The Earth is a huge reservoir of thermal energy, and its internal temperature reaches up to 6,000 degrees Celsius, which is equivalent to the temperature of the sun's surface.
Within 20 kilometers below the Earth's surface, there are about 450 million kilowatt-hours of thermal energy, which is 25,000 times more than all fossil fuels currently known.
Currently, geothermal power is being generated in 29 countries around the world, with a total installed capacity of about 15.4 GW, accounting for 0.3% of global renewable energy generation. Among them, the United States is the leader in geothermal power generation, with about 3.6 GW of installed capacity, accounting for 23% of the world's total.
The United States is also constantly exploring and developing more efficient, advanced and environmentally friendly geothermal energy technologies to meet the challenges of the energy crisis and climate change.
So, can geothermal energy really last 2.3 billion years?
Classification and characteristics of geothermal energy
Geothermal energy refers to the thermal energy in the Earth's interior, which is mainly found in the Earth's crust, mantle, and core. According to the temperature, depth and state of geothermal resources, geothermal energy can be divided into three categories: high-temperature geothermal energy, medium-low temperature geothermal energy and deep geothermal energy.
High-temperature geothermal energy refers to geothermal water or steam with a temperature of more than 150 degrees Celsius, which is generally distributed in areas with high geological activity, such as volcanoes, seismic zones or plate margins, and is located at depths of less than 5 kilometers.
Geothermal power generation
High-temperature geothermal energy can directly use geothermal steam to drive turbines to generate electricity, or geothermal water to provide thermal energy for industrial or agricultural energy needs. The advantages of high-temperature geothermal energy are high power generation efficiency, low cost, and low environmental impact, but the disadvantages are uneven distribution of resources, difficult development, and sometimes accompanied by the risk of harmful gases or geological disasters.
Medium- and low-temperature geothermal energy refers to geothermal water with a temperature between 50-150 degrees Celsius, which is generally distributed in areas with a high geothermal gradient and a depth of less than 5 kilometers. Medium and low temperature geothermal energy can use the heat exchange of geothermal water and secondary working fluid to drive the organic Rankine cycle (ORC) to generate electricity, or a heat pump system that uses geothermal water to provide heating or cooling of buildings.
The advantages of medium and low temperature geothermal energy are that the resources are widely distributed, the development technology is mature, and the environmental impact is small, but the disadvantages are low power generation efficiency and high cost, which sometimes causes the problem of falling groundwater level or geothermal water pollution.
Deep geothermal energy refers to rocks with a temperature of more than 150 degrees Celsius, which are generally distributed in the deep parts of the earth's crust at depths of more than 5 kilometers. Deep geothermal energy can use artificially created cracks to inject water or other fluids to form a heat exchange system, and then use high-temperature and high-pressure fluids to drive turbines to generate electricity, or use thermal energy storage in rocks to provide long-term stable heat energy demand.
Ground source heat pump principle
The advantages of deep geothermal energy are huge resource potential, high power generation efficiency, and low environmental impact, but the disadvantages are that the development technology is not yet mature, the cost is high, and sometimes it causes the risk of earthquakes or geothermal fluid leakage.
Advantages, disadvantages and challenges of geothermal energy
As a renewable energy source, geothermal energy has many advantages, such as:
Geothermal energy is an almost unlimited energy source that is not affected by seasons, climate, geography, etc., and can provide stable baseload electricity or heat.
Geothermal energy is a clean energy source that does not produce emissions of greenhouse gases such as carbon dioxide, nor does it produce pollution from harmful substances such as nuclear waste, which can reduce the burden on the environment.
Geothermal energy is a multi-functional energy source, which can be used in power generation, heating, cooling, agriculture, industry, medical and other fields, which can improve the efficiency and economic benefits of energy utilization.
Geothermal energy is a local energy source, which can reduce dependence on external energy, enhance energy security and autonomy, and also promote local social and economic development.
However, geothermal energy also has some drawbacks and challenges, such as:
The development of geothermal energy requires high investment and operation and maintenance costs, especially the development of deep geothermal energy, high-precision geological exploration, difficult drilling, high-risk fracturing and other technologies, as well as the construction of complex geothermal power stations and transmission systems, which will increase the cost and difficulty of geothermal energy.
The development of geothermal energy may cause some geological and environmental problems, such as the decline of geothermal water level, pollution of geothermal water, leakage of geothermal fluids, degradation of geothermal systems, and earthquake induction, which will affect the sustainability and safety of geothermal energy.
The development of geothermal energy needs to be in harmony with the local society and culture, such as respecting local land ownership, protecting the local natural landscape, and taking into account the wishes of local residents, which will affect the acceptability and feasibility of geothermal energy.
