1. Energy Efficiency and Renewable Energy10
Energy Efficiency and Renewable Energy

2. Just as the 19th century belonged to coal and the 20th century to oil,
the 21st century will belong to the sun, the wind, and energy from within the earth.
Lester R. Brown

4. 10-1 Why Is Energy Efficiency an Important Energy Resource?
Each energy unit saved eliminates the need to produce that energy and saves money
Reducing waste is the quickest, cleanest, and usually the cheapest way to provide more energy, reduce pollution and environmental degradation, slow global warming, and increase economic and national security

5. We Waste Huge Amounts of Energy
Energy is wasted by:
Huge data centers (electronic clouds) filled with racks of electronic servers
Internal combustion engines
Nuclear power plants
Coal-fired power plants

6. Nonrenewable fossil fuels Useful energy Nonrenewable nuclear
Energy Inputs
System
Outputs 9% 7%
41%
85%
U. S. economy
43% 8%
Figure 10-1 Flow of commercial energy through the U.S. economy. Only 16% of all commercial energy used in the United States ends up performing useful tasks. Question: What are two examples of unnecessary energy waste? (Compiled by the authors using data from U.S. Department of Energy) 3%
Nonrenewable fossil fuels
Useful energy
Nonrenewable nuclear
Petrochemicals
Renewable (hydropower, geothermal, wind, solar, biomass)
Unavoidable energy loss
Energy waste
Fig. 10-1

7. Solutions Improving Energy Efficiency Prolongs fossil fuel supplies
Reduces oil imports and improves energy security
Very high net energy yield
Low cost
Reduces pollution and environmental degradation
Figure 10-2 Reducing unnecessary energy waste and thereby improving energy efficiency saves us money and reduces our ecological footprint. Questions: Which two of these advantages do you think are the most important? Why?
Buys time to phase in renewable energy
Creates local jobs
Fig. 10-2

8. We Can Save Energy and Money in Industry and Utilities
Cogeneration or combined heat and power (CHP)
Two energy forms from the same fuel source
Replace energy-wasting electric motors
Recycle materials
Switch from low-efficiency incandescent lighting to
Higher-efficiency fluorescent and LED lighting

9. Case Study: Saving Energy and Money with a Smarter Electrical Grid
Electrical grid system: outdated and wasteful
Convert and expand into a smart grid
Two-way energy and information flow between producers and users
Smart meters
Smart appliances
Remote control
Save $100 billion/yr in the U.S.

10. We Can Save Energy and Money in Transportation
Transportation in the U.S.
28 percent of energy consumed
Two-thirds of the oil consumption
Hidden costs in gasoline: true cost $12 to $16 per gallon
Include subsidies and tax breaks
Paid by the consumer but not at the gas pump

11. More Energy Efficient Vehicles Are Hitting the Roads
Super-efficient cars
Gasoline–electric hybrid cars
Plug-in hybrid electric vehicles
All-electric vehicles
Main deterrent is high cost of batteries
Cars made of ultralight and ultrastrong composite materials
Significantly improves fuel efficiency

12. Internal combustion engine
Conventional hybrid
Fuel tank
Battery
Internal combustion engine
Transmission
Electric motor
Plug-in hybrid
Fuel tank
Battery
Internal combustion engine
Transmission
Electric motor
Figure 10-3 Solutions: A hybrid gasoline–electric engine (left) has a small internal combustion engine and a battery. A plug-in hybrid vehicle (right) would have a smaller internal combustion engine with a second and more powerful battery that can be plugged into a standard 110-volt outlet and recharged. This allows it to run farther on electricity alone.
Stepped Art
Fig. 10-2

13. We Can Design Buildings That Save Energy and Money
Green architecture
Energy-efficient, money-saving designs
Natural lighting
Solar energy
Wastewater recycling
Energy-efficient appliances and lighting
Living roofs (green roofs)
Superinsulation

