1. Renewable and Alternative Energy Sources

2. World Wide Energy Production
15.2% alternative
84.8% fossil fuels

3. U.S. Energy Consumption
The four primary consumers of energy in the U.S. in 2007 were
Industrial 32%
Transportation 28%
Residential 22%
Commercial 18%
93% of the energy generated and used in the U.S. are from nonrenewable resources

4. Alternative Energy Sources
World-wide, with the exception of coal, which has known reserves that will last a couple of centuries, the known reserves of oil are expected to be exhausted in your lifetime...
Clearly, alternative energy sources are needed for the future

5. Alternative Energy Sources
We will look at:
Solar energy
Geothermal power
Hydropower
Tidal Power
Ocean thermal energy conversion
Wind energy
Biomass

6. Solar Energy The Sun is free (nobody owns or controls it)
In principle, the amount of solar energy that reaches the Earth’s surface could provide for all human energy needs forever

7. Solar Energy
The distribution of solar energy over the continental U.S. in watts per square meter
The desert regions of the southwest U.S. receive the most sunlight

8. Clean Solar Energy Solar energy is clean energy
It produces no hazardous solid, liquid or gas wastes
It does not create water or air pollution

9. Solar Energy
The two areas in which solar energy can make the greatest contribution are in space heating and in the generation of electricity
These are uses that account for two-thirds of U.S. energy consumption

10. Solar Heating
The simplest approach to solar heating is passive-solar heating
The building design should allow the maximum amount of sunlight to stream in through south and west windows during the cooler months
This heats the house and materials inside

11. Solar Heating Trees can be positioned to shade the house in summer
Wide eaves can shade windows in summer, but allow winter sunlight to enter
Drapes and shutters can insulate window areas in winter

12. Solar Heating
It has been estimated that 40 to 90% of most homes’ heating requirements could be supplied by passive-solar heating systems
100% solar homes have been built, but such homes usually cost many tens of thousands of dollars more to build
Retrofitting older homes to be solar efficient can be too costly
Over insulation can aggravate indoor pollution

13. Solar Electricity
Direct production of electricity using sunlight is accomplished using photovoltaic cells, also called solar cells
They have no moving parts and are “clean” energy
They are used to power the space station and to provide electricity in remote areas on Earth

14. Solar Electricity
A major limitation is cost, which greatly exceeds the cost of producing electricity using fossil fuels or nuclear power
The best solar cells are only 20% efficient and only provide 50 watts of electricity per square meter of cell size

15. Solar Electricity
A 100 watt light bulb would require 2 square meters of solar cells
And a 100-megawatt power plant would require 2 square kilometers (0.78 square miles) of solar cells
This represents a major use of land and resource, which would use far more steel and concrete than a fossil fuel power plant

16. Storing Solar Electricity
In a solar energy home, extra electricity is stored in batteries for later use
This work well for one house
Unfortunately, no wholly practical technology has been developed to store large amounts of electricity, despite advances in batteries

17. Storing Solar Energy
Some possible schemes for storing the energy of solar generated electricity include breaking up water into oxygen and hydrogen to burn later as fuels
Also pumping water to an elevated reservoir for later use as hydroelectric power generation

18. Solar Energy
Currently, solar energy provide less that 0.5% of the U.S. power needs, but even with existing technology, it could provide up to 15%

19. Solar Electricity
In summation, to make solar energy truly useful for large-scale power generation:
We need more efficient solar cells
We need a means of better storing electricity

20. 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

21. Geothermal Power

22. Geothermal Power
Magma rising from the mantles brings unusually hot material near the surface
Heat from the magma, in turn, heats any groundwater
This is the basis for generating geothermal energy

23. Geothermal Power
The steam and/or hot water is used to create electricity or for heating

24. Geothermal Power Plants
Worldwide, there are now about 40 geothermal power plants, especially in Japan, Mexico and the Philippines
Note that most geothermal power plants are built along plate tectonic boundaries

25. Geothermal Power Plants
How the geothermal energy is used depends on the temperature of the water
Three types of power plants are used to generate power from geothermal energy:
Dry steam
Flash
Binary

26. Types of Geothermal Power
Dry steam plants take steam out of the ground and uses the steam to turn a turbine that spins a generator
This was first done in Italy in 1904
Iceland, a volcanic island, has many geothermal areas that produce steam and are tapped to generate electricity

27. Types of Geothermal Power
Flash plants take super heated water, usually at temperatures over 200°C, out of the ground, allowing it to boil as it rises to the surface, then separates the steam from the water and uses the steam to turn a turbine generator
A flash power plant in Japan

28. Types of Geothermal Power
In binary plants, the hot water flows through heat exchangers, boiling an organic fluid that spins the turbine
For all three types of power plants, the condensed steam and remaining geothermal fluid are injected back into the hot rock to pick up more heat
This is why geothermal energy is viewed as sustainable
It is also very “clean”
Only produces steam

29. The Geysers, California
The largest U.S. geothermal power plant is The Geysers in California (it uses dry steam)
By 1989, a total of 10 billion watts of electricity was being produced by The Geysers and six other plants in the U.S.

