US company achieves major milestone for low-cost carbon capture
26 June 2018
NET Power LLC has successfully achieved first fire of its supercritical carbon dioxide (CO2) demonstration power plant and test facility located in La Porte, Texas. Firing of the 50MWth Toshiba Energy Systems & Solutions Corporation commercial-scale combustor on May 30 involved the integrated operation of the full NET Power process.
Artist's impression of La Porte plant - Image: NET Power
Following rigorous testing, the combustor will be integrated with the turbine and power will be generated. NET Power is targeting the global deployment of 300MWe-class commercial-scale plants beginning as early as 2021.
The company says first fire is a critical milestone for the demonstration plant, as it validates the fundamental operability and technical foundation of NET Power's new power system, which is designed to produce low-cost electricity from natural gas while generating near-zero atmospheric emissions, including full CO2 capture. The achievement also confirms the operation of Toshiba's combustor at commercial scale, as several 50MWth combustors will be used together in NET Power's 300MWe commercial facilities.
NET Power is a collaboration between Exelon Generation, McDermott, and 8 Rivers Capital. Constructed over a 2-year period, the company's 50-megawatt thermal (25MWe) demonstration plant is the world's only industrial-scale supercritical carbon dioxide-based power plant and CO2 cycle test facility.
"This is the exciting culmination of a process that required the hard work and dedication of our investors," said Charlie Bowser, NET Power's President. "We were also very fortunate to bring together an extraordinary group of key contractors and equipment suppliers. Because of the collaborative effort of the extended team, our achievements have fully met our expectations."
The plant is designed to demonstrate NET Power's Allam Cycle technology, which uses a new turbine and combustor developed specifically for the process by Toshiba. Using carbon dioxide (CO2) as a working fluid to drive a combustion turbine, the Allam Cycle eliminates virtually all emissions from natural gas power generation without requiring expensive, efficiency-reducing carbon capture equipment.
The main inventor behind the process is British engineer Rodney John Allam, part of the 8 Rivers Capital team.
As the energy sector and electricity consumers become increasingly carbon-conscious, NET Power and Toshiba are poised to provide the market with the industry's first natural gas power generation technology that is low-cost, flexible, and carbon-emissions free.
In parallel with these demonstration plant tests, NET Power is advancing the development of commercial-scale 300MWe natural gas plants. NET Power is working on projects with power generation, oil and gas, and industrial companies in the US and globally, as well as a number of governmental agencies abroad. With the passage of 45Q carbon capture tax credit reform in the US and the demand for low-cost CO2 in industrial processes that use and sequester CO2, the company sees a large demand for NET Power plants and Toshiba turbines, beginning in the very near term.
Existing natural gas plants burn natural gas with air, which is a mix of oxygen and nitrogen. These technologies emit CO2, which is difficult and expensive to separate from the nitrogen and residual oxygen, making carbon capture uneconomic for traditional power plants. NET Power addresses the cost hurdles of older technologies with a novel process—an oxy-fuel, supercritical CO2 power cycle—that produces electricity efficiently while inherently eliminating all air emissions. The system burns natural gas with oxygen, as opposed to air.
Additionally, instead of using steam, the cycle uses high-pressure CO2 to turn a turbine, in effect turning the CO2 problem into the climate solution. NET Power produces only electricity, liquid water and pipeline-ready CO2, as well as valuable argon and nitrogen, all while operating as efficiently as most natural gas power plants in operation today. Additionally, for a small reduction in efficiency, the technology can operate without water.
The company says this technology will serve as an affordable and reliable cornerstone of the world's clean energy future.
The US has one of only a few state-led efforts to develop sCO2 cycles. Others include South Korea, which is exploring a sCO2 Brayton cycle for a small modular reactor, and China, which has funded research into a cascaded sCO2 system integrated with solar and biomass.
The technology has strong backing from the US Department of Energy (DOE), which touts the technology’s economic and environmental benefits. These include a “broad applicability to [a] variety of heat sources.” Its applications can be expanded to power generation from nuclear, coal, gas, oil, concentrating solar, waste heat recovery, and geothermal, it says.
A handful of projects are underway across the US to explore sCO2 Brayton cycles.
Developers say sCO2 power cycles have the potential to surpass 40% efficiency, compared with Rankine’s efficiency of 33%. That translates into reduced fuel consumption and emissions, low cooling water consumption, and a compact design that should lower capital cost.
However, before they can be used for commercial applications—including for waste heat recovery, concentrating solar power, nuclear, and fossil energy—several technical challenges must be overcome.
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