Solution of producing cheap energy to support our solar plant to go off grid ?

[@The_Bitruvian_Man]

I don't know if it's a German thing, but I love how rational and thorough your engineering mind is. Looking forward to absorbing all your videos, including future ones. Hello from central Canada! 🙂

[@myengines2443]

Thanks for your nice comment!

[@jimgoplayoutsideable]

The free piston sterling is where it's at! It's proven for applications very similar to your own, and it can be greatly simplified. Building a large sterling is almost the same as building your own ICE - not a job for a small shop. I've never seen a practical thermoaccustic, but maybe you have found? It sounds like more foundational design and engineering work would need to be done to get it to work, and then you would have to fine tune it for your application. For one person that could take quite awhile. Also, if you go the route of free piston, perhaps electromagnetic bearings with microcontroller can solve the problem of piston wear. I know that NASA has developed a free piston sterling that has been running maintenance free in a lab for 30 years, so there is a solution to that problem, the question is can you make one in your home shop? Anyway, just my perspective, best wishes on your cool project!

[@myengines2443]

Thanks for your thoughts and your nice comment!

[@giulianow.floriani3693]

Agree! Also, given that it is a close system with a high pressure zone, a one way valve + air bearing approach seams to be crazy valuable. Personally I would say that if you find your way to a cylindrical air bearing minimal concept, it would indicate to me free piston is the better way. Given the high efficiency and very low maintenance. Also, yeah seams complicated to calculate everything. But given that it is an stationary engine and you are not very constraint to mass, you can maybe approximate with physics modeling and then compensate adding mass to each moving body as needed to get the natural frequency as desired. (easier than modifying the springs or rubbers)

[@Robbedoes2]

Commercially available Stirling generators also use a free piston concept. So I guess they did their homework for us, so we only have to follow. They use helium though as gas inside the engine.

[@The_Bitruvian_Man]

@@Robbedoes2 do you have links to said commercially available Stirling generators?

[@eliottc5371]

I hope you go for the thermoacoustic engine because I find them fascinating but it may be wiser to pick the alpha stirling engine (and the IC engine if it doesn't work out)

[@myengines2443]

I also favor the thermoacoustic engine as the concept of no moving parts is really smart!

[@sierraecho884]

I could´t agree more with you.

[@kennethverhoeven3972]

For a second there i thought you said thermonuclear 😂

[@sierraecho884]

@@kennethverhoeven3972 Oh yeah this would be exciting. Ello guyz here iz ze German dude speaking. Today I will show you a thermonuclear home energy solution. XD Hahhaha would love that =)

[@GeoDevine]

Maybe investing more research in the purification of the wood/bio gas coupled with the use of a standard DOH generator will be more time and resources efficient. So, my money are on a standard combustion generator with a modified carburetor for wood/bio-gas fueled by a temperature/light/atmospheric agnostic methane producing bacteria. A 1000$ generator producing 3kw-6kw has cheap, fast and easy standard repair kits. The only problem remaining is the sulphuric filtration of the gas.

[@myengines2443]

Yes you are right, it would be the easiest way. But it also has the drawbacks I described and I am not sure if I can clean the biogas so pure that it does not destroys the engine very fast!

[@RingingResonance]

@@myengines2443 Pass it through a bunch of charcoal, recyclable filter media, then pass it through a condenser that is chilled by cool water or a refrigeration cycle? Engines on their own create their own moisture while running just from the combustion process. They are quite robust in that regard.

[@myengines2443]

I make a great effort to clean the biogas but it doesn't get clean enough to don't harm an IC engine I think! Plz look at my biogas video for it!

[@GeoDevine]

@@myengines2443 kzbin.info/www/bejne/anm7mH6Kprlgopo

[@guerrillaradio9953]

@@myengines2443 You are correct in the gaseous fraction of biogas being notoriously difficult to completely rid it of oxygen, particulates, tar, etc. It can stick a piston to a cylinder wall, a valve to a guide...bad news for sure! I've done limited experimentation, but it thoroughly ruined an old lawnmower engine I ran on it for a couple of months. It had to be fully disassembled and the cylinder re-honed to remove the dark brown tar mess. It was like duct tape, only more sticky, and it was everywhere! Have you considered liquefying the biogas before trying to filter it? I know it is a bit energy intensive, but may be worth it for easier cleaning. Digesters can also make a room temperature liquid fractional distillate, depending on your condenser, temperature, etc. That really simplifies things. Then, it's quite easy to pump the distillate through a commercially available diesel fuel filter, which is very effective and can filter thousands of liters in its lifetime, which could run a generator for a very long time. A typical diesel fuel filter is rated down to about 3 microns, because diesel injection systems must be absolutely spotless.

