New PNNL Geothermal Heat Extraction Process Optimizes Low-Temperature Resources; NYU Stern Study Finds Geothermal Most Efficient Renewable and Improving the Fastest
|PNNL’s metal-organic heat carrier (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. Source: PNNL. Click to enlarge.|
Scientists at the US Department of Energy’s Pacific Northwest National Laboratory (PNNL) have developed a new method for capturing significantly more heat from low-temperature geothermal resources.
PNNL’s conversion system exploits the rapid expansion and contraction capabilities of a new biphasic fluid. When exposed to heat brought to the surface from water circulating in moderately hot, underground rock, the thermal-cycling of the biphasic fluid will power a turbine to generate electricity.
|“Some novel research on nanomaterials used to capture carbon dioxide from burning fossil fuels actually led us to this discovery. Scientific breakthroughs can come from some very unintuitive connections.”|
To aid in efficiency, scientists added nanostructured metal-organic heat carriers, or MOHCs, which boost the power generation capacity to near that of a conventional steam cycle.
The goal of the project is to enable power generation from low-temperature geothermal resources at an economical cost. The research team is targeting the development of a functioning bench-top prototype generating electricity by the end of the year, according to PNNL Laboratory Fellow Pete McGrail.
|PNNL’s Pete McGrail on the process.|
PNNL is receiving $1.2 million as one of 21 DOE Energy Efficiency and Renewable Energy grants through the Geothermal Technologies Program. Some of the research was conducted in EMSL, DOE’s Environmental Molecular Sciences Laboratory on the PNNL campus.
A 2006 technical and economic analysis conducted by the Massachusetts Institute of Technology estimated that enhanced geothermal systems could provide 10% of the nation’s overall electrical generating capacity by 2050. (Earlier post.)
NYU Stern study. A new study by NYU Stern found that geothermal and wind energy are more efficient, and are yielding greater returns on the R&D invested in them, than most other renewable energy alternatives.
NYU Stern Professor Melissa Schilling found that the cost of generating electricity with geothermal or wind energy is a fraction of the cost of solar energy. Additionally, the performance of both is improving much more per dollar of R&D invested in them than solar technologies. This is the first study to explore the trajectory of performance improvement of renewable energy alternatives.
Examining data on government R&D investment and technological improvement, she found:
Geothermal energy is the most efficient renewable energy alternative and is improving the fastest. Wind energy is second.
Fossil fuel technologies are no longer improving (in terms of efficiency) much, if at all. These technologies have likely reached their performance limits, though the government still spends far more on them.
Geothermal energy could become cheaper than fossil fuels with R&D spending of as little as $3.3 billion.
Both geothermal and wind energy technologies have been underfunded by national governments relative to funding for solar technologies, and government funding of fossil fuel technologies might be excessive given their diminishing performance.
Melissa A. Schilling, Melissa Esmundo (2009) Technology S-curves in renewable energy alternatives: Analysis and implications for industry and government. Energy Policy 37 1767–1781 doi: 10.1016/j.enpol.2009.01.004
Praveen K. Thallapally, Jian Tia, Motkuri Radha Kishan, Carlos A. Fernandez, Scott J. Dalgarno, Peter B. McGrail, John E. Warren and Jerry L. Atwood (2008) Flexible (Breathing) Interpenetrated Metal-Organic Frameworks for CO2 Separation Applications. J. Am. Chem. Soc., 130 (50), pp 16842–16843 doi: 10.1021/ja806391k