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Text | Editor: Narration
Preface:
The earth, the blue planet, is pregnant with unlimited energy, oceans, forests, creatures, all contain huge life force, scientific exploration has found that 20,000 meters underground, there is a mysterious clean energy, its reserves are enough to support the development of human beings for 2.3 billion years.
This is geothermal energy, which comes from the heat deep inside the earth and is an inexhaustible treasure trove of energy. Geothermal energy is clean, environmentally friendly, sustainable use, unlike fossil fuels such as coal and oil, its development will reduce human damage to the environment, and the United States has seized the opportunity in this regard, so why should we vigorously develop it?
Geothermal energy deep in the Earth
Geothermal energy comes from the heat inside the earth, is a clean and sustainable form of energy, the high temperature deep in the earth makes the magma in an active state, a large amount of heat is continuously conducted to the surface, this geothermal heat is available everywhere but has long been ignored by human beings, until modern times, human beings gradually realized its huge energy potential.
Geothermal energy, like solar energy and wind energy, belongs to renewable energy, but unlike other renewable energy, geothermal energy is not affected by weather changes and can provide stable energy output, in addition, geothermal resources are very rich, basically in any area of the land can be exploited, is considered to meet the energy needs of human beings for billions of years, can be called an inexhaustible source of green energy.
Geothermal energy can be directly mined to generate electricity and heat, can also be subjected to a variety of deep processing conversion, electricity, high temperature magma water can directly drive turbines to generate electricity, heat, can be used for heating, manufacturing process heat, etc.; In terms of deep processing, it is also possible to extract rare elements and produce a variety of high value-added products such as hydrogen.
At present, about 24 countries in the world have begun to develop and utilize geothermal resources to varying degrees, of which Iceland's use of geothermal energy has developed to a fairly mature stage, renewable energy in its total domestic production of energy accounted for more than 65%, China has also proved rich geothermal resource reserves, has been initially used in power generation heating and other fields.
Although geothermal energy is recognized as one of the ideal renewable energy options, the efficient exploitation of geothermal energy from thousands of meters underground still faces many technical obstacles, magma water corrosion during drilling, high temperature and high pressure wear and tear of equipment make commercial development very difficult, and the deepest geothermal drilling has only reached about 10 kilometers.
However, with scientific and technological progress and material innovation, human beings are expected to achieve large-scale and efficient development and utilization of geothermal resources in the near future, which will greatly reduce the dependence on traditional energy, make the energy structure of countries cleaner, and have a far-reaching impact on the global environment and the sustainable development of human civilization.
Formation mechanism of geothermal energy
The Earth was formed about 4.5 billion years ago, and at first all the planets were in a hot magma state, and in the long history of evolution, the Earth gradually cooled, the surface rocks solidified to form land and oceans, but below the surface, the Earth's interior still maintains a very high temperature.
The structure of the earth can be divided into three main parts: core, mantle and crust, the core includes a liquid outer core and a solid core, the temperature is about 5000 °C, the mantle surrounds the core, the temperature is 2000-4000 °C, and the crust is the outermost part, the environment for human survival.
The reason why the mantle is in a high temperature state is mainly the residual heat in the early days of the formation of the earth, as well as the continuous decay of radioactive elements, which are transmitted to the outside world by convection and heat conduction, maintaining the high temperature of the mantle.
Heat from the mantle is continuously conducted to the outer crust, and geothermal heat is more likely to escape to the surface in areas with a thin crust, such as faults and volcanic belts, which is why geothermal resources are mainly concentrated in these geologically active areas.
When local heat is transported to the shallow layer near the surface, abundant hot water resources are formed, and this underground hot water has important utilization value for human beings, and by drilling geothermal wells, underground hot water can be obtained and converted into electricity or directly used for heating.
The huge heat inside the earth is the fundamental source of geothermal energy, and this continuous flow of geothermal heat is transmitted to the surface through complex geological movements, providing the possibility for human use, and the development of geothermal resources is to use the energy fire of the earth itself.
Mining is difficult – technical barriers to geothermal utilization
The development and utilization of geothermal resources can provide clean and sustainable energy for mankind, but the efficient acquisition of geothermal energy from the depths of the earth still faces many technical difficulties, and at present, the biggest obstacle to commercial exploitation of geothermal resources lies in the limitations of drilling technology.
As the drilling depth increases, the hardness of the formation rock increases sharply, from the soft soil layer into the hard bedrock area, and the geothermal resources are mainly stored in the bedrock layer, these deep rocks are very hard and the wear on the drill bit is very serious.
At the same time, as it penetrates deep into the mantle, the temperature and pressure are also rising rapidly, which will accelerate the deterioration of equipment materials, and the long-term exposure to high temperatures generated by the drilling process is a severe test for the drilling platform.
