The OTHER Free Heat

Shy of installing a solar heating system, you’re always going to be paying for heat, right? There has to be some input of fuel or energy to get heat out on-demand. Or can it be done another way?

Generating Heat

We make heat using more than just a furnace or a boiler. Nearly everything in your facility generates some amount of heat. Some equipment will produce hundreds or thousands of BTUs of heat, and you actually pay to throw that heat away. This is equipment that generates heat as a side effect of running and will probably be damaged if it gets too hot.

Consider for example, a large pump motor. This motor outputs enough torque to crush Sales Guy Scott’s jeep (don’t worry, we won’t be proving that Scott, even if it would look really cool). The thing is a gigantic space heater. There’s friction inside of it from the bearings heating up, there’s a massive amount of heat coming from the windings as we cram amps into them to make these monstrosity spin. The motor casing has fins on it to dissipate the heat. In some installations, it may be necessary to ensure the room has good air flow or even air conditioning to help manage the heat or risk the motor overheating. You’re paying to both generate and counteract that heat generation.

This sort of waste happens everywhere. It happens in manufacturing, chemical processing, and especially in computer data centers. We want some product, we generate heat to get it, and then allow that heat to be exhausted out into the open air, while at the same time paying for a system to heat the facility and provide hot water for the employees or customers.

Waste Heat Recovery

The most efficient thing to do is use the heat we’re already generating. There’s an entire industry built up around this idea. A heat capturing system is installed on or near the wasteful equipment, there’s typically heat exchangers installed that extract heat from the air and do something useful with it, like heating the building’s water supply.

This is something nearly everyone has already experienced at least once, because one industry has near universally adopted it: automotive design. Your car has a little HVAC system in it. At bare minimum, the car can fill the cabin with hot air. It doesn’t cost us any extra fuel to do that. The engine’s coolant is run through a heat exchanger and air is blown over it, through the ducts, and finally out to warm the drivers and passengers. The engine generates heat it doesn’t need and we put it to work. The alternative would be an electric heating system, which would lower fuel mileage or a fuel-burning furnace, which would also lower fuel mileage.

Let’s consider doing this at a larger scale. What if we were to recover all the heat generated by a computer data center? These are facilities like Microsoft’s Azure, Dropbox, and buildings that are essentially silicon from top to bottom on the inside. A single server in a facility like this can suck down 2,000 watts on its own. There are literally thousands of these servers in the facility. Every single server is blasting heat out, that gets sucked up by an air intake, pushed through an air conditioner, and then returned to the servers to cool them. The office spaces of the facility are still heated with a conventional heating system.

Step one is to get the heat out of the servers. The best way to do that is with liquid cooling. We put special water blocks on key components, the CPU and GPU, plumb these together, hook up a pump, and run them to a radiator, if we’re doing this on a personal computer. For a server, we still use the water blocks and plumbing, but the pumping will be provided by something bigger. Step 2 is to do something with that heat. The servers won’t have actual water in their loop, it’ll be a special coolant. In step two we use a heat exchanger to either heat water or air, which then is used to heat the building.

At larger scales, this sort of system can be used to heat nearby buildings. The heating needs of the data center itself will be overwhelmingly met by the servers. Waste heat can be directed into a district heating system, sold to nearby buildings, or even used to power a roof and parking lot ice melting system. In an ideal configuration, these systems will reduce or eliminate the need for a standard heating system or other heat-generating systems at the facility.

Industrial Implementation

Integrating this at your facility will depend on what equipment your facility has, what heat you generate, and how you need to use that heat. In steam generating facilities, there are a plethora of systems to re-use and reprocess waste steam. For other sections of manufacturing though, like building cars, the equipment is probably too specialized and changes too often to have a heat recovery system.

The benefits can be significant in the long run. For some facilities, it’s possible to eliminate most heating costs. Heating costs can easily pass into the hundreds of thousands of dollars for larger buildings. Even cutting that in half is a massive and worthwhile upgrade.

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