Producing energy from hydrogen

Materials World magazine
,
1 Jun 2008

My brother Rex, a University of Birmingham metallurgist, is a keen advocate of the hydrogen cycle as a part-solution to global warming.

In recent times he has been much pre-occupied with the design and construction of the world’s first hydrogen-fuelled canal barge, an enterprise that has been greatly assisted by the fact that the Birmingham to Worcester canal flows through the University campus, providing mooring and the opportunity to carry out test runs. The barge incorporates a metal hydride store linked to a proton exchange fuel cell.

The Chemical Engineering Department has been involved in the hydrogen cycle and a small fleet of hydrogen-powered motor vehicles operate within the campus. A few weeks ago, I was delighted to attend the opening ceremony of the hydrogen filling station located within the university's grounds.

Hydrogen powered vehicles

As far as transport is concerned, in a vehicle powered by electricity generated by an on-board hydrogen fuel cell, the only waste product emitted by the exhaust is harmless water vapour. Insofar as the manufacture of hydrogen involves the consumption of energy, the gas must be regarded as a carrier of energy rather than a source of it. Where electrolysis produces the hydrogen it is important that the electrical power originates from a non-carbon-producing source, such as a wind turbine.

In a letter to The Times (28 April 2008), Professor Rob Thring calculated that every car in Britain could be run on fuel cells using hydrogen from electrolysers powered by electricity from wind turbines, if ‘only’ 20,000 turbines were built. To put this in perspective, the UK has about 20,000 high voltage pylons. A principal drawback with these turbines is that it is not always windy. This is not a serious disadvantage if they are part of the hydrogen cycle, however, because unlike electricity, hydrogen can be stored and drawn at will. Rather than all thesewind turbines, I would prefer carbon-free energy supplied by less than a dozenof the new 1.6GW nuclear stations, which could perform the same function but lessintrusively.

The Birmingham scientists would be the first to admit that there are technical problems to be solved, but these fade into insignificance compared to the obstacles to obtaining international agreement on radical action to combat global warming.

Greenhouse gas emission

To illustrate, the UK generates about two per cent of the world’s greenhouse gases, so whatever steps we take can only have a marginal influence on global climate changes. Burning coal without sequestering the carbon dioxide emissions is most damaging as far as global warming isconcerned.

Nevertheless, in the period up to 2030, the USA is expected to construct, every month, the equivalent of a new 500MW coal-fired electricity station, while China will plan the construction of a large coal-fired power station every week. Indeed, in 2006, Scientific American calculated that if all these stations have a 60-year lifespan, the new generating plants in operation by 2030 would introduce into the atmosphere as much carbon dioxide during their lifetimes as was released by all the coal burned since the dawn of the industrial revolution. Evidently time is not on our side.

Further information

Chemical Engineering Department, the University of Birmingham

'Hydrogen, not biofuels, will power the future', The Times, 28 April 2008