1. Renewable Energy
“The use of solar energy has not been opened up because the oil industry does not own the sun.”
- Ralph Nader

2. Nonrenewable Energy
Nonrenewable energy, including fossil fuels and nuclear power, make up the vast majority of the U.S. energy portfolio.
In the long-term, there are two major issues with this reliance on nonrenewable energy:
Dwindling supplies.
Environmental pollution.

3. Dwindling Supplies
Nonrenewable resources, by definition, are finite and will eventually be used up.
Most of the easily recoverable sources of coal, oil, and natural gas have already been tapped.
As supplies of these resources tighten, or they become more expensive to extract, price will increase.

4. Deep-ocean drilling of oil and hydraulic fracturing of natural gas are examples of resource extraction that would not have been economically viable in the past.

5. Pollution
The extraction, transport, and burning of fossil fuels is also a highly polluting process.

6. Fossil fuels have a lot of modern applications.
Electricity
Fuel for transportation
Heat
The strategies for replacing them is going to vary for each.

7. Electricity
Electricity works by passing electrons from a power source through a series of wires, called a circuit.
Within the circuit there are devices that use the energy released by the electrons to do work (as light, heat, etc)

8. Electric power is measured in watts, the rate at which electrons moving through a circuit are doing work.
A standard incandescent light bulb consumes 60W of power.
A medium-sized car will consume about 100,000W.

9. Electricity consumption is measured in kilowatt-hours.
This includes both power and running-time.
The charge per kilowatt-hour in this bill is 10.7 cents.

10. At the rate shown in this bill, running a 60-watt light bulb for an hour would cost…
60watts x 1 kilowatt/ 1000 watts = 0.06 kilowatts
0.06 kilowatt-hours x $0.107/kwh = $ or cents.

11. Renewable Electricity
The greatest renewable source of electricity production currently in use is hydroelectricity.

12. Hydropower
Hydroelectric power plants use running water to spin a turbine and generate electricity.
Hydroelectricity is very economical, with costs per kilowatt-hour similar to coal.
No pollution is produced.

13. Trade-Offs: Large-Scale Hydropower, Advantages and Disadvantages

14. The construction of the dam has major ecological impacts.
Regular flooding downstream stops, preventing deposition of silt and nutrients.
The reservoir can experience sedimentation, where particles of soil in the river settle to the bottom of the reservoir.
The ecosystem immediately behind the dam becomes flooded.
River water, when stopped, warms faster and begins to evaporate.
Fish and other organisms can no longer move upstream.

15. Any cities or villages in the area of the reservoir will have to be abandoned.
The Three Gorges Dam in China, completed in 2008, displaced 1.13 million people from the Yangtze River region.

16. Another issue with dams is that they produce a constant, steady stream of electricity that cannot be easily adjusted to meet demand.
Some dams have pumped storage, where water will be sent and stored during low-demand times, then returned back through the dam’s turbines when demand is higher.
Kinzua Dam and Seneca pumped storage generating station, Mead, PA

17. Wind Energy
Wind energy is similar to hydroelectricity, except that moving air provides the force to spin the generator.

18. Wind turbines are able to orient themselves to face the oncoming wind.
As the air passes through, the blades rotate.
These are attached to a shaft, which connects to the turbine.

19. Solutions: Wind Turbine and Wind Farms on Land and Offshore

20. A single wind turbine can generate 1-7 megawatts of energy per year, not enough for a large population.
Wind farms are large numbers of wind turbines clustered together.
The Gansu Wind Farm in China produces 6 billion kilowatt-hours of electricity per year.

21. Wind power is comparable in cost to coal.
Possible negative impacts of wind turbines include:
Disruption of bird and bat migration pathways.
Noise.
Disruption of scenery.

