Key points:
1. CCAF model overestimated by 16.8% in 2021, and 10.2% in 2022. This is in alignment with my previous research where I suggested earlier this year that their model was overestimating by 20.6%
https://batcoinz.com/improving-our-estimate-of-bitcoin-energy-consumption/
2. Clear evidence that GreenpeaceUSA's claim that Bitcoin used "as much energy as Sweden" was incorrect, and was based on CCAF historical overstatements
3. CCAF say explicitly that based on new estimates: Bitcoin energy use is "comparable to ... tumble dryers in the US"
4. CCAF have not yet revised their emissions estimates beyond the direct impact of revised energy consumption.
5. They are still overestimating emissions by 67.6% due to emission intensity calculations that are both overestimated, and out-of-date (have not been updated since Jan 2022). This is an improvement upon the previous estimates which were out 106% (
https://batcoinz.com/accurately-dynamically-calculating-bitcoin-network-emissions/)
6. Re: 5 above, CCAF acknowledge: "Emerging concepts we have yet to consider but could reasonably be expected to lower our emission estimates include the potential to mitigate methane emissions by mining operations collocating next to oil fields and utilising otherwise flared natural gas, using and subsequently sealing orphaned gas wells, and mitigating methane emissions from landfills, but also extend to other novel concepts such as waste-heat recovery.
7. While there is still much work to do on the emissions estimate side, CCAF should be praised for updating their model, which is now very much in line with what those with up-to-date industry data such as Luxor, Marathon, Blockware, Coinmetrics, the Bitcoin Mining council and I have been using for some time. They also deserve praise for their transparency about historical overestimations, and transparency about the factors not yet considered that could "reasonably be expected to lower our emission estimates". I agree: 57 M t CO2e/year will reduce to a figure more like my model which says 34 Mt CO2e/year once the impact of offgrid miners and methane mitigation is factored in.
8. Key details from the CCAF report
Full report:
https://jbs.cam.ac.uk/2023/bitcoin-electricity-consumption/
"The backbone of our previous CBECI methodology was the assumption that every profitable hardware model released less than 5 years ago equally fuelled the total network hashrate. This, however, led to a disproportionally large number of older devices compared to newer ones in our assumed hardware distribution"
…we decided to thoroughly re-examine the ASIC mining hardware distribution generated by our previous CBECI model and cross-check the results against other metrics from publicly available data. We found that more recently released equipment appeared to be underrepresented, and equipment nearing the end of its lifecycle was overrepresented.
…we will explore the consequences of these changes when applied retroactively.
The first and most noticeable discrepancy appears in 2021, where our previous CBECI model estimated an electricity consumption of 104.0 TWh, 15.0 TWh higher than the revised model estimate (89.0 TWh).
The 2022 estimate was adjusted downward by 9.8 TWh, from 105.3 TWh to 95.5 TWh. To put this in perspective, the revised figure is comparable to the electricity consumption of countries like Belgium (83 TWh) or the Netherlands (113 TWh), [31] the energy use of tumble dryers in the US (108 TWh)
Emerging concepts we have yet to consider but could reasonably be expected to lower our emission estimates include the potential to mitigate methane emissions by mining operations collocating next to oil fields and utilising otherwise flared natural gas, [32] using and subsequently sealing orphaned gas wells, [33] and mitigating methane emissions from landfills, [34] but also extend to other novel concepts such as waste-heat recovery. [35]
https://twitter.com/DSBatten/status/1697213161894748483
