The OCP heat ♨ reuse opportunity
Reducing the use of fossil fuels in the German economy
Following up on the idea to balance the power grid using data centers, this article explores the opportunity for large scale heat reuse using Germany as an example.
Heat reuse falls squarely within the objectives of the European Green Deal; decarbonization of heating and cooling is a pillar of that approach.
The opportunity for heat reuse
More than 90% of all energy in German buildings is used for heating. Back in 2017 this amounted to 826 TWh, the majority of which was powered (directly or indirectly via district heating) by natural gas, oil and even some coal.
The German heating market is fragmented; many different decision makers are involved in any given change, down to individual homeowners. With 30 cents/kWh for electricity and 6 cents/kWh for natural gas in 2020 (and recent 2022 peaks to 16.5 cents/kWh for gas), current pricing structures discourage any movement away from natural gas. The current conflict in Ukraine triggered a shift away from Russian gas, but even floating LNG is still a natural gas source — with associated emissions.
The electrification of heating with storage option
By changing the sources away from natural gas and oil, and towards district heating and electrical heating appliances, the dependency on fossil resources and the associated emissions can be reduced. Electricity from renewables can increasingly be used, especially when the heating appliances are built with a hot water storage option (boilers) to separate the moment of power usage from when the heat is used. This is also beneficial in combination with local solar panels (i.e. generate heat during a sunny day, take a hot bath at night)
Other storage options exist; for example Dutch startup Cellcius is using K2CO3 salt in a ‘heat battery’. By charging the system for a longer period at a lower temperature (evaporating water from the salt, making it dry) it is possible to improve the quality of the heat, and output (discharge) at a higher temperature, for a shorter period of time.
Heat pumps with auxiliary heat
Especially in colder climates like Germany, heat pumps can use an auxiliary heat source to speed up heating, and to operate under cold outside air conditions (e.g. during winter).
Note that heat pumps can also be used for cooling.
Qarnot crypto heater
As an example electrical heating appliance, consider the Qarnot QC1:
Although marketed as a ‘crypto heater’ at the time, the appliance contained general purpose CPUs and GPUs that could run any application deemed useful. This product was launched more to convey the general idea of using heat from computers to warm houses, in an easy to grasp form factor.
Qarnot refurbished boiler heater
Similarly, Qarnot has options with storage to decouple the use of computation (power) from the moment of heat reuse. This model can use refurbished hardware to extend the lifecycle of servers, and can produce up to 500 or 1000 liter warm water per hour, and more than 35 MWh per year (using 2.5–4kW of electricity, providing up to 64 vCPU cores):
Repurposed compute resources from German data centers
In 2020 German data centers used approximately 16TWh of energy. In terms of 24x7 operation and assuming 70% used for servers, that’s at least 1279 MW of capacity (more if servers are used less than 100% of the time)
Given a 4-year refresh cycle, in Germany 25% of 1279 MW / 4kW ~ 80k units of heat generating hardware becomes available for reuse — without generating new emissions.
By 2050, this would result in 28*80k = 2.2 million units, representing a total of 9 GW deployed capacity (7x what is deployed today, this would replace ‘regular’ data center servers)
Summary: The case for Germany
In the ideal case, German homes would use 826 TWh / 35 MWh = 23.6 million Qarnot QB1 (equivalent) units to electrify their heating — about 50% of households. At a rate of 1 million units per year, this could be achieved by 2046; this could include the 5 to 6 million heat pumps recommended by Agora Energiewende in 2017.
At 4 kW each, this would offer a peak load of about 95 GW — enough to cover the full range of power generated in the country, both conventional and renewable sources.
Each distributed server would provide 64 vCPU cores to run any application of interest. Various business models could be used for financing this transition; for example, cloud providers could sponsor the cost of electricity to bring it closer to the cost of natural gas, and the government could provide subsidies or waive levies for the energy used to power refurbished OCP boilers and heat pumps (like Norway did years ago).
Perhaps a little too over-simplified — but not impossible. What if we would start with upgrading the existing district heating networks? Add to that the 2 million hybrid heat pumps The Netherlands is planning to deploy by 2030, and the 4+6=10 million units per year in the US (HEATR act), and we can see there is ample opportunity.
