Tis indeed a crazy thread run somewhat amuk. Still, appreciate the diversity of opinions, careers, and knowledge. Thanks all for contributing.
Renewable energy
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CreoSophist
New Member
Here is a pretty interesting product for producing electricity from a gasificiation boiler using a free piston stirling engine.
Advertised power generation is 1 kW.
stirling-tech.com
It could be a cool thing for an off-grid property in combination will solar power, if it really works.
Advertised power generation is 1 kW.
Microgen Engine Corporation - Microgen
Microgen-Engine, A revolution in power generation and energy efficiency by using free piston stirling energy
www.microgen-engine.com
BioGen | Combined Energy Technology
stirling-tech.com
It could be a cool thing for an off-grid property in combination will solar power, if it really works.
Looks kinda niche, since the heat output is 20X higher than the electrical output (ofc, its CHP). But applications like space heating that need that much heat (20 kW, 75,000 kBTU/h continuous) might want more than 1 kW max.
These Stirling engines pop-up a lot bc if their stated thermodynamic efficiency and long lifetime (one moving part and no wear surfaces). One company was proposing one for the Space Station that would work on concentrated solar radiation. The same company tried to use the design for an array of CSP collectors in the desert, and ended up bankrupt. The main issue seems to be startup/shutdown, poor throttlability, and accommodating variable temp heat sources and sinks for stable operation.
These Stirling engines pop-up a lot bc if their stated thermodynamic efficiency and long lifetime (one moving part and no wear surfaces). One company was proposing one for the Space Station that would work on concentrated solar radiation. The same company tried to use the design for an array of CSP collectors in the desert, and ended up bankrupt. The main issue seems to be startup/shutdown, poor throttlability, and accommodating variable temp heat sources and sinks for stable operation.
My former employer worked on the first commercial installation in the US of Sterling cycle engines. the company that supplied them went bankrupt and the project was abandoned. Razor went bankrupt trying to commercialize the Sandia National Lab concentrating dish solar technologies but was unable to develop a reliable Sterling cycle heat engine. Dean Kamen claims to have a ready for production design since the Segway but no entity has elected to license it. He claims that he had one running at his home for some period of time. A New Zealand firm tried to commercialize a home Sterling cycle cogeneration system. Some were distributed in England but I think they were all recalled. There are a lot of broken promises for commercial Sterling engines. Carnot cycle efficiency still applies so they are not going to be very efficient unless operated at high temperature differentials.
CreoSophist
New Member
I think it can put out it's rated power output at a lower heat output, but I'm not sure. Their gas unit is producing 1 kw electrical and 6kw thermal, which seems good.
For an offgrid property, there aren't that many options if you want electricity. Solar is good, but only sometimes, and if you are lucky you might be able to install a micro hydro turbine. Other than that you can run an ICE CHP, which is a better option if you have natural gas. For low quality fuels like wood, the stirling engine seems to be the best option.
I don't know if this is the company you are talking about, but they seem to have had success with remote power for NG pipelines.
Remote Power Home - Qnergy
Increase your energy performance and reliability Qnergy’s PowerGen solutions provide continuous, remote electricity for your mission critical applications Qnergy provides proven and reliable remote power generators Powered by our proprietary Free Piston Stirling Engine, our generators are...
www.qnergy.com
In a cabin, I would have a battery bank, a solar panel, a nice since wave inverter with a kill switch (to not drain the battery when not in use) and a small genny for backup. Micro-hydro would be sweet if available, but I'd probably want to use it to feed a battery bank, for surge capacity... like my backwoods espresso machine. And a separate woodstove for heat. Not sure I would care about the integration complexity of a CHP system.
I don't know if this is the company you are talking about, but they seem to have had success with remote power for NG pipelines.
Remote Power Home - Qnergy
Increase your energy performance and reliability Qnergy’s PowerGen solutions provide continuous, remote electricity for your mission critical applications Qnergy provides proven and reliable remote power generators Powered by our proprietary Free Piston Stirling Engine, our generators are...
Yup, that's them.
CreoSophist
New Member
This is probably discussed somewhere else, but what would your choice for batteries be?
Find someone who has good set of the old Edison cell Nickel Iron batteries, preferable the US built or Varta European cells . The Chinese production batteries have a less good reputation (but some are happy with them. Some Edison Cells are still going after 100 years, if the guts get moved into new cases. They do have their downsides, they guzzle water, crank out lots of hydrogen and dont hold a charge for the long term but they can be discharged flat and come back.
I"m no expert, but I think the decision comes down to use case and shelf life. If you are just using the cabin on some weekends, so its a couple dozen cycles per year, I'm sure Lead-Acid would be cheap and last long enough. If you were living there (lots of cycles), you would either get better Lead Acid, like sealed AGM or even Lithium.
In terms of cost per kwh it's pretty hard to beat lead acid. The GC2 6 volt golfcart batteries are generally priced quite low, and often represent the best value.
The downfall to lead acid is the limited charging and discharging rates, it works well if charged with solar over a period of many hours, and discharged at a slower rate for lower output appliances.
IMO lithium is the best in terms of performance, high charging amps (minimizes generator run time should you need to charge this way) and better peak output performance if you need to drive higher loads like a well pump. The downside is cost.
If someone is seriously looking at offgrid I'd suggest reading both these books by Victron Energy, yes there is some marketing material contained within, and Victron equipment is used for all the examples, but the information is generally solid and covers topics well beyond what you will find in most "how to" guides.
www.victronenergy.com
The downfall to lead acid is the limited charging and discharging rates, it works well if charged with solar over a period of many hours, and discharged at a slower rate for lower output appliances.
IMO lithium is the best in terms of performance, high charging amps (minimizes generator run time should you need to charge this way) and better peak output performance if you need to drive higher loads like a well pump. The downside is cost.
If someone is seriously looking at offgrid I'd suggest reading both these books by Victron Energy, yes there is some marketing material contained within, and Victron equipment is used for all the examples, but the information is generally solid and covers topics well beyond what you will find in most "how to" guides.
Wiring Unlimited - Victron Energy
Wiring Unlimited is now available! Download it for free here: Wiring-Unlimited-EN.pdf What is Wiring Unlimited? A Victron Energy book by Margreet Leeftink, Information Developer for Victron Energy B.V. Wiring Unlimited is all about electrical wiring of systems containing batteries, inverters...
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