Energy Efficiency and Renewable Energy

1
Energy Efficiency and Renewable Energy
2
Core Case Study Icelands Vision of a
Renewable-Energy Economy (1)

• Supplies 75 of its primary energy and almost all
  of its electrical energy using
• Geothermal energy
• Hydroelectric power
• No fossil fuel deposits imports oil
• Bragi Arnason Dr. Hydrogen
• Energy vision

3
Core Case Study Icelands Vision of a
Renewable-Energy Economy (2)

• 2003 Worlds first commercial hydrogen filling
  station
• 20032007 three prototype fuel-cell buses
• 2008 10 Toyota Prius test vehicles
• Hydrogen-fueled
• Whale-watching boat partially powered by a
  hydrogen fuel cell

4
Why Is Energy Efficiency an Important Energy
Resource?

• We could save as much as 43 of all the energy we
  use by improving energy efficiency.

5
We Waste Huge Amounts of Energy (1)

• Energy conservation
• Energy efficiency
• Advantages of reducing energy waste
• Quick and clean
• Usually the cheapest to provide more energy
• Reduce pollution and degradation
• Slow global warming
• Increase economic and national security

6
We Waste Huge Amounts of Energy (2)

• Four widely used devices that waste energy
• Incandescent light bulb
• Motor vehicle with an internal combustion engine
• Nuclear power plant
• Coal-fired power plant

Fuel cell
45-65
Incandescent light 5
Fluorescent light 22
Human body 20-25
Steam turbine 45
Fuel cell (45 65)
7
REDUCING ENERGY WASTE AND IMPROVING ENERGY
EFFICIENCY

• Four widely used devices waste large amounts of
  energy
• Incandescent light bulb 95 is lost as heat.
• Internal combustion engine 94 of the energy in
  its fuel is wasted.
• Nuclear power plant 92 of energy is wasted
  through nuclear fuel and energy needed for waste
  management.
• Coal-burning power plant 66 of the energy
  released by burning coal is lost.

8
Net Energy Efficiency Honest Accounting

• Comparison of net energy efficiency for two types
  of space heating.

9
REDUCING ENERGY WASTE AND IMPROVING ENERGY
EFFICIENCY

• Flow of commercial energy through the U.S.
  economy.
• 84 of all commercial energy used in the U.S. is
  wasted
• 41 wasted due to 2nd law of thermodynamics.

10
Solutions
Solutions
Reducing Energy Waste
Reducing Energy Waste
Prolongs fossil fuel supplies
Reduces oil imports
Very high net energy
Low cost
Reduces pollution and environmental degradation
Buys time to phase in renewable energy
Less need for military protection of Middle East
oil resources
Improves local economy by reducing flow of money
out to pay for energy
Creates local jobs
11
Net Energy EfficiencyHonest Energy Accounting

• Net energy efficiency
• the only energy that counts

12
How Can We Cut Energy Waste?

• We have a variety of technologies for sharply
  increasing the energy efficiency of industrial
  operations, motor vehicles, and buildings.

13
We Can Save Energy and Money in Industry (1)

• Cogeneration or combined heat and power (CHP)
• Replace energy-wasting electric motors
• Recycling materials
• Switch from low-efficiency incandescent lighting
  to higher-efficiency fluorescent and LED lighting

14
We Can Save Energy and Money in Industry (2)

• Electrical grid system outdated and wasteful
• Utility companies promote use of energy
• Dow Chemical Company improvements in efficiency

15
WAYS TO IMPROVE ENERGY EFFICIENCY

• Average fuel economy of new vehicles sold in the
  U.S. between 1975-2006.
• The government Corporate Average Fuel Economy
  (CAFE) has not increased after 1985.

Figure 17-5
16
We Can Save Energy and Money in Transportation

• Corporate average fuel standards (CAFE) standards
• Fuel economy standards lower in the U.S. than
  many other countries
• Fuel-efficient cars are on the market
• Hidden prices in the gasoline
• Should there be tax breaks for buying
  fuel-efficient cars, or feebate?

