A Study Of The Appropriate Zoning For Reasonably Developing Of Shallow Geothermal Energy In Hohhot

Shallow geothermal energy is a new environmentally friendly renewable energy with broadprospects in its use. The purpose of this study is to identify the distribution and occurrenceconditions of shallow geothermal energy in Hohhot, to evaluate the shallow geothermal resourcesand their exploitation potential, and to make appropriate zoning for their development. This studywill be reference material for Hohhot to reasonably develop and protect its shallow geothermalenergy, and will also be an example for investigations of shallow geothermal energy resources insome northern areas of China where have similar geological conditions of Hohhot.This study is based on a full collection of the achievements in shallow geothermal energydevelopment and the completly exploration results on the geology, the hydrogeology, and thegeothermal geology of Hohhot. Through a supplementary survey of the Hydrogeology at a scaleof1:50000, the lithology structure of strata and the hydrogeological and geotechnical conditionsof the strata of Quaternary above200m in Hohhot are identified. Appropriate zonings of heatexchangees are divided in the forms of pipe-buried and groundwater exchanges based on theregional geology conditions, groundwater resource and heat exchanges.Trough sampling tests, thermal response tests, pumping and recharge tesets and many othertests, the technical parameters related to zoning are acquired, and both the evaluation of shallowgeothermal energy and the appropriate zoning for reasonably developing of shallow geothermalenergy are made, the environmental response study on shallow geothermal energy development ofHohhot are also be finished.Through this study, the following main results have finished:(1) Conducting the thermal response test to determine the depth of120m is the mostfavorableforHeattransformation.Of the averageheat released at the hole unit of the rock and soil is60W/m,and the average heat obtained at the hole unit of the rock and soil is60W/m.(2) It is the frist study of the thermophysical properties characteristics of Hohhot. Theaverage level of thermal conductivity is from2.08to2.25W/m℃, the parameters ofthermophysical properties are mainly controlled by the stratum lithology, especially by themoisture content.(3) The characteristics of the shallow geothermal field of Hohhot are summarized: theconstant temperature region is in a general depth of35-40m, with a temperature of about10.5℃;the geotemperature gradient is about0.5-3℃/100m.(4) Combing the analytic hierarchy process (ahp) with GIS-based spatial analysis system, itcompletes the adaptive partition evaluation of shallow geothermal energy development andutilization. The big heihe river plain and the southern piedmont plain in Hohhot are suitable fordevelopment and utilization of ground source heat pump. The suitable or the better suitable area is295.25km~2, which is accounting for66%of the evaluation area; and groundwater source heatpump system is mainly suitable for piedmont plain and the northern big heihe river plain, thesuitable or the better suitable area is335.23km~2,which is accounting for75%of the evaluationarea; (5) The Hohhot shallow geothermal heat capacity and available resources are calculated. Theshallow geothermal resources potential, economic and social environment benefit are evaluated.The shallow geothermal resources in Hohhot are rich and have huge potentialities. The totalthermal capacity of Quaternary shallow geothermal resources which depth range within200m is1.72×10~14kJ/℃. Under the condition of considering land utilization coefficient, the total heatpower of available shallow geothermal resources in Hohhot is14.08×10~5kW/47.66×10~5kW(winter/summer). The total area of winter heating is3.13×10~7m~2, and the total area of summercooling is7.33×10~7m~2. Heating area on unit area is520.64×10~4m~2/km~2; Cooling area on unit areais1182.19×10~4m~2/km~2. Under the condition of considering land utilization coefficient, the totalengery of shallow geothermal resources development and utilization is3.91×10~16J/a,0.13342million t/a of standard coal. Economized on coal is350300t/a, that reduces thenumber of the emission from coal ash, nitrogen oxides, sulfur dioxide and carbon dioxide into theatmosphere is879600t/a, reduces the cost of environment pollution treatment is0.95972millionRMB/a.(6) It analyzed the geological environment problems caused by the development andutilization of shallow geothermal resources, and gived the corresponding prevention measures.