Federal researchers hope to bridge the gap between fossil fuels and renewable energy by tapping into vast amounts of low-temperature geothermal resources in America's oil and gas wells.
The U.S. Department of Energy announced this week that it will make an increased effort to leverage oil and gas expertise and test the reliability and efficiency of geothermal co-production from wastewater at its Rocky Mountain Oilfield Testing Center (RMOTC) near Casper, Wyoming.
“This is just one way that both industries can work together, and we see a lot of hybridization with other technologies,” said RMOTC Director Clarke Turner.
The DOE plans to combine efforts of the Office of Fossil Energy and Office of Energy Efficiency and Renewable Energy to test and validate low-temperature (90 to 250 Fahrenheit) geothermal power generation technologies associated with oil and gas production.
The announcement was welcome news to industry insiders who say there haven’t been too many venues where the petroleum industry and clean technology sectors can share ideas. Many in the oil industry are unaware of the potential to generate electricity from wastewater.
“In fact, this is the first that I've heard about it,” Nicole Daigle, a spokeswoman for the Independent Petroleum Association of America, said Wednesday.
But entrepreneurs and researchers who have approached the oil industry say their proposals have been met with skepticism.
“The oil and gas industry is like any established industry – they don’t want to take risks, especially on the production side,” Turner said. “We can take on those risks and show them that this can be marketed.”
For those who have been watching this little segment of the renewable energy sector, the DOE’s recent announcement was a significant step toward better understanding. In September, the Petroleum Association of Wyoming was not invited – apparently due to an oversight – to a major geothermal-oil symposium involving the RMOTC, according to a report in the Wyoming Business Report.
By calling on the expertise and relationships within its Office of Fossil Fuel Energy, the DOE is making strides to change perceptions within both industries, said Ahmad Ghassemi, a Texas A&M University petroleum engineering professor who specializes in unconventional resources.
“This show’s they’re trying,” Ghassemi said. “It’s really going to depend now on whether the oil industry buys into this technology.”
Wyoming’s RMOTC, which has been in operation since 2008, serves as a research and development hub to combine the efforts of various research offices to harnesses energy from co-produced fluids, or hot brine, that were typically considered wastewater from oil and gas operations.
Geothermal power potential near oil and gas production sites has been apparent for decades, but innovation in recent years finally caught up as renewable energy gained political momentum, creating more business opportunities.
“The technology has come a long way in five years, but it’s still really considered to be emerging,” said Maria Richards, coordinator of the Southern Methodist University Geothermal Laboratory.
Some fear the momentum will come to a halt in the current political climate, which came to a flash point Wednesday as rancor unfolded during a meeting of the House Energy and Commerce Committee subcommittee of Energy and Power. GOP leaders with close ties to the petroleum industry had expressed in no uncertain terms their doubts about man-made global warming, leading to concern that those sentiments don’t bode well for federally funded cleantech research.
Through grants, the DOE’s Geothermal Technologies Program has funded 17 projects in various geological conditions that have combined capacities of 3 GW of power via “low-temperature, co-produced and geopressured” resources. The resources could all be producing energy by 2020.
The Wyoming research center is located in the Naval Petroleum Reserve No. 3 (NPR-3), historically known as Teapot Dome. The site, once synonymous with a 1920s bribery scandal involving President Warren Harding’s secretary of the interior, is one of the largest federal petroleum reserves. It also produces 45,000 barrels of hot water (190 Fahrenheit) per day from the Tensleep formation and 28,000 barrels (210 F) from the Madison formation.
The Rocky Mountain Oilfield Testing Center has already harnessed the power of wastewater from oil and gas production to operate a 250 kW Ormat Technologies generator. The unit has produced 1,918 megawatt-hours of electricity to date, making it the world’s first test unit to use co-produced hot water to generate electricity in an operating oil field, the DOE said.
Southern Methodist University researchers have estimated the combined geothermal electric power from oil and gas wells in Texas and six states closest to the Gulf Coast Plain is 1,000 to 5,000 MW if the hot water was pumped and then run through heat exchangers.
The DOE estimates those states have a potential capacity of even more -- 7,800 MW -- from the more than 37,000 known well sites. Some locations hold geo-pressured fluids containing natural gas that had not been economically viable for production. That could change if geothermal energy from hot brine contributes to return on investment. (As profiled in an earlier story, some companies have found it difficult to make the numbers work on these projects).
The DOE, University of North Dakota, and Southern Methodist University are exploring the potential for Organic Rankine Cycle systems to serve as low-temperature geothermal power plants with the oil and gas production process.
“It’s incredible the amount of energy that’s out there in terms of hot water,” said William Gosnold, a professor and chair of Geology and Geological Engineering at the University of North Dakota, which has assisted the DOE with geothermal research in oil and gas fields.
Typical geothermal systems generate electricity when water-based steam at high temperatures (hotter than 350 Fahrenheit) powers turbines. ORC systems use a different fluid, such as the fluorohydrocarbon R245fa, requiring lower temperatures. Gosnold said the DOE’s Wyoming facility could potentially test alternatives to ORC systems, including Kalina Cycle units that have shown greater efficiency with ammonia-water fluids.
Also, next-generation ORCs, like the Calnetix system tested by the University of North Dakota, have improved efficiencies by replacing turbine-gearbox-generator configurations with a single moving part consisting of magnetic bearings and magnets on fan blades.
Gosnold says the oil and gas industry could soon power its own production operations and then sell excess electricity from all the hot water that had once been considered a nuisance because it added an expense for disposal into injection wells.
“It’s great the DOE is going to be working with the fossil fuel industry,” he said. “If they buy into this, we’ll have great renewable energy resources for years to come.”
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