Utilization of oil wells for electricity generation: Performance and economics

• Utilizing oil well makes geothermal plant competitive with other resources.
• R32 seems to be the best working fluid.
• The levelized cost of electricity for geothermal plant is less than 5.6 ¢/kWh.
• The payback time of geothermal plant is less than 6 years.

There is a general agreement that the climate change, which is the most important challenge facing humanity, is anthropogenic and attributed to fossil fuel consumption. Therefore, deploying more renewable energy resources is an urgent issue to be addressed. Geothermal refers to existing heat energy in deep rock and sedimentary basins. Traditionally, geothermal energy has been exploited in places with plentiful hot water at relatively shallow depth. Unfortunately, the high exploration and drilling costs of boreholes is the main barrier to the commerciality of geothermal worldwide. In oil producing countries, such problems can be overcome by utilizing oil or gas wells. The current study presents thermodynamic and economic analyses of a binary geothermal power generation system for commercial electricity generation. Two different source temperatures (100 and 120 °C) and constant sink temperature (29 °C) were considered. The optimal working fluid and optimal design that improve the performance of the plant are determined. For the current costs in Qatar, the economical analysis of 5 MW geothermal plant shows that the levelized cost of electricity for the plant varies from 5.6 to 5.2 ¢/kW. Whereas, the payback period of such plants lies between 5.8 and 4.8 years.