Comment by therein | Hacker News Reader

Comment by therein | Hacker News Reader

I have always wondered, if it would be possible to make a small enough internal combustion engine so that you could just have it laying around in an apartment, sitting a few feet away from you, powering your appliances or charging a 12V or 24V battery. Dispensing the exhaust through a long tube. If all goes well, complete combustion of propane should yield CO2 instead of CO anyway. An additional enclosure shouldn't be an issue given the generator is small enough anyway.

The smallest propane powered generator I can find is basically still not much more silent or smaller than Honda EB2200.

Imagine a 350W generator that you can connect to a camping style propane tank that you use to charge some batteries.

I played around with setting up such a system with a Sterling engine but couldn't achieve high efficiency.

Surprised to see no YouTuber with the necessary machining skills and CNC equipment attempted to build a mini internal combustion engine / inverter generator.

For sure miniature gensets exist! They're often used on gas RC / autonomous airplanes to generate supplemental electricity. Here's one: https://www.youtube.com/watch?v=1yB49G756OI

I think the answer is that the miniaturization reduces efficiency, adds a ton of tiny, expensive parts/maintenance, and doesn't generate a lot of power compared to what you can store in a battery. So while the idea is cool, it's really only applicable in a few specialized use-cases like long-duration drone flight.

You've got to also compare it to other available power generation schemes -- A single 250W solar panel is far cheaper, simpler, and eco-friendly.

>Micro combined heat and power is an extension of the idea of cogeneration to the single/multi family home or small office building in the range of up to 50 kW.[1] Usual technologies for the production of heat and power in one common process are e.g. internal combustion engines, micro gas turbines, stirling engines or fuel cells.

https://en.wikipedia.org/wiki/Micro_combined_heat_and_power

Unfortunately, looks like the smallest CHP unit Dalkia Aegis will sell you in the United States is the Yanmar CP35, which does 204,040 BTU/h. https://aegischp.com/products/product-comparison/

In japan some rural households use propane solid oxide fuel cells in this manner. Instead of combusting the fuel, which is loud, it’s pushed through a piece of exotic ceramic which causes a chemical reaction that splits the fuel into hydrogen gas and water vapor—the resulting free electrons are used for electricity, the hydrogen gas is used as a home/water heater and to keep the ceramic fuel cell at its reaction temperature, and the water vapor is simply vented.

Wouldn’t it be loud as hell? Even 4-stroke small engines are inefficient all things considered.

Washing machines and other appliances used to be powered by ICE when the grid was not widespread

Yes, first 40% efficient ICE was made almost a century ago, but those were very big engines.

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