17
More Energy-Efficient Vehicles Are on the Way

• Superefficient and ultralight cars
• Gasoline-electric hybrid car
• Plug-in hybrid electric vehicle
• Energy-efficient diesel car
• Electric vehicle with a fuel cell

18
Hybrid Vehicles, Sustainable Wind Power, and Oil
imports

• Hybrid gasoline-electric engines with an extra
  plug-in battery could be powered mostly by
  electricity produced by wind and get twice the
  mileage of current hybrid cars.
• Currently plug-in batteries would by generated by
  coal and nuclear power plants.
• According to U.S. Department of Energy, a network
  of wind farms in just four states could meet all
  U.S. electricity means.

19
WAYS TO IMPROVE ENERGY EFFICIENCY

• General features of a car powered by a
  hybrid-electric engine.
• Gas sipping cars account for less than 1 of
  all new car sales in the U.S.

Figure 17-7
20
Fuel-Cell Vehicles

• Fuel-efficient vehicles powered by a fuel cell
  that runs on hydrogen gas are being developed.
• Combines hydrogen gas (H2) and oxygen gas (O2)
  fuel to produce electricity and water vapor
  (2H2O2 ? 2H2O).
• Emits no air pollution or CO2 if the hydrogen is
  produced from renewable-energy sources.

21

Body attachments Mechanical locks that secure
the body to the chassis
Air system management
Universal docking connection Connects the
chassis with the drive-by-wire system in the body
Fuel-cell stack Converts hydrogen fuel into
electricity
Rear crush zone Absorbs crash energy
Drive-by-wire system controls
Cabin heating unit
Side-mounted radiators Release heat generated by
the fuel cell, vehicle electronics, and wheel
motors
Hydrogen fuel tanks
Front crush zone Absorbs crash energy
Electric wheel motors Provide four-wheel drive
have built-in brakes
Fig. 17-8, p. 390
22
WAYS TO IMPROVE ENERGY EFFICIENCY

• Industry can save energy and money by producing
  both heat and electricity from one energy source
  and by using more energy-efficient electric
  motors and lighting ________________
• Industry accounts for about 42 of U.S. energy
  consumption.
• We can save energy in transportation by
  increasing fuel efficiency and making vehicles
  from lighter and stronger materials.

23
Science Focus The Search for Better Batteries

• Current obstacles
• Storage capacity
• Overheating
• Flammability
• In the future
• Lithium-ion battery
• Ultracapacitor
• Viral battery
• Using nanotechnology

24
We Can Design Buildings That Save Energy and
Money (1)

• Green architecture
• Living or green roofs
• Straw bale houses
• U.S. Green Building Councils Leadership in
  Energy and Environmental Design (LEED)

25
We Can Design Buildings That Save Energy and
Money (2)
26
We Can Save Energy and Money in Existing
Buildings (1)

• Insulate and plug leaks
• Use energy-efficient windows
• Stop other heating and cooling losses
• Heat houses more efficiently

27
We Can Save Energy and Money in Existing
Buildings (2)

• Heat water more efficiently
• Use energy-efficient appliances
• Use energy-efficient lighting

28
Why Are We Still Wasting So Much Energy?

• Energy remains artificially cheap
• Few large and long-lasting government incentives

29
WAYS TO IMPROVE ENERGY EFFICIENCY

• We can save energy in building by getting heat
  from the sun, superinsulating them, and using
  plant covered green roofs.
• We can save energy in existing buildings by
  insulating them, plugging leaks, and using
  energy-efficient heating and cooling systems,
  appliances, and lighting.

30
Strawbale House

• Strawbale is a superinsulator that is made from
  bales of low-cost straw covered with plaster or
  adobe. Depending on the thickness of the bales,
  its strength exceeds standard construction.

31
Living Roofs

• Roofs covered with plants have been used for
  decades in Europe and Iceland.
• These roofs are built from a blend of
  light-weight compost, mulch and sponge-like
  materials that hold water.

32
Saving Energy in Existing Buildings

• About one-third of the heated air in typical U.S.
  homes and buildings escapes through closed
  windows and holes and cracks.

33
We Can Cool Buildings Naturally

• Technologies available
• Superinsulation and high-efficiency windows
• Overhangs or awnings on windows
• Light-colored roof
• Reflective insulating foil in an attic
• Geothermal pumps
• Plastic earth tubes underground

34
We Can Use Renewable Energy in Place of
Nonrenewable Energy Sources

• Renewable energy
• Solar energy direct or indirect
• Geothermal energy
• Benefits of shifting toward a variety of locally
  available renewable energy resources
• Forms of renewable energy would be cheaper if we
  eliminate
• Inequitable subsidies
• Inaccurate prices

35
What Are the Advantages and Disadvantages of
Solar Energy?

• Passive and active solar heating systems can heat
  water and buildings effectively, and the costs of
  using direct sunlight to produce high-temperature
  heat and electricity are coming down.

