Construction Begins on Project to Demonstrate Entirely New Natural Gas Power Cycle

Construction of a 50-MWt plant that will demonstrate a novel oxyfuel natural gas power system using Allam Cycle technology with zero atmospheric emissions has kicked off in La Porte, Texas.

The demonstration plant is being built by the technology's developer, Durham, N.C.-based NET Power, along with Exelon Generation, CB&I, and 8 Rivers Capital. NET Power's Allam Cycle-named for its lead inventor, Rodney Allam-burns natural gas (or synthetic gas from coal gasification) with pure oxygen and uses high-pressure, supercritical carbon dioxide (CO₂) as a working fluid in a semi-closed loop to drive a combustion turbine. Its byproducts are mostly liquid water and the CO₂ that is recycled by the process.

The Allam Cycle. Courtesy: NET Power

The technology can produce "pipeline-quality CO₂ that can be sequestered or used in various industrial processes, including enhanced oil recovery," NET Power said in a statement announcing the demonstration project's groundbreaking on March 9. The company has claimed that the system has a net efficiency of 58.9% and has a carbon capture rate of nearly 100%. "Additionally, for a small reduction in efficiency, the technology can operate without water, actually becoming a net water producer," it said.

NET Power is giving the demonstration plant a 50-MWth rating because marketing of power output will "vary with the testing program of the demo, rather than having a constant output to the grid," as company spokesperson Walker Dimmig told POWER.

Exelon and CB&I are funding the $140 million program that includes the demonstration plant's design and construction with a combination of cash and in-kind contributions. The program also includes technology advancement, a complete testing and operations program, and commercial product development.

According to NET Power, Toshiba developed and is now manufacturing the world's first gas turbine combustor for a supercritical CO₂ system. The turbine has an inlet pressure of about 30 MPa and inlet temperature of 1,150C. CB&I is performing the engineering, procurement, and construction of the plant, and Exelon is providing operations, maintenance, and development services. 8 Rivers invented and continues to advance the technology behind the project.

For now, NET Power anticipates that commissioning of the plant will begin in late 2016 with first fire scheduled at the beginning of 2017. The demonstration has enough funding for at least 8,000 hours of operation, Dimmig said.

The company's end goal is to build a commercial power plant, and NET Power is actively talking to potential end-users, particularly in the oil and gas sector, he added.

-Sonal Patel, associate editor (@POWERmagazine, @sonalcpatel)

CORRECTED (March 11): Corrects inlet temperature of Toshiba-manufactuered supercritical CO₂ turbine. Clarifies quote attributed to Walker Dimmig.

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