CAN COAL POWER FUEL CELLS?
Coal Bin Article by Harold Hough August/September 2010
With the current administration’s constant attacks on coal powered electricity, many are asking if there is any way to turn coal into an Obama approved clean energy. The most likely way is to use it in fuel cells, a technology that began to power spacecraft in the 1960s, but is looking more attractive in down-to-earth applications.
Several researchers and companies are pursuing a technology that has the potential of keeping part of the nation's economy coal-fired by skipping the burning step. "Direct carbon" fuel cells efficiently produce electricity straight from the carbon source.
The laboratory-scale technology has the potential of making electricity by using less than half the coal burned today and sharply reducing the costs of capturing carbon dioxide emissions from the fuel.
If they can successfully turn laboratory technology into practical industrial technology, the cells would offer an attractive option for electric utilities that are being pressured by the Obama Administration. Currently, fifty percent of the nation's electricity comes from coal-fired power plants and the administration is restricting the improvement, expansion or building of coal powered electrical plants.
Today, most coal-fired power plants convert the heat from coal combustion into steam. The steam turns a turbine which generates electricity. Energy is lost in each step of this process so that most power plants hover near 30 percent efficiencies. By contrast, direct carbon fuel cells (DCFCs) – a term that encompasses several fuel cell technologies - convert carbon sources to electricity in a single reaction step, just as current fuel cells do with hydrogen. Under various schemes that pulverize coal and feed it into the fuel cell in a slurry of molten salt or other superheated material. The carbon in the coal reacts in the cell to produce a moving stream of electrons (electricity). Such a fuel cell could approach up to 70 percent efficiency - the highest of any fuel cell class.
Actually, DCFCs have a history dating back to the mid-19th century. In the 1980s, labs including Lawrence Livermore National Laboratory and SRI International had small research programs to delve into the chemistry of these cells. But, with coal so plentiful and cheap, there was never much motivation to seriously pursue the idea. Since the late 1990s, DOE's interest in fuel cells has focused mainly on solid-state technologies tailored to the use of hydrogen as a fuel. Carbon-powered alternatives weren’t as interesting.
However, the DCFC concept has garnered more attention as attacks on the coal industry have increased. The cells reduce carbon dioxide emissions as they become more efficient. A 2008 Electric Power Research Institute (EPRI) study estimates that with complete CO2 capture, the cells could produce electricity more cheaply than today's state-of-the-art power plant designs that use a lot of energy to gasify coal, then remove the CO2 and burn the other gases to make power.
One advantage of coal based fuel cells is their practicality in smaller applications. Coal plants have great economies of scale and it’s not economic to make a small one. But there are no economies of scale to make a fuel cell. As a result, they are ideal for smaller-scale systems to power generators and other off-the-grid needs. They also have the potential to back up a utility's power, a function that will be increasingly necessary as more erratic, renewable energy sources power the grid.
However, coal prep will be a major challenge for the coal powered fuel cells. If coal impurities are not removed beforehand, these can degrade the cell and reduce its lifetime. The fuel cells also need to produce more power in a smaller space and last longer than current prototypes. There is also a need for investors who haven’t been frightened off by the erratic policies of the current administration.
Unfortunately, this last factor is the biggest problem. The Obama Administration has proven itself to be anti-mining. Add to this the current recession, which is depressing electrical demand and scaring investment capital. The result is a technology that promises much, but which is left delivering little in the near future.