30. Geothermal Power Plants
By the end of 2005 worldwide use of geothermal energy for electricity had reached 9.3 billion watts, with an additional 28 billion watts used directly for heating
In 1999, it was estimated that the U.S. could produce 100 billion watts of geothermal energy by 2050

31. Geothermal Heat
Even if the geothermal water is not as hot as steam, the warm water can be used to heat buildings, home and even greenhouses
This is routinely done in Russia and Iceland
In fact, using geothermal energy to heat is about 2-3 times as common as using it to create electricity

32. Limitations
Each geothermal field can only be used for a period of time, a few decades, before heat extraction is seriously reduced
Simply put, you can take hot water out of the ground faster than it can be renewed (even if you pump the water back into the ground)
For example, steam pressure at The Geysers has declined rapidly over recent years
It peaked at over 2 billion watts by 1991, but now in 2011 produces about 0.7 billion watts

33. 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

34. Hydropower
One-third (33%) of all power plants in the U.S. are hydroelectric, but they only generate 6% of U.S. electricity needs

35. Hydropower A cross-section of a typical hydroelectric dam
Water flows down the penstock, turns the turbine blades which power the generators

36. Hydropower
Water use for generating hydroelectric power is totally dependent on the available water (duh!!)
The Glen Canyon Dam in Utah is the classic example of building too big of dam for not enough water

37. Hydropower
Hydropower is a very clean, pollution-free, renewable energy source
The water is not consumed, but rather simply passes thru the generating equipment, and since several dams may occur along the same river, the water can be reused and reused

38. Hydropower
If every stream and river in America was dammed to generate power, you still only provide 20% of current U.S. power needs
There are about 1000 dams in the U.S. and there is very little prospect of building any new ones
In fact, some older dams have been removed, such as the 162 years old Edwards Dam in Maine

39. Three Gorges Dam
The Three Gorges Dam is now the largest hydroelectric dam in the world

40. Three Gorges Dam
As a size comparison, it is 5 times larger than the Hoover Dam on the Colorado River

41. Three Gorges Dam
The dam is 185 meters (600 feet) high and 2.3 kilometers (1.4 miles) wide
It has 26 hydroelectric power generators with a collective generating capacity of about 18,000 megawatts (the average nuclear power plant generates about 1000 megawatts)

42. Three Gorges Dam The Chinese began filling the reservoir in 2003
When filled to capacity, the reservoir will hold 22 cubic kilometers of water

43. Three Gorges Dam
As with any engineering project of great magnitude, there are serious problems
The reservoir will eventually stretch over 600 kilometers (375 miles) in length
It will submerge 125,000 acres of prime farmland

44. Three Gorges Dam
1,900,000 people were forced to relocate, many against their will
Entire cities have been abandoned
Over 1200 historic areas are being flooded

45. Three Gorges Dam
Three spectacular river gorges called Qutang, Wuxia and Xiling, all worthy of being national parks, have been flooded

46. Three Gorges Dam
Officials report that the cost is within its US$25 billion budget and insisted early on that the project would pay for itself through electricity generation
However, the project is thought to have cost more than any other single construction project in modern China, with unofficial estimates of US$100 billion or more

47. TRADE-OFFS Large-Scale Hydropower Disadvantages Advantages
High construction costs
Moderate to high net energy
High environmental impact from flooding land to form a reservoir
High efficiency (80%)
Large untapped potential
Environmental costs not included in market price
Low-cost electricity
Long life span
High CO2 emissions from rapid biomass decay in shallow tropical reservoirs
No CO2 emissions during operation in temperate areas
Figure 16.21
Advantages and disadvantages of using large dams and reservoirs to produce electricity (Concept 16-4). Question: Which single advantage and which single disadvantage do you think are the most important? Why?
Danger of collapse
Can provide flood control below dam
Uproots people
Decreases fish harvest below dam
Provides irrigation water
Decreases flow of natural fertilizer (silt) to land below dam
Reservoir useful for fishing and recreation
Fig , p. 418

48. Tidal Power
All large bodies of water, including the oceans and large lakes, have tides
Tidal power captures the energy contained in moving water mass due to tides

49. Tidal Power Two types of tidal energy can be extracted:
Kinetic energy of currents between ebbing and surging tides
Potential energy from the difference in height (or head) between high and low tides

50. Tidal Power
You can use the flowing water between low and high tides to generate electricity, similar to hydropower

51. Tidal Power
Turbines can be place on the ocean floor, for example at the entrance of a bay, where the flowing water can turn the fan to generate electricity

