Heat Reuse Mining combines mining with use of the resulting heat, for example space or water heating. Nearly all electrical input becomes heat, but only captured and needed delivery can replace another heating source.
An ASIC consumes electricity while hashing, and nearly all of it ends up as heat. Bitcoin is not another physical energy output alongside that heat. Reusing waste heat can improve the operation’s usefulness, but adds no energy and cannot recover all the electricity without losses. [Braiins — Energy and thermodynamics for Bitcoiners]
Warm air or liquid must transfer heat to a specific demand. Source and return-water temperatures, flow, heat exchanger and distance matter; chip temperature alone is insufficient. A low-temperature system may accept heat directly, while another may require a heat pump with its own consumption. [IEA — District heating opportunities]
Illustratively, equipment drawing 3 kW for ten hours consumes 30 kWh. If 70% reaches actual heat demand without an additional heat pump, 21 kWh of heat is useful. This is an example, not guaranteed efficiency; losses, auxiliary drives and heat not taken must be measured separately. [Braiins — Energy and thermodynamics for Bitcoiners] [IEA — Data centres and heat reuse assessment]
Direct conversion of electricity into heat resembles resistance heating. A heat pump also moves heat from its surroundings: at an illustrative COP of 3, it delivers 3 kWh of heat per 1 kWh of electricity. COP depends on conditions and temperatures. Mining revenue may change economics, but does not increase an ASIC’s physical heating performance. [IEA — How a heat pump works]
Heat may be needed in winter but lack a customer in summer. All year-round ASIC consumption cannot count as displaced heating. Track overlap between actual demand and operation, summer operation and cooling costs when heat is unused. Nameplate capacity alone does not determine annual savings. [IEA — Data centres and heat reuse assessment] [IEA — Data centres and local energy systems]
Failure, maintenance or expensive electricity can stop mining precisely when heat is needed. The customer needs agreed continuity and potentially backup or storage, whose costs belong in the project. A heating obligation can also limit the ability to switch mining off quickly for demand response. [IEA — Data centres and local energy systems]
In its June 2024 update, MARA announced a 2 MW Finnish pilot supplying heat to a local community. This establishes a project announcement, not automatically independent measurement of delivered MWh or an emissions balance. Installed capacity and population cannot be equated with covering every household’s year-round demand. [MARA — Finland heat-reuse pilot, June 2024]
Include mining and auxiliary electricity, investment, maintenance, noise and delivered heat. Separate BTC revenue from the price of the heat service, and compare a real alternative including its efficiency. Emissions savings depend on electricity origin and the displaced source; heat reuse alone means neither zero consumption nor zero emissions. [IEA — District heating opportunities] [IEA — Data centres and heat reuse assessment]
For the clearest picture, read this entry together with Mining, ASIC Miner, Stranded Energy Mining, Demand Response Mining. The reverse links also lead from Immersion cooling, Hydro cooling.