14. Stepped Art Outside Attic Plant deciduous trees to block
• Hang reflective foil near
roof to reflect heat.
• Use house fan.
• Be sure attic insulation is
at least 30 centimeters
(12 inches).
Outside
Plant deciduous trees to block
summer sun and let in winter
sunlight.
Bathroom
• Install water-saving toilets,
faucets, and shower heads.
• Repair water leaks promptly.
Other rooms
• Use compact fluorescent
light bulbs or LEDs and avoid
using incandescent bulbs
wherever possible.
• Turn off lights, computers, TV,
and other electronic devices
when they are not in use.
• Use high efficiency windows;
use insulating window covers
and close them at night and
on sunny, hot days.
• Set thermostat as low as you
can in winter and as high as
you can in summer.
• Weather-strip and caulk doors,
windows, light fixtures, and
wall sockets.
• Keep heating and cooling
vents free of obstructions.
• Keep fireplace damper closed
when not in use.
• Use fans instead of, or along
with, air conditioning.
Kitchen
• Use microwave rather than
stove or oven as much as
possible.
• Run only full loads in
dishwasher and use low- or
no-heat drying.
• Clean refrigerator coils
regularly.
Basement or utility room
• Use front-loading clothes washer. If possible run only full loads with warm or cold water.
• Hang clothes on racks for drying.
• Run only full loads in clothes dryer and use lower heat setting.
• Set water heater at 140° if dishwasher is used and 120° or lower if no dishwasher is used.
• Use water heater thermal blanket.
• Insulate exposed hot water pipes.
• Regularly clean or replace furnace filters.
Figure 10-4 Individuals Matter: You can save energy where you live. Questions: Which of these things do you already do? Which of them could you start doing now?
Stepped Art
Fig. 10-4

15. Why Are We Still Wasting So Much Energy?
Energy remains artificially cheap
Government subsidies
Tax breaks
Prices don’t include true costs
Few large and long-lasting motivations
Rebates
Other economic incentives

16. We Can Use Renewable Energy to Provide Heat and Electricity
Solar energy: direct or indirect
Geothermal energy
Renewable energy more attractive if we eliminate
Inequitable subsidies
Inaccurate prices
Artificially low pricing of nonrenewable energy

17. 10-2 What Are the Advantages and Disadvantages of Using Solar Energy?
We can heat buildings and water with solar energy
Passive solar heating systems
Active solar heating systems

18. White or light-colored roofs reduce overheating
Vent allows hot air to escape in summer
Summer sun
Heavy insulation
Winter sun
Superwindow
Super-window
Figure 10-5 Solutions: Homes can be heated with passive or active solar systems.
Stone floor and wall for heat storage
PASSIVE
Fig. 10-5

19. Figure 10-5 Solutions (cont’d
Figure 10-5 Solutions (cont’d.): Homes can be heated with passive or active solar systems.
Fig (cont’d.)
Fig b, p. 414

20. We Can Concentrate Sunlight to Produce High-Temperature Heat and Electricity
Types of solar thermal systems
Central receiver system
Power tower (central receiver)
Heliostats
System with curved solar collectors
Collects and focuses sunlight on oil-filled pipes
Produce steam for driving electricity-generating turbines
Solar cookers to cook food and sterilize water

21. We Can Use Sunlight to Produce Electricity
Photovoltaic (PV) cells (solar cells)
Convert solar energy to electric energy
Design of solar cells
Sunlight hits cells and releases electrons
Benefits of using solar cells
Solar-cell power plants around the world
World’s fastest growing way to produce electricity

22. Trade-Offs Solar Cells Advantages Disadvantages
Medium net energy yield
Need access to sun
Some designs have low net energy yield
Little or no direct emissions of CO2 and other air pollutants
Need electricity storage system or backup
Figure 10-9 Using solar cells to produce electricity has advantages and disadvantages. Questions: Which single advantage and which single disadvantage do you think are the most important? Why? Martin D. Vonka/Shutterstock.com (top), pedrosala/Shutterstock.com (bottom)
Easy to install, move around, and expand as needed
Costs high for older systems but dropping rapidly
Solar-cell power plants could disrupt desert ecosystems
Competitive cost for newer cells
Fig. 10-9

23. 10-3 What Are the Advantages and Disadvantages of Using Hydropower?
We can produce electricity from falling and flowing water
Hydropower
Indirect form of solar energy
Uses kinetic energy of moving water
Most common approach involves a high dam across a large river
Advantages and disadvantages
Micro-hydropower generators

