Let's dig deep—Geothermal energy in China

With fossil fuels bringing harm to not only the environment, but socio-economic and political wise as well, it is no surprise that countries around the world are looking to find a much cleaner and sustainable energy source. And China is no exception.

First of all, what even is geothermal energy?

The word 'geothermal' comes from the prefix in Greek — 'geo', which in English, means 'earth', and 'thermal', which means 'heat'. Geothermal power is heat energy generated within the Earth’s crust. It is a renewable energy source that can be harvested for human use. The heat generated comes from the original formation of the planet and the radioactive decay of materials. Such energy contained in the rocks and fluids can be found from shallow depths or even several miles below the Earth’s surface. We will explore this later on.

Geothermal energy in China is abundant. The distribution is mainly concentrated in the eastern region, where the energy demand is the highest. From this, we can see that the distribution of geothermal energy in China is uneven.

There are three types of geothermal energy resources in China—shallow geothermal energy (SGE), hydrothermal energy (geothermal groundwater), and hot dry rocks (HDRs).

1. Shallow geothermal energy (SGE)

It is widely distributed across China and exhibits enormous potential for development and utilization  ( Liu et al., 2015 ). It is equivalent to 7 × 10 ⁹  t of standard coal. According to  Wang et al., 2018a ,  2018b , the constant temperature zones in shallow geothermal fields in China are deep in the southeast and shallow in the northwest.

The main factors affecting the comprehensive thermal conductivity of the rock and soil masses are the structural characteristics of the formations and the hydrological conditions.

2. Hydrothermal energy

China’s hydrothermal groundwater energy resources are equivalent to 1.25 × 10 ¹³  t of standard coal. It is separated from low-temperature hydrothermal resources, with a lower power generating potential; while high-temperature hydrothermal resources have a relatively higher power generating potential.

Such energy resources are generally unevenly distributed and are controlled by a number of factors, for example, the magmatic activity, formation lithology, hydrological and geological conditions.

As shown in Figure 1, the low-temperature hydrothermal resources are mainly distributed in Northern China, Songliao, Ordos, Northern Jiangsu and Jianghan Basins, as well as the mountainous regions along the southeastern coast and the Jiaodong and Liaoning peninsulas.

These resources are mainly used to apply heat and in farming, cultivation and recovering tourist destinations. They have a power-generating potential of only 1.50 × 10 ⁶  kW.

High-temperature hydrothermal resources are mainly located in Taiwan and other regions in southwestern China, such as southwest Tibet, western Yunnan and Sichuan. They have a power-generating potential of 7.12 × 10 ⁶  kW.

It is used in cascade development and it is enough to meet the power consumption and heat supply demands of minority regions in western Sichuan and southern Tibet.  ( Wang et al., 2017c )

3. HDR resources

HDR resources with potential for development are located at the edges of plates and tectonic structures. For example, in neo volcanic zones and in areas where the Earth’s crust is rather thin.

HDR resources are equivalent to 8.56 × 10 ¹⁵  t of standard coal. Therefore, it is a much more sustainable use of renewable energy compared with other renewable energy as it can keep up with the power of standard coal and still emit much less carbon emissions.

As shown in Figure 2, it is mostly concentrated in the southern eastern, western and southern areas, where geothermal energy resources are mostly found.

As we can see from Figure 3, the growth of China’s geothermal energy has skyrocketed over the past twenty years, with this energy being put to use in many places and industries nation-wide. Such geothermal energy is most commonly used in geothermal heat pumps, which are often installed in buildings to transfer heat from the ground to indoor spaces. Meanwhile, geothermal energy is least used in the industrial aspect.

It is no surprise that geothermal heat pumps are the most commonly consumed type of geothermal energy. With the ever increasing population of China, and higher living standards there, people chase for suitable temperatures in rooms no matter the weather outside. 

With geothermal energy being utilized more and more in China, what actually are the benefits? Below is a summary that demonstrates why geothermal energy still has huge potential to become one of the leading characters of the energy sector of the future in China.

