2.5.2.1 Production

Extensive development and utilization of geothermal resources started in the early 1970s in China. Great progress has been made both in depth and in breadth since the implementation of the policy of reform and opening-up. At present, in many places exploitation depth is 2,500m and occasionally over 3,500m. Geothermal water with a maximum temperature of 250¡æ(Well  ZK2001, at Yangbajain, Tibet)has been extensively used for power generation, heating, industry, medical treatment, bathe, aquaculture, greenhouse, mineral water production and irrigation(Fig. 2.5.2). Since China's geothermal resources are characterized by moderate to low temperature, the development of geothermal resources for room heating in cities and towns and constructing hot spring hotels has taken shape. In some areas geothermal resources industry has formed and achieved remarkable social and economical returns. The geothermal station of Tianjin Bureau of Environmental Protection, for instance, has exploited geothermal water at the depth of 3,323.09m(water temperature 84¡æ, discharge 150m3/h)to provide 100, 000 m2 room heating for local residents. In Kunming City, a "Green World Hot Spring Vacation Center"was built around a hot water well, with over 100 people employed and nearly RMB 10 million yuan of profits and tax been paid annually to the state. Since the 1980s, the government of Yingshan County in Hubei Province has expanded the development of geothermal resources to involve 109 projects, covering 8 fields of agriculture, industry, bathe, tourism, etc., with an output value of RMB 45 million yuan. Geothermal resources development has become a new and unique industry in local economy.

According to the statistics on the exploration(investigation)of geothermal fields in 1997 made by the Bureau of Management of Mineral Resources and Reserves  under the former Ministry of Geology and Mineral Resources, of the total 761 geothermal fields in China, 434 geothermal fields are being developed or partly developed at the present, accounting for 57%; the other 327 geothermal fields, which make up 43% , have not been developed or have no clear statistics. In those geothermal fields that have already been utilized, totally 943,976 m3/d of geothermal water  have been pumped out and 1 762.56MW of heat energy have been used, equal to the caloric value of 1.896 million ton of standard coal. The development and utilization of major geothermal fields is shown in Fig 2.5.2 and Table 2.5.7.

2.5.2.2 Distribution of Production

In China, geothermal resource development is restricted by local conditions of geothermal resources and economy, and therefore is mainly concentrated in cities, towns and their ajacent areas where geothermal resources can be developed easily and around nearby geother-mal water outcrops. Geothermal resources are used for different purposes in different areas.

Table 2.5.7 Development status of geothermal resources in China's major geothermal fields

(1)Power generation

The use of geothermal resources for power generation started in the early 1970s when a set of experimental geothermal power stations were set up at Houhaoyao in Hebei; Dengwu in Guangdong; Huitang in Hunan; Suichuan in Jiangxi; Xiangzhou in Guangxi; Zhaoyuan in Shandong; Xiongyue in Liaoning and other places. Up to now, only two experimental geothermal power stations at Huitang in Hunan and Dengwu in Guangdong are operating occasionally, while the others have stopped power generation because of low temperature of available geothermal water.

In the early 1980s, geothermal power stations were constructed in Yangbajain and Nagqu geothermal fields, Tibet with the total installed capacity of 30.4 MW.The installed capacity of the Yangbajain Geothermal Power Station is 25.18 MW and 15.0MW of power are generated with 10.95 m3/d of geothermal water at the temperature between 130~170¡æ to provide power for Lhasa City; and the installed capacity of the Nagqu Geothermal Power Station is 3.0MW and power is generated by using 25, 000 m3/d of geothermal water of 114.5¡æ to provide power for Nagqu.

(2)Geothermal heating is mainly used in big cities like Tianjin and Beijing and has gradually expanded to other cities and towns

Now geothermal heating has been used in 21 places, including southeastern Beijing and Xiaotangshan, downtown Tianjin and its adjacent Tanggu and Dagang, Niutuozhen town and Shenzhou in Hebei; Anshan, Xiongyue, Gaixian, Dandong, Fengcheng, Tanghe and Donggou in Liaoning; Donghai in Jiangsu; Shanxian county, Zhengzhou , Luohe, Xinxiang in Henan; Xi'an City in Shaanxi; and Guide in Qinghai. The accumulated heating floor space is about 4 million m2. Geothermal heating has developed very rapidly in Tianjin where the heating floor space is about 3 million m2. Owing to the development of geothermal resources, real estate industry has been developed around geothermal wells with geothermal heating service for local residents. In southeastern Beijing and Xiaotangshan area geothermal heating has been provided for a floor space of 388,300 m2.  In recent years, geothermal heating has also rapidly developed in Xi'an City of Shaanxi; Zhenzhou City in Henan; Xiongxian County, Shenzhou and Hengshui in Hebei. In Xiongxian County, for instance, geothermal heating floor space has reached 150, 000 m2.

