Australia is in the middle of a bathhouse boom. In East Fremantle, Alchemy Saunas is converting the heritage-listed Royal George into a Roman-style wellness precinct: a 50,000-litre ice pool, a hot magnesium bathing pool, three saunas and a steam room, with doors opening before dawn. Behind the limestone arches, every venue like this shares the same ugly line item: heat. Hot pools, steam rooms and endless showers run on electric or gas boilers that burn money every hour the doors are open.
In 2026, there is a quiet argument gaining ground in the mining industry that those boilers are doing it wrong. (Alchemy is used here as an illustrative example of the industry — GreenMicroHash has no affiliation with the business.)
Heating is the bigger market, not mining
Here is the inversion most investors miss. Heating accounts for roughly 55% of global energy use, and the addressable heating market is on the order of 250 times larger than the entire Bitcoin network. Canada alone spends about 20 times the network's total energy on district heating. The share of mining currently sold as useful heat is close to zero.
A Bitcoin miner is, thermodynamically, a resistive heater that happens to earn revenue. Almost every watt that goes in comes out as heat. Run that heat into a pool loop instead of a fan exhaust and you get the same hot water a boiler would have made — except this boiler pays you back.
The proof already exists overseas. Bathhouse in New York replaced its electric boilers with hydro-cooled miners and now heats its pools and marble hammams at close to energy-neutral cost. MintGreen in Canada pipes miner heat into commercial buildings and an entire Finnish district system.
And as of this winter, the proof exists here too. Hawkesbury Brewing Co on the NSW Central Coast made national news in July for brewing beer with Bitcoin heat: sixteen miners submerged in a tub of non-conductive fluid, warming it to almost 90°C for brewing and sanitation. The system runs only on excess rooftop solar that previously earned next to nothing exported to the grid, and the miners return about $2,000 a month in Bitcoin — nearly covering the brewery's power bill. As its operations manager put it: “People often think this is a Bitcoin story, but it's really an energy story. Every brewery needs heat — we've simply found a smarter way to produce it.”
A brewery's hot-water demand looks a lot like a bathhouse's: large, daily, and non-negotiable. The model is not exotic; it just hasn't reached Australia's wellness industry yet.
How Bitcoin heat reuse works inside a bathhouse
The hardware is not a rack of screaming fans. Hydro-cooled machines like the Antminer S21 XP Hydro (473 TH/s at about 5.7 kW) are quiet, sealed units that heat a water loop to as much as 80°C — hotter than any pool needs. A rack holding four hydro units delivers roughly 22 kW of continuous thermal output, plumbed into the pool and domestic hot water loop through a standard heat exchanger, exactly where the boiler used to sit.
Control is the clever part. The best deployments run firmware that follows return temperature, not hash rate: when the loop runs hot, specific miners throttle to half speed; when it runs cold, everything overclocks. That single control decision removes the need for thermal storage or a dry cooler entirely — if a vendor sells you a system with a dry cooler as a “feature”, you are looking at a control failure marketed as a benefit.
Bathhouse hours fit the machines perfectly. A venue opening at 5am puts the array on a timer an hour before the doors, pre-warming the loop the way a boiler would — except a boiler can't be overclocked on a cold morning or turned down when the pools are already at temperature.
The cost of Bitcoin-heated pools, honestly
Take Western Australia, where a small business pays roughly 30c/kWh. One S21 XP Hydro consumes about 136 kWh a day — around AU$41 of electricity — and returns nearly all of it as pool-grade heat while earning gross mining revenue of roughly AU$28–37 a day at current hash prices.
Net that out and the heat costs about 3–10 cents per thermal kilowatt-hour, against 30 cents from the resistive boiler it replaces — a saving of 65–90% on every unit of heat, swinging with the hash price. For a four-unit array absorbing heat twelve hours a day, that is the difference between roughly AU$30,000 a year in boiler electricity and a few thousand dollars net — before counting the Bitcoin retained on the balance sheet.
Two honest caveats, because a model that hides them is worthless.
Heat pumps are real competition. A modern pool heat pump delivers heat at an effective 6–7.5c/kWh. Miner heat beats that today, but not by an order of magnitude — the gap is the mining margin, and mining is hot roughly one year in four. Anyone pitching a static forecast is guaranteed to be wrong. The correct comparison runs across a full cycle, and the correct pitch is the downside floor: even if mining revenue went to zero, the system heats water at exactly the cost of the resistive boiler you would have bought anyway. The Bitcoin is the rebate, not the business.
The venue is buying heat, not hash. Nobody selling these systems should say “hash price” to a facilities buyer. The product is a digital boiler with a lower net running cost. That framing is not spin — it is the reason the economics survive a bear market, because the heat customer pays the same regardless of what Bitcoin does.
Why this matters to investors
The strategic version of this story is bigger than one bathhouse. When MintGreen modelled a deal with the YMCA, a thousand pool sites at 400 kW each penciled out to roughly 24 exahash — enough to make a swim-centre chain the fifth-largest Bitcoin miner on Earth, by accident. Any business with a constant heat load is a latent mining company, the way McDonald's turned out to be a real estate company.
Australia is unusually well placed. Miners here already thrive where energy is stranded — gas-fired containers in the Cooper Basin, solar-fed immersion sites in South Australia. Heat reuse is the same thesis pointed at demand instead of supply: instead of chasing wasted energy in the outback, the machines move into buildings that were going to burn the energy anyway. And past the 2032 halving, when the block subsidy falls below one Bitcoin, the miners still standing will be the ones with something to sell besides hash. A heat contract is exactly that.
A hot pool in Fremantle pays for its heat whether Bitcoin is at $30k or $300k. That is the most durable revenue in mining — and today, almost nobody in Australia is collecting it.
The bathhouses are being built either way. The only question is whether their boilers keep burning money, or start earning it.
Figures are estimates at August 2026 prices and hash rates; mining revenue is volatile and should be modelled across a full market cycle.
Curious what your heat load is worth in hash? GreenMicroHash can model it.
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