A new report from Cambridge University reveals that sustainable energy now powers over half of global Bitcoin mining.
The Cambridge Digital Mining Industry Report, published in April 2025 by the Cambridge Centre for Alternative Finance, shows a jump from 37.6% green energy use in 2022 to 52.4% today.
The study surveyed 49 mining firms across 23 countries, covering nearly half of the network’s computing power.
Sustainability Gains
The report breaks down clean energy sources: 42.6% comes from renewables like wind and hydropower, while nuclear supplies 9.8%.
This rise in green power use marks a steady move away from coal and oil, helping to curb the carbon footprint of one of the world’s most energy-hungry industries.
Shift in Energy Sources
Natural gas has overtaken coal as the top fuel for Bitcoin mining. Its share climbed from 25% in 2022 to 38.2% today, while coal usage plunged from 36.6% to 8.9%. This shift reflects miners’ search for lower-cost and more reliable supplies, even as they work to improve their environmental record.
Cambridge researchers estimate that Bitcoin mining consumed 138 terawatt-hours of electricity in the past year, about 0.5% of global demand.
They also note a 24% boost in hardware efficiency since 2022. When rigs retire, 86.9% are sold on, repurposed, or recycled, generating around 2.3 kilotonnes of electronic waste in 2024.
Decline in Illicit Use
Alongside energy trends, the study highlights a fall in Bitcoin’s use for illegal activities. Illicit transfers peaked at 0.63% of transactions in 2023 but dropped back to 0.14% in 2024, one of the lowest rates recorded.
Yet even at that low share, illicit transfers still totalled an estimated $40.9 billion last year, pointing to ongoing challenges for regulators and law enforcement.
Global Footprint
North America leads in mining activity, with the U.S. responsible for 75.4% of surveyed hashrate and Canada 7.1%. South America and the Middle East show growing operations, while Northern Europe maintains its established presence.
Miners report that power costs dominate their budgets, which is over 80% of expenses, with median rates of $45 per megawatt-hour for electricity alone and $55.50 per megawatt-hour when all costs are included.
Public Health Impact
A companion study from Harvard’s T.H. Chan School of Public Health, led by Dr. Francesca Dominici, warns that fine particulate pollution from U.S. mining sites travels far beyond their locations.
Published in Nature Communications, the research shows these particles can cross state lines, harming air quality and public health in distant communities.
As Bitcoin mining shifts toward cleaner fuels and wields more efficient hardware, it must still reckon with air-quality and regulatory threats. The new findings underscore progress in sustainability but also highlight the sector’s persistent environmental and social impacts.
Moving forward, miners, policymakers, and health experts will need to work together to balance innovation with the public good.