One of the things that makes me mad is people who should know better mixing up 'energy' and 'electricity'. Of course electricity is a form of energy, but one that is very carbon intensive, but still doesn't contribute as many carbon emissions as gas and oil used for space heating and transport.

For example, in the Observer on Sunday, environment editor Juliette Jowit wrote:

"...'feed-in tariffs' which allow homeowners to sell spare electricity to the national grid to help repay their costs would ensure that people opted for the best technology, which also includes solar panels and ground source heat pumps."

OK, Juliette (adopts exasperated-teacher tone), a feed in tariff is a mechanism to allow householders to sell electricity to the grid. A ground source heat pump consumes electricity to produce heat. So it can't benefit from a feed in tariff. Have you ever tried heating an electrical wire? Would it light even the most efficient lightbulb? (flings chalk at cringing editor)

I'm jesting (of course), but this is really important when discussing the future of our energy supply. There's a large contingent who shout "We need nuclear!", but to effectively cut emissions this way, we would need to convert all our domestic/commercial heating and transport to run on electricity. Which would of course be extraordinarily expensive in terms of capital costs (new power stations, heaters, vehicles) and running costs.

Currently nuclear produces 20% of our electricity supply and those plants are due for replacement - to deliver say 33% of our total energy supply (as one prominent energy expert suggests), this would require a very large number of new nuclear power stations and we would have to find a very large amount of nuclear fuel which of course is finite like gas, oil and coal.

I didn't mean this to turn into an anti-nuclear rant, but we are risking basing this and other similarly important decisions on opinions that are flung about, deliberately or otherwise, without a true understanding of what we are talking about.

Labels: electricity, energy, heat

Like the rest of the carbon accounting/footprinting industry, we've always used DEFRA's published figure for the carbon intensity of electricity of 0.43 kgCO2 per kWh. DEFRA has now released figures showing that the actual carbon intensity of the UK's electricity is about 0.53 kgCO2 per kWh. Some members of the Association for Environmentally Conscious Building think the figure should be even higher at about 1.0 kgCO2 per kWh.

Why is this an issue? Well if you are comparing, say a Ground Source Heat Pump to a gas fired condensing boiler, and if the Heat Pump is working at a co-efficient of performance of 3.5 (that's 3.5 units of heat out for each unit of electricity in), then, under the new DEFRA figures, the GSHP will produce 70% of the carbon dioxide of the boiler, whereas under the old figures it would be just 58%. That's quite a difference and could seriously affect a decision on whether to spend the extra cash required for the Heat Pump.

So why did we use 0.43? Well, we always try to source our data from reliable, published and transparent sources and this was the industry accepted figure. DEFRA is going to continue to use 0.43 until 2010, but from now on we'll be using 0.53 and be keeping an eye on the debate over 1.0.

Labels: carbon footprint, carbon intensity, defra, electricity