It is the great paradox of renewable energy that technologies designed to reduce carbon emissions and so mitigate climate change can be destructive to their immediate environment. Those contradictions could not be more stark than in the proposal for 181 wind turbines across Barvas Moor on the Isle of Lewis. It would have been the largest onshore wind farm in Europe, built on an area of peat bog which had the European Union's highest level of protection for both habitat and birds. The adverse effects on the special protection area of the Lewis peatlands was the reason for the decision by Scotland's energy minister, Jim Mather, to reject the plans by Lewis Wind Power. This decision is welcome but must be put into the context of the SNP's renewable energy policy. Mr Mather made a point of not ruling out other onshore wind farms in the Western Isles. This is significant because there are two other wind farm applications in the south of Lewis and an inquiry will open next month into the 53-turbine scheme at Eisgein. One of the main objectors, the Royal Society for the Protection of Birds, has already said that its principal concern was the cumulative effect of three wind farms on the island.

The council, Comhairle nan Eilean Siar, backed the Barvas proposal largely because it promised 400 jobs during construction and the prospect of investment at the former oil fabrication yard at Arnish, which now makes steel towers for turbines. There is no doubt that the Western Isles need jobs if the population decline is to be halted. The council's vice-convener believes the government has got the balance between the environment and the socio-economic benefits of the wind farm "completely out of kilter", but in this particular environment it is an even more difficult balance than usual. Tourism is the biggest industry in the Western Isles and wildlife is one of the main attractions. Visitors who thrill to the call of the red-throated diver and whose spirits will soar at the prospect of the golden eagles continuing to wheel above the ancient landscape without colliding with turbine blades also support the crofters who offer B&B, the hotels and shops.

It was the scale of Lewis Wind Power's proposals in a fragile eco- system which made rejection the right outcome, but in other more populous parts of the country the growing number of smaller-scale developments intruding on areas which are precious because they are open landscape between built-up areas is generating controversy. With 27 wind farm and eight hydro projects before the Scottish Government's energy consents unit and more at the discussion stage, a coherent policy is overdue. Alex Salmond has taken many opportunities to talk of Scotland's natural resources as a powerhouse for green energy, but there is an urgent need for detail - for example, connecting to the grid, whether more hydro schemes can be built without detriment to the environment and how to fill the potential energy gap after Scotland's present nuclear power stations reach the end of their lives.

The right decision was reached for Barvas Moor, but only after six years of polarising local opinion. That cannot be repeated throughout the country if the targets to produce 31% of electricity demand from renewable sources by 2011 and 50% by 2020 are to be met.