NETL GREENLIGHTS 1 MW FIELD TEST FOR MEMBRANE CAPTURE TECH

Tamar Hallerman
GHG Monitor
11/30/12

The National Energy Technology Laboratory last week approved the testing of a post-combustion membrane capture technology on the world’s largest scale to date. The lab said it greenlighted the California-based Membrane Technology and Research Inc. (MTR) to scale up its Polaris membrane separation system to a 1 MWe pilot-scale slipstream at the Department of Energy’s National Carbon Capture Center in Wilsonville, Ala. beginning next summer. Under development for the last several years with a $19 million grant from the American Recovery and Reinvestment Act, MTR’s technology has been seen as one of the most advanced second-generation post-combustion capture technologies currently under development in DOE’s portfolio.

MTR’s polymeric membrane system consists of thin micro-porous films that are packed into spiral-wound modules. In addition to achieving high levels of CO2 permeance, the technology incorporates a sweep process that uses an existing air stream to generate the driving force for CO2 transport across the membrane, according to the company, which reduces the need for expensive and energy-intensive equipment like compressors or vacuum pumps. “Instead of compressing the air so that it can create a driving force through the membrane, they’re using secondary combustion air from the boiler to create that driving force, and that reduces the energy requirements of that membrane system,” NETL Project Manager José Figueroa said in an interview. MTR estimates the technology can capture 90 percent of a plant’s CO2 emissions with an energy penalty of 20 to 25 percent at a cost of $30 per tonne of CO2 captured.

Membrane Separation Systems Not New

Researchers have for decades used membrane technologies commercially for water purification, natural gas processing and other gas separation purposes, but only within the last decade has it been considered an option to separate CO2 from flue gas generated from coal-fired power plants. In recent years, DOE and NETL have pursued membrane capture as a promising second-generation capture technology that is cheaper and more efficient than the technology currently available on the market. Figueroa said that MTR’s membrane technology is the most advanced in DOE’s portfolio. “It is one of our membrane technologies that’s really at the forefront as far as pilot-scale development,” he said. “A lot of our projects are more in the laboratory scale, so MTR is really kind of informing and educating us as to how membranes operate in a coal-fired flue gas environment.”

While MTR has tested Polaris for more than 4,000 hours on smaller slipstreams in Arizona and at the NCCC, Figueroa said the 1 MWe scale-up will help generate key performance data. He said the project, which has been ongoing since fall 2010 and is expected to run through the end of the Fiscal Year 2015, will likely test at the 1 MWe scale at the NCCC for six months. Meanwhile, MTR will keep running a smaller 0.05 MWe slipstream unit at the Capture Center continuously through 2015 to test the technology’s durability. “We want to find out just how long these membranes last in these flue gas environments. It’s one thing to say it’s tested for 4,000 hours, but it would be even better to understand if it lasts two, three, four years, because that has an effect on the economics,” he said.