ACCOUNTANT Peter Brown makes a convincing financial case for liquefied petroleum gas (LPG) fuelled cars (Letters, September 10).

However, the fact is that, like all fossil fuels, LPG contributes to global warming by releasing into the atmosphere CO2 locked up millions of years ago in the fossilised remains of plants and animals from which all such fuels are derived.

Biodiesel, recently featured in your pages, has no such drawback. Derived from vegetable oils, the CO2 it contains was removed by oil-producing plants from our present atmosphere and will be returned again on combustion, in a short cycle that makes it CO2 neutral.

It also has lower emissions of carbon particulates and sulphur and slightly more efficient combustion. Much biodiesel is a recycled product made by reclaiming used cooking oil.

While motor vehicle use remains widespread, a more logical and sustainable fuel-related tax incentive would therefore be one favouring use of biodiesel. This may, however, need to be directed entirely at fuel duty rather than vehicle purchase because diesel- engined vehicles will run on mineral and biodiesel.

It is difficult to understand why the Government resists introducing such an incentive.

Equally difficult to understand are short-sighted Government plans to release for building farmland that is needed to produce more crops such as oilseed rape, capable of contributing sustainable biological solutions to many of our fuel and materials problems.

Is there some negative, behind-the-scenes influence from the petroleum and building industries here?

Barry Potter,

Knapton Lane,

York.

Updated: 10:03 Tuesday, September 20, 2005