Cambridge University study says Bitcoin mining sustainable energy use hit 52.4%, exceeding Elon Musk’s target to resume Tesla BTC payments

A new Cambridge University study found that the Bitcoin mining industry's sustainable energy sources have grown to 52.4% over the past few years — up from previous estimates of 37.6% in 2022.The Cambridge Digital Mining Industry Report, issued Monday by the Cambridge Centre for Alternative Finance (CCAF) at Cambridge Judge Business School, said 9.8% of sustainable energy use is from nuclear and 42.6% from renewables such as wind and hydropower.The report also found that natural gas has replaced coal as the single largest energy source used in Bitcoin mining. Natural gas use has increased to 38.2% from 25% in 2022, while coal has fallen to 8.9% from 36.6% over the same period.The findings come from a survey by the CCAF of 49 mining firms, including 41% publicly listed, with operations across 23 countries — including Bitfarms, CleanSpark, Hut 8, IREN, MARA and Riot. Covering about 48% of global Bitcoin mining activity by hashrate, the study estimates the network's annual electricity consumption at 138 TWh, or roughly 0.5% of global usage, and its emissions at 39.8 megatonnes of CO2 equivalent, despite a 24% year-over-year improvement in hardware efficiency.Miners also reported that 86.9% of decommissioned hardware is resold, repurposed or recycled, with the study estimating Bitcoin mining generated about 2.3 kilotonnes of e-waste in 2024.Among other data, the study underscored North America's dominant role in Bitcoin mining, with the U.S. accounting for 75.4% of reported activity and Canada following at 7.1%, though there is also emerging activity in South America and the Middle East, alongside ongoing operations in Northern Europe. It also estimated that electricity makes up over 80% of miners' operating expenses, with median reported costs of $45 per MWh for power, and $55.50 per MWh including all expenses. Furthermore, the report also highlighted evidence of Bitcoin miners serving as flexible loads that can help grid operators in times of high demand, curtailing 888 GWh of electrical load in 2023 alone.However, as the industry faces increasing challenges, many mining firms are diversifying into areas like HPC/AI or adopting innovative energy strategies, such as flared gas utilization and waste-heat recovery, to improve efficiency and find new revenue streams, it noted.Evolving perceptions of Bitcoin mining's environmental impactThe CCAF report follows a recent Harvard-led study on Bitcoin mining's environmental impact, slammed by energy experts as "deeply flawed." That study, published in Nature Communications, argues that Bitcoin mining in the U.S. significantly contributes to harmful air pollution, with 1.9 million Americans exposed to increased levels of fine particulate matter between mid-2022 and mid-2023. The researchers tracked 34 of the largest U.S. Bitcoin mines, claiming they consumed 32.3 TWh of electricity — 33% more than the city of Los Angeles — 85% of which from fossil fuels.In response, Daniel Batten, an expert in energy and environmental sustainability, particularly in the context of Bitcoin mining, told The Block the study is "deeply flawed," suggesting that it "looks like the conclusion was 'Bitcoin mining must look bad' then went looking to find data and methodologies that supported that.""This article is a throwback to an early generation of academic work on Bitcoin that uses flawed methodologies and cherry-picked data — an approach that was debunked by Sai & Vranken in 2023," Batten said. "It should not be taken seriously by policymakers and regulators."The Digital Assets Research Institute (DARI) also published a formal rebuttal of the Harvard-led paper, finding similar issues to Batten.Batten argues there is not just an issue with this Harvard-led paper, referencing five other negative academic studies on Bitcoin mining since 2022, often receiving formal rebuttals over similar issues such as the use of non-contemporary datasets, discredited sources, citing news reports over academic articles and selection bias."Despite [Bitcoin mining's] impressive growth, the rapid transformation has outpaced transparent, empirical data collection, often leaving policymakers, researchers and the public reliant on outdated assumptions or anecdotal information," the CCAF report authors stated on Monday."This [CCAF] report directly addresses a persistent data gap by relying on direct practitioner insights rather than abstractions," Alexander Neumueller, Research Lead, Digital Assets Energy and Climate Impact at the CCAF, added. "By offering a granular perspective based on data covering nearly half the global mining activity, we aim to anchor the debate on robust, transparent evidence and inform grounded policy discussions about this rapidly evolving industry."However, the authors stressed the new study is only a starting point, with more research needed on issues like methane mitigation, heat reuse and broader social impacts such as job creation. Ongoing data collection will be essential to support informed policymaking that balances innovation with environmental responsibility, the CCAF said.Will Tesla allow bitcoin for payments again?After Tesla CEO Elon Musk appeared to embrace Bitcoin in 2021, stating that "In retrospect, it was inevitable," the electric vehicle manufacturer made headlines by disclosing it had purchased $1.5 billion worth of bitcoin as part of its treasury management policy. Tesla currently still holds 11,509 BTC, worth around $1.1 billion, according to Bitcoin Treasuries data, with an average cost basis of $33,539 and an unrealized gain of 183.4%.A month later, Musk declared that Tesla would accept bitcoin as a payment method for its electric vehicles in its U.S. store, later rolling out globally. "Tesla is using only internal and open source software and operates Bitcoin nodes directly," Musk said at the time. "Bitcoin paid to Tesla will be retained as bitcoin, not converted to fiat currency." However, just two months later, amid a bitcoin price slump, Musk announced that Tesla would suspend vehicle purchases using bitcoin due to concerns over the environmental impact of mining. "We are concerned about the rapidly increasing use of fossil fuels for Bitcoin mining and transactions, especially coal, which has the worst emissions of any fuel," Musk said in a statement.The company said it would hold on to its remaining bitcoin holdings and would use it for transactions again as soon as mining transitioned to more sustainable energy sources. "When there’s confirmation of reasonable (~50%) clean energy usage by miners with a positive future trend, Tesla will resume allowing Bitcoin transactions," Musk subsequently clarified.Though largely quiet on Bitcoin since, Musk said in a January X Takeover podcast appearance, "I do think there's some merit in Bitcoin, and maybe some other cryptos, and I've sort of got a soft spot for Dogecoin because I like dogs and memes."Nevertheless, Tesla is yet to announce any resumption of bitcoin payment options, and it remains to be seen if it will do so. The Block reached out to Tesla for comment.Disclaimer: The Block is an independent media outlet that delivers news, research, and data. As of November 2023, Foresight Ventures is a majority investor of The Block. Foresight Ventures invests in other companies in the crypto space. Crypto exchange Bitget is an anchor LP for Foresight Ventures. The Block continues to operate independently to deliver objective, impactful, and timely information about the crypto industry. Here are our current financial disclosures.© 2025 The Block. All Rights Reserved. This article is provided for informational purposes only. It is not offered or intended to be used as legal, tax, investment, financial, or other advice.