At 07:30 UTC on July 2, 2019, Cambridge Judge Business School posted a short notice1. The Cambridge Centre for Alternative Finance, or CCAF, had launched the Cambridge Bitcoin Electricity Consumption Index. Called CBECI for short, the index gave a live estimate of the electricity Bitcoin's network uses in a year. The notice put the current annual estimate at 50 terawatt-hours, or TWh.
The notice credited the centre as a whole. CCAF's own credits go further. “The original design was developed and implemented by Michel Rauchs, Anton Dek, and Apolline Blandin,” its About page says3. The BBC, CNBC and Decrypt have all reported the index's figures since568. Its mining map tracked China's 2021 mining ban month by month9. Later data put China back on the map, and a 2023 model change cut the index's past power estimates2.
How the index counts
The index starts from machines. Its model uses the efficiency and economic life of more than 60 mining machines, the launch notice said1. Those machines turn electricity into hashes, the guesses that win new blocks. Bitcoin's total guessing speed across the network is its hashrate.
BBC reported at launch that the model assumes one average electricity price, $0.05 per kilowatt-hour5. From those inputs, the tool estimates the power in use at any moment. Coin Metrics, a data firm, later described the core rule. “Cambridge's power draw estimate is based on evenly weighting marginally-profitable hardware models released in the last five years,” its 2023 report says12.
Both sides, in their own words
Can the index see what miners hide?
“This is not something that will change in the future unless the Bitcoin price is going to significantly go down”
“Cambridge's power draw estimate is based on evenly weighting marginally-profitable hardware models released in the last five years”
Who got the credit in 2019
Launch coverage credited the university. “Bitcoin uses as much energy as the whole of Switzerland, a new online tool from the University of Cambridge shows,” BBC's July 3, 2019 story began5. The story quoted Rauchs, calling him "the tool's co-creator". It gave more space to Alex de Vries of PwC, who had built a similar tool. Dek and Blandin went unnamed.
Crowdfund Insider gave his title. Its July 5, 2019 story said the index “was announced by Michel Rauchs, the Cryptocurrency and Blockchain Lead at CCAF”4. By then the index read 60.45 TWh, JD Alois wrote. The launch notice of July 2, 2019 had said 50 TWh1.
A map of who mines where
The launch notice promised a second phase. In it, “an interactive geographical map of mining facilities globally will be added to the website,” the notice said1. The map went live on May 6, 2020, Decrypt's Liam Frost reported6. CCAF built it from location data from three mining pools: BTC.com, Poolin and ViaBTC. Those pools made up about 37 percent of Bitcoin's hashrate over the period studied, Frost wrote.
CCAF's data begin in September 2019, when Mainland China held 75.53 percent of hashrate9. The United States held 4.06 percent. China still held 34.25 percent in June 2021. For July 2021, the map put China at 0 percent.
Mainland China's average monthly share of Bitcoin's hashrate on CCAF's mining map, in percent
- July and August 2021, after China's ban
- Other months on CCAF's mining map
- Height: Share of hashrate, %
Read the chart as a table
| Item | Value |
|---|---|
| Sep 2019 | 75.53% |
| Oct 2019 | 74.78% |
| Nov 2019 | 72.33% |
| Dec 2019 | 73.46% |
| Jan 2020 | 72.69% |
| Feb 2020 | 72.98% |
| Mar 2020 | 67.06% |
| Apr 2020 | 64.81% |
| May 2020 | 59.48% |
| Jun 2020 | 64.67% |
| Jul 2020 | 66.86% |
| Aug 2020 | 66.86% |
| Sep 2020 | 67.12% |
| Oct 2020 | 67.38% |
| Nov 2020 | 55.58% |
| Dec 2020 | 53.27% |
| Jan 2021 | 53.30% |
| Feb 2021 | 51.58% |
| Mar 2021 | 49.06% |
| Apr 2021 | 46.04% |
| May 2021 | 43.98% |
| Jun 2021 | 34.25% |
| Jul 2021 | 0.00% |
| Aug 2021 | 0.00% |
| Sep 2021 | 22.29% |
| Oct 2021 | 18.09% |
| Nov 2021 | 18.12% |
| Dec 2021 | 19.14% |
| Jan 2022 | 21.11% |
China at 0 percent
Rauchs announced China's drop himself. He wrote CCAF's update of October 13, 2021, as its Digital Assets Lead7. “New data reported by partnering mining pools BTC.com, Poolin, ViaBTC, and Foundry confirms this observation: declared mining operations in mainland China have effectively dropped to zero,” he wrote.
