ÖkoFEN Stirling CHP available in the US ???

[Tom Booth]

https://www.maineenergysystems.com/chp/

https://youtu.be/4lPPjQAUpho?si=IFH15sNIM8o2JkCA


There was, apparently, a demonstration of this Combined Heat and Power system (including a 5kw or 6Kw ? Stirling engine/generator) in Maine earlier this year. I only just found the website so I did not attend and don't even know if it actually happened.

ÖkoFEN is out of Denmark and Main Energy Systems mentions on their site that regulatory issues have made it difficult to bring these wood pellets boilers to the North American market.

I sent an email inquiry asking about the actual availability or the Stirling CHP units in the US.

The Stirling engine used by ÖkoFEN is from Qnergy.

Old article from 2014: https://www.steam-generator.com/okofen- ... hp-boiler/

This video, however was 15 years ago:

https://youtu.be/MmdG5kpko9s?si=SsafVTbwWdriL3sa

In 2009 J.D. Sutton is quoted as saying such systems would be "stamped out like a Chevy and installed like a Maytag,"

In 2010, Infinia will begin repurposing idled auto assembly plants to make solar dishes that can be "stamped out like a Chevy and installed like a Maytag," according to CEO J. D. Sitton (Solutions, 2009)

Better late than never, but should I keep my fingers crossed?

This was 15 years ago:

https://youtu.be/c_uSJl0-Wfc?si=z__-v2wQ1SHP8YoL

Just before the company collapsed, went bankrupt and/or morphed into Infinia which soon declared bankruptcy and the technology was acquired by Qnergy.

There was supposed to be a big installation of Stirling Technology/INFINIA Solar dish generators:

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This is that same location/coordinates via Google Earth:

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Street View:

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I'm not sure if the systems were removed or just photoshopped, but the engine in my shop at least seems real.

[skyofcolorado]

You know, I'm a real advocate of Stirling engines for niche applications, but I just don't see solar being one of them unless you're in space. Look at the engineering, materials, complexity of mechanisms, maintenance of the tracking system, etc. of that installation. Compare to commonly available and dirt cheap PV panels that just sit there for 20 years making the owners money.

Anyone considering this kind of system for solar power generation will surely know how to drive a spreadsheet and in economic terms the numbers will favor PV every time. That's why these are just a curiosity. And it's a real shame too, because there are so many other sources of waste heat that the generators could use, but again, the cost of the engine, modification of the system to direct the heat to it, and the potential economical benefits just never add up in industrial, commercial, or residential settings.

Sadly I don't see a market for these adequate to justify their existence at the current price points per watt. Maybe if there was a commercial LTD that could pull a few kW from the heat in my attic for $250 off the shelf from Lowe's, sure. But overall $/watt is the currency we're dealing with here and they can't compete. A tried and proven, easy to DIY multi-kW model is likely the only way we'll see frequent adoption of the technology, and I have doubts about the stirtling community's will to develop and refine such plans for the casual DIY'r.

[Tom Booth]

You know, I'm a real advocate of Stirling engines for niche applications, but I just don't see solar being one of them unless you're in space. Look at the engineering, materials, complexity of mechanisms, maintenance of the tracking system, etc. of that installation. Compare to commonly available and dirt cheap PV panels that just sit there for 20 years making the owners money.

Anyone considering this kind of system for solar power generation will surely know how to drive a spreadsheet and in economic terms the numbers will favor PV every time. That's why these are just a curiosity. And it's a real shame too, because there are so many other sources of waste heat that the generators could use, but again, the cost of the engine, modification of the system to direct the heat to it, and the potential economical benefits just never add up in industrial, commercial, or residential settings.

Sadly I don't see a market for these adequate to justify their existence at the current price points per watt. Maybe if there was a commercial LTD that could pull a few kW from the heat in my attic for $250 off the shelf from Lowe's, sure. But overall $/watt is the currency we're dealing with here and they can't compete. A tried and proven, easy to DIY multi-kW model is likely the only way we'll see frequent adoption of the technology, and I have doubts about the stirtling community's will to develop and refine such plans for the casual DIY'r.

