Stirlingengineforum.com

Starting to look like the real deal!

This is exciting news indeed, been some time since a 'serious' Stirling engine project looked anywhere near market ready! Will there be an opportunity to buy just the bare engine for the tinkerers amongst us?

NHH

Really exciting news indeed.

Nice that you take the trouble to inform us, i would say: keep going!

nickh - hi thanks for your comments, we will be selling OEM ( bare bones ) engines for all of you to pull apart and enjoy. this will be available as the production lines ramp up productivity.

we are planning to produce up to 1000 engines per month to fulfill already signed orders, and we have the possibility to ramp up to approx 3000 per month at the end of this year.

Am I converting correctly? You said the thermal output is 17.5kW. Is that 60,000 btu/h? Am I correct that the circulating coolant heat output is enough to heat a house in the winter with hot water radiators?

59712.485 btu/h to be precise :) and yes the heat output is enough to heat a hot water tank and fulfill the needs of radiators during the winter.

Hi Danny, and thank you for being part of the team brining this long awaited technology to the home market. :)

Have a question on the below though that you might help clarify

Inresol wrote: To confirm the data - our 'Portable' Stirling CHP unit (GENIOUS™) produces 5kW continuous electrical power, and approx 17.5kW thermal output at an efficiency of 90% (30 / 60 Elec/thermal)

We have
5kW_electric = 22%
17.5kW_thermal = 78%
===========
22.5kW = 100%


At the same time there is a claim of 30/60(/10) output (electric/thermal/"losses")... how does that ad up? That ought to give numbers like eg
5kW_electric = 33% (30)
10kW_thermal = 67% (60)
===========
15kW = 100% (90)

Does this somehow imply that settings can be tweaked for eg "max total kW output" vs eg "higher percentile kW_e"? How does that affect efficiency and total power output?

Had some free time today so called inresol and had a well over 1h conversation with CTO Stefan. So thought I´d pass on some of the info here. Info taken from memory, so take it with a pinch of salt.

The electric output has been measured to 22-30%, depending on a large amount of factors (height above sea-level, fuel used, etc, etc). The engine performs best when "fed" about 900 C heat continously. Less lowers the sterling engine performance, higher produces more heat than "the engine can make efficient use of". So for maximum electrical output (30%-ish), 900 C is the optimum target, which likely is at all times except possibly during cold winter conditions.

The gererator itself is at 94% efficiency and the loss of energy in the battery is about 2%, but working towards a batterybank allows the engine to run much more optimally than if having to sync to eg 50Hz/60Hz AC (20-25% more efficient). Also, my conclusion is that if using the unit also for heating your house, the 6% generator and 2% battery "loss" turns into heat that heats your house, ie no actual loss at all.

Recomended maintainance interval is 20.000h (10-11 years normal operation), but the bearings according to spec should last 90.000h if the engine is never run too hot. A complete sealings and bearings replacement should cost about 600 euro. The engine internal Nitrogen preassue is automatically monitored and an N-filter generates N and pumps it inside the engine whenever needed. This gives extremely low levels of foregin particles inside the engine and thus little to damage it, and the same concept was used on a small 500W engine in the 1950ies produced by Philips (mainly for far off placed radios). Some of those engines still run today.

If wanting to heat it with other fuels than eg pelleted wood, the engine comes with two 65mm inlets/outlets to which any other heatproducer can be connected via insulated pipes.

The included battery and extra batteries are produced inhouse, and containes internally developed circuitry to lower the load and extend life of the battery. Having extra batteries further extend the life of the batteries due to lowering the load and temperatures during peak power output.

The parts are mainly produced in Sweden, by high quality producers, not from cheap imported Asian parts to lower cost but potentially also quality. The public should be able to purchase units from about May-June.

Finally, I have no affiliation to Inresol in any way or form. Just interested in the technology as well as purchasing a unit for myself. :)

Nice information!
It's going on now, it's april, so may/june isn't that far away.
I'd really like to see the final product, so if you have more information: keep us updated!

Regards,

Krijn

What about those of us that already have our own battery bank and live off grid. The engine/generator would be great, but shipping their batteries is a cost barrier. I just need an engine that will make the electrical power and throw a little heat back into the house when needed. I don't need a whole new battery bank or a computer to run the show.

Sigh.

RS

Since I was thinking to possibly run the engine with a rocket-stove I did ask if one needed to buy the whole thing. The answer is no, they will sell units eg without the pellet burner as well as barebone engines.

However, that said, since the internal N preassure is controlled and adjusted automatically I suspect you still need the computer part.

