One of the largest ESB power stations in the Republic is not supplying any power to the national grid due to extensive maintenance work. Emmet Oliver reports.

The thermal power station at Poolbeg in Dublin - where staff costs run at €103,000 a head - consists of three aging individual units producing 490 megawatts of power in total. Two of these will not be available to generate power again until mid-December, according to the ESB, while the largest of these units will not be supplying power for several months at least. The units date from the 1970s.

The largest of three units, which is capable of providing 250 megawatts of power to the grid, has not supplied any power since January, although the ESB insists it was available if required. The company says a major overhaul - taking up to 15 weeks - will be necessary before it can renew its licence, which ran out in September. Any overhaul is not expected to start until the new year at the earliest. In recent weeks, the two smaller units have been taken out of service for repair.

Corrosion was discovered in the boiler of one unit during a scheduled overhaul and ESB staff have taken the second unit, which is similar in design, out of service to see if it has a similar problem. A full inspection will have to take place before potential damage to the boilers can be assessed.

The company will have to pay significant overtime to staff to overhaul the plants and the national grid will be deprived of their output this winter at a time when demand is high among electricity users. Minister for Communications, Marine and Natural Resources Noel Dempsey has been informed of the situation.

About 120 staff work between the three units. While occasional overhauls are common in the electricity industry, ESB's plants have suffered from poor availability over recent years, dropping as low as 76.5 per cent three years ago. This has since recovered to 85 per cent. The ESB last night acknowledged that the Poolbeg units were "operating beyond their design life", but a spokesman denied that staff were being paid despite a significantly reduced workload. "It's quite unusual to be engaged in two major unit overhauls - one planned and one forced - at the same time, consequently all operational staff are fully engaged in this work," said a spokesman.

A combined gas cycle gas turbine plant also operates at Poolbeg, but it is operating as normal. This plant was the source of some controversy recently for the ESB when a consultants report by Deloitte said staff costs there were running at €144,00 a head, although the ESB later contested this figure.

Staff costs at the ESB's generating stations are 20 to 30 per cent higher than equivalent stations in Britain. The Deloitte report said a "significant level of overtime is being paid" which is not the practice for the vast majority of British facilities. This report said staff numbers have reduced in ESB plants over recent years, but there had not been a pro-rata drop in staffing costs. The ESB has 19 power stations. Its nearest rival, Viridian, has just one.

Despite its scale, many of the ESB power plants are very old and the company is anxious to build newer stations.

However, Mr Dempsey is reluctant to see the company entrench its position any further. He wants new entrants to come into the market.

The ESB has yet to receive permission for a new power station at Aghada, Co Kerry, for example. Mr Dempsey is looking at the idea of ESB trading some of its current sites in exchange for approval on Aghada. The Poolbeg site, near Ringsend, would been one of the more valuable sites for any new entrant because it has a connection to the national grid. However, it is possible new entrants would want to build a new station on the existing site.