Plant energy can be used in the form of wood or other fuels. Some plants or plant products can be converted to alcohol or methane. In addition, domestic garbage, which consists largely of paper, can be burned to generate useful energy. If it is allowed to rot, methane is produced. In Modesto, California, methane from the sewage treatment plant has been collected and used in city vehicles. The cost to the city was equivalent to buying gasoline at 30 cents per gallon.
Many early settlers used the power of falling water to drive their mills and factories. Today many large rivers are dammed and the energy of water dropping downward through the dam is used to produce electricity. Today about three percent of energy in the U.S. is supplied by water. Dams are very expensive to build and cause problems like flooding valuable farmland, causing silt buildup up river, and stopping flow of nutrients to ocean for fish. However, there are many dams that have been built for flood control, irrigation, and recreation that do not have turbines installed to produce electricity. These dams alone could produce 1.3% of the total U.S. consumption. Tidal power, the idea of using harnessing the movement of the tide's energy has been around for a long time. It has not been very successful because 1) there are not very many places in the world where the tidal currents are great enough 2) it would be even more expensive than hydroelectric dams 3) of destruction of fish breeding habitats and recreation areas.
Ocean thermal power plants have been developed. This process allows the warm surface waters of tropical oceans to heat pressurized ammonia. The ammonia gas expands against the blades of a turbine and the spinning turbine drives a generator to produce electricity. The gases are cooled and condensed by colder subsurface waters that are pumped into the power plant. Opponents of this project argue that the capital costs of these power plants are so high that it is not economically feasible.
Wind power has been around for years. It has been estimated that wind power could produce 40% of our country's needs. The major problem is economics. In rural areas wind power is economical but of availability and easy to distribute. In metropolitan areas the cost of distribution makes wind power uneconomical.
Energy from the heat of the earth's crust is called geothermal energy. Geothermal energy is economical in certain regions but at its highest potential, it represents only 1% of total power requirements of the U.S.As we list these renewable energy sources, we know somewhere in these we must find the answer to our future energy needs.
2. Investigate the building of large dams to see problems that were encountered.
3. Analyze the potential for renewable energy resources in your home town.
What energy source might eventually be cheaper than fossil fuels?
This lesson addresses Instructional Objective 5.02
The students will develop the following chart and research the data to fill in current use, availability, current cost, pollution problem.
Energy Source in the United States
Energy Source Current Use Future Current Pollution
Availability Cost Problems
oil
natural gas
coal
hydroelectric
heavy oil
nuclear
wood
garbage
solar
wind
tides
geothermal
hydrogen fusion
RESOURCES:
ceceone@utm.edu