SRI International introduced their direct carbon fuels cell (DCFC) technology to the fuel cell research community at the 2005 Fuel Cell Seminar on Monday, November 14. According to their announcement:
DCFCs convert the chemical energy in coal directly into electricity without the need for gasification. SRI's new DCFC technology has several potential benefits. It produces electricity at a competitive cost from a variety of fuels including coal, coke, tar, biomass and organic waste. In addition, it is two times more fuel-efficient than today's coal-fired power plants, resulting in reduced carbon dioxide emissions. The process produces almost pure carbon dioxide, which can be contained in a concentrated stream and easily captured for downstream use or disposal.
The United States, which has extensive coal reserves, will continue to use coal as its primary source of electricity for many years to come. However, today's coal-fired power plants convert coal into electricity with relatively low efficiency. In addition, coal is a source of toxic emissions, greenhouse gases and heavy metal pollutants when used in traditional combustion power plants. For the U.S. to achieve energy independence in an environmentally sustainable and economically feasible way, a clean, efficient and direct process to convert coal into electrical energy is needed.
"A proposed energy source must meet strict criteria to overtake conventional coal-fueled power plants," said SRI's Lawrence Dubois. "The conversion system must use a low-cost domestic resource, have comparable or lower capital and operating costs, achieve higher efficiency, and capture fuel oxidation products internally to achieve zero emissions of toxic and greenhouse gases. SRI's novel DCFC approach has the potential to satisfy all of these demanding requirements."
SRI scientists are developing a DCFC system that uses inexpensive and domestically available coal for clean energy generation. SRI's Materials Research Laboratory is working with international and industrial partners to demonstrate the technical, economic and commercial feasibility of its DCFCs.
SRI's system mixes the best features of two demonstrated technologies: solid oxide fuel cells and molten carbon-air fuel cells. The one-step, clean, high-efficiency energy conversion process transforms the chemical energy of pulverized coal (and other carbon-containing fuels) directly into electricity through the electrochemical oxidation of carbon.
According to a Wired News article:
The process is 70 percent efficient, double that of traditional coal power plants, according to Larry Dubois, vice president of the physical sciences division at SRI.
SRI researchers have shown that in a single step, they can take pulverized coal -- or anything else that contains carbon, including human waste or banana peels, for example -- and directly transform the fuel's chemical energy into electricity by electrochemically oxidizing the carbon.
The byproduct is carbon dioxide -- but it is emitted in such a pure form, Dubois said, that it's easy to contain. "If you have a conventional gas-fired coal plant and capture the (carbon dioxide) -- 75 percent of the cost is separating carbon dioxide from air," he said.
For now, the carbon fuel cells are producing small amounts of power on the scale of a few watts at SRI's laboratory in Menlo Park, California. But Dubois expects their capability to rise to 10 kilowatts by 2009, to 100 kilowatts by 2011 and to 500 kilowatts by 2015.
Red Herring adds these comments:
Unlike hydrogen and methanol fuel cells, SRI’s carbon fuel cells use no catalyst or costly noble metals like platinum. That again cuts costs, and should increase reliability, said Mr. Dubois.
Finally, the technology makes it easier to capture carbon dioxide. Current legislation doesn’t require the capture of carbon dioxide, but “the world is going in that direction,” said Mr. Dubois. Such legislation would give SRI’s fuel cells a competitive advantage because sequestering carbon dioxide from traditional coal plants is a complicated and costly process, and SRI could significantly lower that cost, he said.
If carbon-dioxide-capturing costs are included, SRI’s technology could cost up to 50 percent less than current plants, he added. That could also assuage some environmentalist concerns, as no carbon dioxide emissions would be released into the atmosphere.
Lawrence Livermore National Laboratory also has a development program for the DCFC as has been pointed out by Jessie Jenkens. Their extensive website contains an excellent writeup on DCFC's, a very brief portion of which is below:
The breakthrough Lawrence Livermore method, the result of a two-year study funded by the Laboratory Directed Research and Development Program, pushes the efficiency of using fossil fuels for generating electricity far closer to theoretical limits than ever before. If adopted on a large scale, direct carbon conversion would help to conserve precious fossil resources by allowing more power to be harnessed from the same amount of fuel. It would also improve the environment by substantially decreasing the amount of pollutants emitted into the atmosphere per kilowatt-hour of electrical energy that is generated. Perhaps most important, it would decrease emissions of carbon dioxide, which are largely responsible for global warming.
“What if we could nearly double the energy conversion efficiency of fossil fuels in electric power generation over the conversion efficiency of today’s coal-fired power plants—which is about 40 percent—and thereby cut the carbon dioxide emissions per kilowatt almost in half?” asks lead researcher John Cooper, scientific capability leader for electrochemistry and corrosion in Lawrence Livermore’s Chemistry and Materials Science Directorate. “And what if we could produce a pure carbon dioxide byproduct for sequestration or industrial use at no additional cost of separation while avoiding the air pollution problems associated with combustion?”
Cooper explains that direct carbon conversion requires a unique kind of fuel cell. A fuel cell is an electrochemical device that efficiently converts a fuel’s chemical energy directly to electrical energy without burning the fuel. However, instead of using gaseous fuels, as is typically done, the new technology uses aggregates of extremely fine (10- to 1,000-nanometer-diameter) carbon particles distributed in a mixture of molten lithium, sodium, or potassium carbonate at a temperature of 750 to 850°C. The overall cell reaction is carbon and oxygen (from ambient air) forming carbon dioxide and electricity.
The reaction yields 80 percent of the carbon–oxygen combustion energy as electricity. It provides up to 1 kilowatt of power per square meter of cell surface area—a rate sufficiently high for practical applications. Yet no burning of the carbon takes place.
This sounds almost too good to be true. Electricity from coal without gasification at 70% efficiency. Development has a long way to go, but its worth the wait. Sounds like a great technology to fast track. Why are we we even considering a hydrogen economy?
Lawrence Livermore material added on December 4, 2005.
SRI International Presents Novel Direct Carbon Fuel Cell Technology at Industry Event, Press release, November, 11, 2005
Fuel Up With Banana Peels, Wired News, December 2, 2005
Coal Fuel Cell Has Promise, Red Herring, November 14, 2005
Carbon Conversion Fuel Cell, Lawrence Livermore National Laboratory website