Air pollution is always a widely discussed environmental issue in China, especially as China is rich in fossil fuel resources, coal combustion forms due to the process of coal mining. As a result, large amounts of greenhouse gases with particulate matter reach the atmosphere. Smog occurs.

On the other hand, geothermal energy provides green, low-carbon, and renewable clean energy, with abundant reserves and massive potential for application. It produces much less carbon dioxide, particulate matter and other toxic substances, just one-sixth of the carbon dioxide emitted by a natural gas power plant. This represents that it does not contribute much to greenhouse effect and climate change compared to using traditional fossil fuels. This can mitigate the problem of air pollution and smog in China effectively.

Geothermal energy is unlimited like other renewable energy, but what is special about it is that it is always available. It is not impacted by daytime, nighttime, season, climate nor any weather conditions. On average, a geothermal power plant will produce energy for around 8,600 hours a year, while in solar plants the average is around 2,000 hours per year. Therefore, the constant energy production rate is more predictable and plannable.

Geothermal energy can create more indirect employment than any other type of renewable energy. In terms of numbers, that translates to 34 jobs per installed megawatt, which is much higher than the 19 created by wind power and the 12 by photovoltaic energy. In China, due to a large population, the development of geothermal energy and the amount of installed power would guarantee permanent employment for many people and it can also bring up other job opportunities for other jobs.

Geothermal energy does not require any special maintenance. As they are closed systems, the pressure of the fluid in the piping self-regulates and the number of electrical and mechanical elements that can break down is also very small. As no fuel is involved in the process, meaning there would be no risk of fires so it can guarantee excellent reliability.

On the other hand, nuclear power was also supported by another group of people. However, when the reactor's residual power exceeds the heat that can be removed by the cooling systems, a nuclear meltdown happens. It causes huge negative impacts towards humans, the environment and the socio-economic industry, especially in China. It shows that geothermal energy has a lower risk and is safe for China to develop.

In China, The 13th Five Year Plan (2016-2020) on Geothermal Energy was released by the National Energy Administration (NEA) on 23 January 2018 is effective as of 1 January 2016. The 13th 5YP on geothermal energy summaries the achievements and challenges of the geothermal sector in 2015 and states the plan of the development.

• 1.1 billion square meters of new geothermal heating (cooling) areas be developed
• Newly increased geothermal power installed capacity 500 MW

• By 2020, total geothermal heating (cooling) area is expected to reach 1.6 billion square meters, and geothermal power generation installed capacity to reach about 530MW.
• By 2020, the annual utilization volume of geothermal energy should reach to 70 million tons of standard coal, and annual utilization volume of geothermal heating should reach to 40 million tons of standard coal.
• Annual geothermal energy utilization in Beijing-Tianjin-Hebei region should reach about 20 million tons of standard coal.

There is a development trend of shallow geothermal energy (SGE) in China. What are the causes?

Due to the large heating demand of energy for heating and cooling the buildings, the amount of energy consumed to meet the heating demand is expected to reach 3–4 × 10 ⁹  t of standard coal as coal was the main energy source before. The provision of conventional energy resources has become difficult, and prominent environmental problems such as air pollution were resulted, causing in great pressure for environmental protection. The Chinese government has advocated implementing green building plans and increasing the proportion of renewable energy used. As a result, SGE has become an important choice for heating and cooling buildings.

The development of SGE has increased rapidly in recent years. As urbanization progresses, the use of SGE could expand further. According to the National New-type Urbanization Plan (2014–2020) published by the State Council of the PRC, the rate of urbanization of permanent residents in China is expected to reach approximately 60%. Rapid urbanization results in a rapid increase in the building area. According data for 2012 published by the China Real Estate Society, the new building area in China (approximately 2 × 10 ¹⁰  m ² ) accounts for approximately half of the total new building area in the world each year. The total building area in China was estimated to be 6.6 × 10 ¹¹  m ²  in 2017. The urban per capita residential area is expected to reach 43 m ²  by approximately 2040, when the civil building area will reach a peak of 92 billion m ² . Heating the newly added building area can effectively facilitate the utilization of SGE. Based on the growth trend, the area heated and cooled by SGE is expected to reach 1.092 × 10 ¹⁰  m ²  in 2020. The increase in SGE may peak during the “Fourteenth Five-year Plan” period.

