Week In Science

The article New process generates hydrogen from aluminum alloy to run engines, fuel cells describes a potential new technology which may enable the refueling of engines with nothing more than water.

Using water as a fuel derivative is a technological dream. The fuel derivative- hydrogen- would burn and after combining with oxygen form water. In effect creating a man made cycle. But how would the cycle be initiated? The answer may come from some University of Purdue researchers and the key component of the process could be an alloy composed of aluminum and gallium. When water is added to the alloy researchers have been able to extract hydrogen; the hoped for replacement of gasoline in internal combustion engines.

The discoverer is Jerry Woodall, professor of electrical and computer engineering. Woodall works with doctoral students Charles Allen and Jeffrey Ziebarth. The linked article quotes Woodall as saying: "The hydrogen is generated on demand, so you only produce as much as you need when you need it." Produced on demand indicates a storage efficiency that could become an economic factor determining which hydrogen generating technology wins out.

The details of Woodall's technology involve pellets of the aluminum-gallium alloy contained within a small tank. When water is added the resulting hydrogen that is produced can be routed to an engine. The underlying chemical basis for what occurs involves a strong attraction of the alloy for the oxygen of the water molecule. Solid aluminum alone does not produce the needed reactions with water but gallium acts as a catalyst promoting the aluminum-water reaction. In addition gallium inhibits a "skin" formation associated with oxidation. The skin would coat aluminum and interfere with continued reactions involving oxygen and aluminum.

The split of water molecules yields hydrogen and aluminum oxide, which is also known as alumina. The economic viability of technology based on the research of Woodall et. al. could depend on the efficiency with which aluminum oxide is recycled and the proce of gallium which exceeds that of aluminum. Fortunately gallium is not consumed during the hydrogen production process.

The waste products of the hydrogen generating process are gallium and aluminum oxide and the waste product of the energy yielding combustion process is environmental friendly water. Those toxic vehicle emissions of today would become history. Another potential environmentally friendly by-product of the process would be the replacement of lead-acid batteries with fuel cells based on the hydrogen technology.

Other advantages of the water-alloy approach include the increased efficiency of hydrogen combustion compared to fossil fuels and obviating the need for expensive transport and storage of hydrogen gas.