From Prof Jeffrey Sachs.

Sir, Mr James Page's dismissal of coal in place of Middle East oil (Letters, December 29) wrongly assumes that we are stuck with current coal-burning technologies. In fact, whether we use coal or Middle East petroleum to meet our energy needs, and whether we use these fuels to produce gasoline or to produce hydrogen as the energy carrier, we will need to introduce new carbon capture-and-disposal technologies to limit decisively the rise of atmospheric carbon due to our use of carbon fuels.

One possible strategy, for example, would be to use coal to produce hydrogen for use in cars and to capture the carbon emissions (and other pollutants from coal combustion) at the hydrogen production plants. There are other promising technological options that should also be considered. With a proper lead time and effort, clean coal (or tar sands and oil shales) with carbon capture and disposal is within economic and technological reach.

Jeffrey D. Sachs, Director, Earth Institute, Columbia University, New York, NY 10027, US