36
We Can Heat Buildings and Water with Solar Energy

• Passive solar heating system
• Active solar heating system
• Countries using solar energy to heat water

37
USING RENEWABLE SOLAR ENERGY TO PROVIDE HEAT AND
ELECTRICITY

• Denmark now gets 20 of its electricity from wind
  and plans to increase this to 50 by 2030.
• Brazil gets 20 of its gasoline from sugarcane
  residue.
• In 2004, the worlds renewable-energy industries
  provided 1.7 million jobs.

38
Heating Buildings and Water with Solar Energy

• We can heat buildings by orienting them toward
  the sun or by pumping a liquid such as water
  through rooftop collectors.

Figure 17-12
39
Passive Solar Heating

• Passive solar heating system absorbs and stores
  heat from the sun directly within a structure
  without the need for pumps to distribute the heat.

Figure 17-13
40

Trade-Offs
Passive or Active Solar Heating
Advantages
Disadvantages
Energy is free
Need access to sun 60 of time
Net energy is moderate (active) to high (passive)
Sun blocked by other structures
Quick installation
Need heat storage system
No CO2 emissions
Very low air and water pollution
High cost (active)
Very low land disturbance (built into roof or
window)
Active system needs maintenance and repair
Moderate cost (passive)
Active collectors unattractive
Fig. 17-14, p. 396
41
We Can Use Sunlight to Produce High-Temperature
Heat and Electricity

• Solar thermal systems
• Central receiver system
• Other collecting systems
• Unfeasible for widespread use
• High cost
• Low new energy yields
• Limited suitable sites
• Sunny, desert sites

42
We Can Use Solar Cells to Produce Electricity (1)

• Photovoltaic (PV) cells (solar cells)
• Convert solar energy to electric energy
• Design of solar cells
• Benefits of using solar cells
• Solar-cell power plants
• Near Tucson, AZ (U.S.)
• 2007 Portugal

43
Producing Electricity with Solar Cells

• Solar cells convert sunlight to electricity.
• Their costs are high, but expected to fall.

Figure 17-16
44
Producing Electricity with Solar Cells

• Photovoltaic (PV) cells can provide electricity
  for a house of building using solar-cell roof
  shingles.

Figure 17-17
45

Single solar cell
Solar-cell roof


Boron enriched silicon
Roof options
Junction
Phosphorus enriched silicon
Panels of solar cells
Solar shingles
Fig. 17-17, p. 398
46
Producing Electricity with Solar Cells

• Solar cells can be used in rural villages with
  ample sunlight who are not connected to an
  electrical grid.

Figure 17-18
47
Producing Electricity with Solar Cells
48
We Can Use Solar Cells to Produce Electricity (3)

• Key problem
• High cost of producing electricity
• Will the cost drop with
• Mass production
• New designs

49
The Solar Power Industry Is Expanding Rapidly

• Solar cells 0.2 of the worlds electricity
• 2040 could solar cells produce 16?
• Nanosolar California (U.S.)
• Germany huge investment in solar cell technology
• General Electric entered the solar cell market

50
Trade-Offs
Solar Cells
Advantages
Disadvantages
Fairly high net energy
Need access to sun
Work on cloudy days
Low efficiency
Quick installation
Need electricity storage system or backup
Easily expanded or moved
No CO2 emissions
High land use (solar-cell power plants) could
disrupt desert areas
Low environmental impact
Last 2040 years
Low land use (if on roof or built into walls or
windows)
High costs (but should be competitive in 515
years)
Reduces dependence on fossil fuels
DC current must be converted to AC
51
Advantages and Disadvantages of Producing
Electricity from the Water Cycle

• Water flowing over dams, tidal flows, and ocean
  waves can be used to generate electricity, but
  environmental concerns and limited availability
  of suitable sites may limit the use of these
  energy resources.

52
PRODUCING ELECTRICITY FROM THE WATER CYCLE

• Water flowing in rivers and streams can be
  trapped in reservoirs behind dams and released as
  needed to spin turbines and produce electricity.
• There is little room for expansion in the U.S.
  Dams and reservoirs have been created on 98 of
  suitable rivers.

