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NETL’s Chemical Looping Reactor Pilot-Scale Test Facility
Back in February, we shared that DOE’s National Energy Technology Laboratory (NETL) researchers were exploring the potential of using copper in a process known as chemical looping to capture carbon dioxide (CO2) emissions from coal-fired power plants. Their research is bearing fruit as more than 40 hours of chemical looping operations have been conducted using copper —a new lab record.
In traditional coal-fired power plants, coal is first crushed, and then combusted in air to produce steam that powers turbines. This process produces not just oxygen but other gases as well. But in chemical looping, only oxygen is carried to the combustion process – producing a virtually pure stream of CO2 that can then be captured and more easily stored or reused. The hurdle has been finding a material that can effectively carry the oxygen to the process.
Here’s where copper comes in. Copper holds many advantages as an oxygen carrier, including good fuel conversion and heat management. It also generates heat when it reacts with fuel, which makes the operation easy. On the downside, copper melts at temperatures well below those found in power plants. To meet this challenge, NETL researchers designed a mixed-metal oxygen carrier of iron oxide and copper oxide to create an oxygen carrier that could stand the heat.
First-generation particles developed by NETL were hindered by their size, 150–300 microns, which proved too small to avoid particle losses during operation. The second-generation oxygen carrier has larger particles, 200–600 microns, which overcome this drawback while still maintaining the advantages of a copper hybrid oxygen carrier. NETL researchers have put about 500 pounds of this second-generation particle through stringent testing in the NETL Chemical Looping Reactor Pilot-Scale Test Facility, resulting in the 40-hour chemical looping operation.
While the technology is still being developed, NETL researchers are optimistic about the future possibilities. Ranjani Siriwardane, the NETL materials engineer heading up the project, considers the successful tests encouraging. “This test showed that many of the operational barriers associated with chemical looping combustion can be resolved. Furthermore, the knowledge and experience that was gained during this test can be leveraged to improve performance in the future."