U.S. Energy Secretary Steven Chu yesterday announced $20 million for seven projects aimed at researching and developing cutting-edge geothermal technologies. These seven projects will demonstrate the technical and economic feasibility of non-conventional geothermal energy technologies in three research areas: low temperature fluids, highly pressurized geothermal fluids and geothermal fluids recovered from oil and gas wells. This funding will help demonstrate and commercialize innovative technologies to lower the high initial costs of geothermal development and help make the operational deployment of low temperature geothermal units more economical.
“These innovative projects have the potential to expand the use of geothermal energy to more areas around the country,” said Secretary Chu. “The development of these technologies will allow us to tap into additional renewable energy resources, reduce carbon pollution and create new jobs.”
Geothermal energy uses the earth’s heat to generate consistent, low-cost renewable energy resources with a small environmental footprint. Like solar panels and wind turbines, geothermal could reduce U.S. demand for fossil fuels, significantly cut carbon pollution and create a new sector of jobs. Unlike solar and wind, geothermal energy is reliable, unhindered by cloud cover or low winds.
Low temperature resources are widely available across the country and offer an opportunity to significantly expand the national geothermal portfolio. However, most low temperature geothermal resources are not hot enough to be harnessed through traditional geothermal processes, including dry steam or flash steam power plants, which typically use water at temperatures greater than 360°F. These projects aim to take advantage of geothermal fluids that won’t “flash” on their own for electricity generation, but could be used in binary-cycle power plants. In binary cycle technologies, the water from the geothermal reservoir is used to heat another working fluid, which is vaporized and used to turn the turbine or generator units.
Four of the earmarked projects use the low temperature technology. Nevada-based Energent Corporation will demonstrate the innovative features of a geothermal power plant using a scale-resistant heat exchanger design that will allow increased use of low temperature resources, with the potential to increase power production from the brine flow by 40%.
Another company, GreenFire Energy, will provide field evaluations of a low temperature carbon dioxide-based geothermal electric power generation plant in an existing CO2 production field and shallow wells. Modoc Contracting Company has proposed to create a complete “cascaded” use of a geothermal resource that will demonstrate energy-efficient use of the geothermal fluids. The company will procure, install and commission an engineered, scalable and replicable generator unit to use the waste heat from an existing geothermal plant. The “cascading” application will have significant implications for the nearly 1,500 potential low to moderate temperature well sites located within towns and medium-sized cities in the western United States.
California-based Oski Energy, LLC will test an innovative power cycle technology that uses a mixture of ammonia and water as the working fluid. It will deploy novel system design techniques that will allow optimized, real-time, self-tuning of the power cycle process that will compensate for variations in the geothermal production fluid and flow rate, as well as changes in ambient temperature that adversely affect power generation.
Geothermal coproduction with oil and gas wells also has significant potential to produce electricity for field use or to be sold to the electrical grid. In the United States, an average of ten barrels of water is produced with every barrel of oil. Historically, this coproduced hot water has been treated as a waste product. Using the water to generate power, however, provides a significant, clean source of energy that can extend the economic life of oil and gas fields.
ElectraTherm, Inc. seeks to demonstrate the financial and technical viability of producing electricity from heat coproduced in geothermal brine, with an expected heat-to-power generator output capacity in the 30-70 kilowatt range. The project will result in the optimization of a low-cost, modular and mobile power plant that can be employed on small resources in remote locations.
Highly pressurized geothermal production is a type of geothermal resource that occurs in deep basins where fluid and gas occur naturally under very high pressure. These geothermal reservoirs often contain dissolved natural gas that may not be economical to produce alone, but can be economically developed in combination with geothermal energy production. These “geopressured” reservoirs are located along the Pacific coast, in Appalachia, beneath the Gulf of Mexico and in other deep sedimentary basins in the United States, so these projects will diversify and expand the country’s potential to develop renewable geothermal energy.
Louisiana Geothermal, who, along with NRG Energy Inc. brought in the largest grants at $5 million each, aims to demonstrate economical electricity production from geopressured resources. The creation and operation of a power generation facility will supply valuable cost and engineering data for future geothermal projects. NRG will evaluate and characterize a target geothermal reservoir for development of a power plant. The company seeks to demonstrate and identify viable energy production from geopressured geothermal resources with the potential for cost-effective recovery of heat, kinetic energy and natural gas.See All Tags