Problems to overcome
There are still some significant problems to overcome before fuel cells become widely used.
Poisoning of the fuel cell by Carbon Monoxide (CO) drastically reduces the life of low temperature fuel cells. This gas is present in the hydrogen supply to the cell when the hydrogen is created by reforming fossil fuels or coal gasification, and is difficult to filter out.
High temperature fuel cells do not suffer from CO poisoning; however the high temperatures increase the effect of sources of corrosion. A lifetime of 40,000 hours is expected in stationary power applications and 5,000 in automotive applications before fuel cells can compete with conventional systems.
Sulphur in the fuel supply can be problematic, just as CO poisoning. However, technological advances are being made in removing sulphur from fuels to acceptable levels. Sulphur oxides can cause acid rain.
The cost of fuel cells is dominated by the cost of materials; although increasingly the use of high cost materials like Platinum is decreasing. Fuel cells will compete with conventional sources when they enter the market, therefore fuel cells in high cost per kilowatt applications like battery replacement and stationary power are likely to be competitive before transport applications. In fact, General Electric recently reported a projected price of under $400/Kw for it’s 5.4kW system, at this price fuel cells become competitive with gas turbines and diesel engines in similar sized stationary power applications.
However to compete with automotive power plants, the cost would have to drop to under $50/Kw. In transport applications there is also the issue of fuel costs, it is unlikely that future cars will reform petrol or diesel on board, and so will use another fuel like hydrogen or methanol. The cost of these fuels in terms of distance travelled will depend upon the efficiency of the fuel cell.
There have been many false dawns for fuel cells, and there is nothing to say that the lifetime and cost issues can be successfully resolved. Certainly a large amount of development work is still ahead.