Nuclear and Geothermal Updates

Pacific Northwest National Laboratory (PNNL)’s introduction of a metal-organic heat carrier, or MOHC, in the biphasic fluid may help improve thermodynamic efficiency of the heat recovery process. This image represents the molecular makeup of one of several MOHCs.

1. PNNL developed a superior type of heat-extracting fluid that could dramatically improve the economics of producing renewable power from low-temperature geothermal resources

MIT Technology report : Lab fellow Pete McGrail says the liquid is used to absorb the heat from hot water that’s been pumped from underground into a geothermal plant’s heat exchanger. The liquid can potentially boost the rate of heat capture by 20 to 30 percent. Researchers engineered proprietary nanomaterials made up of metals linked by organic molecules. They found that adding the nanomaterials to a fluid such as hexane or pentane significantly enhanced the heat-trapping properties of the liquid.

McGrail and his research team stumbled on a way to boost the energy-conversion rate as the two loops pass through a heat exchanger. Initially, they had developed proprietary materials for another project to improve the capture of carbon dioxide emitted from a fossil-fuel plant. They realized that the materials had remarkable thermodynamic qualities when added to an organic fluid. The new fluid has the potential to capture up to 30 percent more heat from a closed water loop, and, because of its rapid expansion and contraction capabilities, it can achieve higher pressures for driving the turbine.

“It’s one of those moments in the lab where you look at the data and say, ‘Wow!'” says McGrail. His group has received a $1.2 million grant from the Department of Energy’s geothermal technologies program to build a benchtop prototype that shows the properties of the fluid in action.

“Hopefully we’ll get a test loop system together by the end of the year. We’ll put together a complete working unit with heat exchanger, compressor, pumps, and a turbine system so we can see the whole process working,” he says.

The lion’s share of the cost of geothermal is in drilling and preparing production wells, says Susan Petty, chief technology officer of Seattle-based AltaRock Energy, a developer of enhanced geothermal systems. “If you’re going to get a 20 percent or higher improvement in efficiency, that’s 20 percent less well,” she says. “That is really, really significant.”

2. This projection adjusts the World Nuclear Association’s July 1, 2009 world nuclear build report. Adjustments were made for known uprate plans. The top 9 countries ranked by how much nuclear power they are adding.

Project that the US completes Watts Bar 2 by 2013.

3. A 16 page study from New York University of the S curves of energy technology improvement : show that both wind energy and geothermal energy are poised to become more economical than fossil fuels within a relatively short time frame. The evidence further suggests that R&D for wind and geothermal technologies has been under-funded by national governments relative to funding for solar technologies, and government funding of fossil fuel technologies might be excessive given the diminishing performance of those technologies.

Geothermal energy could become cheaper than fossil fuels with R&D spending of as little as $3.3 billion.

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