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    Ditching the Grid With a Woodstove and a $100 Stirling Engine (Q+A)

    Written by

    Michael Byrne


    Given one of my more immediate life goals is to be living in a somewhat self-contained cabin somewhere far away from all of this — yet still have a way to keep my deer meat frozen and my laptop charged — the Volo Stirling engine is very relevant to my interests. Basically, it’s a lot like an internal combustion engine, except instead of the heat coming from inside the engine via exploding gasoline, the heat comes from outside the engine, like from a woodstove. It’s an old concept, dating back to 1812, that got shoved to the side with the advent of the grid and the internal combustion engine. Detroiter Tim Sefton and his Volo Designs are aiming to bring it back, with plans to have a consumer-ready Stirling engine capable of generating a household’s worth of electricity ready by spring 2012, for less than $100.

    Sefton financed the project via Kickstarter, with the goal being to raise a meager $4,500. He easily beat that. I asked him a few questions:

    Who do you imagine buying these?

    There are basically three markets — residential home market[s] (backup power, alternative power), off the grid market[s], and rural/impoverished market[s] (third-world).

    What is your own personal interest in the Stirling engine? What’s its root?

    We love to invent, coupled with an engineering background. The Stirling engine is a masterpiece of simplicity (although the thermodynamics are tricky), so once we got into it, we were hooked.

    Why isn’t something like this out there already available to consumers?

    There are two segments that Stirlings are being made for today — the desktop novelty Stirling engine, which you can’t get any real work out of, and the industrial stirling which typically runs in the tens of thousands of dollars. We are targeting the sweet spot between these segments, big enough for real work, but small enough for affordability.

    How does this do cost-wise? Your cost in this case is pellets or wood to keep a fire going. How does that compare to a gasoline generator/solar/just buying electricty from the grid?

    It comes down to efficiency of generating work from fuel – the stirling engine theoretically is more efficient then the internal combustion engine, but a bit less than a high powered steam turbine (the type that some power plants utilize). Our engine will not be that efficient, but the price point should make it a solid alternative to petroleum or electrical industrial generated electricity. Keep in mind the two goals of the project are 1) energy Infrastructure independence and 2) flexible fuel utilization (you can use wood pellets, natural gas, wood, solar, or garbage to generate the heat).

    Are you currently connected to the grid? Do you plan on ditching it?

    Yes, I’m connected to the grid, and I’m sure to be connected to for some time still. We want to sell our surplus energy back into it. The Stirling can help alleviate the current burden [on] our existing electrical grid.

    What are some of the biggest disadvantages of powering your house/cabin with one of these? Besides the obvious having to keep heat on it.

    The engine is not self-starting at this point, thats probably the biggest drawback. There is very little maintenance needed for Stirlings — no oil, no spark plugs, no valves. We still are far away from creating a local energy appliance but thats the direction we’re headed. Electronics for storage of the energy are needed along with what we call a fire box (where the heat is generated).

    Is it possible to keep a constant power source to a house via this engine, without it running constantly? Like, can it charge batteries during periods of low-consuption for fire-free periods?

    The Volo Stirling will have a electronics kit that acts to buffer the power for times of need, but our first step is to completed development of the engine, then we’ll move on to the electronics/energy storage system. There are a lot of storage system[s] in the market today that would be a good fit.


    Reach this writer at michaelb@motherboard.tv.