The temperature is over 7000 degrees! What should humans do？

The interior of the earth

There is a huge amount of heat hidden.

Can you guess?

What is the highest temperature in the center of the earth?

This heat energy from the interior of the earth

Is geothermal energy.

Such as hot springs

Is a form of geothermal energy.

If you slice the earth,

Including the crust, mantle and core.

The core can reach nearly 7000 degrees Celsius.

Successful exploitation of geothermal energy

Not only promote the development of new energy in China

It will also help China achieve the goal of "double carbon"

September 4, 2023

CCTV10 "Perspective of New Technology" is broadcast.

Looking for "the heat of the center of the earth"

Liu Jinxia, Professor-level Senior Engineer of China Petrochemical Company.

Li Ruixia, Researcher of Xinxing (Beijing) New Energy Research Institute of Sinopec

Tell you in the program:

What is geothermal?

How to wipe out the heat of 4000 and 5000 kilometers underground?

Why can geothermal heat still cool?

……

What is geothermal?

Geothermal energy is heat energy from the interior of the earth. In recent years, with the continuous efforts of Chinese scientific and technical personnel, geothermal energy has made great progress in both the scope of exploitation and utilization and the breakthrough of technical depth.

How to distinguish different depths of geothermal energy?

200 meters is called shallow geothermal energy; 200 meters to 3000 meters, called hydrothermal geothermal energy, the temperature can reach about 100 degrees Celsius; At a depth of 3000 meters, there is a high-temperature rock mass, the temperature can exceed 180 degrees Celsius or even above 200 degrees Celsius, but there is no fluid in it or only a small amount of water. This high-temperature rock mass is called dry-hot rock.

Dry-hot rock VS hydrothermal geothermal energy

The temperature of dry-hot rocks is 70-80 degrees Celsius, or even more than 100 degrees Celsius. You can heat directly after changing the heat, so the efficiency will be higher. However, compared with hydrothermal geothermal energy, although the temperature of dry-hot rock is very high, there is no natural fluid, so it needs artificial injection of fluid to generate high-temperature water or steam, and then it can be used for power generation or heating.

Little knowledge:

What is the current situation of geothermal resources development and utilization in China?

China is one of the earliest countries to develop and utilize geothermal resources. According to records, as early as 2000 years ago, there was a custom of hot spring bathing in China. In the 20th century, many countries, including China, began to develop and utilize geothermal energy for heating and power generation on a large scale.

China is rich in geothermal resources, and more than 3,200 geothermal areas have been discovered. In the past 30 years, with the continuous breakthrough of exploration and mining technology, the exploitation and use of geothermal energy in China have also increased year by year. At present, the scale of direct utilization of geothermal energy in China has ranked first in the world for many years.

What are the advantages of geothermal energy compared with traditional energy sources?

Green and clean, compared with fossil energy, geothermal energy has no emission of carbon dioxide, sulfur dioxide and dust; Compared with renewable energy, it has wide distribution, large reserves, large scale and stability, and can be localized and distributed.

At present, the annual recoverable amount of shallow geothermal resources in China can reach 700 million tons of standard coal; Hydrothermal geothermal energy in the middle and deep layers, with an annual recoverable amount of more than 1.8 billion tons of standard coal; The annual reserves of dry-hot rocks are huge, and the annual recoverable amount reaches 8.6 trillion tons of standard coal.

In recent years, wind power photovoltaic has developed rapidly, mainly used for power generation, but the effective utilization time of wind power generation is from 2000 to 3000 hours a year, and the photoelectric time is about 1000 hours. But geothermal energy can reach 8000 hours in power generation.

At present, geothermal energy is mainly used directly. By the end of 2021, China’s geothermal heating area is about 1.33 billion square meters, replacing standard coal by nearly 38 million tons, which is equivalent to reducing carbon dioxide emissions by 100 million tons. Therefore, the effect of geothermal green carbon reduction is very significant.

How to use geothermal energy?

There are two kinds of geothermal utilization: geothermal power generation and direct utilization. People often say that hot spring bathing, heating and refrigeration belong to direct use. China’s direct utilization has reached 37% of the world’s direct utilization, ranking first in the world for many years.

According to the evaluation report of the World Energy Association, geothermal energy accounts for 66% of the global renewable energy, far exceeding solar energy and wind energy. Because geothermal energy is not affected by natural conditions such as seasonal climate and day and night, it can provide uninterrupted power supply, and its annual utilization rate is 5-8 times that of solar energy and wind energy.

