Edward Jolly questioned the reduction in the carbon intensity of electricity (Letters, BSj 11/05) – but, as Ted King pointed out, there has indeed been a substantial reduction.

This has been mainly due to the replacement of coal-fired steam turbine generators by gas-fired combined-cycle plant. These not only have higher thermal efficiencies, but also use a lower-carbon fuel source.

One consequence of this is that it may already be more carbon-efficient to burn gas in a power station and then use the electricity to drive a heat pump than it is to burn the gas in a condensing boiler.

There is one caveat, though. Not all power stations are equal in terms of generating carbon emissions. Analysis that we were involved in (‘Interactions between electricity-saving measures and carbon emissions from power generation in England and Wales energy policy’) showed that reducing the demand for electricity is much more effective in reducing carbon emissions, for the simple reason that as demand drops, it is usually the more carbon intensive power stations (eg coal) that are shut down first. The use of an average carbon intensity for UK electricity generation doesn’t truly reflect this saving.

Roger Hitchin, Christine Pout, for and on behalf of BRE

Source

Building Sustainable Design