applications, for example, power in space missions, the technology is an ideal match. However, when the technology was tried for stationary applications, the inability of the fuel cells to accept fuels and oxidants that were not ultraclean necessitated fuel/oxidant treatment subsystems, which increased the complexity and cost of these fuel cells. In the 30 years of DOE support for fuel cells, there has been little or no commercial application that resulted in substantial public benefit and no commercial product without DOE subsidies. This leads one to question the ability of subsidies to drive a new product to market if that product does not have significant stand-alone commercial benefits.

The promised efficiency of fuel cells is a moving target. Gas turbine combined cycles have become the accepted power generation technology for the utility industry, and their efficiencies are projected under the DOE ATS program to reach 60 percent. Thus, there is no doubt that opportunities exist to increase the efficiency of conventional systems, so fuel cells will need to meet higher efficiency and lower capital cost targets in order to be considered. As fuel cell systems become more complex in order to compete, it will be more difficult to achieve market acceptance. Systems that have to rely on many elements working together in order to produce a desired result are normally viewed by the utility industry as having reliability issues. This was one of the major concerns that limited the use of gas turbine combined-cycle technology in its early stages of development. Overcoming the reliability issue will require many years of successful operation at the full-scale demonstration scale.

In the 30 years of the program, major companies have terminated their internal programs and have exited DOE-sponsored programs. The only thing that has kept this program going is an extremely strong advocacy group and the significant DOE program funding.

In many ways, the fuel cell program shares characteristics with the MHD program. It is difficult if not impossible for DOE to drive a program to the point of commercial reality with its funding alone unless there is a real effort by industry, with the manufacturing infrastructure and financial support, to commercialize the technology. DOE has not been very successful here in determining if an industrial partner is seriously undertaking the R&D or just in the program to receive DOE funding support. Although industrial support for fuel cell program has increased in recent years, it has yet to be shown that the program will result in benefits that are in line with the more than $1 billion that has been invested in this technology area.

Driven in large measure by the desire to find ways to use abundant domestic coal resources, DOE’s Office of Fossil Energy (FE) conducted R&D on magnetohydrodynamics (MHD) technology for 16 years because of its perceived potential as a major technology for electric power generation using coal. The program successfully proved the concept of using MHD technology but was discontinued in 1993 because of the high cost of designing, constructing, and operating a complete MHD system.

Both an MHD power generator and a conventional generator are based on the electromagnetic induction principle. A conductor moves through a magnetic field inducing an electric field in the conductor. While a conventional generator relies on the copper windings of the rotating conductor, an MHD generator uses the gaseous products of combustion that are ionized by raising them to sufficiently high temperatures in seeded conductive material. Thus, a perceived advantage of the MHD concept is the absence of moving parts.

The DOE R&D concept for a central-station electric power station based on MHD technology consisted of two cycles in series—an MHD topping cycle, from which power would be extracted directly, and a steam bottoming cycle, in which power is produced in a conventional steam turbine cycle:

• In the topping cycle, coal is burned in a pressurized combustor with preheated air or oxygen-enriched air to produce a combustion gas having a temperature of 2482°C to 2760°C. At this temperature, the combustion gas is only slightly conductive due to thermal ionization. An easily ionized seed material such as potassium is added to increase conductivity, and the combustion gas is expanded through the MHD generator, located in the magnetic field. As the gas exits the generator, it is decelerated in a diffuser and discharged at approximately 1982°C into a steam boiler.

• In the bottoming cycle, NO_x emissions are controlled by tailoring the time-temperature profile within the radiant boiler to keep the NO_x content within allowable levels and by fuel-rich combustion. SO_x is removed from the gas stream by reaction with potassium seed from the topping cycle to form a recoverable solid product. Use of an electrostatic precipitator or a baghouse at the exit of the boiler controls particulate emissions. Spent seed removed from the bottoming cycle is supplied to a regeneration system, where it is converted to a non-sulfur-containing form for reinjection into the topping cycle.

Initial MHD research in the United States was conducted primarily at universities and private companies. Early government interest in MHD was directed at developing power sources for space and military applications and centered in agencies such as the Department of the Interior’s Office of Coal Research, the National Science Foundation, the Atomic Energy Commission, the National Aeronautics and Space Administration, and the Department of Defense. The energy crises of the early 1970s focused more attention on MHD’s potential as a central-station power-generating concept using abundant coal resources, leading to increased R&D sup-