Reusing Datacentre Heat to Warm Homes and Water
A Server Strapped to the Hot Water Tank
The silence in Giles Gibson’s kitchen lasts only as long as it takes the water to run hot. What that silence contains is a small computer server, attached to the hot water cylinder in his London home, working without a fan or a hum loud enough to notice. When Gibson turns on the hot tap, the water that comes out is not heated by gas but by that tiny datacentre (a building full of computers that process and store data) strapped to the tank. The server generates heat as it operates, and that heat transfers to the water, so the warmth is not lost into the air. That lost warmth is a big environmental problem with large datacentres around the world. Gibson estimates that the hot water bills for his four-bedroom house in south-east London have fallen by between 10 and 15 pounds a month since he had the system installed last year. “As soon as I read about it, I thought: ‘This is obvious — why wouldn’t you do this?’” he says. [1] “It just makes sense to take a computer out of a datacentre and to strap it next to your water tank and get free heat.” The system comes from heata, a Surrey-based company that operates a sustainable cloud computing business (using remote servers over the internet to process or store data). Heata sends processing jobs from its clients to the servers in people’s homes. Each device has roughly the computing power of eight laptops. Charlie Beharrell, commercial director of heata, says the company aims to provide about 80 percent of the heat needed for a home’s hot water. “The water in their hot water cylinder will effectively be heated by our server, and they might have to use the gas boiler for the peakier moments in the day, like when they have a bath,” Beharrell says. [1] “The idea is that the primary heating system is working a lot less hard to heat the water than it would normally have to do if our system wasn’t in place.” The system can only work in homes with vented, unpressurised water cylinders (hot-water tanks open to atmospheric pressure, not sealed), typically recognisable by the blue insulation around the outside. A container holding the server is attached to the front of the cylinder after engineers cut a hole in the insulation. It is glued to the cylinder with a heat-conducting paste so the unit can conduct heat to the cylinder with no plumbing involved. There is no cost for the installation. “It takes a couple of hours and we modify it for the domestic water system,” Beharrell says. Heata pays for the electricity that is used to keep the server running, while the homeowner pays for the fibre broadband connection that is necessary. Beharrell says that millions of homes are fitted with vented water cylinders, while the units can also work with heat pumps (devices that move heat from outside air or ground into a home). The installation leaves the existing boiler in place for the moments when the server’s heat is not enough. The homeowner gets a lower hot water bill, and the company gets a place to run its computing jobs.
Mineral Oil, Raspberry Pis, and a Radiator
A HeatHub unit in a home in Essex, where rows of Raspberry Pi computers warm mineral oil that feeds a radiator. The heat generated by them is captured and put to use. The freezer-sized HeatHub units are made by the Wales-based company thermify and, like heata’s, also recycle the energy created when computers process tasks. They work differently from the heata system and the makers say they could one day replace domestic boilers. The heat created by the rows of Raspberry Pi computers (small, low-cost single-board computers) warms a mineral oil that surrounds them. The computers are packed in rows to concentrate the heat they produce. “The computers get the mineral oil hot,” says thermify’s chief executive, Travis Theune. [1] “We send that through a heat exchanger (a device that transfers heat from one fluid to another without mixing them). The heat exchanger heats up the water that’s going through a radiator, and the radiator delivers heat to the room. It’s the same basic concept as an induction heater (a heater that uses magnetic fields to generate heat in a conductive material).” The existing units have 480 computers in them, which carry out tasks for companies that buy time to process the work they want done. Theune says that the company plans to make a range of units to cater for different-sized homes. For example, a three- to four-bedroom house will have a unit which is about the size of a washing machine, while a flat could have one the size of a microwave. He says that the thermify systems will cost homeowners 40 pounds a month, based on an average-sized home. A bigger house, that requires more energy, will cost more, and a flat less, he says. The planned cost includes installation, leasing the unit and repairs, and comes with a minimum 10-year contract. The company claims that the device will lead to a 14 percent reduction in bill costs compared with homes with a gas boiler, and 34 percent for those households with a heat pump, over a 15-year period. The savings come from not having to pay for the installation of a boiler or a heat pump. The mineral oil acts as the medium that carries heat from the chips to the water. The HeatHub unit is designed to sit in a home and perform the same function as a conventional heating system, with the computing work paying for the heat it delivers.
The Waiting List and the Combi Boiler Problem
The system is not suitable for homes with combi boilers (combined central-heating and instant-hot-water boilers), which do not have the vented cylinder it needs. A version for unvented cylinders (sealed hot-water tanks that operate under pressure) is in development. Heata’s units are now in 100 homes and there are 3,000 people on the waiting list for installation. Heata and thermify are not alone in pursuing the idea: the Dutch startup Nerdalize ran a similar pilot in the Netherlands, and the UK’s Deep Green has installed heat-recovery units in swimming pools and leisure centres. The two approaches differ in scale: heata spreads single servers across individual homes, while thermify concentrates hundreds of chips in one unit per household. “So over a year, it adds up, and it’s just another little extra that helps,” Gibson says. “Having one of these units is a no-brainer.”
Sources
1. Guardian — Quote source (original article)