With shortages of fossil energy, especially oil and natural gas, and heavy biomass energy use occurring in both developed and developing countries, a major focus has developed worldwide on renewable energy systems. Renewable energy systems include wind power, biomass, photovoltaics, hydropower, solar thermal, thermal ponds, and biogas.

Currently, a heavy focus is on biofuels made from crops, such as corn, sugarcane, and soybeans, for use as renewable energy sources. Wood and crop residues also are being used as fuel. Though it may seem beneficial to use renewable plant materials for biofuel, the use of crop residues and other biomass for biofuels raises many concerns about major environmental problems, including food shortages and serious destruction of vital soil resources.

All renewable energy systems need to be investigated because humankind has only about 40 years of oil and gas reserves remaining. There is a 50 to 100 year supply of coal resources in the ground, but coal will become increasingly difficult to extract and will greatly increase the global warming threat.

Serious energy conservation and research on viable renewable energy technologies are needed. This book considers the effectiveness and economics of several renewable energy technologies of current interest, including biofuels, solar and wind.

Auteur

David Pimentel is a professor of ecology and agricultural sciences at Cornell University, Ithaca, NY 14853-0901. His Ph.D. is from Cornell University. His research spans the fields of energy, ecological and economic aspects of pest control, biological control, biotechnology, sustainable agriculture, land and water conservation, and environmental policy. Pimentel has published more than 600 scientific papers and 25 books and has served on many national and government committees including the National Academy of Sciences; President's Science Advisory Council; U.S Department of Agriculture; U.S. Department of Energy; U.S. Department of Health, Education and Welfare; Office of Technology Assessment of the U.S. Congress; and the U.S. State Department.

Résumé
The petroleum age began about 150 years ago. Easily available energy has s- ported major advances in agriculture, industry, transportation, and indeed many diverse activities valued by humans. Now world petroleum and natural gas s- plies have peaked and their supplies will slowly decline over the next 4050 years until depleted. Although small amounts of petroleum and natural gas will remain underground, it will be energetically and economically impossible to extract. In the United States, coal supplies could be available for as long as 4050 years, depending on how rapidly coal is utilized as a replacement for petroleum and natural gas. Having been comfortable with the security provided by fossil energy, especially petroleum and natural gas, we appear to be slow to recognize the energy crisis in the U. S. and world. Serious energy conservation and research on viable renewable - ergy technologies are needed. Several renewable energy technologies already exist, but sound research is needed to improve their effectiveness and economics. Most of the renewable energy technologies are in uenced by geographic location and face problems of intermittent energy supply and storage. Most renewable technologies require extensive land; a few researchers have even suggested that one-half of all land biomass could be harvested in order to supply the U. S. with 30% of its liquid fuel! Some optimistic investigations of renewable energy have failed to recognize that only 0. 1% of the solar energy is captured annually in the U. S.

Contenu
Renewable and Solar Energy Technologies: Energy and Environmental Issues.- Can the Earth Deliver the Biomass-for-Fuel we Demand?.- A Review of the Economic Rewards and Risks of Ethanol Production.- Subsidies to Ethanol in the United States.- Peak Oil, EROI, Investments and the Economy in an Uncertain Future.- Wind Power: Benefits and Limitations.- Renewable Diesel.- Complex Systems Thinking and Renewable Energy Systems.- Sugarcane and Ethanol Production and Carbon Dioxide Balances.- Biomass Fuel Cycle Boundaries and Parameters: Current Practice and Proposed Methodology.- Our Food and Fuel Future.- A Framework for Energy Alternatives: Net Energy, Liebig's Law and Multi-criteria Analysis.- Bio-Ethanol Production in Brazil.- Ethanol Production: Energy and Economic Issues Related to U.S. and Brazilian Sugarcane.- Ethanol Production Using Corn, Switchgrass and Wood; Biodiesel Production Using Soybean.- Developing Energy Crops for Thermal Applications: Optimizing Fuel Quality, Energy Security and GHG Mitigation.- Organic and Sustainable Agriculture and Energy Conservation.- Biofuel Production in Italy and Europe: Benefits and Costs, in the Light of the Present European Union Biofuel Policy.- The Power Density of Ethanol from Brazilian Sugarcane.- A Brief Discussion on Algae for Oil Production: Energy Issues.