The new 2160MW natural gas power station in Pembroke boosted its green credentials during the construction phase through the use of low-carbon Phoenix Portland fly-ash cement (BS EN 197-1 CEM II/B-V 42,5N) produced just 90 miles away which incorporated fly-ash from its sister power station.
Operator RWE npower worked closely with Aberthaw-based CelticAsh and Lafarge Tarmac’s Cement Works at East Aberthaw during the plant’s construction phase to overcome a number of tricky technical challenges, whilst saving around a quarter of the normal CO2 emissions associated with making the cement.
Allan Everett, general manager of CelticAsh, said Pembroke was in an almost unique position of being able to use high quality ash from its sister power station to replace around a quarter of the clinker in the cement to meet its structural concrete requirements and the need for good long-term durability.
“The use of such local ‘ingredients’ effectively produced a special low-carbon Welsh cement,” he says.
“Each of the five turbine halls was poured in a single session lasting 10 hours. The ash content of the cement (typically around 30 per cent) significantly reduces its heat of hydration, which in turn reduces the risk of thermal cracking in large concrete pours.”
He says that Lafarge Tarmac met the challenge of a lack of readymix sites nearby by building a state-of-the-art mobile concrete plant especially for the project. “This was set up on location at Pembroke to reduce the number of vehicles needed, whilst lowering CO2 emissions further – more wins for the environment.”
Pembroke Power Station is one of the most efficient in Europe, and is supplied by natural gas through a new pipeline that runs deep under Milford Haven and connects the power station to the National Grid’s National Gas Transmission System. 22,500 tonnes of Phoenix Portland fly-ash cement was used, incorporating 7000t of CelticAsh fly-ash.