Geothermal Power Generation Worldwide: Global Perspective, Technology, Field Experience, and Research and Development

This article discusses the state of art in harnessing geothermal power for medium- and large-scale generation of electricity (and for space heating) worldwide. It reviews technology, field experience, research, and development, together with current, probable, possible and potential developments in the USA, developed, and developing countries in near future and long term. First, world consumption of geothermal energy is discussed. Here, worldwide installed capacities for geothermal electricity, the countries with the highest share of electricity generated from geothermal power, capacity factors, and direct use of geothermal energy is reviewed. Then, cost of renewable energy, i.e., current installation cost for electricity generation and heat generation, for biomass, solar photovoltaic, solar thermal, hydro, geothermal, wind, and tidal power is reviewed. Geothermal power in the United States is examined. Highlighted is 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. The central part of the article discusses field experience with innovative geothermal plants considering geothermal power plant analysis and design (optimization in design of geothermal power plants, optimization of prime movers, heat cycle considerations, resource considerations, and environmental considerations). A review of experimental plants (proposed systems and tested systems), and innovative power plants in commercial operation (low, moderate, and high enthalpy resources) is then discussed. The article goes on to examine R&D programs that are underway to significantly enhance the use of geothermal power. Highlighted is typical research and development projects such as enhanced heat transfer in air-cooled condensers, materials research, instruments for real time monitoring of geothermal processes, plant optimization, removal of non-condensable gases from binary power plants, silica and metals extraction, and small-scale power plant field verification projects. Geothermal drilling R&D is also reviewed.