22. TRADE-OFFS Wind Power Advantages Disadvantages
Moderate to high net energy yield
Steady winds needed
Backup systems needed when winds are low
High efficiency
Moderate capital cost
Plastic components produced from oil
Low electricity cost (and falling)
Environmental costs not included in market price
Very low environmental impact
High land use for wind farm
No CO2 emissions
Figure 16.23
Advantages and disadvantages of using wind to produce electricity (Concepts 16-5). With sufficient and consistent incentives, wind power could supply more than 10% of the world’s electricity and 10–25% of the electricity used in the United States by Question: Which single advantage and which single disadvantage do you think are the most important? Why?
Quick construction
Visual pollution
Easily expanded
Noise when located near populated areas
Can be located at sea
Land below turbines can be used to grow crops or graze livestock
Can kill birds and interfere with flights of migratory birds
Fig , p. 421

24. Geothermal Energy
Geothermal power, like nuclear and coal, works by boiling water to steam.
Naturally-occurring heat from the Earth is used in place of fuel.
At a geothermal plant, two wells are drilled.
One injects cold water towards the underground heat.
The second directs steam to the turbine.

25. Solar Energy
An enormous amount of energy (over 1,000 watts per square meter) hits the Earth every day.
This energy is very diffuse, spread out across the entire surface area of the planet.
Two separate technologies have been developed to convert solar energy into electricity.

26. Parabolic solar collection involves using curved reflective surfaces that collect light and focus it onto a concentrated point.
The heat is absorbed and used to boil water into steam, which spins a turbine.

27. Photovoltaic cells capture solar energy and convert it directly to electrical current.
Solar electricity tends to be times the cost of electricity from coal or other renewable sources.
Not available on overcast days or at night.

28. 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 can be blocked by trees and other structures
Quick installation
Environmental costs not included in market price
No CO2 emissions Very low air and water pollution
Figure 16.11
Advantages and disadvantages of heating a house with passive or active solar energy (Concept 16-3). Question: Which single advantage and which single disadvantage do you think are the most important? Why?
Need heat storage system
Very low land disturbance (built into roof or windows)
High cost (active)
Active system needs maintenance and repair
Moderate cost (passive)
Active collectors unattractive
Fig , p. 412

29. Trade-Offs: Solar Energy for High-Temperature Heat and Electricity

30. TRADE-OFFS Solar Cells Advantages Disadvantages Need access to sun
Fairly high net energy yield
Low efficiency
Work on cloudy days
Need electricity storage system or backup
Quick installation
Easily expanded or moved
Environmental costs not included in market price
No CO2 emissions
High costs (but should be competitive in 5–15 years)
Low environmental impact
Figure 16.20
Advantages and disadvantages of using solar cells to produce electricity (Concept 16-3). Question: Which single advantage and which single disadvantage do you think are the most important? Why?
Last 20–40 years
High land use (solar-cell power plants) could disrupt desert areas
Low land use (if on roof or built into walls or windows)
Reduces dependence on fossil fuels
DC current must be converted to AC
Fig , p. 417

31. Geography
Electricity generation by solar, wind, hydrokinetic, or geothermal plants is restricted by the natural geography of the United States.

32. The Great Plains have the highest average wind speeds and the greatest potential for wind power.

33. Areas with significant elevation differences and river courses are ideal for hydroelectricity generation.

34. The western states are the most favorable for geothermal energy production.

35. The deserts of the southwest are ideal for solar electricity generation.

36. Heat
Besides electricity, significant amounts of fossil fuels are burned for heat, especially natural gas.

37. Biomass
Traditionally, humans have relied on burning biomass, such as wood, charcoal, and dung as a source of heat.
These fuels will replenish, but produce similar levels of pollution to fossil fuels.
Excess demand can also lead to deforestation.

