When we feel the excess heat coming off of our overworked computers, most of us start hastily closing browser tabs. But where the average computer user sees danger, Lawrence Orsini sees a tremendous opportunity.

“Computers are really good heaters — that’s where they shine,” says Orsini, a former auto machinist and veteran of the energy efficiency industry. “Instead of dumping that excess heat into the atmosphere, like we do now, we should be capturing that heat and put it to good use.”

That’s the basic idea behind Orsini’s startup, Project Exergy: rather than transporting electricity across power lines to generate our heat — and wasting most of the power in the process — Exergy proposes that households and business can generate the heat they need onsite, using computation.

Project Exergy’s prototype, “Henry,” converts computation into stored heat with 60–70% efficiency. Principal Lawrence Orsini built Henry with off-the-shelf parts as proof of Project Exergy’s basic concept.

In thermodynamics terms, “exergy” refers to the maximum amount of useful energy in a system. It’s an appropriately compact rallying cry for wringing as much use as we can out of the heat that we’re already generating with our universe of computational devices, and even more so, the server farms that power what we misleadingly refer to as “the cloud.”

Far from being airy and untethered from our earthly concerns, Orsini points out, the cloud is a massive consumer of energy and producer of waste heat. Energy is consumed every time we perform a Web search, upload a selfie, or publish a blog post; by some estimates, moving a megabyte of data across the Web is equivalent to burning one lump of coal. So the server banks that power this ceaseless dance of data produce a tremendous amount of heat — heat that is then dumped into the atmosphere. Compounding the absurdity is the fact that these servers need to be kept cool — a process that generates even more heat.

“In the name of efficiency, companies like Amazon and Google have started moving their server farms out to colder locations, closer and closer to the Arctic Circle,” Orsini says. “But if you look at it in terms of wasted heat, it’s tremendously inefficient.”

As a proof of concept, Orsini has already built a working prototype, affectionately nicknamed “Henry,” and put it to use in his apartment in lower Manhattan. Henry is a massive PC — “a gaming rig on steroids,” Orsini says — atop a thermal storage tank, which collects and stores the excess heat generated by the computer. The computer itself performs a multitude of functions, like streaming videos to a projector and controlling the lighting and the sound system. Water blocks — metal wafers filled with water that are bolted to the circuitry — capture and transfer the heat into the storage tank below.

The beauty of the concept is that the computation itself can serve any purpose. Last winter, Orsini used the Frankensteinian rig to mine cryptocurrency; between the money he saved on electricity, and the money he mined, he came out with a little bit of money in his pocket. Henry has also been used to fold proteins, as part of a distributed computation scheme in which universities outsource their computation to idle personal computers.

Impressively — and deliberately — Orsini built his prototype using only off-the-shelf parts.