Geothermal Power Generation Options and Technologies

Abstract

Geothermal energy has a potential for several applications including geo-exchange, direct thermal application, and power generation. Whereas the untapped capacity is over 100 GW globally, its growth realizes only 3-4% growth per year. Limitations of geothermal energy includes scarcity of exploitable sites, remote locations often far from load centers and undesirable gaseous emissions. Project development faces challenges of poor funding, technology, and long gestation periods of between 5 and 10 years for conventional power plants. Smooth implementation of geothermal project requires, social acceptance, through minimization of environmental effect, avoidance of adverse effects on the people and giving direct benefits to local communities. It is through both subsurface and power plant technologies that environmental challenges of geothermal power plants are addressed. Research and development into new, efficient and cost-effective technologies will enhance safety and environmental integrity with respect to geothermal energy and electricity development. A geothermal power plant project generally goes through exploration or prefeasibility stage, drilling or feasibility stage and development stage which involves development of production wells, reinjection wells, steam gathering system and power plant construction and commissioning. The last phase is power plant operation and maintenance before the plant is finally retired upon end of the generation contract or license. These phases of the cycle before generation combined take relatively long and there is need to improve. The use of Wellhead power plants currently provides a quick access to geothermal electricity ahead of full development of a conventional power plant hence enabling quicker access to geothermal electricity. Better technology in upfront activities will significantly reduce the high risks and costs while power plant conversion technologies and better reservoir management and engineering will increase output, resource availability and efficiency of resource exploitation.