Geothermal power generation in China signals green future

China, less than a decade after beginning its program to deploy geothermal energy on a massive scale, now has the largest amount of geothermal district heating of any country in the world.

Cornell University

Introduction – geothermal energy potential in China

According to research by Chinese scientists (1, 2) geothermal resources can provide green, low-carbon, and renewable clean energy, with abundant reserves and massive potential for application. 

Use of geothermal heating for buildings is well advanced in China, which now has the largest amount of geothermal district heating of any country in the world.

Sinopec Green Energy Geothermal Development, is the world’s largest developer of projects that use underground heat to keep buildings warm during winter, and expects to grow by 25 per cent annually over next five years.

The company is a joint venture between Reykjavik-based Arctic Green Energy, which owns 46 per cent, and state-owned oil and gas giant China Petrochemical Corporation (Sinopec Group), which owns the remaining 54 per cent.

While China has abundant geothermal resources, the application of geothermal power for electricity generation in China is still at an early stage.

Geothermal resources suitable for electricity generation in China are unevenly distributed, with the development of geothermal power generation being most feasible in areas such as southern Tibet, western Sichuan, western Yunnan, and Taiwan.

The scientists suggest that solar-geothermal hybrid power generation would improve the thermal performance of geothermal power plants, and also reduce the cost of solar power generation. In addition, excellent development potential exists for oil-geothermal and mining geothermal power generations.

A geothermal power station recently commenced operation in Shanxi

A geothermal power station became recently operational, the Shanxi Department of Natural Resources announced on March 22, 2021 after rich geothermal resources were found in the north of Shanxi more than a year ago.

Zhang Penglong, an official of the department, said at the news conference that construction of the geothermal power station began in October. The first two sets of power generators became operational on Jan 18 and 20.

It all began in March 2020, when a local geological survey team made the discovery. During a drilling operation they found “large-volume, high-temperature and high-pressure geothermal fluid”. They were in an exploration site at the border of Yanggao and Tianzhen counties in the northern Shanxi city of Datong.

“With a temperature of more than 160 C and a volume of 231 cubic meters per hour, it was the largest-volume and highest-temperature geothermal fluid discovered in a single drilling well in the northern part of China,” Zhang said.

The Shanxi No 1 Geological Survey Team had begun a drilling survey of a potential geothermal site in Yanggao and Tianzhen counties in August 2019.

Ren Chuangye, head of the team, recalled that the drilling of the large-volume well was conducted in the winter of 2019-20. Work at local cement batching plants had been put to a halt because of the Spring Festival and the COVID-19 outbreak that followed.

“That really challenged our operation,” Ren said. “We had to mix concrete cement manually to make sure that the well could be properly supported and reinforced.”

“Our efforts paid off,” said Shi Hongzheng, deputy head of the team.”When we drilled to a depth of 1,624 meters underground, hot water with an extremely high temperature gushed out of the drilling pipe.”

“My teammates and I were excited at that moment, as we were aware that we had likely witnessed a milestone discovery in geothermal surveying in Shanxi province or even in the whole country,” Shi said.

Five minutes later, the gush was controlled as a valve was put on the drilling pipe with great effort. The measurements of water volume, temperature and pressure showed that this was a record-breaking discovery, Shi said.

The news spread throughout Shanxi and the provincial government quickly approved a plan to build a geothermal power station on the site.

Construction of the geothermal power plant, consisting of two generators, took only about 100 days to complete.

According to Zhang Penglong of the Shanxi Department of Natural Resources, the geothermal site can supply heat to neighboring areas in addition to power generation.

“It is estimated that the thermal energy volume of the single well is 1,200 megajoules a year, which equals nearly 40,000 metric tons of coal equivalent,” Zhang said.

The hot water from the well, with rich content of minerals and trace elements, can also be used for health spas, according to the official.

He went on to say that the geothermal power station represents a new direction in diversifying Shanxi’s energy industry.

The local energy industry used to heavily rely on coal mining. Shanxi is one of the leading coal production bases in China.

“Due to environmental concerns, Shanxi is implementing an industrial transformation plan to reduce reliance on coal and develop new, clean energy resources like solar and wind power, as well as natural gas,” Zhang said.

The northern part of Shanxi has played an important role in this transformation with the rapid development of solar and wind energies.

Tianzhen county, for instance, has harnessed sunshine to develop its photovoltaic－solar power－industry.

Since 2013, Shanxi’s leading energy company Jinneng Holdings has invested 2.5 billion yuan ($382 million) in developing one of the largest photovoltaic industry parks in North China in Tianzhen. By the middle of 2020, the total electricity generated there amounted to 110 million kilowatt-hours.

Meanwhile, a so-called 100-village photovoltaic project has been developed in the county, with solar farms built in 109 villages. The project has benefited about 14,000 residents across 4,200 households, according to county officials.

The new geothermal power plant in the border area of Tianzhen and Yanggao has been described as a breakthrough in the development of the new energy industry in Shanxi.

“The Earth is a planet with huge amount of energy, which is released in the forms of earthquakes, volcanic eruptions and geothermal energy,” said Ren Chuangye of Shanxi No 1 Geological Survey Team.

“Geothermal energy is a kind of clean, renewable energy with huge reserves,” Ren said. “The reserves of geothermal energy at a depth of 10 kilometers under the planet’s surface are 50,000 times that of all the fossil fuels, which shows a huge development potential if we have the technologies for massive exploration.”

The scientist said he is optimistic about potential in the area where he works now. He expects more geothermal wells with a large volume will be discovered in the near future.

Sources:

• Energy Science & Engineering, ‘Geothermal power generation in China: Status and prospects’, 29 May 2019. https://doi.org/10.1002/ese3.365

• China Daily, 2021-04-09. http://epaper.chinadaily.com.cn/a/202104/09/WS606f8b8fa31099a23435544a.html