(3)Medical treatment and health care

China has a long history of using geothermal resources for medical treatment and health care. In the early phase the natural outcrops-hot springs were used and there have been two phases of rapid developments since the mid-20th century. The first phase was in the 1950s. After the founding of the People's Republic of China a set of sanatoriums were set up around hot springs in some areas. The second one was after the reform and opening up policies were implemented and in the 1990s particularly when a series of hot spring vacation centers or medical treatment and health recovery centers were established with the comprehensive functions of medical treatment, bathe, health care, entertainment and tourism to meet the new demand of society. During this period, quite a lot of hot spring vacation centers were constructed or improved, including the China Medical Treatment and Health Recovery Center in southern Beijing, the Green World Hot Spring Vacation Center in Kunming, vacation centers at Guantang of Qionghai; Nantian of Sanya City; Xinglong of Wanning and Lanyang of Danzhou in Hainan; hot spring entertainment centers in Tanggu, Tianjin City; and hot spring vacation village at Duncun in Shanxi. According to statistics up to now 126 geothermal fields have been used for medical treatment and health care in China, involving 20 provinces, autonomous regions and municipalities.(4)BatheThe use of geothermal water for bathing is common throughout the whole country. In the 434 geothermal fields which have been utilized, 266 or 61% have been totally or partly used for bathe. In Beijing, for example, out of the 92 geothermal wells in 8 geothermal fields 64 wells have been used for bathe, 70% of the total. About 50,000 persons/time take bathing with geothermal water per day , consuming 3.29 million m3 of geothermal water per year(averaging 0.2m3 per person/time), 40% of the total yield of geothermal water pumped out in Beijing. It is estimated that some 138 million m3 of geothermal water are used for bathe every year in the country and provide geothermal water bathe for 690 million persons/time.

(5)Aquiculture

Aquiculture with geothermal water started in the early 1970s in Beijing, Tianjin and Fujian and has expanded to 47 geothermal fields in over 20 provinces(autonomous regions and municipalities). About 200 aquacultural farms have been constructed with some 2 million m2 fishponds for breeding carps, grass carps, eels, soft-shelled turtles, shrimps and bullfrogs. Geothermal water used for aquiculture amounts to about 15 % of the total consumption of geothermal water. At the Xiaotangshan geothermal field in Changping County in Beijing, 2 aquicultural farms with a total water surface area of 138,000 m2 have been constructed by the local Bureau of Husbandry and Aquaculture. Annually the two farms consume 1.2 million m3 of geothermal water from 8 geothermal wells and yield 200,000 kg of fish, thus indicating an average consumption of 9 m3 of geothermal water per m2  and 6 m3 of geothermal water per kg of fish. It is estimated that 14 million m3 of geothermal water are consumed for aquiculture in China. The major geothermal fields with aquiculture are listed in Table 2.5.8.

Table 2.5.8 Major geothermal fields with aquicultural farms in China

(6)Mineral water production

Drinking natural mineral water production  started in the late 1980s in nearly 40 places, mainly in Beijing, Anhui, Guangdong, Guangxi, Chongqing, Guizhou, Yunnan, Shaanxi and Qinghai provinces(autonomous regions and municipalities). The geothermal water used is mainly of low temperature with some useful microelement contents meeting the state standards for drinking mineral water and its contents of harmful constituents lower than the state standards, that is, geothermal water with a content of dissolved solids less than 0.6 g/L and a temperature lower than 50¡æ. For quality characteristics of geothermal water for producing mineral water see Table 2.5.9.

Table 2.5.9 Quanlity of typical geothermal waters used for drinking natural mineral water production

(7)Agriculture

Geothermal water of low temperature(less than 40¡æ)and low degree of mineralization is mainly used for agriculture, mostly for irrigation and partly for greenhouse to plant special vegetables, flowers and to grow seedlings. Incomplete statistics show that in China geothermal water has been used in 117 places for irrigation; geothermal greenhouses have been constructed in 77 localities with a total acreage of 410,000 m2.