53
PRODUCING ELECTRICITY FROM THE WATER CYCLE

• Ocean tides and waves and temperature differences
  between surface and bottom waters in tropical
  waters are not expected to provide much of the
  worlds electrical needs.
• Only two large tidal energy dams are currently
  operating one in La Rance, France and Nova
  Scotias bay of Fundy where the tidal amplitude
  can be as high as 16 meters (63 feet).

54
We Can Produce Electricity from Falling and
Flowing Water

• Hydropower
• Worlds leading renewable energy source used to
  produce electricity
• Hydroelectric power Iceland
• Advantages
• Disadvantages
• Micro-hydropower generators

55
Tides and Waves Can Be Used to Produce
Electricity (1)

• Produce electricity from flowing water
• Ocean tides and waves
• So far, power systems are limited
• Norway
• New York City

56
Tides and Waves Can Be Used to Produce
Electricity (2)

• Disadvantages
• Few suitable sites
• High costs
• Equipment damaged by storms and corrosion

57

Trade-Offs
Large-Scale Hydropower
Advantages
Disadvantages
Moderate to high net energy
High construction costs
High environmental impact from flooding land to
form a reservoir
High efficiency (80)
Large untapped potential
High CO2 emissions from biomass decay in shallow
tropical reservoirs
Low-cost electricity
Long life span
Floods natural areas behind dam
No CO2 emissions during operation in temperate
areas
Converts land habitat to lake habitat
May provide flood control below dam
Danger of collapse
Uproots people
Provides water for year-round irrigation of
cropland
Decreases fish harvest below dam
Decreases flow of natural fertilizer (silt) to
land below dam
Reservoir is useful for fishing and recreation
Fig. 17-20, p. 400
58
Advantages and Disadvantages of Producing
Electricity from Wind

• When environmental costs of energy resources are
  included in market prices, wind energy is the
  least expensive and least polluting way to
  produce electricity.

59
PRODUCING ELECTRICITY FROM WIND

• Wind power is the worlds most promising energy
  resource. Why?
• It is abundant, inexhaustible, widely
  distributed, cheap, clean, and emits no
  greenhouse gases.
• Much of the worlds potential for wind power
  remains untapped.
• Capturing only 20 of the wind energy at the
  worlds best energy sites could meet all the
  worlds energy demands.

60
PRODUCING ELECTRICITY FROM WIND

• Wind turbines can be used individually to produce
  electricity. They are also used interconnected in
  arrays on wind farms.

61
PRODUCING ELECTRICITY FROM WIND

• The United States once led the wind power
  industry, but Europe now leads this rapidly
  growing business.
• The U.S. government lacked subsidies, tax breaks
  and other financial incentives.
• European companies manufacture 80 of the wind
  turbines sold in the global market
• The success has been aided by strong government
  subsidies.

62
Using Wind to Produce Electricity Is an Important
Step toward Sustainability (2)

• Saudi Arabia of wind power
• North Dakota
• South Dakota
• Kansas
• Texas
• How much electricity is possible with wind farms
  in those states?

63
Producing Electricity from Wind Energy Is a
Rapidly Growing Global Industry

• Countries with the highest total installed wind
  power capacity
• Germany
• United States
• Spain
• India
• Denmark
• Installation is increasing in several other
  countries

64
Using Wind to Produce Electricity Is an Important
Step toward Sustainability (1)

• Wind indirect form of solar energy
• Captured by turbines
• Converted into electrical energy
• Second fastest-growing source of energy
• What is the global potential for wind energy?
• Wind farms on land and offshore

65

Trade-Offs
Wind Power
Advantages
Disadvantages
Moderate to high net energy
Steady winds needed
High efficiency
Backup systems needed when winds are low
Moderate capital cost
Low electricity cost (and falling)
High land use for wind farm
Very low environmental impact
No CO2 emissions
Visual pollution
Quick construction
Noise when located near populated areas
Easily expanded
Can be located at sea
May interfere in flights of migratory birds and
kill birds of prey
Land below turbines can be used to grow crops or
graze livestock
66
Wind Energy Is Booming but Still Faces Challenges

• Advantages of wind energy
• Drawbacks
• Windy areas may be sparsely populated
• Winds die down need back-up energy
• Storage of wind energy
• Kills migratory birds
• Not in my backyard

67
We Can Get Energy by Burning Solid Biomass

• Biofuels
• Production of solid mass fuel
• Plant fast-growing trees
• Biomass plantations
• Collect crop residues and animal manure
• Advantages
• Disadvantages

68
PRODUCING ENERGY FROM BIOMASS

• Plant materials and animal wastes can be burned
  to provide heat or electricity or converted into
  gaseous or liquid biofuels.

