Author Description

The U.S. is heavily dependent on fossil fuels to produce electricity. Geothermal energy, the heat in the earth's crust, can provide an alternative source of energy for electricity production as well as reduce fossil fuel consumption. The economic analysis presented in this study focuses on binary cycle geothermal electricity production. Variables such as well flow rate, geothermal gradient and electricity prices were varied to study their influence on the economic payback period for binary cycle geothermal electricity production. Payback periods represent the amount of time (in years) necessary to recover initial costs of plant construction. Well flow rate has the greatest influence on economic results. A 10-year payback period can be achieved with almost any scenario as long as the electricity sales rates are above 6 cents/kWh and the well flow rate is high (16,649 lit/min). At a more modest flow rate (3,459 lit/min), most scenarios have payback periods below 20 years as long as sales rates are above 6 cents/kWh. However, at the lowest flow rate (322 lit/min), no scenario results in a payback less than 20 years unless electricity sales prices reach at least 17 cents/kWh. Because geothermal gradient is not as influential as flow rate, a large fraction of the U.S. with modest thermal gradients can economically produce geothermal electricity as long as site conditions allow high flow rates.