18 Sep 2022

Repurposing waste heat from bitcoin mining can lower heating costs and mitigate emissions

Heating is the world's largest energy end-use. Luckily, bitcoin mining generates heat that we can repurpose to heat homes or use for food production. This article explains how bitcoin mining heat recovery lowers heating costs and mitigates emissions.
Source: Arcane Research
This article is an excerpt from our research report titled "How Bitcoin Mining Can Transform the Energy Industry". The research report lays out five characteristics of bitcoin miners, which make them uniquely flexible energy consumers, and explains four energy problems bitcoin miners can help solve. This article explains one of these problems: How bitcoin mining can lower heating costs and mitigate emissions from heating. Let's get into it.
Heating is the world's largest energy end-use
Providing heating for homes, industries, and other applications is the world's largest energy end-use, accounting for almost half of global final energy consumption in 2021.Industrial processes are responsible for 51% of the energy consumed for heating, while another 46% is consumed in buildings for space and water heating and, to a lesser extent, cooking. The remainder is used in agriculture, primarily for greenhouse heating.Unsurprisingly, accounting for half of the world's energy use, heating is also the single largest source of global CO2 emissions. Heating accounts for roughly 40% of the world's CO2 emissions and 30% of CO2 equivalent emissions.
Source: Climate Watch
Fossil fuels are the most common heating energy source, accounting for about three-quarters of the energy mix. The remaining quarter is almost equally split between traditional use of biomass and modern renewables.
Source: IEA
Bitcoin mining generates a lot of heat
Have you ever wondered what happens to all the electricity that goes into the bitcoin mining machines? The electricity goes through hashboards to produce hashes that the miner sells to a mining pool that sends a continuous stream of bitcoin back. Not only does the machine generate bitcoin, but also a large amount of heat as the electricity dissipates on the resistive hashboards.
Source: Arcane Research
The bitcoin mining industry generates about 100 TWh of heat annually, which is sufficient to heat Finland. Most of the heat from bitcoin mining is not captured and repurposed but pumped out from the data centers into the air.
Bitcoin miners can repurpose their waste heat for district heating or food production
Bitcoin miners are starting to see the potential in recovering the heat. This growing focus is primarily driven by a potential for lowering costs as the industry becomes increasingly competitive, but the possibility of reducing carbon emissions is also a driving force. Unsurprisingly, most innovation happens in colder areas like Canada and Scandinavia, where heat is more valuable than in hotter bitcoin mining hubs like Texas.Disposing heat is the biggest engineering challenge in mining, which is why the first industrial mining facilities were built in cold environments. Miners can utilize two different technologies to cool down their machines. The most common is air cooling. Immersion cooling is a new method in which the machine is fully submerged in a thermally conductive liquid with greater insulating properties than ordinary air. It's much more expensive to build an immersion cooling system than a traditional air-cooling system, but it also provides superior cooling capabilities.When repurposing heat, a miner should ideally use immersion cooling since the fluid carries heat much more efficiently and is easier to direct than air. It's still possible to repurpose heat from bitcoin mining using air cooling, but it's much less efficient than immersion cooling, which can recover 96% of the heat.Another factor to remember is that bitcoin miners generate heat between 40॰C and 50॰C, although it's possible to run the machines as hot as 80॰C. This is considered low-grade heat and can't be used for some purposes that require higher temperatures. Still, bitcoin miners generating low-grade heat can provide baseload heating for many purposes, including district heating and food production. We will now go through some examples.District heatingThe Canadian company Mintgreen is a pioneer in repurposing waste heat from bitcoin mining. This leading position has allowed them to work with the city of North Vancouver to supply heat for 100 buildings with 7000 apartments. This involves a heat purchase agreement over 12 years, in which Lonsdale Energy Corp., the city-owned district heating company, purchases a baseload of heat generated by Mintgreen's proprietary Digital Boilers® that are powered by renewable energy. The Digital Boilers® contain bitcoin mining machines that are immersion-cooled. A pump moves the non-conductive cooling fluid to a heat exchanger, which imparts heat directly to