Miners compete on one main cost: electricity. CCAF found it makes up more than 80% of their cash operating costs. That pushes them toward the cheapest power on earth, which is often power nobody else can use.
The mix (CCAF survey, data 2024)
- Sustainable: 52.4% – hydro 23.4%, wind 15.4%, nuclear 9.8%, solar 3.2%, other 0.5%.
- Fossil: 47.6% – natural gas 38.2%, coal 8.9%, oil 0.5%.
- In CCAF's 2022 estimate the sustainable share was 37.6% and coal 36.6%.
The survey covered 49 firms with about 48% of hashrate, so the figures are an estimate, not a census.
stranded energy
Because a mine is just containers of machines plus an internet link, it can move to where energy is trapped: remote hydro, surplus wind or solar, or gas at oil fields that would otherwise be flared. CCAF reports that off-grid and flare-gas projects are gaining traction.
Why flaring matters
Burning gas in a generator instead of a flare does not make it clean, but it turns a waste product into income. Methane that escapes unburned is a strong greenhouse gas, so the climate effect depends on how well each flare and engine burns. We give no general figure because none is backed by a primary source.
Takeaway
Bitcoin is not powered by "coal" or "green" energy as a rule. It is powered by the cheapest energy available, and that increasingly means energy with no other buyer.