Thread by @ThomasGibon, As of 2020, #coal remains a major energy carrier for electricity supply [...]

Thomas Gibon

ThomasGibon

As of 2020, #coal remains a major energy carrier for electricity supply globally.

Coal is among the most #greenhousegas emission-intensive ways to supply power to the grid, we need a phase-out.

The @IPCC tells us it emits 820 g CO₂ eq./kWh on a lifecycle basis.

As of 2020, #coal remains a major energy carrier for electricity supply globally.Coal is among the most #greenhousegas emission-intensive ways to supply power to the grid, we need a phase-out.The @IPCC tells us it emits 820 g CO₂ eq./kWh on a lifecycle basis.

This value of [820 g CO₂ eq./kWh] has been widely used, for example by two of my most favorite websites on the internet: @OurWorldInData and @electricityMap.

This value of [820 g CO₂ eq./kWh] has been widely used, for example by two of my most favorite websites on the internet: @OurWorldInData and @electricityMap.

However, the scientific literature is pretty clear that coal power actually emits *at least* 1000 g CO₂ eq./kWh.

Here is a representation of all coal power plants in the world, with their lifecycle emissions ( https://doi.org/10.1038/s41893-019-0221-6):

Let's look at the emissions of individual hard coal and #lignite power plants in Germany for instance. This gives an average of 1141 and 950 g CO₂ eq./kWh, respectively.

...or 1073 weighted average for "coal".

https://energy-charts.info/charts/emissions/chart.htm?l=en&c=DE

These are up-to-date values, so how come the @IPCC gave us 820 six years ago, while we're still at >1000?

The main source cited by the IPCC is a great work of review, which lists the following sources and #lifecycle GHG values for pulverized coal power.

http://dx.doi.org/10.1016/j.ijggc.2012.12.003

Let's see the oldest source (doi:10.1016/S1750-5836(07)00024-2), which gives 795 as an average in the table.

They give 676 g CO₂/kWh in direct emissions for a pulverized coal plant, calculated as 92 g CO₂/MJ * 3.6 kWh/MJ / 49% of efficiency.

(and 849 for pulverised lignite)

Now looking at actual numbers for power plant #efficiency, 49% *really* looks high.

This @generalelectric report tells us that the global average is 34%, with potential improvement to 38%.

https://www.ge.com/reports/wp-content/themes/ge-reports/ge-power-plant/dist/pdf/GE%20Global%20Power%20Plant%20Efficiency%20Analysis.pdf

Another source also gives 49% of pulverized coal power efficiency, and another one (which refers to the 2007 paper as a primary source), etc.

I have no idea where this 49% comes from.

The best performing countries in the world are doing about 38%.

Can best available technology deliver, then?

Well only "Advanced ultra-supercritical pulverized coal" plants can reach 49% efficiency. It doesn't seem like any of them is available commercially yet (I hope I'm wrong).

https://www.sciencedirect.com/topics/engineering/pulverised-coal

SO, I feel a bit bad because I have used optimistic numbers in my own work, but:

can someone explain where "49%" comes from?

how did it end up (as a basis for 820 g CO₂ eq./kWh) in the @IPCC AR5? (instead of what should have been >1000)

To clarify, both 820 and ~1000 are on Figure 7.6, but not on Table A.II.6, which contains values that have been reused for many other works...

https://www.ipcc.ch/site/assets/uploads/2018/02/ipcc_wg3_ar5_annex-ii.pdf

Anyway, stop using 820 for coal.

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