As for your battery bank, are you sure its up for the job? The inresol batteries are high-tech 300V (or was it 600V) batteries with internal individual cell monitoring and load balancing, with individually tested components before assembly and specifically designed containers to ensure the battery doesnt overheat during the heavy 5kW input/output loads. So while old type low voltage led-acid batteries for sure will work, the question i guess is for how long. CTO Stefan btw was one of the designers of the first 3 models of electric car quickcharge systems here in Sweden (30min for a fully charged car), and inresol both had and currently have car related projects under NDA, so the knowledgelevel inhouse at inresol is at the forefront of automotive electric car industry. And they´ve put that knowledge into their own batteries as well. (Yes, a full 30min or so of my discussion with Stefan was about batteries and the electric subsystems :D. In his mind, its an absolutely vital part of a no maintainance working CHP unit based on a Stirling engine).

Another thing I forgot to mention previously is that they had one engine running for 12 years (the lower electric output one), picked it apart, changed bearings and sealings, and started it up again. The most notable difference was slightly quieter operation, the performance was the same. So albeit the unit is new, they have had proper longterm runtime tests on most components.

stedevil wrote:Since I was thinking to possibly run the engine with a rocket-stove I did ask if one needed to buy the whole thing. The answer is no, they will sell units eg without the pellet burner as well as barebone engines.

However, that said, since the internal N preassure is controlled and adjusted automatically I suspect you still need the computer part.

Then I just lost interest. My little Kubota EL300 doesn't need a computer and is as reliable as hell. I don't understand why one needs a computer to monitor an maintain the engine gas charge. A simple regulator similar to what's used on propane tanks should suffice to hold the gas pressure at a given setting. Is there something I'm missing here?

As for your battery bank, are you sure its up for the job? The inresol batteries are high-tech 300V (or was it 600V) batteries with internal individual cell monitoring and load balancing, with individually tested components before assembly and specifically designed containers to ensure the battery doesnt overheat during the heavy 5kW input/output loads.

I'm pretty sure it's up to the job since we've been living completely off the grid for nearly 14 years. It's the job I've refined during that time. The high voltage is the problem here. My bank runs at 12V. Only with a grid tie inverter does one need these insanely high DC voltages, and I am not tied to the grid. My last battery set lasted for nearly 8 years. I expect to get 10 or better out of the current bank. I seriously doubt the cost/benefit ratio would lean towards these batteries over time.

So while old type low voltage led-acid batteries for sure will work, the question i guess is for how long.

See above. Where's the longevity data for these batteries, and are they being used off grid?

CTO Stefan btw was one of the designers of the first 3 models of electric car quickcharge systems here in Sweden (30min for a fully charged car), and inresol both had and currently have car related projects under NDA, so the knowledgelevel inhouse at inresol is at the forefront of automotive electric car industry. And they´ve put that knowledge into their own batteries as well. (Yes, a full 30min or so of my discussion with Stefan was about batteries and the electric subsystems :D. In his mind, its an absolutely vital part of a no maintainance working CHP unit based on a Stirling engine).

No such thing as a maintenance free electro-mechanical system, and when I hear such claims my eyes begin to roll as a matter of reflex.

I neither need, want nor care about their super great batteries. What advantage can I get from a battery bank that can be charged in 30 minutes? None. Color me unimpressed.

Another thing I forgot to mention previously is that they had one engine running for 12 years (the lower electric output one), picked it apart, changed bearings and sealings, and started it up again. The most notable difference was slightly quieter operation, the performance was the same. So albeit the unit is new, they have had proper longterm runtime tests on most components.

Sounds great, but I don't see this as a viable alternative to the readily available and proven technology for off grid application for reasons given. If the engine can be used as a stand alone prime mover I'd have less reservations, and outright doubts. This could spring from the fact that I've been reading about such schemes for years and nothing has become commercially available here in the US, and this news doesn't change that one iota.

R

theropod2 wrote: A simple regulator similar to what's used on propane tanks should suffice to hold the gas pressure at a given setting. Is there something I'm missing here?

Maybe you are not missing anything? It could be as simple as you suggest. I didnt ask specifically for details in this area as for me the wifi features and remote monitoring will be of good use, so I would want the computer in any case. Hopefully there will be more details about it on the upcoming webpage.

The high voltage is the problem here. My bank runs at 12V. Only with a grid tie inverter does one need these insanely high DC voltages, and I am not tied to the grid.

Well, its not just for on-grid reasons high voltage makes sense. 5kW of electricity at 12V is a massive 417 Ampere current. You can weld with that. And the thickness of the copper leads reaquired are pretty massive as well, just to not burn your house down. Additionally one would need 100 12V batteries to get the charge current to each down to just above 4 A. Then again, I have no experience with off-grid living. Maybe hundreds of batteries in the bank is the norm?

Where's the longevity data for these batteries, and are they being used off grid?

I assume you can write them and ask? And please post the info back here as others might find the data interesting as well.

No such thing as a maintenance free electro-mechanical system, and when I hear such claims my eyes begin to roll as a matter of reflex.

Instead of just reflex eyerolling, maybe suggest why that would be impossible? Its not like it will need an oilchange since there is no oil.

What advantage can I get from a battery bank that can be charged in 30 minutes? None. Color me unimpressed.

