Evaluation on utilization potential of shallow geothermal energy in major cities of Guizhou

Guizhou,a province located in the southwest of China,possesses a total area of 1,414 km2 and ten major cities including Guiyang,Zunyi,Xingyi,Tongren,Liupanshui,Kaili,Duyun,Bijie,Anshun and Gui'an.Carbonate rocks and carbonate rocks intercalating clastic rocks widely extend cutover the province,which accounts for more than 90% of the total urban planning area and an ecologically vulnerable environment in each city.As a clean,new and renewable green energy,shallow geothermal energy has many advances,such as wide distribution,large reserve and can be very helpful to solve many ecologically environmental problems of the cities in Guizhou.To evaluate the utilization potential of the shallow geothermal energy,in this paper,the geothermal environment conditions was comprehensively studied;data derived from field thermal response tests and heat physical property measurements of rock and soil bodies sampled in the major cities of Guizhou were analysed.The research results show that for the most rock samples in the major cities of Guizhou,the thermal conductivity coefficient rangs from 2.0 to 4.0 W · (m · K)-1;the thermal diffusion coefficient varies from 0.5 to 3.0 mm2 · s-1.The average value of the thermal conductivity of rock and soil is in the range of 2.5-3.5 W · (m · K)-1 and the thermal diffusion coefficient is 1.0-1.5 mm2 ·s-1.By applying volumetric calculation method,the total heat-capacity at the depth of 100 m below surface is 35.20 × 1013 kJ · ℃-1,while summer and winter heat transfer powers are 520.2 × 104 kW and 342.3 × 104 kW,respectively.In terms of resource utilization potential,the shallow geothermal energy can provide for refrigeration in summer time over an area of 7.43× 108 m2 and for heating in the winter over an area of 6.51× 108 m2.