Considering the climatic, hydrological, and geological conditions, the areas that SGE is developed and utilized in China are categorized into different areas.

These areas are primarily located in regions with hot summers and cold winters, including Beijing, Tianjin, Hebei, Shandong, Henan, Liaoning, Jilin, Shaanxi, Shanghai, Hubei, Anhui, and Jiangsu and are mostly in plains, basins, and other regions with relatively rich water resources. In these areas, it is suitable to use SGE to centrally cool buildings in the summer and heat them in the winter on a large scale, as well as to provide hot water to buildings. Additional efforts should be made to promote SGE in these zones. For example, in Shenyang, GSHPs are used to heat a total building area of 3.60 × 10 ⁷  m ² , and there are 620 urban GSHP projects. SGE has exhibited excellent heating and cooling performance, has notably helped conserve energy and reduce emissions and the amount used is still growing rapidly ( Wang et al., 2015 ).

These areas are mainly located in the mountainous and hilly regions of the aforementioned provinces and municipalities, such as the Taihang Mountain region. In these areas, SGE is suitable for heating buildings in the winter and cooling them in the summer at a small scale. Compared to year-round central utilization zones, year-round scattered utilization zones have a lower population density and are slightly economically limited. Considering the actual operating costs and performance, scattered development and utilization of SGE for single buildings should be promoted in these zones.

These areas are primarily located in cold regions, such as Heilongjiang, Jilin, Inner Mongolia, Xinjiang, Qinghai, and Tibet. These areas have a high heating demand but an extremely low cooling demand. The development and utilization of SGE should be focused on providing heat during the winter. In the summer, auxiliary equipment, such as solar energy systems, can be used to replenish underground heat. In these areas, SGE is suitable for heating single buildings in a scattered manner.

These areas are mainly located in regions with hot summers and warm winters, such as Yunnan, Guangxi, Guangdong, Fujian, Hainan, and Taiwan. These areas have a substantial cooling demand, whereas their heating demand is negligible. In these areas, the development and utilization of SGE should focus on cooling during the summer. To maintain an underground heat balance, domestic hot water can be supplied in the winter based on the residents’ actual needs. SGE is suitable for cooling single buildings in a scattered manner in these zones.

In order to develop SGE better, there are a few development tasks to enhance the utilization of SGE.

1. Surveys and evaluations of scattered development should be focused on rural areas in northern China that have a demand for heat, such as the Beijing–Tianjin–Hebei and surrounding regions. The development and adaptation of SGE is suitable in these areas and can help conserve energy, reduce emissions, and mitigate smog problems.

2. The surveys and evaluations of efficient utilization of SGE in new urban areas should focus on the Yangtze River economic zone to address its winter heating problem.

3. By considering the unique climatic conditions, innovative SGE utilization models in special areas (e.g., extremely cold and hot areas) should be investigated. Based on demonstration facilities, the problem of heat accumulation in single heat sources and in cold and heat sources should be addressed, so that it SGE can be used to help construction in special areas, such as military and civilian integration areas.

4. A focus should be placed on prospecting and evaluating geothermal resources in certain areas, such as the subcenters of Beijing, the Beijing–Tianjin–Hebei cooperative development zone, the Yangtze River Delta along the middle and lower reaches of the Yangtze River and the Changsha–Zhuzhou–Xiangtan city cluster.

Despite the many advantages of geothermal energy, challenges have also been posed in the development and adaptation of this resource. These concerns need to be overcome by China in order to fully make use of this natural resource.

The great potential of geothermal energy as an indigenous resource has not been well recognized in China. The development and utilization of geothermal energy require multidisciplinary cooperation, and need consideration of local conditions. 

