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Comment by jasoncartwright | Hacker News Reader

>As I write this, the UK's intensity is 326 gCO₂eq/kWh, which is nothing to write home about.

Yeah, that's true, but you've taken a reading there at the worst time of day whilst it's not windy here. The other week we achieved the second lowest carbon intensity daily average ever (the lowest was in the summer last year).

Here's what the UK carbon intensity of electricity looks over a larger time scale (8yrs) https://electricityproduction.uk/carbon-intensity/?t=8y

Also, I don't believe that (whilst I love their visualisation) the Electricity Map UK gCO2/kWh measurement is very accurate. For starters, they don't appear to separate out different types of gas plants. The CO2 intensity of OCGT is 3x that of CCGT.

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Electricity Map is using 490 gCO2/kWh for UK gas, which is pretty much exclusively CCGT. This does seem high. The US average [1] seems to be around 418 gCO2/kWh whereas electricityinfo.org [2] seems to be using 394 gCO2/kWh and so gets a rather different value for current UK carbon intensity.

[1] https://www.eia.gov/tools/faqs/faq.php?id=74&t=11 [2] http://electricityinfo.org/real-time-british-electricity-sup...

> For starters, they don't appear to separate out different types of gas plants. The CO2 intensity of OCGT is 3x that of CCGT.

What makes you believe that? They list CCGT and OCGT separately, it's just that (unless every site I've seen about UK energy is wrong) there isn't a lot of OCGT generation in the UK because it's uncompetitive. Which would be for the same reason it increases CO2 intensity - it's inefficient to run. In the UK market it doesn't make up for that enough by being cheap to build and fast to spin up so as to create an incentive to build a lot more.

Not that I have any stake in the accuracy of electricitymap's statistics, but I don't think there's any point seperating out OCGT from CCGT generation. OCGT makes up a negligible share of realised generation (and indeed, even generation capacity is rather limited). The few plants that are still in operation need very specific market conditions to make their operation worthwhile, especially considering that 3x CO2 output means 3X fuel input, and 3x fuel costs. It's better to think of them as grid-stability mechanisms, like diesel generators, or the industrial load-shedding schemes.

Looks like their average during peak season 8 years ago was 550 and now it is around 200. That is an impressive drop

> The CO2 intensity of OCGT is 3x that of CCGT.

The efficiency of OCGT is about 40%. The efficiency of CCGT is about 60%. So, no, the CO2 intensity is not "3x".

My apologies, you're correct. I use 394 gCO2/kWh for CCGT and 651 gCO2/kW for OCGT in my calculations

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