Pressure Technologies created some excitement today as its equipment allowed the first gas produced from waste water to be injected directly into the National Gas Grid.The Sheffield-based oil and gas kit supplier's subsidiary Chesterfield BioGas (CBG) pumped the organically produced gas from Thames Water's waste water treatment site in Didcot, Oxfordshire.Chesterfield's equipment allows dirty biogas generated in the waste water treatment process to be upgraded to 97% pure methane (biomethane).Centrica is buying the gas to sell to its domestic users."Pressure Technologies hopes to see significant growth in the CBG business, which supplies upgrading systems, biomethane to grid packages and compressed natural gas refuelling stations," it said in a statement.Energy and Climate Change Secretary, Chris Huhne, said it was "an historic day" for the companies involved, and Pressure chief John Hayward called it "a defining moment for the UK energy market".