Preliminary data from the Cambridge Centre for Alternative Finance indicates that hydropower has overtaken natural gas as the single largest energy source powering the Bitcoin mining network. If confirmed, the shift would change how the industry’s electricity profile is commonly understood, although Cambridge has stated that the figures remain preliminary and subject to revision.

The finding comes from Cambridge’s continuing work to track the Bitcoin network’s electricity consumption and the power sources behind it through the Cambridge Bitcoin Electricity Consumption Index. The dataset ranks the energy sources used in Bitcoin mining, and the preliminary reading places hydropower ahead of natural gas at the top of that list.

Cambridge has not presented the numbers as final. The centre records changes to its estimates in a published change log, and preliminary readings can be revised as additional data is incorporated and methodology or inputs are updated.

What the preliminary ranking shows

The main change in the latest preliminary reading is the ranking of Bitcoin mining’s largest power source. According to Cambridge’s current data, hydropower now ranks above natural gas as the leading source of electricity used by the network.

The caveat is significant: the estimates are provisional. A future update to the Cambridge index could alter the ranking if new data changes the balance between hydropower, natural gas and other electricity sources used by miners.

Why the leading energy source matters

The largest power source in Bitcoin mining is more than a technical detail. It is often used in public discussions about the network’s environmental profile and the composition of the electricity that supports mining activity.

A hydropower lead, if it remains in place after revisions, would put a renewable source at the front of Bitcoin’s energy mix rather than a fossil fuel. That distinction is central to a long-running debate over Bitcoin mining’s environmental footprint and whether the network is becoming more dependent on renewables or remains closely tied to fossil-fuel generation.

The distinction also matters because an electricity mix ranking is not the same as a full emissions assessment. Emissions depend on how much electricity miners use, where that electricity is generated and the carbon intensity of the power sources involved, which is why a change in the leading source does not by itself quantify the network’s climate impact.

Power sourcing is also a major operational issue for miners. Electricity is one of the largest variables affecting mining economics, and the sector has faced sustained financial pressure, including cases such as Poolin filing for Chapter 11. The source, availability and cost of power can influence whether mining operations remain profitable.

What the data does not yet establish

The current Cambridge reading does not settle broader questions about emissions reductions, geographic concentration or long-term changes in the Bitcoin mining energy mix. Those conclusions would require confirmed time-series data that the preliminary ranking does not yet provide.

A ranking that places hydropower first today could change in a later update. Cambridge’s future revisions may clarify whether hydropower’s lead reflects a durable change in mining’s electricity profile or a temporary reordering within the dataset.

For now, the finding is best understood as a preliminary signal from the Cambridge index rather than a confirmed milestone in Bitcoin mining’s energy mix.