Alternative Energy Sources

1. Alternative Energy Sources

2. Future Energy Needs World energy consumption is expected to increase by 60% between 2000 and 2020

3. World Energy Production

4. Alternative Energy Sources With the exception of coal, which has known reserves that will last a couple of centuries, the known reserves of oil and gas 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: Methane clathrate Nuclear Fusion Solar energy Geothermal power Hydropower Tidal Power Ocean thermal energy conversion Wind energy Biomass

6. Burning Ice Methane clathrate, also called methane hydrate or methane ice, is a solid form of water that contains a large amount of methane within its crystal structure

7. Burning Ice About 10 years ago, it was discovered that extremely large deposits of methane clathrate occur under sediments on the ocean floors, usually along the coastlines

8. Burning Ice The size of these oceanic deposits is staggering For example, it has been estimated that over 1 quadrillion cubic feet of methane ice lies offshore of North and South carolina alone There is more methane ice than all other fossil fuels combined

9. Burning Ice Can global warming liberate these methane ice deposits? This would profoundly increase the greenhouse effect Methane is a far more efficient greenhouse gas than carbon dioxide The amount of methane locked in methane hydrates is estimated to be 3000 times more than is currently in the atmosphere

10. Nuclear Fusion Nuclear fusion is what powers the sun

11. Nuclear Fusion Nuclear fusion is the process by which two smaller atomic nuclei combine to form a larger atomic nuclei, with an accompanying release of energy In the sun, two hydrogen nuclei combine to form a helium nuclei, with a corresponding release of energy

12. Nuclear Fusion For technical reasons, on Earth, fusion is best done with isotopes of hydrogen, specifically deuterium and tritium

13. Nuclear Fusion Natural hydrogen only contains 0.015% of deuterium Tritium is much much rarer (and is slightly radioactive) However, hydrogen is very plentiful on Earth, with the oceans containing an essentially inexhaustible supply of water

14. Nuclear Fusion Nuclear fusion will be the “cleanest” type of nuclear power However, it will take decades of research and billions of dollars to develop the technology

15. 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

16. 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

17. 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

18. 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

19. 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

20. 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

21. 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

22. 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

23. 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

24. 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 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

25. 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

26. 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

27. 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%

28. 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

29. Geothermal Power

30. 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

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

32. Geothermal Power Plants Worldwide, there are now about 40 geothermal power plants, especially in Japan, Mexico and the Philippines

33. Geothermal Power Plants Note that most geothermal power plants are built along plate tectonic boundaries

34. 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

35. Types of Geothermal Power Dry steam plants take steam out of the ground and use 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

36. 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

37. 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”

38. 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 kilowatts of electricity was being produced by The Geysers and six other plants in the U.S.

39. 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

40. 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

41. 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 produces about 1.2 billion watts

42. Hydropower 33% of all power plants in the U.S. are hydroelectric, but they only generate 6% of U.S. electricity needs

43. 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

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

45. 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

46. 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

47. 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

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

49. 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

50. Tidal Power Tidal Power Another option is to use offshore turbines, rather like an underwater wind farm This has the advantage of being much cheaper to build, and does not have the environmental problems that a tidal barrier would bring