Heliophage


Energy and electricity are not the same
January 7, 2012, 6:29 pm
Filed under: Interventions in the carbon/climate crisis

Lord knows this shouldn’t need saying, but it does. Earlier this week I received a press release from a UK green electricity company claiming that for a couple of months last year wind power had provided 10% of the UK’s energy needs. Today, The Guardian prints a Reuters report saying that during the post-christmas gales it was 12.2%. The same report ended up at Scientific American and quite a lot of other places. In both cases the  numbers came from the UK Renewable site (Reuters’ source here) with which I have no beef. But both had taken figures explicitly about electricity consumption and claimed that they reflected total energy use.

I really don’t understand how it is that people sitting in warm homes or offices with cars going past their windows think that electricity and energy are the same thing. But here are the numbers. Page 59 of the latest International Energy Agency figures (pdf) gives TPES (total primary energy supply) for the UK as 197mtoe (million tons of oil equivalent). Converting that into the sort of units electricity is measured in (the IEA provides a handy converter here) you get 2290TWh. In the same table on page 56 you will see that UK net electricity consumption given as 350TWh. So only about 15% of the UK TPES is consumed as electricity.

The two numbers are not quite equivalent. The share of TPES devoted to generating electricity is larger than the amount of electricity consumed, because more than half the energy content of coal and gas burned at power stations doesn’t actually get turned into electricity. So though I don’t have figures to hand on how much of the TPES is devoted to electricity generation, its probably around twice that much, which fits with my sense that about 30-40% of energy supply is used for generating electricity.

Anyway, everyone makes mistakes, but this one is both egregious, distressingly common and genuinely harmful. When people hear that Britain’s rather paltry wind fleet is generating 10% of its energy they are seriously misled about the scale of the decarbonisation challenge. In good months, as far as I can see, wind currently provides a bit less than half of the country’s renewable electricity, which means about 5% of its consumed electricity, which means less than 1% of its TPES.

The renewables company corrected its press release as soon as I pointed out the error. I trust that the Reuters and its subscribers will too.

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