The direct utilization of medium-low temperature geothermal energy in China is mainly in geothermal heating, medical care, bathing and tourism, aquaculture, agricultural greenhouse planting and irrigation, industrial production, mineral water production, etc., and the cascade utilization technology of geothermal resources and underground aquifer energy storage technology have been gradually developed. At present, among the utilization modes of geothermal water in China, heating accounts for 18.1%, medical bathing and entertainment accounts for 65.2%, and planting and breeding accounts for 9.1%. Others accounted for 7.7%.
(1) geothermal heating. Concentrated in large and medium-sized cities such as Beijing, Tianjin, Xi 'an, Zhengzhou and Anshan in the north, as well as oil-producing towns such as Daqing in Heilongjiang, Bazhou in Hebei, Gu 'an and Niutuo Town, the medium-low temperature geothermal water, hot tail water and shallow geothermal energy at 61 ~ 111℃ are developed and utilized. Some areas with hot springs exposed, especially in the north, have used geothermal heating to varying degrees and achieved good results. According to statistics, in 1991, the national geothermal heating area was 191×114m2, and it developed to 1111×114m2 in 2111. At present, the heating area together with ground source heat pumps is close to 2111×114m2, with a rapid growth rate (Table 1-12). In 2114, the exploitation of geothermal water in Tianjin reached 2468×114m3, and the heating area reached 947×114m2, accounting for nearly half of the national geothermal heating area. Tianjin's use of geothermal energy for district heating has become a model in China, and it has also made Beijing-Tianjin-Hebei geothermal district heating a large-scale industry, which is driving the development of geothermal district heating in the north. North China Petroleum Administration Bureau has built several demonstration projects using deoiled hot water for heating, which has solved the heating problem of local oil field bases and saved millions of yuan in fuel and electricity costs every year. Making full use of waste oil wells and developing geothermal resources in oil fields is one of the directions of economic restructuring in resource-exhausted oil fields.
Table 1-12 Summary of Geothermal Heating in China
Geothermal water heating, with its advantages of cleanness, little air pollution, low operating cost and high comprehensive utilization of resources, coupled with heat pump technology, has received widespread attention in areas where conventional energy is relatively scarce and geothermal resources can be developed, and has received obvious economic and social benefits, with broad development prospects. According to statistics, the cost of geothermal heating is about 31% lower than that of boiler heating.
(2) medical care. Geothermal fluid has a high temperature, contains special chemical and gas components, a small amount of bioactive ions and radioactive substances, etc., and has obvious medical and health care effects on the function adjustment of various systems and organs of human body. In various hot spring sanatoriums, geothermal energy can be used for hydrotherapy, gas therapy and mud therapy. With the development of economy and the improvement of people's living standards, a number of "hot spring resorts" or "medical rehabilitation centers" integrating medical treatment, bathing, health care, entertainment and tourism have been established in many areas throughout the country. According to statistics, there are 126 geothermal fields for medical care in China, covering more than 21 provinces (autonomous regions and municipalities).
(3) Bathing and traveling. Bathing with geothermal water is almost all over the country. According to incomplete statistics, more than 211 hot spring and hot water sanatoriums have been built in China, and 431 hot spring baths have highlighted medical utilization. In addition to nursing homes, all or part of geothermal fields that have been developed and utilized account for more than 61% of the total number of geothermal fields. There are 1611 public hot spring baths and hot spring swimming pools in China. Based on the proportion of geothermal water used for bathing in Beijing to the total geothermal water consumption in the city, it is estimated that the amount of geothermal water used for bathing in China is about 38 million m3 per year, and geothermal energy is 716.45MW, which is equivalent to saving or reducing the consumption of 771,111 tons of standard coal every year, providing geothermal water for 688 million people.
Many hot spring areas in China are both health resorts and tourist attractions, and some hot spring areas have built places dedicated to the royal family in history. For example, Xiaotangshan in Beijing has a pavilion pool dedicated to Cixi, Lintong in Shaanxi has Huaqing Palace, and Linru Hot Spring in Henan has Wuhou Pool and Bagua Building dedicated to Wu Zetian. After the founding of New China, China has established nursing homes for employees in many hot spring areas. In recent years, with the development of China's tourism industry, hot spring recuperation and tourism have developed particularly rapidly. At the same time, exploration work has been carried out in many hot spring areas, which not only expands the resources, but also achieves the warming effect, providing more and more places for recuperation and tourism.
Some high-temperature hot springs and boiling spring areas in southern Tibet, western Yunnan, western Sichuan and Taiwan Province have not only high-energy geothermal resources, but also colorful geothermal landscapes, which have attracted worldwide attention. For example, Tengchong, Yunnan Province is the only well-preserved volcanic hot spring area in mainland China, with rare volcanoes, geothermal landscape and precious medical mineral water value; Datun Volcano Hot Spring Area in Taiwan Province Province is also a hot spring resort and tourist attraction.
At present, the common forms of geothermal tourism development in China are: developing tourism by using peculiar geothermal landscape, such as local fountains, intermittent fountains, boiling springs, boiling mud ponds, jet holes and other peculiar geothermal geological phenomena; Use local geothermal resources and beautiful landscape to develop geothermal tourism projects integrating hot spring baths, resorts and entertainment; Use artificial landscapes and exotic flowers and grasses in modern large geothermal greenhouses to set up teahouses or constitute ecological garden restaurants; Using modern large-scale agricultural geothermal greenhouse to develop high-tech agricultural sightseeing and shopping; Use geothermal aquaculture and modern high-density aquaculture technology to develop geothermal aquaculture, including fishing; Use the famous hot spring culture to develop tourism. It is estimated that the annual heat utilization of hot springs in China is only equivalent to the heat of (11 ~ 15) × 114 t standard coal, and a lot of heat energy has not been effectively utilized.
