GEOTHERMAL POWER GENERATION: GLOBAL PERSPECTIVES; U.S.A. AND ICELAND; TECHNOLOGY, DIRECT USES, PLANTS, AND DRILLING

Abstract

This paper discusses the state of the art in harnessing geothermal power for medium- and large-scale generation of electricity and for space heating worldwide. It reviews current, probable, possible, and potential developments in both developed and developing countries in the near future and long term. The author first reviews world energy consumption and then discusses relative contribution of energy sources in the world in OECD countries, summarizes installed geothermal capacities for electricity generation, and examines direct use of geothermal energy worldwide together with the technical potential of renewable energy sources. The central part of the article examines geothermal energy in the United States, highlighting heat flow, tectonic controls, types of geothermal systems, United States geothermal potential, geothermal energy in the United States, operating conditions for electricity generation, and environmental constraints. Then the author considers Iceland's primary power consumption, production of electricity in Iceland, low-temperature geothermal resources, and high-temperature geothermal resources. The paper then examines the Geothermal Technologies Programme in the United States, reviewing the goals of geo-science and supporting technologies, exploration and drilling research, and energy systems research and testing; enhanced geothermal systems, and direct use of geothermal energy, considering district heating, agriculture, and aquaculture applications and future developments. Finally, improving geothermal power plants is discussed and typical R&D projects are reviewed. Highlighted are such research and development projects as enhanced heat transfer in air-cooled condensers, materials research, instruments for real time monitoring of geothermal processes, plant optimization, removal of noncondensable gases from binary power plants, and silica and metals extraction. The article also discusses geothermal drilling R&D aimed at reducing drilling costs by 25∼50%.