38. TRADE-OFFS Solid Biomass Advantages Disadvantages
Large potential supply in some areas
Nonrenewable if harvested unsustainably
Moderate to high environmental impact
Moderate costs
Environmental costs not included in market price
No net CO2 increase if harvested, burned, and replanted sustainably
Increases CO2 emissions if harvested and burned unsustainably
Plantation can be located on semiarid land not needed for crops
Low photosynthetic efficiency
Figure 16.24
General advantages and disadvantages of burning solid biomass as a fuel (Concept 16-6A). Question: Which single advantage and which single disadvantage do you think are the most important? Why?
Soil erosion, water pollution, and loss of wildlife habitat
Plantation can help restore degraded lands
Plantations could compete with cropland
Can make use of agricultural, timber, and urban wastes
Often burned in inefficient and polluting open fires and stoves
Fig , p. 422

39. TRADE-OFFS Biodiesel Advantages Disadvantages Reduced CO emissions
Increased NOx emissions and more smog
Reduced CO2 emissions (78%)
Higher cost than regular diesel
High net energy yield for oil palm crops
Environmental costs not included in market price
Low net energy yield for soybean crops
Moderate net energy yield for rapeseed crops
May compete with growing food on cropland and raise food prices
Figure 16.25
General advantages and disadvantages of using biodiesel as a vehicle fuel, compared to gasoline. Question: Which single advantage and which single disadvantage do you think are the most important? Why?
Reduced hydrocarbon emissions
Loss and degradation of biodiversity from crop plantations
Better gas mileage (40%)
Can make engines hard to start in cold weather
Potentially renewable
Fig , p. 424

40. Solar Heating
Energy from the sun can also be gathered to use as a source of heat.
Passive solar heat structures have no moving parts, but use south-facing windows to gather and absorb as much solar heat as possible.

41. Active solar heat structures pump water or another liquid through a collector.
Can be used for household radiant heating, or as a source of hot water for showers and cooking.
Image source:

42. Transportation The third major energy need is fuel for transportation.
Most of the cars, planes, and ships of the world run on petroleum products – gasoline, diesel, etc.

43. Alternative Fuels
Vehicles can be run on other fuels besides petroleum- based ones.
Biofuels, like ethanol, are generated from using bacteria or yeast to ferment plant matter.
Currently, the biggest source of this plant matter is corn. This can influence food prices.

44. TRADE-OFFS Ethanol Fuel Advantages Disadvantages High octane
Lower driving range
Low net energy yield (corn)
Some reduction in CO2 emissions (sugarcane bagasse)
Higher CO2 emissions (corn)
Much higher cost
High net energy yield (bagasse and switchgrass)
Environmental costs not included in market price
Figure 16.27
General advantages and disadvantages of using ethanol as a vehicle fuel, compared to gasoline. (Concept 16-6B). Question: Which single advantage and which single disadvantage do you think are the most important? Why?
May compete with growing food and raise food prices
Reduced CO emissions
Can be sold as E85 or pure ethanol
Higher NOx emissions and more smog
Corrosive
Potentially renewable
Can make engines hard to start in cold weather
Fig , p. 426

45. Hydrogen fuel cells use a chemical reaction between hydrogen and oxygen gas to generate an electric current.
H2 + O2 → H2O
Refueling is difficult, as pure hydrogen is a gas and difficult to store and transport safely.
No waste products are produced, except for water vapor.

46. TRADE-OFFS Hydrogen Advantages Disadvantages Fuel cell
Can be produced from plentiful water
Not found as H2 in nature
Energy is needed to produce fuel
Low environmental impact
Negative net energy
Renewable if produced from renewable energy resources
CO2 emissions if produced from carbon-containing compounds
No CO2 emissions if produced from water
Environmental costs not included in market price
Good substitute for oil
Nonrenewable if generated by fossil fuels or nuclear power
Competitive price if environmental and social costs are included in cost comparisons
High costs (that may eventually come down)
Figure 16.31
Advantages and disadvantages of using hydrogen as a fuel for vehicles and for providing heat and electricity (Concept 16-8). Question: Which single advantage and which single disadvantage do you think are the most important? Why?
Will take 25 to 50 years to phase in
Easier to store than electricity
Short driving range for current fuel-cell cars
Safer than gasoline and natural gas
No fuel distribution system in place
Nontoxic
Excessive H2 leaks may deplete ozone in the atmosphere
High efficiency (45–65%) in fuel cells
Fig , p. 430

47. Cars could be indirectly run on renewable energy if they had powerful enough batteries to store a charge needed to run the car for long periods of time.
Lead-acid batteries, currently in use, are too large and do not hold enough energy.
Nickel-Metal Hydride batteries, used in early generation hybrid cars, have a higher storage capacity, but will quickly lose a stored charge when not in use.
Lithium-ion batteries are the smallest and have the best storage capacity, but are also expensive to produce.
The Tesla Model S runs on lithium-ion batteries, with a range of 265 miles.

