Wind farms, cleaner than fossil fuel-burning power stations, are considered blots on the landscape by some people.

While they might be good for the world, they aren't necessarily good in your backyard.

This was the argument which helped end the Mt Cass wind farm project in North Canterbury.

The Forest and Bird wildlife protection group, after successfully opposing the wind farm this month alongside other groups, said it supported wind power but not on that particular ridge as it was unique and so important.

But with demand for electricity rising and international targets for greenhouse gas emissions falling, those decisions are about to become much harder to make. Society will have to balance the immediate impact on the environment with the wider issues of climate change.

New Zealand electricity consumption is rising at between 1 and 2 per cent each year and new sources of generation are needed.

The Environment Ministry believes 20 per cent of electricity could come from wind in the future, compared with 2.5 per cent now.

Few environmental groups would want to see a new coal or gas fired power station.

Dams for hydro-generation, which like wind does not emit greenhouse gases, arguably have more irreversible effects on the environment than wind turbines.

But the public appetite for black-outs is nil.

And while the Mt Cass development would have altered a unique limestone ridge to create a relatively small amount of electricity, other cases will be more finely balanced.

Two proposals before boards of inquiry this month - Project Hayes in central Otago and Hauauru ma raki north of Raglan - could add enough generation capacity to power all the homes Wellington, Dunedin and Christchurch.

But for every planned farm there is a local group that passionately believes it will destroy an important landscape.

Project Hayes has attracted opposition from ex-All Black Anton Oliver, poet Brian Turner and concerned locals. As more wind farm projects crop up, it will be more difficult for groups such as Forest and Bird and the Green Party to juggle genuine local concerns with their support for renewable energy.

Anti-Auckland rumblings are already being heard from the windy hills around Palmerston North, where many locals oppose Mighty River Power's proposed Turitea wind farm.

Opponents say the turbines would not be needed if the big city was more economical with its power usage.