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, while saving around a quarter of the normal CO2 emissions associated with making the cement.
Allan Everett, general manager of CelticAsh, said Pembroke was in the rare 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 said. “Each of the five turbine halls was poured in a single session lasting 10 hours. The ash content of the cement (typically around 30%) significantly reduces its heat of hydration, which in turn reduces the risk of thermal cracking in large concrete pours.”
He said that Lafarge Tarmac [as the company is now called] met the challenge of a lack of readymix sites nearby by building a 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 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. Some 22,500 tonnes of Phoenix Portland fly-ash cement was used, incorporating 7,000 tonnes of CelticAsh fly-ash.
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