48. Getting Energy from the Earth’s Internal Heat
Geothermal energy: heat stored in
Soil
Underground rocks
Fluids in the earth’s mantle
Geothermal heat pump system
Energy efficient and reliable
Environmentally clean
Cost effective to heat or cool a space

49. Basement heat pump Figure 16.28
Natural capital: a geothermal heat pump system can heat or cool a house almost anywhere. It heats the house in winter by transferring heat from the ground into the house (shown here). In the summer, it cools the house by transferring heat from the house to the ground.
Fig , p. 427

50. TRADE-OFFS Geothermal Energy Advantages Disadvantages
Very high efficiency
Scarcity of suitable sites
Can be depleted if used too rapidly
Moderate net energy at accessible sites
Environmental costs not included in market price
Lower CO2 emissions than fossil fuels
CO2 emissions
Low cost at favorable sites
Figure 16.29
Advantages and disadvantages of using geothermal energy for space heating and for producing electricity or high-temperature heat for industrial processes (Concept 16-7). Question: Which single advantage and which single disadvantage do you think are the most important? Why?
Moderate to high local air pollution
Low land use and disturbance
Noise and odor (H2S)
High cost except at the most concentrated and accessible sources
Moderate environmental impact
Fig , p. 428

51. Energy Conversion Efficiencies
In addition to finding alternative, renewable energy sources, it is also important to reduce energy consumption.
Energy Efficiency is a measure of the percentage of energy consumed that actually performs the desired work.
Incandescent light bulbs: 5-10% efficient
Compact fluorescent: 20-33% efficient
LED: % efficient

52. Promoting Renewable Energy
Distributional surcharges are small charges levied on all utility customers to help finance research and development of renewable energy.
A renewable portfolio is a state mandated minimum percentage of energy that utilities must get from renewable sources.
Green pricing is the practice of some electricity suppliers offering plans (at a premium) that only use renewable sources for electricity.
California has enacted a 33 percent renewable portfolio standard set for 2020.

53. Promoting Renewable Energy
The energy star program is a federal initiative to promote and provide incentives for purchasing more efficient devices and appliances.

54. SOLUTIONS Making the Transition to a More Sustainable Energy Future
More Renewable Energy
Improve Energy Efficiency
Greatly increase use of renewable energy
Increase fuel-efficiency standards for vehicles, buildings, and appliances
Provide large subsidies and tax credits for use of renewable energy
Include environmental costs in prices for all energy resources
Mandate government purchases of efficient vehicles and other devices
Encourage government purchase of renewable energy devices
Greatly increase renewable energy research and development
Provide large tax credits or feebates for buying efficient cars, houses, and appliances
Reduce Pollution and Health Risk
Offer large tax credits for investments in energy efficiency
Figure 16.33
Suggestions of various energy analysts for helping us to make the transition to a more sustainable energy future (Concept 16-9). Question: Which five of these solutions do you think are the most important? Why?
Cut coal use 50% by 2020
Phase out coal subsidies
Reward utilities for reducing demand for electricity
Levy taxes on coal and oil use
Greatly increase energy efficiency research and development
Phase out nuclear power subsidies, tax breaks, and loan guarantees
Fig , p. 432

55. Energy conservation tends to be highly tied to consumer prices.
In response to 1970’s oil prices, average U.S. automobile gas-mileage increased from 13 mpg in 1975 to 28.8 mpg in

56. Falling fuel prices in the 1980s-early 2000s discouraged further improvements in fuel economy.
The recent popularity of smaller cars, hybrid cars, and electric cars has improved average MPG again.

57. Total Costs of Electricity from Different Sources in 2004

58. What Can you Do? Shifting to Sustainable Energy Use