Lonsdale Energy Corp's district heating system.Food productionMany food production processes require low-grade baseload heat that bitcoin miners can provide. In 2020, Mintgreen started working with Shelter Point Distillery to supply their whiskey production process with bitcoin mining-generated heat. The whiskey producer requires thermal energy for the barrel aging process. Mintgreen designed a bitcoin mining-powered whisky aging machine that allows them to age the whisky faster than they would have been without the extra heat.Several miners in Scandinavia are either actively repurposing their excess heat or planning to do so. Genesis Mining is participating in a research project in northern Sweden which studies the prospects of repurposing waste heat from bitcoin mining to grow fruits and vegetables in greenhouses. They do this by piping the hot air from the machines into a greenhouse. The project found that a relatively small mining container of 600 kW provides sufficient heat for a 300m² greenhouse, even in winter temperatures as low as -30॰C.Most miners in Norway are planning how to repurpose waste heat from bitcoin mining for food production. Plans include supplying heat to greenhouses, algae farmers, and salmon farmers. Norwegian miners are presently under heavy political pressure due to their energy consumption, and repurposing the excess heat from their operations is a way to show that mining provides environmental benefits. Due to these political incentives, we will likely see massive bitcoin mining heat innovation in Norway during the coming years.
Repurposing waste heat from bitcoin mining lowers heating costs and reduces carbon emissions
Repurposing heat from bitcoin mining has three main advantages. First, the income from bitcoin mining subsidizes the cost of the electricity used to produce the heat. Mintgreen can compete in the district heat market and use the payment from selling the heat to lower its electricity rate to among the lowest in the bitcoin mining industry. Their bitcoin mining competitiveness further reduces risk so they can enter decade-long heat purchase agreements.The reduced heating costs also allow for increased food production in northern regions historically considered too cold for extensive food production. According to Mattias Vesterlund, a senior researcher at RISE in Sweden who cooperated with Genesis Mining in their greenhouse project, "a 1 MW data center would have the ability to strengthen the local self-sufficiency up to 8% with products that are competitive on the market". A bitcoin mining facility of 1 MW is relatively small, so we can only imagine what a 100 MW data center could do.In addition to lowering heating costs, using bitcoin mining for district heating can reduce carbon emissions if the machines are powered by renewable electricity. Mintgreen's CEO Colin Sullivan estimates that the company saves 20,000 tons of carbon emissions over the expected 12-year term of the district heating partnership. The CO2 savings come from replacing the natural gas boilers the city's district heating system is using.Thirdly, repurposing the heat from bitcoin mining is essentially using the same energy twice. This offsets energy used by the bitcoin mining industry since it outcompetes other miners that are not repurposing their heat.
Source: Mintgreen
Mintgreen estimates that their bitcoin mining district heating system provides a yearly reduction of 3,100 tons of CO2 per MW. Of this amount, 1,300 tons come from 1 MW of offset energy consumption in the bitcoin mining industry and a 1,800-ton reduction from 1 MW of reduced natural gas heating.In addition to reducing heating costs and mitigating carbon emissions, repurposing the excess heat from mining operations can impact the geographic distribution of the bitcoin mining industry. Currently, bitcoin mining operations are centered in regions with abundant and cheap electricity. Since heating costs and electricity prices are correlated, a miner that repurposes its heat can operate in places previously considered unsuitable for bitcoin mining due to high electricity prices.Two main properties make bitcoin mining superior for heat recovery compared to other energy-intensive industries. First, the location agnosticism of bitcoin mining means that a bitcoin miner can take its operation anywhere heat is needed. Secondly, bitcoin mining is a modular process and can be scaled to give just the amount of heat required. These characteristics of bitcoin mining have allowed companies like Mintgreen to build bitcoin mining-powered heaters, which subsidize their heating costs with income from bitcoin mining.We will likely continue seeing massive innovation in repurposing heating from bitcoin mining. Surging electricity prices and heating costs will drive both bitcoin miners and consumers of heating to seek creative solutions to reduce costs.
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