I pointed this out to him via email and he acknowledged that he had mistakenly used data for total emissions vs the electric power sector. He promised to issue a correction but I never saw it.
It appears that Ember gets their data from the IEA. Based on my research and data available at the EIA, https://www.eia.gov/electricity/data/state/ , the numbers differ slightly from those presented here, for NM where I live, carbon intensity numbers for 2001 are 944 vs 765 and 489 vs 434 for 2021.
I don't know for sure why the carbon intensity figures from Ember are slightly different from the EIA. I suspect that Ember takes the electricity production by source data from EIA, but that they have standard emissions factors that they then use to calculate emissions and carbon intensity.
Ember also produces a global electricity dataset, and for this they will probably use constant intensity figures for different sources (probably with several categories for different types of coal). I expect they apply the same intensity figures to the US state data to keep it consistent.
I previously noticed quite a difference between the Ember intensity figures for the UK vs. the figures published by the government and I think this was partly down to differences in the emissions factor for biomass.
Again, not 100% sure but it's my best guess for why there are small differences.
I think you’re probably right about the difference being due to coal. The numbers seem to be converging as the mix gets cleaner. I will compare the mix when I have time.
I did a spot check this morning for the US average for 2001 and 2021 and the percentage of generation for particular source are within a few tenths of percent between the database at the EIA and the numbers presented here. So the main difference must be due to specific emissions of sources like coal.
An interesting aside is wondering why there isn't better consensus between these two agencies on specific emissions. It seems like the answer matters when it comes to determining global total CO2 emissions and related projections for getting to net zero.
I also noticed that the numbers cited by Hannah from Ember are different from the US EIA state values. For Virginia, carbon intensity numbers from EIA and Ember, respectively, are 635 and 510 gm CO2/kWh for 2001, and 294 and 329 gm CO2/kWh for 2021. I'd be interested in knowing how IEA's tally differs from the US EIA's.
In any case, the graphical presentation is terrific!
As for the Harry Stevens article in the Washington Post, I had also spotted the error in the article (viz., using total energy emissions rather than electricity emissions as the basis for carbon intensity estimates) and sent him an email on it, but haven't heard back in terms of correcting it.
Vermont looks great (slide 5) - until you realize production fell sharply when they prematurely closed Vermont Yankee (and made up for it with hydro from Quebec and nuclear from NH). Essential to include data on production volume imho.
Nice charting. Seems I should branch out from Excel.
I think the renewable electricity biz involves a bit of double counting. Many wind and solar farms still sell renewable energy "certificates." So Amazon or GM may say a warehouse in Missouri or factory in Kentucky uses 100% renewable electricity, but that renewable power is really just serving the customers in Oklahoma or Iowa. I know you specify "generation" but folks may overestimate how much renewable power is contributing nationwide by hearing both numbers.
Also, IMHO, the gas industry and gas power plants get a pass by using only onsite CO2 emissions to determine the GHG intensity of power. Upstream and midstream methane venting and leakage add 10% to 50% depending on the calculation of methane-fueled generation's CO2e and assumptions and attribution of loss fractions. Big error bars. Of course coal mines vent some methane too.
Great work! Would it be possible to add "nuclear" to the "Share of electricity by source across US states" map on slide 4?
Sorry, not sure why that column was missing from the visualisation.
I've added it now on slide 4.
Thank you!
Great, thanks!
Hannah,
This is good stuff. I appreciate the link to Ember.
A couple months ago, Harry Stevens at the Washington Post had tried to do something similar but he had grabbed the wrong dataset from the EIA, the US Energy Information Administration, https://www.washingtonpost.com/climate-environment/interactive/2023/clean-energy-electricity-sources/?itid=ap_harrystevens .
I pointed this out to him via email and he acknowledged that he had mistakenly used data for total emissions vs the electric power sector. He promised to issue a correction but I never saw it.
