Last October's landslide at Derrybrien, in south Galway, was the worst possible advertisement for Ireland's embryonic wind power industry. Certainly, the surreal images of mushy peat and soil flowing downhill like cold lava will not easily be forgotten.
The landslide rolled down some 1,500 metres through Coillte forestry in the Slieve Aughty mountains before stopping at an unoccupied house. "It was like an earthquake - trees were bobbing up and down like corks on water," Thomas Conroy, a Coillte contractor, said at the time.
Investigations started straight away, but the cause was clear. As confirmed by a report published earlier this month, site clearance and development works for a 60-megawatt wind farm consisting of 71 turbines had destabilised the soft ground beneath the blanket bog.
The ESB subsidiary, Hibernian Wind Power, which is developing the €60 million wind farm, accepted the findings of the report by Applied Ground Engineering Consultants. Its managing director, Brian Ryan, said they would have "implications for all wind farm developments in the State".
Some of the report's 17 recommendations are obvious - for example, that a geological consultant should be employed full-time to supervise site development and construction work on relatively unstable blanket bog sites.
This is one of the "lessons" Hibernian intends to take on board.
Local residents represented by the Derrybrien Landslide Action Group were furious this week that Galway County Council was permitting the company to resume work on the 870-acre site, subject to conditions. They want work to be suspended until an independent investigation is carried out.
The Derrybrien case calls into question the preference of wind farm developers for upland blanket bog. Though wind speeds are obviously stronger in elevated locations, the logistics of getting up there, of preparing sites, providing access roads and excavating foundations carry risks.
Developers have also drawn flak for choosing sites which are either within or close to Special Areas of Conservation (SACs) under the EU Habitats Directive. And though Irish SACs still have "candidate" status, because of governmental slowness in designating them, they can't simply be ignored.
The Irish Peatland Conservation Council (IPCC) appealed to An Bord Pleanála against Leitrim County Council's decision to approve plans by Airtricity for a 25-turbine wind farm on upland blanket bog, claiming it would threaten an important SAC on Boleybrack Mountain.
Caroline Hurley, the IPCC's conservation officer, described Boleybrack as "one of the most intact, wild expanses of upland blanket bog left in Ireland" and asked why the National Parks and Wildlife Service was not opposing the Airtricity scheme and a smaller 12-turbine scheme by Stuart Hydro Ltd.
Airtricity said it had intended to develop a much larger wind farm at Boleybrack. However, after consulting the National Parks and Wildlife Service, it had agreed to reduce the number of turbines to 25. The project had was appealed to An Bord Pleanála by three parties, including the IPCC.
The record of the appeals board on wind farms has been patchy. Where local authorities have refused permission on amenity or other grounds, these decisions have been reversed by the board in nearly a third of all cases because of its "tendency to give greater weight to national policies".
As more wind farms are installed, fewer people appear to be overly concerned about their visual impact - other than in particularly scenic locations. Neither have fears been confirmed that the noise they make is "like the moans from a mass crucifixion", as one Welsh critic put it.
A survey published by Sustainable Energy Ireland last November found that people living near wind farms do not, in general, consider they have had any adverse impact on the scenic beauty and wildlife of the area while more than 60 per cent favour further developments.
Wind power technology is improving all the time. The average turbine size in Germany, which has taken to wind in a big way, went from 470 kilowatts in 1995 to 1.4 megawatts in 2002. Enercon, its leading wind power company, is testing a 4.5-mw turbine which could produce electricity for 15,000 people.
GE Wind Energy, Airtricity's partner in the offshore Arklow Banks project, has developed a turbine for particularly windy sites with a rotor blade diameter of 104 metres (343 ft) and a tower height of between 98m and 140m. To put that in perspective, the latter would be taller than Dublin's Spire.
Offshore is increasingly seen as the way to go, even though the development costs are much higher - some €2.5 million per megawatt installed, compared to €1.1 million on land. But they offer the advantages of higher wind speeds, fewer environmental restrictions and, of course, economies of scale.