After researching the situation pretty thoroughly, in 2010 these Stirling dish companies were all tooled up, the car manufacturing plant assembly lines ready to go to start mass production and glad to get the work, for both commercial and residential use on a massive world wide scale that anyone who could afford to buy a car could at least afford.

The main reason for the massive sudden failure appears to have come primarily from the utilities that the solar fields needed to distribute the power

First the utilities demanded a minimum contract for ridiculously high Kilowatt production before they would provide a connection forcing the companies to overextend themselves financially, then when the Stirling solar companies had spent all their resources and gone into debt but did manage to meet the targets, the utilities reneged on the contracts causing the Stirling solar companies to go bankrupt.

No time was wasted dismantling the sites, already in production, to be sold as scrap.

Nothing wrong with the technology. Relative to other technologies, the payback on investment was better than photovoltaics, even with the over-engineered systems built to NASA/military type specifications

Talking about maintainance?

The things could run for 30 years without being touched, running on some space probe till they left the solar system or beyond.

[Tom Booth]

Seems like everything was going along smoothly with a lot of optimism all around up until the time this guy got appointed as Energy Secretary.

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And, not long afterwards:

https://youtu.be/yzU_Mo5ElVE?si=yoUdNirXVIAuV8jX

[skyofcolorado]

Talking about maintainance?

The things could run for 30 years without being touched, running on some space probe till they left the solar system or beyond.

I was talking about the tracking mechanism. The engines are obviously solid, but they need tracking for solar, and everyone that's dealt with that knows the reliability issues at play. And in other waste heat instances there will likely be maintenance there too regarding heat transport.

Anyway, $/watt vs. benefit realized is what it comes down to for probably every application, maintenance or not. They don't exactly have a good track record on retail cost for any application where you or I may use them.

Unless it's DIY out of tin cans and latex of course.

[Tom Booth]

I don't know, but GOE's Stirling Dish system looks remarkably similar to the Sun Catcher's that were decommissioned.

https://youtu.be/_rl1H-53Mks?si=xKNdtsMC_lKVYYCl

Anyway, it seems the technology has been put to good use around the world in countries outside the USA, where, it was originally developed, but for some reason, I believe, or heard that until recently, importation into the US was banned.

Hard to argue the technology is flawed or economically not viable when it's being successfully deployed in these other countries.

[Tom Booth]

Talking about maintainance?

The things could run for 30 years without being touched, running on some space probe till they left the solar system or beyond.

I was talking about the tracking mechanism. ....

And PV systems don't use tracking?

I can hardly think of anything simpler than tracking the sun.

"..they need tracking for solar, and everyone that's dealt with that knows the reliability issues at play"

Maybe you could site some actual examples or case study or something because I've seen several simple DIY solar tracking systems.

A friend of mine built one and it's still working for his family and he's been dead for 10 years

[skyofcolorado]

And PV systems don't use tracking?

I can hardly think of anything simpler than tracking the sun.

At the current price point of PV, we just add more panels to fixed mounts to make up for the slight gain in Wh/day you would get with tracking. It's really not that much due to atmospheric effects at the extents. LifePo4 storage is phenomenal for capturing whatever power is produced, and it doesn't matter to me if that's more peak power mid-day with a larger array, or lower, but more consistent power with a tracking system. I paid under $0.25/W for my panels five years ago. They're cheaper now. For power from the sun, Stirling doesn't come close to PV in $/Watt.

Tracking with a dish-based Stirling is a mandatory thing, and it's not just a single axis like PV trackers. It's a huge fraction of the cost. Completely impractical in the current market. Dollar for dollar they would be far better off with an untracked trough-style array that circulates a transfer fluid to the engine, or just replace the whole thing with a pallet of PV panels.

Yeah, heat engines are cool, and I love to build them. They have practical niche uses. But my source of heat is not the sun. They are literally the only way I can use my heat source to make power with any efficiency. When the day comes that I can buy thermal PV panels to replace the engine I'll do that. They exist, just not at a price point that makes sense.

