¿ìè¶ÌÊÓƵ

RAPID spray evaporation (RSE) provides a way of turning seawater into fresh water at a fraction of the cost of conventional desalination methods. Developed by AquaSonics International of Atlanta, Georgia (¿ìè¶ÌÊÓƵ, 12 July, p 15), the process interested me as it is widely believed that access to clean drinking water – or, rather, the lack of it – could become a cause of wars.

I showed the ¿ìè¶ÌÊÓƵ report to Hilary Benn, an overseas development minister, and asked for his view. Benn said that the challenge to increase the supply of water is not purely technological: other desalination technologies have been promoted as a way to meet the anticipated rising demand for fresh water. And the cost of desalination, through the use of alternative and novel technologies such as RSE, has fallen dramatically in recent years.

However, he added that there are often other limiting factors, requiring a more integrated approach to managing water. Local communities may fail to join in the planning and management of water supplies; reliable energy sources and spares may be unavailable; water sources may be inefficiently used and local workforces inadequately trained to operate and maintain the required equipment, he said.

So be it, but I recommend anyone wanting more information on this important matter to peruse the Department for International Development’s Addressing the Water Crisis: Healthier and more productive lives for poor people.

WILL rising fuel prices make the clean green hydrogen dream a reality? It’s a question that ¿ìè¶ÌÊÓƵ asked recently (16 August, p 3). Tony McNulty, the Department for Transport’s green minister, tells me he is cautious. Most current estimates, he says, suggest that renewably produced hydrogen would be much more expensive than petrol or diesel at the pump, assuming comparable levels of fuel duty. For hydrogen to become cost-competitive to the consumer, one or more of a number of considerations would have to come into play:

• the price of crude oil would have to increase dramatically

• the cost of producing and distributing renewably produced hydrogen would have to come down significantly as new technologies are developed or through economies of scale

• hydrogen would have to be taxed very lightly, or not at all

• hydrogen vehicles would have to become more efficient relative to internal combustion engines;

• the price of fuel cell vehicles would need to fall dramatically.

Devotees of hydrogen, of whom I am one, should not give up hope. The government is to assess the implications of large-scale use of hydrogen and biofuels in transport systems. A report is due early next year. Meanwhile a dedicated website – – has been set up to provide stakeholders with details of the assessment, and to invite comments on drafts of the report as they develop.