Do "CT" for the earth, what are the magic points of geothermal technology?

At present, many oil field enterprises and geological and mineral enterprises have turned to the field of geothermal development, and after introducing oil drilling technology into the field of geothermal development, they have made important breakthroughs in the field of medium and deep geothermal development.

In the past, we mainly used shallow geothermal energy, because of shallow burial and relatively low technical content. If we want to take out geothermal energy in a wider range or deeper level, we need to overcome some difficulties and tackle key technical problems.

Where is the technical difficulty? Through geological research, researchers will face some difficulties in opening strata, finding horizons and drilling wells, just like "doing CT" for the earth.

If there is water underground, such as some underground caves, the greater the water volume and the higher the temperature, the more likely it is to collapse and leak during well drilling. In recent years, through the introduction of petroleum technology and tackling key problems, the well has been successfully drilled.

If you want to get heat, you need a medium, and the heat can’t come up by itself. You only have to pump up the hot water underground for heat exchange. After changing the heat, the hot water will become cold, and then the cold water will be re-injected into the original layer and heated. In this way, a cycle is formed, which is to take heat.

If there is no water underground, it is also necessary to drill a well to create a thermal storage space underground, which is similar to dry-hot rock, which is equivalent to taking heat without taking water. The future focus is on developing dry-hot rock.

A large rock mass is under the ground. If the well is drilled and a hole is used to inject cold water, the heating speed is too slow and the amount is not enough. If a space is created underground for fracturing, some cracks and cracks are pressed and the water is injected. After using space to heat the water, another well is pumped out. Because of the high temperature of rock mass, steam or steam-water mixture can be used for power generation and heating. The progress of technology has promoted the scale development.

In addition, the sandstone reservoir in the basin is very rich in resources in China, and its reserves are very large, but the problem is how to recharge. This sandstone formation has small pores. In order to ensure that the geothermal water can be safely returned to the original reservoir after being used up, technicians continue to tackle key problems and eliminate impurities, physical blockage and chemical blockage, so as to achieve sustainable utilization.

In what fields does geothermal work?

Besides hot springs and power generation, geothermal energy can also be used in agriculture. Low-temperature hot water can be used for agricultural planting. If the water quality meets the requirements, rice can be directly irrigated. In addition, it can also be used for the cultivation of flowers and special vegetables. In the Bohai Bay area on the southeast coast, it is also used for the cultivation of high value-added animals, and it is also used for thermal insulation with hot springs. In agricultural utilization, geothermal energy has been used to dry vegetables and peppers in Tianjin and Hebei.

Little knowledge:

What fruits and vegetables can be grown by geothermal energy in greenhouses?

Yunnan Midu cherry tomato digital agriculture characteristic advantage park, in 2022, the output of single cherry tomato in the park exceeded 5,000 tons, and the output value reached 110 million yuan.

Different from the traditional greenhouse, geothermal energy is being planned here to replace the traditional natural gas boiler heating, which is expected to reduce the cost by more than 30%. Using geothermal energy to heat agricultural greenhouses can ensure the temperature of greenhouses in winter, and realize the anti-seasonal growth of crops and the wintering of heat-loving plants.

In addition, geothermal energy will not produce any carbon dioxide emission, crops grow in the greenhouse, and disposable films used for agricultural production insulation and some pesticides and fertilizers needed to prevent pests and diseases are also reduced, thus realizing green production, low carbon and environmental protection, further reducing energy consumption and carbon emission, improving planting efficiency and helping energy conservation and emission reduction.

Geothermal energy, even refrigeration?

In fact, the reason for using heat energy for heating is very simple. However, it is estimated that many people can’t understand the "reverse operation" of geothermal cooling. Let me explain it to you. Geothermal cooling can be said from two aspects:

One is to use "shallow geothermal" to realize cooling. Shallow geothermal heating and cooling are widely used in our country, because shallow geothermal is basically 20 or 30 meters below the ground. Here is a constant temperature layer, and the temperature is basically close to the local annual average temperature.