Medium-low temperature geothermal resources have been developed and utilized as hot springs, recreation, bathing and medical treatment, which has been favored by consumers, and also triggered a geothermal development upsurge around real estate development and tourism. In the way of development and utilization, geothermal development has its own characteristics according to different needs. For example, Beijing hot spring tourism has emerged in large numbers, which has promoted the development of the real estate industry; Guangdong and other places launched the "Hometown of Hot Springs in China" brand to attract domestic and foreign guests.
(4) breeding. Beijing, Tianjin, Fujian, Guangdong and other places started earlier, and now they have spread to 47 geothermal fields in more than 21 provinces (autonomous regions and municipalities), with about 311 farms and fish ponds with an area of about 445×114m2. The water consumption of aquaculture in China accounts for about 5.7% of the total hot water consumption, mainly for tilapia, eel, turtle, freshwater shrimp, bullfrog, ornamental fish and fry wintering. Due to the rapid development of hot spring aquaculture in various places, fresh fish sell well at home and abroad and have achieved remarkable economic benefits. In addition, there are geothermal hatching birds, geothermal drying vegetables, geothermal heating biogas digesters and livestock bathing pools, which have also achieved good results.
(5) Agricultural greenhouse planting and irrigation. Geothermal is a compound resource, which is very suitable for off-season, off-site breeding and planting of organisms. Geothermal energy can be used to heat the greenhouse, geothermal water can be used to cultivate temperate aquatic organisms, and minerals in geothermal water can also provide needed nutrients for organisms. In the north of China, geothermal energy is mainly used for planting high-grade fruits, vegetables, edible fungi and flowers, and in the south, it is mainly used for raising seedlings. According to statistics, there are geothermal greenhouses and greenhouses in China, with an area of 133×114m2, of which Hebei Province alone accounts for 47×114m2. Using geothermal water for agricultural planting irrigation can not only promote early maturity, but also have obvious effect of increasing production. At present, China's greenhouse planting and exploitation of geothermal resources is equivalent to 21.5×114t/a standard coal, accounting for 3.4% of the total annual exploitation of geothermal resources.
At the same time, China has established many agricultural utilization demonstration sites of geothermal water cascade utilization, such as Jinghai County, Xiongxian County, Xinzheng County and Fuzhou City, which have achieved remarkable comprehensive benefits and have been popularized throughout the country. At the same time, the demonstration of geothermal agricultural utilization, the extensive use of geothermal energy has enlivened the rural economy, and also promoted the economic development of counties and townships and ethnic minority areas throughout the country.
(6) industrial production. At present, it is mainly used in textile printing and dyeing, washing, tanning, papermaking, wood and grain drying, etc. Among them, underground hot water in hot spring area has been well utilized and benefited in textile industry and chemical industry. At the same time, some geothermal water can also extract industrial raw materials, such as sulfur from Tengchong Rehai Sulfur Pond by elutriation, mirabilite and natural sulfur from Jiutai Hot Spring Area in Eryuan County, and natural sulfur from Datun Volcano Hot Spring Area in Taiwan Province since Ming and Qing Dynasties. In Huabei Oilfield, geothermal water tracing is used to transport oil in the Ordovician deep part of the sealed oil well, which completely replaces boiler hot water tracing and has achieved obvious economic and social benefits.
(7) mineral water production. China began to develop geothermal water to produce drinking natural mineral water in the late 1981s. According to statistics, there are nearly 51 places in China that use geothermal water to produce drinking natural mineral water, mainly in Beijing, Tianjin, Anhui, Guangdong, Guangxi, Chongqing, Guizhou, Yunnan, Shaanxi, Qinghai and other provinces (autonomous regions and municipalities directly under the Central Government). Geothermal water with salinity below 1.6g/L and temperature below 51℃ is mainly used.
in addition, in terms of geothermal utilization technology, in order to solve the problems of high discharge temperature of geothermal tail water, low utilization rate of resources, environmental thermal pollution and sustainable utilization of geothermal water, the cascade utilization technology of geothermal resources and the recharge technology of the same layer and different layers have been gradually developed, so as to extract thermal energy from geothermal water in multiple stages and utilize geothermal energy in multiple levels. Among them, geothermal cascade utilization technology gives full play to the advantages of floor radiant heating and geothermal heat pump, and is applied in drying technology, heating vaporization, distillation, washing, salt extraction, chemical extraction and so on. The geothermal recharge technology is used to summarize and popularize the underground aquifer cold storage and heat storage technology, which realizes "summer irrigation and winter use" for heating, "winter irrigation and summer use" to solve refrigeration, recycle energy, and form an urban closed heating and refrigeration system; By 2117, Tianjin had developed and utilized geothermal water by "one opening and one irrigation", and the recharge rate of geothermal water reached 15.8. Among them, the recharge rate of bedrock hot water can reach 111%, and a set of recharge technology of Neogene Guantao Formation has been explored, which has achieved a breakthrough in geothermal water recharge in Neogene.