24. Hydroelectric Power Plant

25. Large-Scale Hydropower
Trade-Offs
Large-Scale Hydropower
Advantages
Disadvantages
High net energy yield
Large land disturbance and displacement of people
Large untapped potential
High CH4 emissions from rapid biomass decay in shallow tropical reservoirs
Low-cost electricity
Figure Using large dams and reservoirs to produce electricity has advantages and disadvantages (Concept 10-3). Questions: Which single advantage and which single disadvantage do you think are the most important? Why?
Low emissions of CO2 and other air pollutants in temperate areas
Disrupts downstream aquatic ecosystems
Fig

26. 10-4 What Are the Advantages and Disadvantages of Using Wind Power?
Using wind to produce electricity is an important step toward sustainability
Wind: indirect form of solar energy
Captured by turbines
Converted into electrical energy
Second fastest-growing energy source
Wind farms: on land and offshore
Advantages and disadvantages

27. Wind Energy Potential

28. Trade-Offs Wind Power Advantages Disadvantages High net energy yield
Needs backup or storage system when winds die down
Widely available
Visual pollution for some people
Low electricity cost
Little or no direct emissions of CO2 and other air pollutants
Figure Using wind to produce electricity has advantages and disadvantages. Questions: Which single advantage and which single
disadvantage do you think are the most important? Why?
Low-level noise bothers some people
Can kill birds if not properly designed and located
Easy to build and expand
Fig

29. 10-5 Advantages and Disadvantages of Using Biomass as an Energy Source
We can produce energy by burning solid biomass
Biomass: plant materials and animal wastes
Burn or turn into biofuels
Production of solid mass fuel
Plant fast-growing trees
Biomass plantations
Collect crop residues and animal manure
Advantages and disadvantages

30. Trade-Offs Solid Biomass Advantages Disadvantages
Widely available in some areas
Contributes to deforestation
Moderate costs
Clear-cutting can cause soil erosion, water pollution, and loss of wildlife habitat
Medium net energy yield
No net CO2 increase if harvested, burned, and replanted sustainably
Can open ecosystems to invasive species
Figure Burning solid biomass as a fuel has advantages and disadvantages (Concept 10-5A). Questions: Which single advantage and which single disadvantage do you think are the most important? Why?
Increases CO2 emissions if harvested and burned unsustainably
Plantations can help restore degraded lands
Fig

31. We Can Convert Plants and Plant Wastes to Liquid Biofuels
Examples: biodiesel and ethanol
Biggest producers of biofuel
Brazil
United States
European Union
China
Advantages and potential problems

32. Case Study: Is Ethanol the Answer?
Ethanol from plants and from agricultural, forestry, and municipal wastes
Brazil produces ethanol from sugarcane
Environmental consequences
United States: most ethanol from corn
Cellulosic ethanol
Debates over greenhouse gas emissions

33. Trade-Offs Liquid Biofuels Advantages Disadvantages
Reduced CO2 emissions for some crops
Fuel crops can compete with food crops for land and raise food prices
Fuel crops can be invasive species
Medium net energy yield for biodiesel from oil palms
Low net energy yield for corn ethanol and for biodiesel from soybeans
Figure Using ethanol as a vehicle fuel has advantages and disadvantages compared to using gasoline (Concept 10-5B). Questions: Which single advantage and which single disadvantage do you think are the most important? Why?
Medium net energy yield for ethanol from sugarcane
Higher CO2 emissions from corn ethanol
Fig

34. Waste (Garbage)
Waste is a major source of biomass and other burnable materials produced by society.
The burning of solid waste only makes economic sense when the cost of waste disposal is taken into account.
Using municipal waste as a source of energy:
Reduces landfill volume.
Requires large volume and dependable supply, and must be sorted.
Produces air pollution, including pollutants not found in other forms of biomass.

35. 10-6 What Are the Advantages and Disadvantages of Geothermal Energy?
We can get energy by tapping the earth’s internal heat
With geothermal energy, heat is stored in:
Soil
Underground rocks
Fluids in the earth’s mantle

36. Trade-Offs Geothermal Energy Advantages Disadvantages
Medium net energy yield and high efficiency at accessible sites
High cost except at concentrated and accessible sites
Lower CO2 emissions than fossil fuels
Scarcity of suitable sites
Figure Using geothermal energy for space heating and for producing electricity or high-temperature heat for industrial processes has advantages and disadvantages (Concept 10-6). Questions: Which single advantage and which single disadvantage do you think are the most important? Why?
Low cost at favorable sites
Noise and some CO2 emissions
Fig