For example, in Beijing, it is about 16 degrees Celsius more than 30 meters underground. As we all know, our household air conditioners are divided into indoor units and outdoor units. When cooling in summer, we are equivalent to discharging the hot air inside the house to the outside. However, as Beijing is particularly hot this summer, it is very difficult to discharge the heat when it reaches more than 40 degrees Celsius. The use of ground source heat pump is equivalent to burying the outdoor unit underground, which is only 16 degrees Celsius, and the temperature will automatically flow from high to low like water. Therefore, it will be easier to discharge the hot air in the house to 16 degrees Celsius, which is more efficient than our household air conditioner.

Second, the use of "hydrothermal geothermal" to achieve cooling, at present, there are some experimental applications in China, mainly in Guangdong, and there is no large-scale promotion. Although our country is very rich in resources, the temperature grade is basically low, which is suitable for heating and hot springs, but its temperature is lower in power generation or refrigeration. In the past, we said geothermal energy, which means heating, but now it can be directly used to provide cooling, which may have broken through the cognition of many of us, and this is also because of the changes brought about by our technological breakthrough.

Case: Xiongxian County-"Smoke-free City"

Take Xiong ‘an as an example. Around 2014, the whole Xiongxian county has become a "smoke-free city"-there is no coal boiler in the whole city, and the city uses geothermal heating. After the establishment of xiong’an new area in 2017, Xiong ‘an’s energy planning introduced the concept of "geothermal+",that is, geothermal plus a part of gas and a part of electricity.

This is because xiong’an new area is a main city, five sub-cities and many nodes. In the main city, the building density is relatively high. If geothermal energy is used, the drilling density can’t be satisfied. Therefore, adopting the "geothermal+"model not only makes full use of geothermal energy, but also saves natural gas and electricity, minimizing the use of this fossil energy and traditional energy.

The utilization of geothermal resources brings us life.

What direct changes have been brought about?

The most intuitive change is the improvement of the environment. As we all know, the smog in Beijing was very serious a few years ago, especially in the heating season. However, in recent years, the change from coal to electricity and gas, especially from coal to geothermal, has obvious effects on environmental improvement. First of all, there is no geothermal emission; Secondly, for ordinary people, the cost of geothermal heating is flat compared with before, and it is more environmentally friendly.

What is the impact of scientific and technological breakthroughs on the promotion of geothermal energy?

China is rich in geothermal resources, especially in the use of heating, and our technology is very mature. Then why have many places not used geothermal energy? Is it because there is no geothermal resource? Actually, it’s not.

Geothermal energy is the heat in the earth’s interior, so there is geothermal energy under the earth’s crust, but the difficulty of development and utilization is different in different places, some places are more difficult and some places are easier, which leads to the difference in cost. Then we need to solve this problem with scientific and technological research, reduce the cost, and turn the resources that we could not exploit before into exploitable resources, so that residents in these places can also use geothermal energy.

What are the difficulties in the popularization and application of geothermal energy?

Our country is rich in geothermal resources, but in fact, our current utilization is very small. First, because our current survey of resources is actually not in place. For the development of geothermal resources, we must find out where the geothermal energy is, so that we can effectively develop it. Second, some technical aspects need further breakthroughs. Third, for the further development of resources, in fact, we still have a certain gap with foreign countries. If we can take out deeper resources, we should make greater progress in the large-scale utilization of geothermal energy in our country.

Imagine:

Development and application of geothermal energy

What changes will the future bring to our lives?

How will the continuous development and application of geothermal energy change our life in the future? I believe this issue is also of concern to everyone.

Did you find out? Nowadays, the new residential area has higher and higher technology content and higher living comfort. In the future, as geothermal energy enters thousands of households, let’s imagine that after returning home, we can soak in a hot spring, which is comfortable to listen to. (In Xiong ‘an, some communities can be realized now! )

Heating in winter, the community is very clean, there is no such thing as dust and granulation, and then the temperature can ensure that we are very comfortable; Cooling in summer, there is no need to hang the outdoor unit outside, and there is no need to blow hot air. There is no air conditioner or wall-hung boiler in the living environment, and the pipes are all underground … We really realize green, clean, healthy, environmentally friendly and low-carbon.

With the continuous development of deep mining equipment and technology in China, China’s geothermal mining has been extended to 5000 meters underground, and its application scope is wider and its forms are more diversified. The direct utilization of geothermal power generation, geothermal heating, geothermal refrigeration and so on ranks first in the world for many years.

Original title: "The temperature is more than 7000 degrees! What should humans do? 》

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