Heat Reuse Mining means using heat produced by Bitcoin mining. Some of it is directed to a place where it is needed, such as a heating system. The benefit is replacing part of another heat supply; the mining machine still consumes electricity.
Imagine Anna heats a workshop with an electric resistance heater. She places an ASIC beside it: a specialised machine searching for the solutions needed to add Bitcoin blocks. A block is a group of transactions prepared for addition to Bitcoin’s public history. The machine repeatedly runs calculations, looking for a result that meets the network’s requirement for adding such a block. The ASIC also consumes electricity and warms its surroundings. Anna can use that heat to replace some heating. Almost all the electricity becomes heat; no extra energy is created. A possible Bitcoin reward is the financial result of mining, not a second energy output. Calling it waste heat does not mean the electricity or equipment was free. [1]
The idea is easy to picture in a warm workshop. In a house with water-based heating, heat must travel from the machine to another circuit. A heat exchanger can transfer it between separate air or liquid streams. What matters is the temperature of the air or liquid actually collected, not just the hot chip. Return-water temperature, flow rate and losses along the way matter too. Underfloor heating needs different conditions from a system requiring very hot water. A heat pump can raise the recovered heat to the temperature the heating circuit needs. Its electricity use must be included in the accounts too. [2]
Take a simple example: Anna’s machine draws a constant 3 kW for ten hours. It consumes 30 kWh of electricity. Kilowatts describe demand at a moment; kilowatt-hours describe energy consumed over time. If 70 % of that energy reaches a needed heating use without an additional heat pump, the building uses 21 kWh of heat. The rest may escape in transit or arise when the building does not need it. These are illustrative figures, not an efficiency promise. Pumps, fans and other auxiliaries must be included according to the measurement boundary; the same consumption must not be counted twice. [1] [2]
When its heat is used directly, an ASIC is physically closer to an electric resistance heater. A heat pump works differently: electricity powers equipment that moves additional heat from the surroundings into the building. At an illustrative COP 3, it delivers 3 kWh of heat for 1 kWh of electricity. COP is the coefficient of performance, the ratio of delivered heat to electricity consumed; it varies with temperatures and operating conditions. This creates no energy from nothing. Mining income may lower Anna’s net monetary costs, but does not increase the ASIC’s physical heating performance. Cheaper operation and lower consumption are different questions. [3]
In winter, Anna may need most of the delivered heat. In summer, the workshop is warm without the machine and no longer needs space heating. Water heating may provide another use, but that demand is not unlimited either. If the ASIC keeps running and heat goes outdoors, that part of operation replaces no heating. Storage may defer use, but has limited capacity and heat losses; a small tank alone cannot bridge an entire season. Annual accounting must therefore follow when heat is produced and actually taken, including cooling during periods without a heat customer. [4]
One freezing morning, the machine may fail or expensive electricity may stop mining. The need for heat does not disappear. Anna must know how long storage can cover demand and when another heat source takes over. In a larger project, an agreement between miner and heat customer also allocates this responsibility. Backup, maintenance and controls belong within the project. A duty to supply heat may also limit quick shutdowns under Demand Response Mining, which adjusts electricity demand to prices or grid needs. [5]
In its update for June 2024, MARA reported launching a 2 MW pilot in Finland whose heat would serve a local community. This illustrates a concrete application: connecting computing operations to a network distributing heat to buildings. The company’s announcement alone does not establish annual MWh delivered or independently verified emissions savings. Equipment capacity and population size do not show that the machine alone heats every home throughout the year. That conclusion would require actual deliveries, downtime and the share of other heat sources. [6]
Anna ultimately compares a full year of operation with heating the workshop without mining. Costs include the machine, heating modifications, all electricity within the accounting boundary, servicing and backup. Alongside delivered heat and BTC revenue, she considers noise. Savings from displaced heating and a payment for selling that same heat must not automatically be added as two benefits to the same participant. The climate result depends on the electricity source and the heat source actually displaced. Heat reuse can make sense, but by itself guarantees neither profit nor lower emissions nor zero consumption. [2] [5]
For the clearest picture, read this entry together with Mining, ASIC Miner, Stranded Energy Mining, Demand Response Mining, Bitcoin. The reverse links also lead from Immersion Cooling, Hydro Cooling, Braiins Publishing, Thermodynamic Money.