52. Tidal Power
Another option is to use under water turbines, which is like an underwater wind farm
This is currently being tested offshore of Scotland’s Orkney Islands
The ebbing and surging tidal flows turn 100 foot propellers, which each produce 1 megawatts of electricity

53. OTEC
Ocean energy thermal conversion (OTEC) is a new, clean technology that is still in the developmental stage
It exploits the temperature difference between warm surface water and the cold water at depth to run a “heat engine”
A heat engine is a device placed between a high temperature reservoir and a low temperature reservoir that produces energy

54. OTEC
Either the warm water is used directly to run a turbine, or the heat is used to vaporize a working fluid (ammonia) which runs the turbine
The cold water is used to chill down the water or vapor
Drinkable, distilled fresh water is a by-product

55. OTEC
The temperature difference must be at least 40oF (22oC) year round, which is only found near the equator
So this emerging technology is best for tropic islands

56. OTEC
A test plant is currently being constructed at Keahole Pointe on the Kona coast of Hawaii and should become operational in 2013

57. Wind Energy
Wind energy has been utilized for thousands of years

58. Wind Energy
The wind is free, commonly available and can provide clean, pollution-free energy
Today’s wind-turbines are very high tech

59. Wind Energy
In most places, the cost of commercial wind power on a large scale is not now economically competitive with conventionally generated electricity
One important factor is that with a doubling of wind speed, power output increases by a factor of 8

60. Wind Energy
The numbers indicate the percentage of 1990 regional electricity demand that full utilization of wind energy could meet
Clearly, the great plains have significant wind energy potential

61. Wind Energy
U.S. wind power capacity from 1981 to 2002

62. Wind Energy
U.S. wind power capacity from 1996 to 2008

63. Wind Energy
The U.S. remains the world leader in wind energy, but Europe has embarked on an very ambitious wind-power development program
It is predicted that by 2030, wind energy will supply at least twice the electricity it does now

64. Wind Energy Limitations
It would take about 1000 one-million watt windmills to equal the energy output of one sizable fossil fuel power plant
The windmills can be noisy
And they are hard on migrating birds

65. 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

66. Biomass Energy Biomass energy is derived from organic matter
Stoves that burn wood are the classic example
In fact, there had been a 20-25% increase in the use of wood stoves over the past several decades

67. Biomass Fuels or Biofuels
Biofuels differ from other renewable energy sources, such as wind, hydroelectric, geothermal and solar, as they are primarily used in the transportation sector and are derived from recently living matter, both plant and animal

68. Ethanol Fuel
Ethanol fuel is a biofuel alternative to gasoline, which is gaining popularity world-wide
Car engines can be designed to run on 10%, 50% even 100% pure ethanol
It is cleaner burning than gasoline
Worldwide, the use of ethanol is rapidly increasing

69. “E” Numbers
Ethanol fuel mixtures have "E" numbers which describe the percentage of ethanol in the mixture by volume, for example, E85 is 85% ethanol and 15% gasoline
Low ethanol blends, from E5 to E25, are also known as gasohol, though internationally the most common use of the term gasohol refers to the E10 blend

70. Gasohol
E10 gasohol is becoming more commonly found at gas stations in the U.S. (Tennessee is way behind)
As the “10” indicates it is made from a mixture of
gasoline (90%) and ethanol (10%)
Gasohol has higher octane, or antiknock, properties than gasoline and burns more slowly, more cooler, and more completely, resulting in reduced emissions of some pollutants

71. Ethanol Fuel
Automotive ethanol capabilities vary widely country to country, but most spark-ignited gasoline style engines will operate well with mixtures of up to 10% ethanol
Brazil is the world leader in ethanol fuels
In Brazil, ethanol-powered and flexible-fuel vehicles are manufactured to be capable of operation by burning hydrated ethanol, an azeotrope of 93% ethanol and 7% water

72. Ethanol Fuel
Ethanol fuel is produced from sugar cane in Brazil, which is a more efficient source of fermentable carbohydrates than corn as well as much easier to grow and process in the tropical climate

73. UT & Switchgrass
The UT Biofuels Initiative has started testing the use of switchgrass, which is believed to offer a greater ethanol yield than corn in a temperate climate, such as in Tennessee

74. UT & Switchgrass
The project represents the culmination of years of corporate research and development and a highly touted $40.7 million investment from the state of Tennessee to build a plant for demonstrating technology developed by DuPont Danisco Cellulosic Ethanol

75. 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

76. 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

77. Alternative Energy Sources
Most of the world still relies very heavily on fossil fuels, but slowly but surely, attention is being diverted to alternative energy
Energy use in the future will not be dominated by a single source

78. Alternative Energy Sources
The most important aspects of most alternative energy sources is that they promise clean, pollution-free energy