37. 10-7 The Advantages and Disadvantages of Using Hydrogen as an Energy Source
Will hydrogen save us?
Hydrogen as a fuel
Eliminate most of the air pollution problems
Reduce threats of global warming
Challenges
Negative net energy yield
Expensive fuel cells are the best way to use hydrogen
Air pollution and CO2 levels dependent on hydrogen production method

38. Trade-Offs Hydrogen Advantages Disadvantages
Can be produced from plentiful water at some sites
Negative net energy yield
Fuel cell
CO2 emissions
if produced from carbon-containing compounds
No CO2 emissions if produced with use of renewables
Figure Using hydrogen as a fuel for vehicles and for providing heat and electricity has advantages and disadvantages (Concept 10-7). Questions: Which single advantage and which single disadvantage do you think are the most important? Why?
Good substitute for oil
High costs create need for subsidies
Needs H2 storage and distribution system
High efficiency in fuel cells
Fig

39. 10-8 How Can We Make the Transition to a More Sustainable Energy Future?
Choosing energy paths
How will energy policies be created?
General conclusions
Gradual shift to smaller, decentralized micropower systems
Transition to a diverse mix of locally available renewable energy resources
Fossil fuels will still be used in large amounts

40. Bioenergy power plants Wind farm
Small solar-cell
power plants
Bioenergy power plants
Wind farm
Solar-cell
rooftop
systems
Commercial
Fuel cells
Rooftop solar-
cell arrays
Residential
Small wind
turbine
Smart electrical
and distribution
system
Figure Solutions: During the next few decades, we will probably shift from dependence on a centralized macropower system, based on a few hundred large coal-burning and nuclear power plants to a decentralized micropower system, in which electricity is produced by a large number of dispersed, small-scale, local power-generating systems. The smaller systems would be largely based on locally available renewable energy resources and could feed the power they produce into a new smart grid. Question: Can you think of any disadvantages of a decentralized power system?
Microturbines
Industrial
Stepped Art
Fig

41. Solutions Making the Transition to a More Sustainable Energy Future
Improve Energy Efficiency
More Renewable Energy
Increase fuel-efficiency standards for vehicles, buildings, and appliances
Greatly increase use of renewable energy
Provide large subsidies and tax credits for use of renewable energy
Provide large tax credits or feebates for buying efficient
cars, houses, and appliances
Greatly increase renewable energy research and development
Reduce Pollution and Health Risk
Reward utilities for reducing demand for electricity
Phase out coal subsidies and tax breaks
Greatly increase energy efficiency research and development
Figure Energy analysts have made a number of suggestions for helping us make the transition to a more sustainable energy future (Concept 10-9). Questions: Which five of these solutions do you think are the most important? Why?
Levy taxes on coal and oil use
Phase out nuclear power subsidies, tax breaks, and loan guarantees
Fig

42. 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
Emphasize consumer education

43. Energy Conservation
There is typically a relationship between the cost of an item and its energy efficiency.
Often, poorly designed, energy-inefficient buildings and machines can be produced inexpensively.
The short-term cost (purchase price) is low, but the long-term cost for upkeep and energy utilization is high.
Typically, the cost of more efficient buildings or machines is higher, but the difference in initial price is made up by savings in energy cost over several years.
This is known as the payback period.

44. Figure Individuals matter: You can reduce your use and waste of energy. Questions: Which three of these steps do you think are the most important ones to take? Why? Which of these steps are you taking now, and which ones do you plan to take?
Fig

45. Energy Conservation

46. The Economics and Politics of Energy Use
A direct link exists between economic growth and the availability of inexpensive energy.
Most industrial societies want to ensure a continuous supply of affordable energy.
The higher the price of energy, the more expensive goods and services become.
Subsidies help keep energy costs down.

47. Fuel Economy and Government Policy
Automobile fuel efficiency is one area in which government policy has had significant impact.
Most of the differences in gasoline prices among countries are a result of taxes and reflect differences in government policy toward motor vehicle transportation.
Do cars in the United States have high or low gas mileage levels compared to other countries?

49. Fuel Economy and Government Policy
Governments often charge road users to help build and repair roads by taxing fuel.
Many European countries raise more money from fuel taxes than they spend on building and repairing roads.
U.S. only raises 50% of monies needed for roads from fuel taxes.
Low fuel costs in the U.S. encourage more travel, which increases road repair costs.