol

Answer 110

cellulose has no nutritional value and is abundant, unlike the starch in corn/sugarcane or other crops for ethanol; commercially feasible production would allow for the use of low-value crop waste (corn husks, corn stalks, etc.) to produce it and prevent severe nutrition deprivation in soil

Question 111

What makes bioenergy carbon-neutral in principle?

Answer 111

has no net carbon dioxide release as burning biomass just releases carbon dioxide that plants recently pulled from the air during photosynthesis

Question 112

What makes bioenergy NOT carbon-neutral in practice?

Answer 112

forests are destroyed to plant crops (while forests hold more carbon in vegetation and soil than cropland) and fossil fuels are used in the production of biomass and its forms of energy (for fertilizers, pesticides, tractors, trucks, etc.)

Question 113

Why do most vehicles rely on gas over electricity?

Answer 113

electricity is not easily stored in large amounts for later use

Question 114

Fuel cells

Answer 114

essentially hydrogen batteries; hydrogen is a carrier as opposed to a primary source of energy but stores a lot of energy conveniently, efficiently and cleanly; use hydrogen to produce electricity for power

Question 115

How does hydrogen fuel drive electricity generation in fuel cells?

Answer 115

hydrogen molecules lose electrons at a negative electrode, leaving hydrogen cations (protons) to traverse a membrane; electrons then travel from the negative electrode to a positive electrode and generate a current; water is formed when oxygen combines with protons and electrons from the positive electrode

Question 116

Benefits of hydrogen fuel

Answer 116

can decrease dependence on foreign fuels and helps with climate change; will never run out; clean and nontoxic if used properly; few emissions that can be decreased with certain sources of hydrogen and electricity; only waste is water, heat and negligible traces of other compounds; highly efficient, with 35-70% of the energy produced being usable or up to 90% if the system captures heat as well as electricity; cells never need recharging unlike standard batteries and produce electricity whenever hydrogen is supplied

Question 117

How can the use of hydrogen fuel be expanded?

Answer 117

governments can fund research to develop it and auto companies can develop vehicles to run on it

Question 118

Hydrogen molecules exist freely in the Earth's atmosphere.

Answer 118

false (only atoms bind to other molecules)

Question 119

Electrolysis

Answer 119

refers to using an energy (electricity) input to split hydrogen atoms from oxygen atoms in water (or other sources of hydrogen, including fossil fuels and biomass); can provide the hydrogen gas for hydrogen fuel; source of electricity and hydrogen determine if the process causes pollution (fossil fuels and biomass use less input but cause emissions)

Question 120

The reaction of hydrogen and oxygen in fuel cells (2H₂ + O₂ --> 2H₂O + electricity) is the ___ electrolysis.

Answer 120

reverse of

Question 121

Drawbacks of hydrogen fuel

Answer 121

there is a lack of infrastructure to support it (through transport, storage and provision of fuel); leakage of hydrogen can deplete stratospheric ozone and increase the lifetime of methane in the atmosphere