69
PRODUCING ENERGY FROM BIOMASS

• The scarcity of fuelwood causes people to make
  fuel briquettes from cow dung in India. This
  deprives soil of plant nutrients.

Figure 17-24
70
Advantages and Disadvantages of Biomass as an
Energy Source (1)

• Solid biomass is a renewable resource, but
  burning it faster than it is replenished produces
  a net gain in atmospheric greenhouse gases, and
  creating biomass plantations can degrade soil
  biodiversity.

71

Trade-Offs
Solid Biomass
Advantages
Disadvantages
Large potential supply in some areas
Nonrenewable if harvested unsustainably
Moderate to high environmental impact
Moderate costs
CO2 emissions if harvested and burned
unsustainably
No net CO2 increase if harvested and burned
sustainably
Low photosynthetic efficiency
Plantation can be located on semiarid land not
needed for crops
Soil erosion, water pollution, and loss of
wildlife habitat
Plantations could compete with cropland
Plantation can help restore degraded lands
Often burned in inefficient and polluting open
fires and stoves
Can make use of agricultural, timber, and urban
wastes
72
We Can Convert Plants and Plant Wastes to Liquid
Biofuels (1)

• Liquid biofuels
• Biodiesel
• Ethanol
• Biggest producers of biofuel
• Brazil
• The United States
• The European Union
• China

73
Converting Plants and Plant Wastes to Liquid
Biofuels An Overview

• Motor vehicles can run on ethanol, biodiesel, and
  methanol produced from plants and plant wastes.
• The major advantages of biofuels are
• Crops used for production can be grown almost
  anywhere.
• There is no net increase in CO2 emissions.
• Widely available and easy to store and transport.

74
Case Study Producing Ethanol

• Crops such as sugarcane, corn, and switchgrass
  and agricultural, forestry and municipal wastes
  can be converted to ethanol.

• Switchgrass can remove CO2 from the troposphere
  and store it in the soil.

75
Case Study Producing Ethanol

• 10-23 pure ethanol makes gasohol which can be
  run in conventional motors.
• 85 ethanol (E85) must be burned in flex-fuel
  cars.
• Processing all corn grown in the U.S. into
  ethanol would cover only about 55 days of current
  driving.
• Biodiesel is made by combining alcohol with
  vegetable oil made from a variety of different
  plants..

76

Trade-Offs
Ethanol Fuel
Advantages
Disadvantages
High octane
Large fuel tank needed
Lower driving range
Some reduction in CO2 emissions
Low net energy (corn)
Much higher cost
High net energy (bagasse and switchgrass)
Corn supply limited
May compete with growing food on cropland
Reduced CO emissions
Higher NO emissions
Can be sold as gasohol
Corrosive
Hard to start in cold weather
Potentially renewable
Fig. 17-27, p. 407
77
Case Study Producing Ethanol

• Biodiesel has the potential to supply about 10
  of the countrys diesel fuel needs.

78
Case Study Is Ethanol the Answer? (1)

• Ethanol converted to gasohol
• Brazil Saudi Arabia of sugarcane
• Saved 50 billion in oil import costs since the
  1970s
• United States ethanol from corn
• Reduce the need for oil imports?
• Slow global warming?
• Reduce air pollution?

79
Case Study Is Ethanol the Answer? (2)

• Cellulosic ethanol alternative to corn ethanol
• Sources
• Switchgrass
• Crop residues
• Municipal wastes
• Advantages
• Disadvantages

80
Case Study Is Biodiesel the Answer?

• Biodiesel production from vegetable oil from
  various sources
• 95 produced by The European Union
• Jatropha shrub promising new source
• Advantages
• Disadvantages

81

Trade-Offs
Biodiesel
Advantages
Disadvantages
Reduced CO emissions
Slightly increased emissions of nitrogen oxides
Reduced CO2 emissions (78)
Higher cost than regular diesel
Reduced hydrocarbon emissions
Low yield for soybean crops
Better gas mileage (40)
May compete with growing food on cropland
High yield for oil palm crops
Loss and degradation of biodiversity from crop
plantations
Moderate yield for rapeseed crops
Hard to start in cold weather
Potentially renewable
Fig. 17-29, p. 408
82
Case Study Biodiesel and Methanol

• Growing crops for biodiesel could potentially
  promote deforestation.
• Methanol is made mostly from natural gas but can
  also be produced at a higher cost from CO2 from
  the atmosphere which could help slow global
  warming.
• Can also be converted to other hydrocarbons to
  produce chemicals that are now made from
  petroleum and natural gas.

