Bioenergy, Geothermal

DOE: $20 Million More for Geothermal

In spite of the lack of action in the U.S. Congress this year, the Department of Energy has been extremely busy handing out money for research and development.

Over the last few weeks, DOE has awarded almost $100 million for research and development projects in wind, solar, hydrokinetics and biomass. Add another $20 million to that list for geothermal.

The DOE announced a variety of research and development efforts in geothermal this week, awarding millions of dollars to companies testing co-production methods (siting geothermal projects with oil and gas wells), low-temperature fluids and different geo-pressured fluids.

Geothermal co-production with oil and gas wells has significant potential to produce electricity for field use or to be sold to the electrical grid. In the United States, an average of 10 barrels of water is produced with every barrel of oil. Historically, this co-produced 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 was the only company to receive money in the co-production space. You can see a model of its generator below.

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 (182°C).

The projects announced this week 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.

Companies awarded money in the low-temperature space include: Energent Corporation, GreenFire Energy, Modoc Contracting Company and Oski Energy.

Another company, Raser Technologies, has been working on low-temperature “modular” geothermal power plants. While the company has run into numerous problems with lower-than-expected temperatures in its wells (and thus generating far less electricity than expected), the idea is an interesting one. Below is a video that illustrate’s Raser’s power plant model.

Finally, highly pressurized or geo-pressured fluid 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. Geo-pressured 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.

NRG Energy and Lousiana Geothermal were awarded money for projects in this field.