Energy Efficient Air Conditioning System Using Geothermal Cooling-Solar Heating in Gujarat, India

It is well known that one unit of electrical energy saved is equal to more than two units produced. One way of economizing the power is utilization of energy efficient systems at all locations. In the present study, the air conditioning system is analysed and an innovative way is suggested. We use natural low temperature of shallow sub surface (1 - 3 m) of the earth—geothermal cooling system. It is known that majority of the households and the apartment complexes in India have two tanks for water storage. One is the underground water sump and the other is the overhead water tank. In our study, we use these two water storage systems for space cooling during summer and also for heating during winter. The main aim of our paper is air-conditioning of the space in an economic way to save electricity. It is based on a simple idea of transferring the low temperature from underground water sump to the room in the house using water as a mode of transport. Since India is a tropical country located at low latitude, most of the year, the air temperature is high and demands space cooling. However, for a couple of months during severe winter months (Dec.-Jan.) at Ahmedabad, heating of the space is required. For heating the space, we suggest to use the well-known solar water heater. Effective use of heat exchanger is shown through computation, modelling schemes and lab experiment. We recommend geothermal cooling for 10 months in a year and solar hot water system during 2 months of winter. It is observed that the ambient air temperature of 35°C - 40°C in the room can be brought down to 26°C without much consumption of electricity. In a similar manner, the room temperature at night (13°C) during winter in Ahmedabad can be increased to 27°C through circulation of water from solar water heater in the heat exchanger.

Characteristics and prospect of geothermal industry in China under the“dual carbon”target

Geothermal energy utilization in China had been promoted actively during the 13^(th)Five-Year Plan period(2016-2020),with resultant achievements showing unique Chinese characteristics.Buildings(measured by areas)heated/cooled by intermediate-to-deep geothermal energy increased more rapidly than those by shallow geothermal energy.Geothermal power generation was restricted by the distribution of the resource and the sufficiency of local power supply.With the proposition of“dual carbon goal”by the central government of China and the coming era of great development of renewable energy,geothermal energy will be provided more development opportunities in room heating/cooling and power generation in the country ever than before.However,tackling technology bottlenecks and introduction of appropriate policy support are still urgently needed for nurturing a healthy environment for geothermal industry.Analysis suggests that a near-to medium-term development of geothermal energy shall be focused on a comprehensive and efficient utilization both through heating/cooling and power generation.Room heating/cooling by intermediate-to-deep and shallow geothermal energy shall be promoted nationwide according to local resource endowment and economic conditions.Geothermal power generation in Yunnan and Tibet shall be pushed forward in an orderly way.For medium-and long-term development,focus shall be put on power generation by using low to medium temperature geothermal energy and hot dry rocks.The"hot spring+"model shall be adapted in steps on a regular basis.To achieve these,measures including attaching importance to tackling key technologies,promoting standards for geothermal energy development and utilization,strengthening geothermal energy exploration and evaluation,and seeking for necessary policy support shall be taken.