ABOUT a third of energy used in the UK is obtained from gas – for electricity generation, industrial processing, heating and cooking.

The continuing reduction in North Sea reserves and the need to replace much coal-fired electricity generation by gas means that even if the ambitious targets for renewable energy are met, gas will still be required in substantial quantities for many years to come.

Without development of onshore reserves, although there are ample global reserves of gas, imports will have to increase, with all that that implies for security of supply.

The drilling of deep boreholes in North Yorkshire has been carried out over several decades for coal and other mineral deposits and for gas exploration and extraction.

The measures taken to minimise the environmental impact at the surface are well established, as also is the engineering design and control of drilling required to ensure that surface waters and aquifers are not contaminated during and after the cessation of drilling operations.

The adverse effects of input water with additives (about one per cent) used to carry out fracturing and any associated seismic effects are unlikely to be significant. But the fracking return water, which will contain suspended and dissolved materials from the strata, will require treatment for re-use or treatment for consented discharge.

The argument for the exploitation of unconventional gas (shale gas and coal-bed gas) should be based on an objective assessment of the need, environmental effects and associated current and additional controls required, rather than on emotive assumptions voiced by opponents.

David Randon, Blue Slates Close, Wheldrake, York.