A grand idea, but how realistic is it?

A grand idea, but how realistic is it?

Financial Times, 8 September 2004 -

The hydrogen economy: the European Union, the US and other governments are planning to spend billions of dollars on the advancement of this clean fuel. Clive Cookson reports.

After all the hype about the hydrogen economy as a magic solution to fuel shortages and global warming, a reaction was inevitable. And sure enough, there is now a steady fizz of reports and articles warning that people and politicians are expecting too much, too soon from hydrogen.

Yes, hydrogen sounds like the ultimate clean fuel, with water vapour the only by-product as it releases energy. Hydrogen can either be burned like a conventional hydrocarbon or, more promisingly, used to generate electricity directly in a fuel cell.

However, gigantic technical and logistical problems lie in the way of creating a global hydrogen economy. Even Iceland, which aims to take advantage of its unique geothermal resources - and its geographical isolation - to become the first national hydrogen economy, does not expect to wean itself off fossil fuels in less than 40 years.

The US, the EU and other governments have promised to spend billions of dollars on hydrogen fuel programmes. Their proponents say research and development on such a large scale is justified by the need to find alternatives to fossil hydrocarbon fuels, before shortages and/or serious climate change force the world to make drastic cuts in their consumption.

Others argue, however, that excessive emphasis on hydrogen will draw financial and scientific resources away from other technologies - such as hybrid petrol-electric cars and fuel cells running on natural gas - that would lead to much more efficient use of fossil fuels. They believe these developments could reduce emissions of carbon dioxide, the main greenhouse gas, more effectively and quickly than a grandiose but impractical plan to dispense altogether with hydrocarbons.

The first problem with hydrogen is that, although it is the most abundant chemical element in the universe, on earth it only occurs combined with other elements such as carbon.

There are two main ways to generate free hydrogen. The cheapest method today is to strip it off natural gas molecules with steam in apparatus called a "reformer". But this process itself generates carbon dioxide - in which case, sceptics ask, why not use the natural gas directly as a fuel?

The other - and ultimately more promising - route is to "split" water into its two constituents, hydrogen and oxygen, with an electric current. Again, if the electricity itself is ultimately generated by burning fossil fuels, there may be little point in doing so. But if the electricity is generated by non-fossil sources, the whole process will add no carbon dioxide to the atmosphere.

Although the Icelandic initiative will use geothermal power to produce hydrogen by splitting water, the world as a whole does not have non-fossil sources of electricity that can do the job on a scale or at a cost that would make hydrogen even remotely competitive with natural gas.

More futuristic ideas are being investigated. These range from a new generation of high-temperature nuclear plants that could split water thermally, to genetically-engineered microbes that could make hydrogen from water through a biological process. However, it is hard to see any of these coming to fruition for several decades.

After the hydrogen has been made, there are still huge obstacles to overcome in transporting, storing and using it. Storage is a challenge because hydrogen gas is so light: a given volume contains much less energy, even when compressed under high pressure, than any hydrocarbon fuel.

Liquid hydrogen is probably not practical for a mass market application such as road transport because it has to be kept below -253ÂºC, and other storage proposals that rely on absorbing hydrogen in other materials are unproven.

Distribution is another potential nightmare. If hydrogen is to replace petrol and diesel as a fuel for vehicles, it either will have to be generated locally at thousands of individual filling stations or generated centrally and distributed through pipes and/or tankers. Whichever approach is chosen, the required infrastructure will cost several hundred billion dollars to build.

"We are facing a 'chicken and egg' problem that will be difficult to overcome," says Michael Ramage, who led a recent study of the hydrogen economy for the US National Academy of Sciences (NAS). "Who will invest in the manufacture of fuel cell vehicles if there is no widespread hydrogen supply? At the same time, who will invest in facilities to produce hydrogen if there are not enough fuel cell vehicles to create sufficient income for the hydrogen producers?"

Even the well publicised renaissance in fuel cells - discovered in the 1830s but little used, other than in spacecraft, until very recently - will have to go a lot further before they are cheap and reliable enough to power mass market cars. Indeed, some motor industry experts believe that a hydrogen-burning version of the petrol-driven internal combustion engine may do the job better than fuel cells.

This year's NAS report concludes that, even in the best case scenario, the transition to a hydrogen economy in the US would take "many decades" and any reductions in oil imports and carbon dioxide emissions during the next 25 years would be minor.

"Our study suggests that while hydrogen is a potential long-term energy approach, the government should keep a balanced portfolio of research and development efforts to enhance US energy efficiency and develop alternative energy sources," says Mr Ramage, former head of Exxon research and engineering.

In other words, do not put too many eggs in the hydrogen basket.