83

Trade-Offs
Methanol Fuel
Advantages
Disadvantages
High octane
Large fuel tank needed
Some reduction in CO2 emissions
Half the driving range
Lower total air pollution (3040)
Corrodes metal, rubber, plastic
Can be made from natural gas, agricultural
wastes, sewage sludge, garbage, and CO2
High CO2 emissions if made from coal
Expensive to produce
Can be used to produce H2 for fuel cells
Hard to start in cold weather
Fig. 17-30, p. 408
84
Advantages and Disadvantages of Biomass as an
Energy Source (2)

• Liquid biofuels derived from biomass can be used
  in place of gasoline and diesel fuels, but
  creating biofuel plantations could degrade soil
  and biodiversity and increase food prices and
  greenhouse gas emissions.

85
We Can Convert Plants and Plant Wastes to Liquid
Biofuels (2)

• Major advantages over gasoline and diesel fuel
  produced from oil
• Biofuel crops can be grown almost anywhere
• No net increase in CO2 emissions if managed
  properly
• Available now

86
We Can Convert Plants and Plant Wastes to Liquid
Biofuels (3)

• Studies warn of problems
• Decrease biodiversity
• Increase soil degrading, erosion, and nutrient
  leaching
• Push farmers off their land
• Raise food prices

87
What Are the Advantages and Disadvantages of
Geothermal Energy?

• Geothermal energy has great potential for
  supplying many areas with heat and electricity
  and generally has a low environmental impact, but
  locations where it can be exploited economically
  are limited.

88
Getting Energy from the Earths Internal Heat (1)

• Geothermal energy heat stored in
• Soil
• Underground rocks
• Fluids in the earths mantle
• Geothermal heat pump system
• Energy efficient and reliable
• Environmentally clean
• Cost effective to heat or cool a space

89
Getting Energy from the Earths Internal Heat (2)

• Hydrothermal reservoirs
• Iceland
• Geothermal energy two problems
• High cost of tapping large-scale hydrothermal
  reservoirs
• Dry- or wet-steam geothermal reservoirs could be
  depleted
• Hot, dry rock another potential source of
  geothermal energy?

90
GEOTHERMAL ENERGY

• Geothermal energy consists of heat stored in
  soil, underground rocks, and fluids in the
  earths mantle.
• We can use geothermal energy stored in the
  earths mantle to heat and cool buildings and to
  produce electricity.
• A geothermal heat pump (GHP) can heat and cool a
  house by exploiting the difference between the
  earths surface and underground temperatures.

91
Geothermal Heat Pump

• The house is heated in the winter by transferring
  heat from the ground into the house.
• The process is reversed in the summer to cool the
  house.

Figure 17-31
92
GEOTHERMAL ENERGY

• Deeper more concentrated hydrothermal reservoirs
  can be used to heat homes and buildings and spin
  turbines
• Dry steam water vapor with no water droplets.
• Wet steam a mixture of steam and water droplets.
• Hot water is trapped in fractured or porous rock.

93

Trade-Offs
Geothermal Energy
Advantages
Disadvantages
Very high efficiency
Scarcity of suitable sites
Moderate net energy at accessible sites
Depleted if used too rapidly
Lower CO2 emissions than fossil fuels
CO2 emissions
Moderate to high local air pollution
Low cost at favorable sites
Noise and odor (H2S)
Low land use
Low land disturbance
Cost too high except at the most concentrated
and accessible sources
Moderate environmental impact
Fig. 17-32, p. 410
94
The Advantages and Disadvantages of Hydrogen as
an Energy Source

• Hydrogen fuel holds great promise for powering
  cars and generating electricity, but to be
  environmentally beneficial, it would have to be
  produced without the use of fossil fuels.