[Tom Booth]

And PV systems don't use tracking?

I can hardly think of anything simpler than tracking the sun.

At the current price point of PV, we just add more panels to fixed mounts to make up for the slight gain in Wh/day you would get with tracking. It's really not that much due to atmospheric effects at the extents. LifePo4 storage is phenomenal for capturing whatever power is produced, and it doesn't matter to me if that's more peak power mid-day with a larger array, or lower, but more consistent power with a tracking system. I paid under $0.25/W for my panels five years ago. They're cheaper now. For power from the sun, Stirling doesn't come close to PV in $/Watt.

Tracking with a dish-based Stirling is a mandatory thing, and it's not just a single axis like PV trackers. It's a huge fraction of the cost. Completely impractical in the current market. Dollar for dollar they would be far better off with an untracked trough-style array that circulates a transfer fluid to the engine, or just replace the whole thing with a pallet of PV panels.

Yeah, heat engines are cool, and I love to build them. They have practical niche uses. But my source of heat is not the sun. They are literally the only way I can use my heat source to make power with any efficiency. When the day comes that I can buy thermal PV panels to replace the engine I'll do that. They exist, just not at a price point that makes sense.

Well, you are entitled to your choice/preference/options given your particular circumstances or situation.

Duel axis tracking however increases efficiency about 45% and is often used I think, even for PV and is certainly relevant for many where space is limited.

Haven't heard of LifePo4 before but a cursory search seems to indicate they have the same issues as any other battery storage. Can freeze in cold weather, average 7 year life, can't take much heat either, voltage drop etc.

If I were designing a system from scratch, I'd probably use concentrated solar, trough with minimal tracking and some form of heat storage with a Stirling engine for on demand power 24/7

Head storage is literally dirt cheap (sand battery) and lasts potentially indefinitely. The sand is not going to degrade or wear out, ever.

I think in the long term, Stirling engines would end up much more practical and less costly, for one thing there would, I think, be more competition, but I think that is perhaps also the problem.

Anyone can literally build a Stirling engine out of practically anything. Certainly any existing engine manufacturer could churn them out. Any metal shop, welder, etc. It could be a high school shop project.

The entry level for manufacturing PV panels on the other hand, from scratch is not so low that just anybody anywhere could make a go of it.

Investors like patents. The patent on a Stirling engine ran out a long time ago. You can't have a monopoly and get stinking filthy rich building Stirling engines and you can't put a meter on it.

[Tom Booth]

Well I didn't get an email response, but I just got off the phone with Main Energy Systems.

The demonstration was actually a few years ago and they themselves were not impressed by the performance of the Qnergy engine.

It did not output the rated 5KW. Maybe 3.5 and the engine from Qnergy alone cost $25,000 - $30,000

So, on a "light commercial" size heater (200,000 BTU's) running full bore, putting out maybe 3 Kw not really practical or economical. With the cost of retrofitting the engine, the engine plus pellet furnace would cost like 50 to 60 thousand.

They never sold any and are no longer even really interested unless or until the price of the Stirling engines comes down and/or performance improves. Overall, $30,000 for an engine just to "trickle charge" your batteries.

There was also a 600 watt Qnergy Stirling potentially for a residential unit for about $16,000 (just the engine) but they were not able to get one with 60 cycle output to test in combination with their heating system. Qnergy could only supply them with European 50 cycle.

But apparently it was "fun" to try and they think the CHP idea is good, conceptually and could possibly work but the price tag for the Stirling engines would have to come down.

He wasn't sure if ÖkoFEN is even still offering the units with the Stirling engines, but if they are, he didn't think they could be selling many.

About what I was expecting.

[Tom Booth]

Personally though, he said they were just venting the furnace to the open air not doing anything with the heat other than running the engine.

200,000 BTU's does not seem like all that much. The same as my salamander kerosene heater I plan on testing my 3KW engine with.

I'd be quite thrilled to get 1000 watts from something I was heating with anyway and feel like I was sitting pretty in a cabin somewhere, but you can forget paying $25,000 IMO that is just a ridiculous, artificially inflated price.