No fuel like an old fuel
15 Jan 2000
An alliance between BG Technology and Alstom is set to speed up the development of fuel cells based on proton exchange membrane (PEM) technology. The cells, convert the energy from the hydrogen/oxygen reaction into electricity, and produce no harmful emissions.
The fuel cell technology itself is Alstom's, through an alliance with Ballard Generation systems formed in 1997. In a PEM cell, the hydrogen and oxygen react without mixing. Hydrogen and air streams pass on either side of an electrolyte membrane which only allows hydrogen ions - protons - and electrons to pass through. The cells are efficient and quiet, and produce no emissions. Moreover, they produce heat, so can be used in combined heat and power plants.
BG's contribution is its know-how in gas processing, particularly in converting natural gas into hydrogen. This vital link in the technology includes cleaning and purifying the gas to make it suitable for steam reforming, as well as the reforming itself. `Gases from different regions vary enormously in chemical composition.' explains BG Technology principal scientist Andrew Dicks. When the gas is burned, this is irrelevant; but when it has to be converted chemically, it's vital.
BG has also developed a compact steam reformer for converting natural gas into hydrogen via the water-shift reaction - methane and water reacting over a nickel catalyst to produce carbon monoxide and hydrogen. The reformer is a combination reactor and heat exchanger using diffusion-bonded plates, developed in association with Chart Marston (see PE Sept, p50 and this issue News); the catalysts are deposited as thin films on either side of the heat exchanger plates.
BG and Alstom anticipate that the first use for the PEM system will be in providing secure power supplies for hospitals and banks; they could also be used as uninterruptible power supplies for process plants.