In addition, the complexity of the complex geothermal environment and liquid fluid activity in the ground increases the risk of drilling, the stress field may cause severe drilling slope, and various foreign fluids will also cause corrosion and erosion of equipment.
At present, the deepest exploration well in the world has only reached a depth of 12 kilometers, and to achieve large-scale commercial exploitation of geothermal resources, it is necessary to penetrate more than 20 kilometers of the earth's crust, which is still an insurmountable challenge for existing drilling technology.
The biggest difficulty in mining geothermal resources is the limitation of drilling technology, and only by solving obstacles such as rock hardness, high temperature and high pressure, and geological environment complexity can humans promote the sustainable use of geothermal resources.
The mining process of the countries of Soviet Russia and the United States
The development and utilization of geothermal resources has a history of more than 100 years, as early as the 19th century, human beings began to use geothermal resources, with the advancement of science and technology, countries have launched systematic geothermal resources development, among which, the Soviet Union, Russia and the United States are the most representative.
In the 70s of the 20th century, the Soviet Union launched an unprecedented ultra-deep drilling program with a target depth of 14 kilometers, which took 5 years, but due to the hardness of the rock far beyond expectations and the complex influence of in-situ stress, it was actually only 12 kilometers before it could continue to advance, and finally had to be abandoned.
Later, Russia encountered a similar dilemma in oil and gas drilling, in the Odoputu oil field, Russia used the world's most advanced drilling equipment, but due to the significant increase in rock hardness, eventually only extended to 12 kilometers, geothermal resource development faced technical obstacles, its core challenges are still in the ultra-high hardness of the rock and extreme high temperature and high pressure environment.
At present, a startup called Quaise Energy in the United States claims to have developed a new microwave radio frequency drilling technology called "wave drilling", which the company claims can achieve drilling at a depth of 20 kilometers, but industry experts are not optimistic about its commercialization prospects, because whether microwave radio frequency can effectively destroy rock is still unknown, and the geological risks of large-scale mining cannot be predicted.
Countries have made some progress in the development of geothermal resources and accumulated valuable experience, but there is still a large technological gap that has not yet been crossed to achieve the goal of large-scale economic exploitation of geothermal resources, which requires governments and enterprises to increase investment in scientific research to make more original breakthroughs and make geothermal energy truly a clean and sustainable future energy source.
The development of geothermal resources has a long way to go, and ultra-deep drilling technology is still the key to the progress of progress, only by solving the "stuck neck" problem of rock hardness and extreme geological environment can human beings accelerate the commercial utilization of geothermal resources.
Continental geothermal development history
In the 70s of last century, under the background of the country's strong support for the development of the western region, the mainland began the industrial development and utilization of geothermal resources, in 1977, China's first geothermal power station, Tibet Yangbajing geothermal station was completed and put into operation, marking the birth of the mainland geothermal industry.
In the 80s, following Yangba well, a number of geothermal power stations were established in southwest, north China and other resource-rich areas, and in the 21st century, the mainland has built a number of geothermal power stations, geothermal power generation scale accounts for about 5% of the total renewable energy power generation.
At present, the development of geothermal energy in mainland China is in a period of transformation and upgrading, on the one hand, focus on increasing the development of high temperature, deep geothermal scale mining is the key direction in the future, on the other hand, accelerate the diversified utilization of geothermal energy, vigorously expand geothermal heating, greenhouse planting, tourism and leisure and other industries, to achieve broader social and economic benefits.
Compared with the huge resource potential, there is still a certain gap in the development and utilization of mainland geothermal resources, the main constraint of geothermal development is drilling technology and cost, the next step, the state will increase scientific and technological research and development and policy support, reduce the cost of deep development, improve the overall capacity of large-scale mining.
Geothermal development also needs to pay attention to the balance with environmental protection, reasonably set the development density, reduce the potential impact on the surrounding ecosystem, at the same time, improve the efficiency of resource utilization, and achieve efficient and sustainable development of geothermal resources through scientific and technological progress.
Mainland geothermal development is in a period of rapid development of strategic opportunities, which requires the state and enterprises to strengthen cooperation, break through key core technologies, cultivate professional talents, and provide strong impetus for the sustainable development of the geothermal industry.
Epilogue:
The development and utilization of geothermal resources will reduce human dependence on fossil fuels, alleviate environmental pollution, and make the global energy structure greener.
However, the exploitation of ultra-deep geothermal energy still faces many technical obstacles, at the current stage, we need to carefully promote, strengthen scientific and technological innovation, balance development and environmental protection, the development of geothermal resources has a long way to go, but it will change the world's energy production and consumption mode, promote human civilization to a higher peak.
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