Well, that its not useful for you doesn't mean noone else might find it useful. People with an electric car eg might find it pretty handy.

Sounds great, but I don't see this as a viable alternative to the readily available and proven technology for off grid application

Maybe you are right, perhaps its better to let us on-gridders try it first before you off-gridders give it a go. But potentially there will be some off-gridders that might want to toy around with it while having proper backup equipment they trust. :)

I think the computer is more an advantage than a disadvantage.
Nowadays everything is computer-controlled, and with that more is possible. You can do everything mechanically, but that can also fail. You're right, mechanical things can be fixed with duct-tape and WD-40, electronic problems are not so easy.

I think the concept is very nice, and i'm curious to the outcome. I will remain sceptical till there are units on sale.

Regards,

Krijn

stedevil wrote:

theropod2 wrote: A simple regulator similar to what's used on propane tanks should suffice to hold the gas pressure at a given setting. Is there something I'm missing here?

Maybe you are not missing anything? It could be as simple as you suggest. I didnt ask specifically for details in this area as for me the wifi features and remote monitoring will be of good use, so I would want the computer in any case. Hopefully there will be more details about it on the upcoming webpage.

The high voltage is the problem here. My bank runs at 12V. Only with a grid tie inverter does one need these insanely high DC voltages, and I am not tied to the grid.

Well, its not just for on-grid reasons high voltage makes sense. 5kW of electricity at 12V is a massive 417 Ampere current. You can weld with that. And the thickness of the copper leads reaquired are pretty massive as well, just to not burn your house down. Additionally one would need 100 12V batteries to get the charge current to each down to just above 4 A. Then again, I have no experience with off-grid living. Maybe hundreds of batteries in the bank is the norm?

I know all this and live with it daily. My battery bank, and large AC inverter, are housed in a separate steel structure and indeed the feed cables from my 3,500 amp hour bank to inverter are massive 00 gauge. They are only 1.5 meters long and are fed from huge solid copper buss bars connecting all the individual battery cabling. Each battery is fused at 35 amps. The alternating current from the inverter is then fed to the house and all loads as AC travels better than DC.

At the C/20 charging rate I can safely pump 175 amps into that bank, which divided between the 8 12V batteries is 21.9 amps each. My entire charging capacity (wind, solar and diesel) cannot attain this limit. Where this 4 amp charging rate comes from I have no idea. Good lead/acid batteries can live at the C/20 rate just fine and can take up to C/40 for short bursts.

Where's the longevity data for these batteries, and are they being used off grid?

I assume you can write them and ask? And please post the info back here as others might find the data interesting as well.

I really don't give a rats backside. I'm not the one defending this outfit and feel no burden or motivation to find out. It would cost a fortune to ship this system (in both money and carbon footprint) and I'll invest in more domestically produced solar panels before considering this outfit. My only interest is in the engine, and potential off grid application. If it isn't applicable for off grid use no biggie. Little is. There are bloody huge swathes of the world where my off grid situation is the norm rather than the exception. Of course those folks don't have a pile of money to invest in a system in hopes it will actually work.

Shipping proprietary super batteries all over the world doesn't make one bit of sense to me.

No such thing as a maintenance free electro-mechanical system, and when I hear such claims my eyes begin to roll as a matter of reflex.

Instead of just reflex eyerolling, maybe suggest why that would be impossible? Its not like it will need an oilchange since there is no oil.

Seriously? Generators lose function with a coil failure, if this computer crashes the system dies and all the associated technology has inherent failure rates. No matter what is built it will eventually fail. I've yet to see anything to convince me otherwise. When humanity achieves perfection let me know.

What advantage can I get from a battery bank that can be charged in 30 minutes? None. Color me unimpressed.

Well, that its not useful for you doesn't mean noone else might find it useful. People with an electric car eg might find it pretty handy.

Never suggested it wouldn't be useful to others. I'm asking questions based on my interests and needs.

Yep, and if the grid is available it's cheaper, and more efficient, to use it to charge the batteries in such a car. If the grid isn't available charging batteries this fast is not going to be cheap and I see no need for the speed.

Sounds great, but I don't see this as a viable alternative to the readily available and proven technology for off grid application

Maybe you are right, perhaps its better to let us on-gridders try it first before you off-gridders give it a go. But potentially there will be some off-gridders that might want to toy around with it while having proper backup equipment they trust. :)

I've read all sorts of claims over the years, but little has come of it. I'd just like to see a less complicated prime mover that could be used where there already isn't power available. There's little need for all that waste heat in the tropics. Maybe they can use this as a springboard for a system that is far less complicated, and more suited for off grid application, but right now it sounds like a real expensive toy.

Being off grid means you have equipment you trust and understand as a matter of course, and I think you're missing this critical point. No power company guy shows up if our electricity goes away. Most folks that live like I do know what works and why. Unless a clear advantage is offered by this system, which hasn't been demonstrated, I will continue to express my concerns until such time as our host says otherwise.

R