A Durham energy company’s $140-million quest to create the world’s first zero-emissions power plant is advancing from the laboratory to the real world.
NET Power broke ground last month on an experimental power plant near Houston, Texas, and expects to start generating electricity there in March 2017. Some are predicting that if NET Power’s experiment works and produces power without polluting, scores of these futuristic energy projects would sprout in the coming years in the U.S. and around the world.
“This is no longer vaporware,” NET Power chief executive Bill Brown said of the Texas project. “We have invented something that might save the planet.”
Among the pollutants the power plant is designed to block: carbon dioxide, the greenhouse gas that’s blamed for global climate change. Instead of releasing CO2 into the atmosphere, the NET Power plant would capture carbon dioxide and store it for permanent injection underground or for industrial applications.
NET Power’s plant would be so clean it would not require a smokestack. The ultimate selling point is that NET Power’s technology would cost about the same to build as a conventional power plant, thus obliterating the principal obstacle to pollution-free energy.
Brown said that a number of U.S. utilities have expressed interest in building a full-scale version of the plant if the 25-megawatt trial version succeeds in Texas. Brown, who spent years financing deals on Wall Street, is also co-founder of 8 Rivers Capital, the Durham technology commercialization firm behind NET Power.
Even if the project proved to be an engineering miracle, however, the NET Power plant would not please everyone. For one thing, it is designed to burn natural gas. The dependence on a fossil fuel, typically extracted by means of fracking, automatically renders NET Power’s “zero-emissions” claim a non-starter for some environmental advocates.
Additionally, NET Power intends to make its excess carbon dioxide available to energy companies for use in dislodging crude oil from subterranean geologic formations, a key step in advanced oil recovery. So the technology would either benefit from gas drilling or it would promote oil drilling.
‘Black swan technology’
Still, NET Power has attracted some high-profile environmental advocates, as well as prestigious industrial partners. Tim Profeta, director of Duke University’s Nicholas Institute of Environmental Policy Solutions, is chairman of 8 Rivers Capital’s board of advisers.
He acknowledges the tradeoffs but said NET Power is a “worthy bargain.”
“It is truly a black swan technology that could change the game in power generation,” Profeta said. “The company expects it will become the preferred technology for power generation.”
Another supporter is John Thompson, the Fossil Transition Project director at the Boston-based Clean Air Task Force.
“If this technology works, it creates an entirely new pathway to economically cut CO2 at a massive scale in a very short period of time,” Thompson said. “Even if half of what they claim pans out, it’s a big deal. If 25 percent of what they claim pans out, it’s still potentially important.”
The technology in question is called the Allam Cycle, in which natural gas is not burned with air, but with a blend of pure oxygen and carbon dioxide. In this combustion process, the natural gas, oxygen and carbon dioxide burn at a pressure more than 10 times the pressure used in a conventional gas turbine.
This thermodynamic feat, which will be tested under real-life conditions next year in La Porte, Texas, approximates a rocket engine and has never been attempted by the power industry. Unlike a disposable rocket booster, however, the NET Power combustor would have to operate reliably for the duration of a power plant’s expected lifespan, anywhere from 25 to 50 years.
“The technical challenge here lies in designing durable hardware capable of thousands of hours of continuous operation and efficient combustion over the range of conditions required in a power plant,” according to a paper presented at the June 2015 proceedings of the American Society of Mechanical Engineers Turbo Expo in Montreal, Canada.
The ASME paper’s presenters are researchers at the Toshiba Corp., one of NET Power’s corporate partners in the zero-emissions venture. Another partner is Chicago-based Exelon Corporation, the nation’s largest operator of nuclear power plants.
Also involved is the Chicago Bridge & Iron Co., a construction conglomerate commonly known as CB&I, which inherited its share of the NET Power project in 2013 when it acquired one of the original partners, the Shaw Group, a global engineering and construction firm.
That makes NET Power a virtual company without a staff of its own, drawing on outside experts and business partners for its intellectual property and R&D.
Disposing of the CO2
A logistical challenge for NET Power will be the disposal of carbon dioxide. NET Power says utilities that build its power plants could sell the CO2 they capture to energy companies for oil exploration. The other option is dumping it underground in regions with adequate geological formations for permanent deep injection.
Currently, injecting CO2 underground – called sequestration – has been tried in pilot projects but remains too costly to be adopted as an industry practice. That’s because capturing and compressing carbon dioxide at a conventional power plant would require multimillion-dollar retrofits. The NET Power plant skips the retrofit stage because it is designed and built to compress and capture the gas.
The other option, advanced oil recovery, already represents nearly 6 percent of U.S. onshore oil production. But this carbon dioxide is not sourced from the utility industry. Rather, the energy industry obtains its CO2 from a handful of natural geologic domes where the gas has naturally accumulated over eons. NET Power says its power plants can supply CO2 as well as the geologic domes.
A 295-megawatt NET Power plant, the size of the company’s planned commercial-scale design, would generate about 800,000 tons of carbon dioxide annually. NET Power estimates the utility that owns the facility could sell the gas for as little as $5 per ton and up to $50 per ton for use in advanced oil recovery, depending on the cost of oil and on other factors.
Thus a NET Power plant would generate between $4 million and $40 million in additional revenue from CO2 sales for its utility owner, according to the company’s estimates.
Or the utility could simply “vent” the CO2 into the air until disposal options become available. That’s the plan for NET Power’s pilot project under construction in Texas.
Meanwhile, depressed energy global costs could be a boon for NET Power.
“The technology would be much in demand because we have such an abundance of low-cost natural gas,” said Jim Rogers, who retired as CEO of Duke Energy in 2013 and now teaches a Renewables and the World’s Poor course with Profeta at Duke University.
“If this technology works – and we’ll soon know – it would be transformative,” Rogers said. “It would be a way to produce zero-carbon electricity using natural gas. If this happens, we’ll have zero-carbon nuclear, zero-carbon renewables and zero-carbon natural gas.”
With scores of power plants in the United States slated for retirement and replacement over the next two decades, the timing for NET Power is opportune, noted Julio Friedmann, a senior fellow at the Lawrence Livermore National Laboratory in California and immediate past principal deputy assistant secretary in the U.S. Department of Energy’s Office of Fossil Energy.
“It speaks volumes that they have strong support from industrial leaders and utilities,” said Friedmann, who has been following NET Power for five years. “They’ve chosen the right thing at the right time and they’re doing it the right way.”