The development of geothermal power started relatively late in China, and therefore many issues still remain unsolved. China is suffering from stagnant technological advancements, and policies and regulations regarding the development of geothermal power are unclear. Combined with the lack of reasonable industry planning, the development speed of geothermal energy lags behind others.

A problem that comes with geothermal power plants is the potential for surface instability. Geothermal plants remove water and steam from reservoirs within the earth, and the land above such reservoirs may sink slowly over time. The frequency of earthquakes occurring may also increase, as geothermal plants are usually located near fault zones or geological "hot spots" that are especially prone to instability and earthquakes. Drilling deep into the earth and removing water and steam can also trigger small earthquakes. However, most geothermal plants re-inject used water into the earth via an injection well to reduce the risk of land subsidence.

Another concern is that the extraction of geothermal energy from the grounds also leads to the release of greenhouse gases, such as hydrogen sulfide, carbon dioxide, methane and ammonia. The greenhouse effect intensifies global warming, and eventually leads to climate change. However, the amount of gas released is still significantly lower than in the case of fossil fuels.

Despite being considered a sustainable and renewable energy source, specific locations with geothermal resources might cool down over time, making it impossible to harvest more in the future.

The proper management of this technology is needed to maintain the sustainability of geothermal energy, ensuring that fluid needs to be pumped back into underground reservoirs faster than it is being depleted, to avoid irreversible impacts.

The only non-depletable option is the sourcing of geothermal energy directly from magma, but the technology is still immature. It may be a worthy investment for the Chinese government though as magma is proven to be around for billions of years on Earth.

Price tags for a geothermal power plant range from around $2-$7 million with a 1-megawatt capacity. As the development and extraction cost for geothermal power is relatively expensive, individual households also need to pay more for it. Moreover, geothermal heat pumps are also costly.

Moreover, the need for drilling and installing a complex system into one’s home makes the initial cost climb high. However, the return is very promising, as it is estimated that the general investment can be earned back within 2 to 10 years.

2030/2060 goal:

On 22 September 2020 at the United Nations General Assembly, Chinese President Xi Jinping announced China's ambition to achieve carbon neutrality by 2060 and reach its emission peak before 2030.

May 2021 – Establishment of leading group on carbon peaking and carbon neutrality

• The first plenary meeting of the newly established leading group on carbon peak and carbon neutrality took place in Beijing.
• Chinese Vice Premier Han Zheng stressed efforts to accomplish the country's carbon peak and carbon neutrality goals on schedule.
• He also highlighted, targeted operable policy measures to optimize the industrial structure, promote the adjustment of the energy structure and support research and development on green and low-carbon technologies.

November 2021 - Action plan for carbon peaking in public institutions proposes specific targets for key areas, including:

• Promoting solar PV and solar heating projects: By 2025, new buildings of public institutions will have 50% of their roofs installed with solar PV. By 2025, newly added area of heating or cooling using heat pumps will reach 10 million square meters
• Controlling coal consumption: By 2025, the share of coal consumption will reduce to be-low 13%. Achieving that goal will require deep emissions cuts in the short-term, with emissions to fall 90% compared with a “no policy” scenario by 2050, and demand for coal to drop to near zero.
• Selecting 300 green and low-carbon piloting public institutions and 2,000 pilots for energy conservation oriented public institutions
• Public institutions shall include carbon emission per unit of floor space as a binding indicator in the work planning and assessment system to conserve energy and resources.

13th Five Year Plan: 

The government has made plans for large-scale wind farms in desert regions, and that, in practice, China will be aiming at more ambitious targets for both wind and solar energy.

This research and introduction on geothermal energy barely scratched the surface of how useful, complex and world-changing geothermal energy resources can actually be. There are plenty of research papers written on different aspects and impacts of geothermal energy in China.

We hope that through this research, we can bring light to geothermal energy in China, and how effective and efficient it is. At the same time, we also hope to convince and offer suggestions on how to improve and enhance energy efficiency in the world, especially in China.

The world cannot rely on fossil fuels such as coal any longer. It is time we need to find another alternative energy source, and geothermal energy, as shown in today's research, has proven itself to be available and a noteworthy suggestion.

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