Sealminer A4 Ultra Hydro
Bitcoin & Bitcoin Cash ASIC Miner
886TH
HASHRATE
9.45W/TH
EFFICIENCY
8373W
POWER
£862.14
EST. MONTHLY
NO PAYBACK
EST. ROI
Image: Crystal Lagoons / MintGreen · Original source. Lagoon photography supplied with the collaboration announcement; it does not establish a completed mining-heat installation.
Renewables and heat reuse
MintGreen and Crystal Lagoons describe a memorandum of understanding exploring the use of Bitcoin-mining heat to warm recreational lagoons and extend swimming seasons.
- Project at a glance
- Lagoon heating concept
- Source date and context
- Undated MOU page; reviewed September 2026
- Published financial detail
- The sources reviewed do not include full project accounts.
- Our comparison
- A UK example per 1,000 miner kWh
About 5 minutes to read
A lagoon heating proposal, not a commissioned site
MintGreen and Crystal Lagoons announced an agreement to explore using mining heat in recreational lagoons. Extending the swimming season is one of the stated aims. The source records an MOU and a proposed application; it does not identify a commissioned lagoon or publish operating results. It is best read as a design opportunity rather than an installation with a demonstrated return.
“Extend the swimming season into the colder months.”
Water stores heat but also loses it
Mining heat→isolated heat exchanger→lagoon water
A large volume of water can absorb changes in heat supply, but evaporation, wind and exposure continue to remove energy. Local weather, covers, surface area and the desired water temperature all matter. If the lagoon would otherwise close for winter, extra swimming months could create new income. That needs a separate forecast from savings on a heating bill that already exists.
What the numbers could look like in the UK
The calculation below uses assumed UK prices to show how the costs fit together. It is our example, not this project’s reported earnings. Replace the inputs with current machine estimates and the costs at your own site.
Illustrative UK calculation
Income and running costs
1,000 kWh used by miners, plus 50 kWh for pumps and fans. All amounts in pounds.
Operating contributionBefore equipment and installation costs
−£9.60−0.96p per miner kWh
This example buys electricity at 12p/kWh and values useful heat at 6p/kWh. These are assumed prices. The heat value should be replaced with the actual cost of the heating you would otherwise use, or the price a customer agrees to pay.
| Mining income | 8p per miner kWh; an assumed rate, not a live earnings estimate |
|---|---|
| Electricity | 12p/kWh × 1,050 kWh = £126.00 |
| Pool fee | 2% of gross mining income |
| Useful heat | 80% of miner electricity = 800 kWh; valued at 6p per delivered kWh |
| Other running costs | £10 per 1,000 miner kWh; an allowance to replace with your own costs |
| Costs still to add | Equipment, installation, finance, tax, depreciation, major replacements and any costs above the allowance |
The contribution is what remains from mining income and useful heat after the stated running costs. It is not net profit: the equipment and other excluded costs still have to be recovered. Pumps and fans use electricity but earn no mining income in this calculation.
| Gross income per miner kWh | Without heat value | With useful heat |
|---|---|---|
| 5p | −£87.00 | −£39.00 |
| 8p Chart example | −£57.60 | −£9.60 |
| 11p | −£28.20 | £19.80 |
- Mining income needed to cover running costs
- 8.98pper miner kWh
- Highest electricity cost or export value supported
- 11.09pper total electricity kWh
These are two ways to read the same example. Adding equipment costs or a larger maintenance allowance raises the income needed and reduces the electricity price the project can afford.
Compare heating options and work out annual costs
Use the heating system you would actually choose as the comparison. For example, a heat pump using electricity at 20p/kWh with a seasonal COP of 3 has an electricity cost of about 6.67p per kWh of heat. A resistance heater at that tariff uses 20p per kWh of heat. These are calculation examples, rather than measurements from this project.
For an annual estimate, use the miner electricity expected during hours when running makes sense. Scale the contribution by annual miner kWh divided by 1,000, then deduct fixed annual costs. Recalculate if electricity prices, mining income or usable heat change.
Simple payback is the total installed cost divided by positive annual cash contribution. There is no payback under a scenario with zero or negative contribution. The sources reviewed here do not provide the full project accounts needed to calculate an actual payback for this installation.
Decide whether the benefit is a saving or a new service
Large water volumes store heat, but evaporation and seasonal demand still determine the load.
Start with local weather, surface area, covers, desired temperature and a defensible heating baseline. Obtain a commissioning plan and define the heat-sale boundary.
Questions worth asking
- Would the lagoon otherwise be heated in those months?
- If not, is this a new service cost rather than an avoided bill?
Try your own electricity and heat figures
Compare available miners and dated earnings estimates. Include heat only where you can use it or have a customer for it.
Sources and photographs
Sources checked on 29 September 2026. Project facts and quotations come from the publications below; the UK calculations and practical assessment are The Mining Shop’s analysis. This article is based on published material, rather than a site visit.
Photographs: Crystal Lagoons / MintGreen (source).
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