Massachusetts Institute of Technology (MIT) researchers have come up with a plan that could make it possible to generate electricity from coal with much greater efficiency — possibly reaching as much as twice the fuel-to-electricity efficiency of today’s conventional coal plants, MIT said recently.
The new hybrid approach advocated by MIT researchers could mean a 50% reduction in carbon dioxide (CO2) emissions based on power output, MIT said in an April 4 news release.
The concept, proposed by MIT doctoral student Katherine Ong and Ronald C. Crane (1972) Professor Ahmed Ghoniem, is described in their paper in the Journal of Power Sources. The key is combining into a single system two well-known technologies: Coal gasification and fuel cells.
The attraction of combining these two systems, Ong said, is that both processes operate at similarly high temperatures of 800 degrees Celsius or more.
Combining them in a single plant would thus allow the two components to exchange heat with minimal energy losses. In fact, the fuel cell would generate enough heat to sustain the gasification part of the process, she says, eliminating the need for a separate heating system, which is usually provided by burning a portion of the coal.
Conventional coal-burning power plants typically have very low efficiency; only 30% of the energy contained in the fuel is actually converted to electricity. In comparison, the proposed combined gasification and fuel cell system could achieve efficiencies as high as 55% to 60%, according to MIT’s research simulations.
The next step would be to build a small, pilot-scale plant to measure the performance of the hybrid system in real-world conditions, Ong said.
Because the individual component technologies are all well developed, a full-scale operational system could plausibly be built within a few years, she said. “This system requires no new technologies” that need more time to develop, she says. “It’s just a matter of coupling these existing technologies together well,” Ong said.
The system would be more expensive than existing plants, she said, but the initial capital investment could be paid off within several years due to the system’s increased efficiency.
“If we’re going to cut down on carbon dioxide emissions in the near term, the only way to realistically do that is to increase the efficiency of our fossil fuel plants,” Ong said.
The International Energy Agency (IEA) has projected that, even with the new agreements in place, global coal-fired power generation will increase over the next few decades.
Finding a cleaner way of using coal could be a big step toward achieving CO2 reductions while meeting the needs of a growing and increasingly industrialized world population, MIT said.
A copy of Ong’s research is available for sale through the Journal of Power Sources.