In a control room surrounded by the Welsh countryside, Simon Willis watches as engineers fire up the kiln, ratcheting it up to 1,400C to break down limestone to make cement for Britain’s planned construction boom.

Bone meal, wood, cardboard and other waste have helped replace coal in the fuel mix. But the Padeswood cement plant still belches about 650,000 tonnes of carbon dioxide each year, mostly from the limestone as it breaks down, putting it on the wrong side of the nation’s push to limit climate change. 

To tackle these emissions, Padeswood has another plan: extract the carbon dioxide out of the flue gas, pipe the emissions about 60km northwards, and bury it all more than a kilometre offshore below the seabed in Liverpool Bay for perpetuity.