Therefore, the development of geothermal energy needs to be comprehensively evaluated and optimized in terms of technology, economy, environment, society and other aspects to maximize the utilization and minimize the impact of geothermal energy.
The current situation and future prospects of geothermal energy development in the United States
The United States is a global leader in geothermal energy, with abundant geothermal resources, advanced geothermal technology, well-established geothermal policies, an active geothermal market, and extensive geothermal cooperation.
The development of geothermal energy in the United States can be divided into the following aspects:
Geothermal power generation: The United States is the world's largest geothermal power producer, with 3.6 GW of installed geothermal power capacity at the end of 2022, accounting for 23% of the world's total, mainly in the western states of California, Nevada, Utah and other states.
Geothermal power generation in the United States mainly uses high-temperature geothermal resources, using dry steam, flash or secondary cycle technologies, as well as some new geothermal power generation technologies, such as carbon dioxide geothermal power generation, supercritical water geothermal power generation, etc. Geothermal power projects in the United States have good economic and environmental benefits, with an average cost of US$0.07/kWh and an average CO2 emission of 0.05 kg/kWh, much lower than fossil fuel power generation.
There is also great potential for geothermal power generation in the United States, which is estimated to have 30 GW of available resources, of which deep geothermal energy has a higher potential of more than 100 GW.
Geothermal heating: The United States is the world's largest geothermal heating country, with 3.7 GW of installed geothermal heating capacity in the United States reaching 3.7 GW by the end of 2022, accounting for 16% of the world's total, mainly in the eastern states of New York, Pennsylvania, Maryland and other states. Geothermal heating in the United States mainly uses medium and low temperature geothermal resources, using technologies such as ground source heat pumps or water source heat pumps, as well as some new geothermal heating technologies, such as geothermal floors, geothermal snow melting, etc.
Geothermal heating projects in the United States have good energy savings and comfort, with an average energy saving rate of 40-70% and an average payback period of 5-10 years. There is also great potential for geothermal heating in the United States, where it is estimated that 10 GW of resources are available for geothermal heating, of which the potential for deep geothermal energy is even higher, reaching more than 50 GW.
Other geothermal uses: The United States also uses geothermal energy for some other uses, such as geothermal agriculture, geothermal industry, geothermal medical treatment, geothermal tourism, etc. The use of geothermal energy for agricultural production in the United States, such as greenhouse cultivation, animal breeding, aquaculture, etc., can improve the quality and yield of agricultural products and increase farmers' income.
The use of geothermal energy for industrial production in the United States, such as papermaking, pharmaceuticals, food processing, etc., can reduce energy consumption and costs, and improve the competitiveness of products. The use of geothermal energy for health care in the United States, such as spa therapy, hydromassage, mud bath beauty, etc., can improve people's health and quality of life.
The United States uses geothermal energy for tourism and entertainment, such as thermal baths, geothermal parks, geothermal museums, etc., which can attract tourists and create jobs.
The development of geothermal energy in the United States benefits from its strong scientific research strength, sound policy support, active market competition, and extensive international cooperation. The United States has a number of geothermal energy research institutions, such as the National Renewable Energy Laboratory (NREL), the Office of Geothermal Technology (GTO), the Geothermal Resources Council (GRC), etc., which continue to promote the basic research and application development of geothermal energy, and improve the technical level and economic benefits of geothermal energy.
The United States has formulated a series of policies and measures for geothermal energy, such as federal tax incentives, state subsidies, grid access guarantees, land use permits, etc., which provide strong legal guarantees and economic incentives for the development of geothermal energy. The U.S. has multiple geothermal energy market players, such as the Geothermal Energy Association (GEA), the Geothermal Energy Industry Association (GEIA), and the Geothermal Energy Development Corporation (GDC), which promote the commercialization and scale of geothermal energy through competition and cooperation.
The United States also cooperates with many countries and organizations in geothermal energy, such as the International Energy Agency (IEA), the International Geothermal Association (IGA), the International Geothermal Center (IGC), etc., which promote the globalization and multilateralization of geothermal energy through information exchange, technology transfer, project cooperation, etc.
Geothermal energy location
Geothermal energy is an endless source of energy that can be used by humans for 2.3 billion years, and it is hidden 20 kilometers underground. The United States is actively developing this energy source to meet energy transition and climate goals.
The development of geothermal energy in the United States has rich experience and achievements, but also has some challenges and opportunities. The United States needs to continue to promote geothermal energy technology innovation, cost reduction, environmental protection, and social participation to maximize the use and minimize the impact of geothermal energy.
The development of geothermal energy in the United States is not only of great significance to the United States itself, but also has a positive impact on the development of geothermal energy in the world. We look forward to the United States continuing to play a leading role in geothermal energy and providing more solutions and contributions to humanity's energy and environmental problems.
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