Geothermal energy is expected to heat up



At present, China's geothermal energy is still a minority energy compared with wind energy and solar energy. As a renewable energy source, geothermal energy has many forms of resource utilization. In the future, more extensive adaptation to local conditions, scientific development, and on-demand energy supply will become the inevitable choice for large-scale development of geothermal energy.

There is a cheap, pollution-free source of energy for heating, and a safe, stable, and inexhaustible source for power generation: geothermal energy. At the second plenary meeting of the organizing committee of the 2023 World Geothermal Congress held recently, Ren Jingdong, deputy director of the National Energy Administration, said: "Geothermal energy is a new energy with rich reserves, wide distribution, stability and reliability. Vigorously promoting the development and utilization of geothermal energy is an important starting point for the implementation of carbon peak action based on China's energy resources endowment and planned steps." As the "Olympics of geothermal industry", the World Geothermal Congress will be held in China for the first time this year, which is expected to promote the development of geothermal energy in China to a new level.

Geothermal energy "family is huge", usually referred to as geothermal energy exists in the earth's internal rock and soil body, fluid and magma body and can be developed and utilized by human energy, including soil source, underground water and surface water source 3 types of shallow geothermal energy, as well as hydrothermal type of deep geothermal energy and dry hot rock geothermal resources. The well-known hot springs and ground source heat pumps for heating are typical ways of utilizing geothermal energy.

As a renewable energy source, geothermal energy is as ubiquitous as scenery resources, with the advantages of large reserves, high utilization efficiency, low operating costs, energy saving and emission reduction. The utilization of geothermal energy resources has many forms, such as power generation, heating, cooling, and even making low-pressure steam higher than its own temperature, and the tail water can extract rare mineral elements, and can achieve a variety of functions through cascade utilization, greatly improving the utilization rate. At the same time, geothermal energy is not affected by external factors such as seasonal, climate, day and night changes, and has strong stability, which is an indispensable force to achieve the goal of "dual carbon".

China is rich in geothermal energy resources. The survey and evaluation results of China Geological Survey show that the annual exploitable resources of shallow geothermal energy in 336 cities at or above the prefecture level are equivalent to 700 million tons of standard coal. The annual exploitable resources of hydrothermal geothermal resources in China are equivalent to 1.9 billion tons of standard coal. The hot and dry rock resources buried at 3000 to 10000 meters are equivalent to 856 trillion tons of standard coal. Compared with the total energy consumption of 5.24 billion tons of standard coal in 2021, geothermal energy can be described as a huge energy treasure house.

Since the "13th Five-Year Plan" period, China's geothermal industry has made remarkable development. By the end of 2020, the scale of direct geothermal utilization in China has reached 40.6 GW, accounting for 38% of the global total, ranking first in the world for many consecutive years. China's geothermal heating and cooling area has reached 1.39 billion square meters, with an average annual growth rate of about 23% in the past five years. In the promotion of clean heating in winter in northern China, geothermal energy heating has played an important role, and some new urban areas and counties have achieved 100% clean heating by using geothermal energy.

Despite this, China's geothermal energy is not yet "hot". Compared with wind and solar, geothermal energy is still a niche energy source. The "14th Five-Year Plan" for Renewable Energy Development proposes to actively promote the large-scale development of geothermal energy, actively promote mid-deep geothermal energy heating and cooling, comprehensively promote the development of shallow geothermal energy, and orderly promote the development of geothermal energy power generation. The "Several Opinions on Promoting the Development and Utilization of Geothermal Energy" makes it clear that by 2025, the geothermal heating (cooling) area will increase by 50% compared with 2020, and the installed capacity of geothermal power generation in the country will double compared with 2020. Following this guidance, geothermal energy will see an acceleration.

Taking into account factors such as industrial maturity, resource matching, and urgency of demand, geothermal heating has the conditions for rapid promotion. In the cold and cold areas in the north, geothermal energy can be developed locally in a distributed way to meet the heating needs, and geothermal energy can also be sent to the urban heating network after being heated by a high temperature heat pump, so as to give full play to the advantages of geothermal heating in a wider range. In hot summer and cold winter areas such as the middle and lower reaches of the Yangtze River, due to the developed surface and underground water systems and the demand for both cold and heat loads, various forms of shallow geothermal energy can be fully utilized for combined cold and heat supply, which can not only meet the long-term winter heating demand of the middle and lower reaches of the Yangtze River basin, but also reduce the demand for fossil energy and electricity for household natural gas and electric heating.

Because much of the available geothermal energy resources are far from the energy market, the best use of geothermal energy requires turning it into electricity and transporting it over long distances. China's high-temperature geothermal resources are mainly located in southern Tibet, western Sichuan, western Yunnan and other regions, is the main position of geothermal power generation. Geothermal power generation can form multi-energy complementarity with unstable power sources such as stroke power and photovoltaic power sources in regional power grids, providing stable and reliable basic power sources and peak load capacity. In the future, with the breakthrough of dry hot rock power generation technology, geothermal power generation is expected to achieve a larger scale development.

Geothermal energy is also a generalist. The temperature of geothermal energy supply is close to the temperature required for greenhouse planting, artificial breeding and incubation, as well as drying, heating, sterilization and other processes in many industries, which is an important direction for geothermal energy to carry out diversified industrial applications and tap a broader clean alternative market.

In general, the current geothermal energy is still hovering at the gate of commercialization, and the inexhaustible heat energy of the earth's interior has not been developed. In the future, more extensive adaptation to local conditions, scientific development, and on-demand energy supply will become the inevitable choice for large-scale development of geothermal energy. It is necessary to increase exploration investment and planning layout, strengthen scientific and technological leadership and equipment innovation, strengthen forward-looking layout and revolutionary geothermal theory and technology research, and continue to promote the geothermal industry to reduce costs and increase efficiency.