Conditions at the 190-metre high Crater Hill site, monitored since 2005, include an average annual wind speed of around 8 m/s at hub height. It is one of the few ice-free areas on Ross Island, although the volcanic scoria and half-metre of permafrost do not make the site an easy one to work on, notes Meridian. While the team has a full 24 hours of daylight to work in, the construction season only wlasts from November to February. All logistics have required careful planning. There is no easy way to get replacements when working thousands of miles away from suppliers and engineering facilities.
Lack of water for concrete production has proved one of the more unusual challenges, requiring the use of pre-fabricated foundations built in New Zealand. Eight 13-tonne pre-cast concrete blocks, bolted together via a "steel spider", provide the base for each turbine. So far, cold conditions and high winds have slowed work, but the team from Meridian and New Zealand's Antarctica base expect to complete the foundations this season. A 4.16 kV feeder cable to take the electricity from McMurdo to Scott Base is also being laid.
Next season the team plans to install and commission the three Enercon turbines, which will have a combined capacity of almost 1 MW. Two slightly smaller versions of the turbine have been in operation at Australia's Mawson Station since 2003, proving they can cope with the fierce conditions. In October, the Mawson turbines generated almost 130,000 kWh, representing a saving of 15,000 litres of fuel. The turbines are specially modified, using low-temperature steel, additional insulation, anti-snow seals, and providing for internal tower access.
Due to the very dry Antarctic environment, de-icing equipment is not required. As local temperatures can drop to almost minus 60¡C, the shaft is connected directly to the generator, reducing stress and wear, as well as the need for maintenance all year round. Instead, maintenance will be done annually during the warmer summer season.
When commissioned in February 2010, the Ross Island turbines are expected to cut diesel use by 11%, reducing the amount of fuel needing to be transported there by almost half a million litres. The three turbines are expected to reach a net capacity factor of 37.4%. In addition, an annual saving of 1242 tonnes of carbon dioxide emission is expected.