No, UK Electricity will NOT be zero-carbon by 2025

Recently, in Spring 2019, the UK celebrated its first week without coal power generation since 1882. Without doubt this represents an important milestone and marker in our transition to cleaner energy.

In 2012 coal made up 43% of UK generation. That was down to 5.5% last year and so far this year it’s <3%. From a peak carbon intensity of 510 gCO2/kWh in 2007, this year that number is down to less than 250. That’s great progress, achieved not just by the reduction in coal usage, but by big growth in renewables (wind, in particular) too. Those renewables haven’t replaced coal on their own though – gas generation, half as carbon-intensive as coal, has increased from 26% to over 40% in that same 2012-to-present-day period. (If you want an excellent site for seeing these data graphed, I can recommend



A number of these no-coal-for-a-week articles have carried a quote along the lines of this one (e.g. from The Guardian’s story on the subject):

“Fintan Slye, the director of National Grid ESO, said he believed Britain’s electricity system could be run with zero carbon as soon as 2025.”

In too many blog posts and articles I’ve read, this quote has been lazily morphed into statements along the lines of “Britain’s electricity system could be zero-carbon by 2025”.

Spoiler alert: it won’t be. We aren’t going to remove >40% of gas generation within just six years. (Remember the share of gas generation has been growing, not shrinking).

Look at that quote again. It says Britain’s electricity system “could be run with” zero carbon. That is absolutely not the same as “could be” zero carbon.

So let’s be absolutely clear, National Grid are NOT predicting a zero carbon generation mix by 2025; certainly not all the time (which statements about “a zero-carbon electricity system” seem designed to imply). They are simply saying that, within that timeframe, they will have operational and market/transactional systems in place to be capable of managing such a mix – whenever it happens.

Don’t take my word for it – take theirs. Here’s the link to their “Zero carbon operation of Great Britain’s electricity system by 2025” page (which links to a downloadable document on the subject). And here’s the key quote from the latter:

“Our ambition is that, by 2025, we will have transformed the operation of the electricty system such that we can operate it safely and securely at zero carbon whenever there is sufficient renewable generation on-line and available to meet the total national load.”

Remember, National Grid’s job is to manage the generation mix available to them. It’s out of their hands how quickly that will evolve.

So, could there be times when Britain’s electricity mix is zero-carbon by 2025? Certainly.

For example, looking at the last seven days, when demand has been low gas has been as little as 16% of the mix and <4GW (at 5am on May 5th). As more renewables come online (offshore wind in particular), it’s not a great leap to imagine gas being squeezed out completely on windy nights. And National Grid will be able to handle this and the lights will stay on. Which is excellent news!

But does that mean “Britain’s electricity system will be zero-carbon by 2025”? No.


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