It appears that Ember gets their data from the IEA. Based on my research and data available at the EIA, https://www.eia.gov/electricity/data/state/ , the numbers differ slightly from those presented here, for NM where I live, carbon intensity numbers for 2001 are 944 vs 765 and 489 vs 434 for 2021.
I'm not sure why the difference???
Just FYI and Thanks,
Dean
Thanks, Dean.
I don't know for sure why the carbon intensity figures from Ember are slightly different from the EIA. I suspect that Ember takes the electricity production by source data from EIA, but that they have standard emissions factors that they then use to calculate emissions and carbon intensity.
Ember also produces a global electricity dataset, and for this they will probably use constant intensity figures for different sources (probably with several categories for different types of coal). I expect they apply the same intensity figures to the US state data to keep it consistent.
I previously noticed quite a difference between the Ember intensity figures for the UK vs. the figures published by the government and I think this was partly down to differences in the emissions factor for biomass.
Again, not 100% sure but it's my best guess for why there are small differences.
I think you’re probably right about the difference being due to coal. The numbers seem to be converging as the mix gets cleaner. I will compare the mix when I have time.
I did a spot check this morning for the US average for 2001 and 2021 and the percentage of generation for particular source are within a few tenths of percent between the database at the EIA and the numbers presented here. So the main difference must be due to specific emissions of sources like coal.
An interesting aside is wondering why there isn't better consensus between these two agencies on specific emissions. It seems like the answer matters when it comes to determining global total CO2 emissions and related projections for getting to net zero.
I also noticed that the numbers cited by Hannah from Ember are different from the US EIA state values. For Virginia, carbon intensity numbers from EIA and Ember, respectively, are 635 and 510 gm CO2/kWh for 2001, and 294 and 329 gm CO2/kWh for 2021. I'd be interested in knowing how IEA's tally differs from the US EIA's.
In any case, the graphical presentation is terrific!
As for the Harry Stevens article in the Washington Post, I had also spotted the error in the article (viz., using total energy emissions rather than electricity emissions as the basis for carbon intensity estimates) and sent him an email on it, but haven't heard back in terms of correcting it.
Thanks, Randy
FYI. I kept working with Harry and he has posted an updated version, https://www.washingtonpost.com/climate-environment/interactive/2023/clean-energy-electricity-sources/?itid=sf_climate_climate-lab_article_list . I tried to get him to use kg/MWh but to no avail. He worked the EIA to make sure he had the right database. I actually prefer their compilation files that have the same data, https://www.eia.gov/tools/faqs/faq.php?id=74&t=11&itid=lk_inline_enhanced-template - see section on State-level emissions and electricity generation by type of fuel.
Nicely done...
Thanks for putting together 😁
good job!
Is there still a case for a Vermont homeowner to put solar panels on her roof?
that figure becomes money if the products made in that state face an EU CBAM. example here: https://grid.is/@ngogerty/low-carbon-benefit-by-energy-source-g_q7rS_dShi:0t:g_sgrzA
Vermont looks great (slide 5) - until you realize production fell sharply when they prematurely closed Vermont Yankee (and made up for it with hydro from Quebec and nuclear from NH). Essential to include data on production volume imho.
Amazing work. Thank you!
Nice charting. Seems I should branch out from Excel.
I think the renewable electricity biz involves a bit of double counting. Many wind and solar farms still sell renewable energy "certificates." So Amazon or GM may say a warehouse in Missouri or factory in Kentucky uses 100% renewable electricity, but that renewable power is really just serving the customers in Oklahoma or Iowa. I know you specify "generation" but folks may overestimate how much renewable power is contributing nationwide by hearing both numbers.
Also, IMHO, the gas industry and gas power plants get a pass by using only onsite CO2 emissions to determine the GHG intensity of power. Upstream and midstream methane venting and leakage add 10% to 50% depending on the calculation of methane-fueled generation's CO2e and assumptions and attribution of loss fractions. Big error bars. Of course coal mines vent some methane too.