His post also flagged a weak spot. The shares for Ireland and Germany likely came from miners "rerouting through those countries via VPNs or proxy servers," Rauchs wrote7. A VPN routes traffic through another country, so a miner's location reads as that country.
CNBC ran the news on October 13, 2021, too. MacKenzie Sigalos dated a 35.4 percent United States share to July8. CCAF's file puts 35.12 percent in July and 35.4 percent in August9. Rauchs's own post gives 35.4 percent for data "to the end of August 2021"7.
China comes back
The next update reversed the drop. On May 17, 2022, CCAF posted data for September 2021 to January 202210. China's share jumped to 22.29 percent in September 20219. China stood at 21.11 percent in January 2022. The United States led with 37.84 percent.
CCAF questioned its own numbers. “A comeback of this magnitude within the period of one month would seem unlikely given physical constraints, as it takes time to find existing or build new non-traceable hosting facilities at that scale,” its post said10. The post pointed to miners who “conceal their location by using virtual private networks (VPN) or other proxy services”. Rauchs had named that same weak spot in his post of October 13, 20217.
Did Chinese miners ever stop? The map leaves that open. Its change log lists the last mining map update on May 17, 2022, with data through January 20222.
The recount
CCAF changed its power model on August 31, 20232. The old model weighted every profitable machine equally. Its replacement also weighs each model's release date and the date it went into service.
The change cut past estimates. In CCAF's v1.2.0 download, archived on March 20, 2023, 2021 stands at 104.89 TWh15. Its v1.5.0 download, archived on March 27, 2024, puts 2021 at 89.00 TWh16. The 2022 figure fell from 107.65 TWh to 95.53 TWh.
Cambridge cut its 2021 Bitcoin electricity estimate from 104.9 to 89.0 TWh in August 2023
Yearly estimates before and after Cambridge's Aug. 31, 2023 model change, in terawatt-hours (TWh)
- Model before Aug. 2023
- Model after Aug. 2023
Read the chart as a table
| Item | Model before Aug. 2023 | Model after Aug. 2023 |
|---|---|---|
| 2017 | 14.4 TWh | 12.9 TWh |
| 2018 | 45.4 TWh | 43.3 TWh |
| 2019 | 57.1 TWh | 54.6 TWh |
| 2020 | 68.5 TWh | 67.1 TWh |
| 2021 | 104.9 TWh | 89.0 TWh |
| 2022 | 107.7 TWh | 95.5 TWh |
CCAF's report on the change gave its own round numbers. “The first and most noticeable discrepancy appears in 2021, where our previous CBECI model estimated an electricity consumption of 104 terawatt-hours (TWh), 15.0 TWh higher than the revised model estimate (89.0 TWh),” the report read, as quoted by Decrypt's Andrew Throuvalas14. Alexander Neumueller has led the index since November 20213. “This led to overestimating the number of older hardware and underestimating the proportion of newer hardware,” he told Decrypt.
The case for the index
Rauchs argued that the index measures something built into Bitcoin. "It is really by design that Bitcoin consumes that much electricity," he told BBC's Tech Tent podcast in February 202111. “This is not something that will change in the future unless the Bitcoin price is going to significantly go down,” Rauchs added. BBC put the index's estimate then at about 121.36 TWh a year.
He also read the 2021 map as good news for Bitcoin. “The effect of the Chinese crackdown is an increased geographic distribution of hashrate across the world, which can be considered a positive development for network security and the decentralised principles of Bitcoin,” Rauchs wrote7. Even the index's critic gives it credit. Coin Metrics wrote that CCAF's approach is "widely deemed the gold standard"12.
The case against
Coin Metrics published its own estimate in June 2023, and Decrypt reported it on June 1313. Karim Helmy was its lead author. His team estimated each mining machine's market share from nonce patterns, the numbers miners cycle through while guessing12. The report put the network's power draw at about 13.4 gigawatts in May 2023, against Cambridge's 15.9 gigawatts. That is about 16 percent less, the report says.
Then the report took aim at Cambridge's method. “This is a relatively blunt tool: it’s deeply exposed to temporary fluctuations in bitcoin’s price, relies on the assumption of a uniform network-wide electricity price, and isn’t particularly accurate during bull markets,” Coin Metrics wrote12. After the August 2023 revision, Helmy told Decrypt: "The new methodology continues to overestimate energy consumption in bull markets."14
The record holds a twist. CCAF's About page thanks its critic by name. “The Coin Metrics team, in particular Karim Helmy and Lucas Nuzzi, have provided robust input data and useful guidance on data sourcing and methodology,” the page says3.
