geothermal energy

geothermal energy
Name	Geothermal energy
Caption	Geothermal powerplant with steam plumes
Type	Renewable energy
Primary	Earth's internal heat
Commercial since	20th century
Notable projects	Geysers, Hellisheiði, Nesjavellir, Larderello

geothermal energy

Geothermal energy harnesses heat from the Earth's interior to produce electricity, provide heating, and support industrial processes. It intersects with technologies and infrastructures developed by companies and institutions such as Chevron Corporation, General Electric, Siemens, Iceland Geothermal Cluster, Ormat Technologies, and Calpine Corporation. Major deployment projects involve places including The Geysers, Hellisheiði Power Station, Nesjavellir Geothermal Power Station, and Larderello, and are influenced by policies from entities like the International Energy Agency, United Nations Framework Convention on Climate Change, European Commission, and national agencies such as the United States Department of Energy.

Overview

Geothermal systems tap subsurface heat that originates from processes associated with planetary formation, radioactive decay, and magmatic intrusions in regions like Ring of Fire, Iceland, New Zealand, Japan, and Indonesia. Operators such as Reykjavík Energy, Enel SpA, Toshiba Corporation, and Mitsubishi Heavy Industries convert that heat through engineered wells, turbines, heat exchangers, and distribution networks serving cities like Reykjavík, Napa, Naples, and Akita. Research programs at institutions including Lawrence Berkeley National Laboratory, Idaho National Laboratory, Imperial College London, and Massachusetts Institute of Technology develop reservoir modeling, drilling innovations, and reservoir stimulation methods applied by firms like SLB (Schlumberger), Halliburton, and Baker Hughes.

Geologic and Thermal Principles

Heat transport in geothermal reservoirs is governed by conduction, convection, and, in high-enthalpy systems, magmatic heat transfer beneath volcanic arcs such as Cascade Range, Andes Mountains, and Marianas Islands. Permeable formations, fracture networks, and aquifers—exposed in basins like Salton Trough and calderas including Long Valley Caldera—store and transmit thermal energy. Exploration combines geophysical methods developed by organizations like US Geological Survey, GeoScience Australia, British Geological Survey, and National Institute of Advanced Industrial Science and Technology using seismic, magnetotelluric, and gravity surveys to map heat anomalies. Thermodynamic properties of fluids in hydrothermal, hot dry rock, and supercritical reservoirs are modeled with tools from Schlumberger, Halliburton, and academic groups at Stanford University and ETH Zurich.

Technologies and Power Generation

Electricity generation uses technologies such as dry steam, flash steam, and binary-cycle plants pioneered at sites like Larderello and The Geysers. Components include downhole pumps, binary heat exchangers manufactured by GE Power, organic Rankine cycle (ORC) units from Turboden, and geothermal turbines by Mitsubishi Heavy Industries and Siemens Energy. Enhanced Geothermal Systems (EGS) employ stimulation methods tested in projects affiliated with Department of Energy Frontier Observatory for Research in Geothermal Energy and partnerships with Chevron and Ormat Technologies. Hybrid systems integrate geothermal with solar thermal or combined heat and power (CHP) installations deployed by utilities including Iberdrola, EDF, and Tokyo Electric Power Company. Drilling technology improvements from National Oilwell Varco and directional drilling firms reduce costs in deep projects like those proposed near Salton Sea.

Direct Use and District Heating

Direct-use applications supply heat for district heating schemes in municipalities such as Reykjavík and Águas de São Pedro, greenhouses near Almería, aquaculture in Icelandic fisheries, and industrial process heat for companies like Alcoa and ArcelorMittal. Heat pumps, distributed by firms like Daikin Industries and Carrier Global, upgrade low-temperature resources for residential and commercial heating. District heating networks use pipework and heat-exchange technology developed by engineering firms including Siemens, Veolia, and ENGIE, and are supported by municipal programs in cities such as Stockholm, Helsinki, and Malmö.

Environmental Impacts and Risks

Environmental considerations include induced seismicity observed at EGS test sites, subsidence at production fields like Larderello, and emissions of non-condensable gases (CO2, H2S) historically measured at The Geysers and Wairakei. Water chemistry and scaling issues affect infrastructure and have been studied by research centers including Geological Survey of Canada and CSIR in South Africa. Regulations and standards from bodies like Environmental Protection Agency (United States), European Environment Agency, and national regulators in New Zealand and Iceland address monitoring, mitigation, and emergency response. Lifecycle assessments by Intergovernmental Panel on Climate Change contributors compare greenhouse gas intensity to fossil fuels and to other renewables such as wind power projects by Vestas and Siemens Gamesa.

Economics and Policy

Capital intensity, learning curves, and resource risk shape economics; financing models involve multilateral institutions such as the World Bank, Asian Development Bank, European Investment Bank, and export credit agencies like Export-Import Bank of the United States. Policies including feed-in tariffs implemented in Germany, renewable portfolio standards in California Renewable Portfolio Standard, tax incentives like the Investment Tax Credit (United States), and carbon pricing mechanisms developed in European Union Emissions Trading System affect project viability. Private investment from corporations such as Google and utility-scale portfolios managed by Ormat Technologies and Calpine influence deployment alongside public research funding from DARPA and national science foundations.

History and Global Deployment

Historical exploitation of geothermal hot springs dates to antiquity in regions like Rome and Japan; industrial electricity generation began at Larderello in the early 20th century with entrepreneurs and engineers connected to companies later evolving into Enel. Mid-20th-century expansion includes projects in New Zealand and Iceland, with late-20th and early-21st-century growth in United States, Philippines, Indonesia, and Kenya. International collaborations through International Renewable Energy Agency, World Geothermal Congress, and bilateral programs have advanced capacity in emerging markets such as El Salvador, Costa Rica, Turkey, and Ethiopia. Contemporary large-scale fields include developments operated by Ormat Technologies, Calpine Corporation, Enel Green Power, and national utilities like KenGen.

Category:Energy sources