Geothermal power
[4] International markets grew at an average annual rate of 5 percent over the three years to 2015, and global geothermal power capacity is expected to reach 14.5–17.6 GW by 2020.
[3] Countries generating more than 15 percent of their electricity from geothermal sources include El Salvador, Kenya, the Philippines, Iceland, New Zealand,[6] and Costa Rica.
Prince Piero Ginori Conti tested the first geothermal power generator on 4 July 1904 in Larderello, Italy.
Experimental generators were built in Beppu, Japan and the Geysers, California, in the 1920s, but Italy was the world's only industrial producer of geothermal electricity until 1958.
Subsidence at Wairakei-Tauhara has been an issue in a number of formal hearings related to environmental consents for expanded development of the system as a source of renewable energy.
[13] An organic fluid based binary cycle power station was first demonstrated in 1967 in the Soviet Union[12] and later introduced to the United States in 1981[citation needed], following the 1970s energy crisis and significant changes in regulatory policies.
In 2006, a binary cycle station in Chena Hot Springs, Alaska, came on-line, producing electricity from a record low fluid temperature of 57 °C (135 °F).
The development of binary cycle power plants and improvements in drilling and extraction technology may enable enhanced geothermal systems over a much greater geographical range.
[15] Demonstration projects are operational in Landau-Pfalz, Germany, and Soultz-sous-Forêts, France, while an earlier effort in Basel, Switzerland was shut down after it triggered earthquakes.
By the laws of thermodynamics this low temperature limits the efficiency of heat engines in extracting useful energy during the generation of electricity.
The efficiency of the system does not affect operational costs as it would for a coal or other fossil fuel plant, but it does factor into the viability of the station.
In order to produce more energy than the pumps consume, electricity generation requires high-temperature geothermal fields and specialized heat cycles.
[citation needed] Because geothermal power does not rely on variable sources of energy, unlike, for example, wind or solar, its capacity factor can be quite large – up to 96% has been demonstrated.
The Earth's crust effectively acts as a thick insulating blanket which must be pierced by fluid conduits (of magma, water or other) to release the heat underneath.
[15] Estimates of the electricity generating potential of geothermal energy vary from 35 to 2000 GW depending on the scale of investments.
A 2006 report by the Massachusetts Institute of Technology (MIT) that included the potential of enhanced geothermal systems estimated that investing US$1 billion in research and development over 15 years would allow the creation of 100 GW of electrical generating capacity by 2050 in the United States alone.
To restore some of the former capacity, supplemental water injection was developed during the 1990s and 2000s, including utilization of effluent from nearby municipal sewage treatment facilities.
[33] The International Renewable Energy Agency has reported that 14,438 megawatts (MW) of geothermal power was online worldwide at the end of 2020, generating 94,949 GWh of electricity.
[36] Al Gore said in The Climate Project Asia Pacific Summit that Indonesia could become a super power country in electricity production from geothermal energy.
[37] In 2013 the publicly owned electricity sector in India announced a plan to develop the country's first geothermal power facility in the landlocked state of Chhattisgarh.
[42] As of 2021, five countries (Kenya, Iceland, El Salvador, New Zealand, and Nicaragua) generate more than 15% of their electricity from geothermal sources.
[43] For comparison, a coal-fired power plant emits 1,001 kg of CO2 equivalent per megawatt-hour when not coupled with carbon capture and storage (CCS).
[44] Stations that experience high levels of acids and volatile chemicals are usually equipped with emission-control systems to reduce the exhaust.
Geothermal stations can also inject these gases back into the earth as a form of carbon capture and storage, such as in New Zealand[44] and in the CarbFix project in Iceland.
[45] In addition to dissolved gases, hot water from geothermal sources may hold in solution trace amounts of toxic chemicals, such as mercury, arsenic, boron, antimony, and salt.
The modern practice of injecting geothermal fluids back into the Earth to stimulate production has the side benefit of reducing this environmental risk.
The project in Basel, Switzerland was suspended because more than 10,000 seismic events measuring up to 3.4 on the Richter Scale occurred over the first 6 days of water injection.
A typical well doublet in Nevada can support 4.5 megawatts (MW) of electricity generation and costs about $10 million to drill, with a 20% failure rate.