What to watch
Two records will show which side holds up. The first is the gap between CCAF's estimate and Coin Metrics' hardware count in the next bull market1214. A mining map update past January 2022 is the second2. CCAF's latest index version, v1.8.0, went live on July 9, 2026, with six new mining machines in its list. In the v1.5.0 download, the index's estimate for 2023 stands at 121.13 TWh16.
Sources
- Cambridge Judge Business School, "Cambridge Bitcoin Electricity Consumption Index (CBECI)," July 2, 2019, https://www.jbs.cam.ac.uk/2019/cambridge-bitcoin-electricity-consumption-index-cbeci/
- Cambridge Centre for Alternative Finance, "CBECI: Change Log," read Oct. 13, 2026, https://ccaf.io/cbnsi/cbeci/change_log
- Cambridge Centre for Alternative Finance, "About CBECI," read Oct. 13, 2026, https://ccaf.io/cbnsi/about/cbeci
- JD Alois, "Cambridge Centre for Alternative Finance Launches Energy Consumption Tracker for Bitcoin," Crowdfund Insider, July 5, 2019, https://www.crowdfundinsider.com/2019/07/149173-cambridge-centre-for-alternative-finance-launches-energy-consumption-tracker-for-bitcoin/
- BBC News, "Bitcoin's energy consumption 'equals that of Switzerland'," BBC, July 3, 2019, https://www.bbc.com/news/technology-48853230
- Liam Frost, "You can now watch Bitcoin being mined around the world," Decrypt, May 6, 2020, https://decrypt.co/27879/you-can-now-watch-bitcoin-being-mined-around-the-world
- Michel Rauchs, "Geographic shift," Cambridge Judge Business School, Oct. 13, 2021, https://www.jbs.cam.ac.uk/2021/geographic-shift/
- MacKenzie Sigalos, "U.S. officially the top destination for bitcoin miners, beating out China for the first time," CNBC, Oct. 13, 2021, https://www.cnbc.com/2021/10/13/us-beats-china-as-the-number-one-destination-for-bitcoin-miners.html
- Cambridge Centre for Alternative Finance, CBECI mining map data download (mining_countries, v1.2.0), Internet Archive capture of July 7, 2022, https://web.archive.org/web/20220707140623/https://ccaf.io/cbeci/api/v1.2.0/download/mining_countries
- Cambridge Centre for Alternative Finance, "Bitcoin mining – an (un)surprising resurgence?," Cambridge Judge Business School, May 17, 2022, https://www.jbs.cam.ac.uk/2022/bitcoin-mining-new-data-reveal-a-surprising-resurgence/
- Cristina Criddle, "Bitcoin consumes 'more electricity than Argentina'," BBC, Feb. 10, 2021, https://www.bbc.com/news/technology-56012952
- Karim Helmy, Lucas Nuzzi, Alex Mead, Kyle Waters and the Coin Metrics Team, "The Signal & the Nonce: Tracing ASIC Fingerprints to Reshape Our Understanding of Bitcoin Mining," Coin Metrics, June 2023, https://5264302.fs1.hubspotusercontent-na1.net/hubfs/5264302/special-insights/coinmetrics-research_the-signal-and-the-nonce.pdf
- André Beganski, "How Much Energy Does Bitcoin Really Use? Less Than You Might Think," Decrypt, June 13, 2023, https://decrypt.co/144438/how-much-energy-does-bitcoin-really-use-less-than-you-might-think
- Andrew Throuvalas, "Cambridge Updates Bitcoin Mining Index to Reveal True Power Consumption," Decrypt, Sept. 1, 2023, https://decrypt.co/154593/cambridge-updates-bitcoin-mining-index-reveal-true-power-consumption
- Cambridge Centre for Alternative Finance, CBECI yearly data download (v1.2.0, price 0.05), Internet Archive capture of March 20, 2023, https://web.archive.org/web/20230320232759/https://ccaf.io/cbeci/api/v1.2.0/download/data/yearly?price=0.05
- Cambridge Centre for Alternative Finance, CBECI yearly data download (v1.5.0, price 0.05), Internet Archive capture of March 27, 2024, https://web.archive.org/web/20240327184549/https://ccaf.io/cbeci/api/v1.5.0/download/data/yearly?price=0.05