95
Hydrogen Is a Promising Fuel but There Are
Challenges (1)

• Hydrogen as a fuel
• Eliminate most of the air pollution problems
• Reduce threats of global warming
• Some challenges
• Chemically locked in water and organic compounds
• Fuel cells are the best way to use hydrogen
• CO2 levels dependent on method of hydrogen
  production

96
Hydrogen Is a Promising Fuel but There Are
Challenges (2)

• Production and storage of H2
• Hydrogen-powered vehicles prototypes available
• Can we produce hydrogen on demand?
• Larger fuel cells

97
HYDROGEN

• Some energy experts view hydrogen gas as the best
  fuel to replace oil during the last half of the
  century, but there are several hurdles to
  overcome
• Hydrogen is chemically locked up in water an
  organic compounds.
• It takes energy and money to produce it (net
  energy is low).
• Fuel cells are expensive.
• Hydrogen may be produced by using fossil fuels.

98
Converting to a Hydrogen Economy

• Iceland plans to run its economy mostly on
  hydrogen (produced via hydropower, geothermal,
  and wind energy), but doing this in
  industrialized nations is more difficult.
• Must convert economy to energy farming (e.g.
  solar, wind) from energy hunter-gatherers seeking
  new fossil fuels.
• No infrastructure for hydrogen-fueling stations
  (12,000 needed at 1 million apiece).
• High cost of fuel cells.

99

Trade-Offs
Hydrogen
Advantages
Disadvantages
Can be produced from plentiful water
Not found in nature
Energy is needed to produce fuel
Low environmental impact
Negative net energy
Renewable if from renewable resources
CO2 emissions if produced from carbon-containing
compounds
No CO2 emissions if produced from water
Nonrenewable if generated by fossil fuels or
nuclear power
Good substitute for oil
High costs (but may eventually come down)
Competitive price if environmental social costs
are included in cost comparisons
Will take 25 to 50 years to phase in
Short driving range for current fuel-cell cars
Easier to store than electricity
Safer than gasoline and natural gas
No fuel distribution system in place
Nontoxic
Excessive H2 leaks may deplete ozone in the
atmosphere
High efficiency (4565) in fuel cells
Fig. 17-33, p. 412
100
A SUSTAINABLE ENERGY STRATEGY

• Shifts in the use of commercial energy resources
  in the U.S. since 1800, with projected changes to
  2100.

Figure 17-34
101
How Can We Make a Transition to a More
Sustainable Energy Future?

• We can make a transition to a more sustainable
  future if we greatly improve energy efficiency,
  use a mix of renewable energy resources, and
  include environmental costs in the market prices
  of all energy resources.

102

More Renewable Energy Increase renewable energy
to 20 by 2020 and 50 by 2050 Provide large
subsidies and tax credits for renewable
energy Use full-cost accounting and life-cycle
cost for comparing all energy alternatives Enco
urage government purchase of renewable energy
devices Greatly increase renewable energy RD
Improve Energy Efficiency Increase
fuel-efficiency standards for vehicles,
buildings, and appliances Mandate govern- ment
purchases of efficient vehicles and other
devices Provide large tax credits for buying
efficient cars, houses, and appliances Offer
large tax credits for invest- ments in energy
efficiency Reward utilities for reducing
demand for electricity Encourage indepen- dent
power producers Greatly increase
energy efficiency research and development
Reduce Pollution and Health Risk Cut coal use
50 by 2020 Phase out coal subsidies Levy taxes
on coal and oil use Phase out nuclear power or
put it on hold until 2020 Phase out nuclear
power subsidies
Fig. 17-36, p. 415
103
Choosing Energy Paths (1)

• How will energy policies be created?
• Supply-side, hard-path approach
• Demand-side, soft-path approach

104
Choosing Energy Paths (2)

• General conclusions about possible energy paths
• Gradual shift to smaller, decentralized
  micropower systems
• Transition to a diverse mix of locally available
  renewable energy resources Improved energy
  efficiency
• How?
• Fossil fuels will still be used in large amounts
• Why?

105
Economics, Politics, Education, and Sustainable
Energy Resources

• Government strategies
• Keep the prices of selected energy resources
  artificially low to encourage their use
• Keep energy prices artificially high for selected
  resources to discourage their use
• Consumer education

106
Case Study Californias Efforts to Improve
Energy Efficiency

• High electricity costs
• Reduce energy waste
• Use of energy-efficient devices
• Strict building standards for energy efficiency