[Pal, 2(9): September, 2013] ISSN: 2277-9655 Impact Factor: 1.852 http: // www.ijesrt.com (C) International Journal of Engineering Sciences & Research Technology [2566-2569] IJESRT INTERNATIONAL JOURNAL OF ENGINEERING SCIENCES & RESEARCH TECHNOLOGY Comparison of Electricity Generation and Direct use of Geothermal Energy R.K. Pal Department of Mechanical Engineering, Panjab University SSG Regional Centre, Hoshiarpur-146020, Punjab, India ravinder_75@yahoo.com Abstract Geothermal energy can be used for generating electricity or can be used for direct applications. The present work is to compare the energy efficiency of two methods of geothermal energy utilization. The comparison of the two methods shows that energy efficiency is more in the case of direct use of geothermal energy. The geothermal energy utilization in case of direct use is more than in case of electricity generation by an amount 18 GWt and 252 GWt for India and world respectively. Keywords: Geothermal energy, heating load, geothermal electricity, sustainable energy. Introduction Geothermal energy is a renewable form of energy. It can be used for producing electricity or for direct application. Electricity can be produced from the geothermal energy in two ways depending on the amount of geothermal energy available and its temperature. Large amount of high temperature geothermal water or steam available can be used in steam power plants. Other way called binary fluid technology can be used for low to average temperatures geothermal fluid. In this method two fluids are used, the secondary fluid must have low boiling point and also have high vapour pressure. Usually the secondary working fluid is isobutane or isopentane. The binary fluid power generation method works on the conventional Rankine cycle. Usually electric power generation is limited to about 150 o C fluid temperatures, but with the binary fluids lower temperatures of the order of 100 o C can be used for power generation [3]. In certain cases temperature as low as 85°C can be used for power generation [2]. The direct applications of geothermal energy are many. The space heating is main use of direct utilization of geothermal energy in the world (33%) [3, 1]. The distribution of direct uses of geothermal energy is shown in Fig. 1 [1]. The perfect inlet temperature to homes for space heating is around 80 o C [3]. In the year 2004 around 270 PJ of geothermal energy was utilized for the purpose of direct heating [4]. In space heating Iceland is the leader, around 85% of the houses in Iceland are heated by means of geothermal energy [6]. Direct utilization of geothermal energy has several advantages in comparison to electricity generation. Like a lot higher energy efficiency of the order of 50 - 70% as compared to 5 - 20% for geothermal electricity generation plants, the time of development is very less and very less money investment is required. Also direct application can utilize both low and high temperature geothermal energy resources. However direct utilization is much more site specific, as steam or hot water is seldom transported over lengthy distances from the geothermal energy site. [3]. Geothermal heating unit is designed based on the knowledge of heat transfer, geology of the place and availability of land [5]. Estimated geothermal energy