[@fredwupkensoppel8949]

Interesting, we seems to have very similar ideas. I looked into the same issue and came up with the same pros and cons. In the pursuit of low maintenance, I'm convinced that a sacrifice of efficiency is inevitable. A very simple system would be a boiler connected to a steam turbine - not as complex multi-staged one as the ones used in power plants like you showed, but perhaps a modified turbo charger is a good start to evaluate how much efficiency we leave on the table. The whining noise can probably be dampened to neighbour-friendly levels through a brick construction, perhaps with a double wall filled with fine sand to get a very dense enclosure. The upside would be that the setup can be both flexible (the turbine can be placed in many different places around the boiler), compact and mechanically simple (only two moving parts - the turbine and the electric generator connected to the output shaft - perhaps with a belt to avoid having to exactly align the shafts, but that's about it). I'd say it's worth a shot, but I admit I have not done any math nor experimentation on this and there is very little precedent to be found online.

[@myengines2443]

Steam really seems to be still very popular as I see in the many comments here! If my Stirling concepts fail I will try a steam variant but the idea of a boiler and many steam and water which needs a lot of space is not very attractive for me. A reliable Stirling can just run in my workshop and directly heat it without any wet mess.

[@fredwupkensoppel8949]

@@myengines2443 Yeah, they have significant advantages which I hope you can leverage given enough time.

[@Vega-380]

Very good analysis! I liked your criterias. My work is related with anaerobic digesters for small farms, we normally use internal combustion (genset) but I'm trying to find something more suitable for small gas quantity... thanks for sharing your video!

[@myengines2443]

You are welcome!

[@Bretzeljunge]

Free Piston Stirling engine is what i would like to see. I know that it is hard to calculate and not easy to manufacture. But it would be interesting to see and you definetly have the skills and the shop to produce it. Maybe start easy by dissasembling the one from microgen. You could try to reengineer it and also see if your calculations match the reality of the engine when you use its other values as input. Then expand from there. They should be available used somewhere from the boilers that had them installed. Great work so far!

[@myengines2443]

I think the Microgen units are too high tech to reegineer them! But thanks for your nice comment!

[@Bretzeljunge]

@@myengines2443 Hm thats too bad. Are there other more simplified FPSE that are or were on the market? You definetely need something to start from. What about the Generator? If you take the route of the FPSE, would you then also spool up your own generator? Otherwise it might be wise to start with an existing linear generator and then try to match the values that it needs through the stirling engine.

[@myengines2443]

Matching values because the have to is very bad. I prefer to make everything by myself so it fits perfectly. It will take longer but the result is better!

[@plinble]

If you're not phase changing working fluids, the best you can hope for is Carnot efficiency?

[@kreynolds1123]

Just wondering why the stirling engine was unsuitable for continouse charging? If its about c vs dc then rectification solves that, a pi filter (Capacitor inductor capacitor) smooths the output. And if the voltage is inappropriate still, then a dc to dc converter can get you to an apropriate voltage. And lastly a charge controller can ensure your not overcharging your batteries. Or was there another problem?

[@myengines2443]

The problem is that the power levels I achieved are so low that it has to run 24/7 to produce enough energy in winter. As a hobbyist it is very hard to get it reliable enough that the Stirling can run 10000's of hours without major maintenance. It makes no sense if I had to replace the whole running gear every few weeks!

[@kreynolds1123]

@@myengines2443 if low level ebergy (heat) is needed for winter use. Converting solar pv watts or wind energy to move 3× to 4× more energy into your home with a stirling heat pump with an electric motor. I've thought about using solar thermal with a heat exchange fluid and use stirling cycle to upgrade the heat being pushed into my home as to Supplemental heat. Supposing a coefficient of performance of 3 is relatively easy to achieve, then I could turn 500 watts of electricity into 1500 watts of heat. Just making some back of the napkin calculations and guesses. It shouldn't be too hard to make a solar thermal panel that has 1k of solar radiation shinning on it. Supposing it's collection efficiency is 50% would mean 500 watts of heat of solar thermal heat per pannel, and 3 three pannels would provide 1500 watts of solar heat. Supposing it's (20f or -6.67c) outside and the solar thermal raised the thermal transfer fluid temperature to (60f or 15.56c), then one would need to upgrade the temperature to (120f or 48.89c) with a heat pump while achieving a target COP of 3 or better. In theory, one could drop the thermal transfer fluid to below ambient temperature and pull in energy from both ambient heat and solar, but then there's risk of condensing frost on the solar thermal pannels which would lower their solar collection efficiency. it might be better to add more pannels in parallel to add collection capacity. And using a storage tank can store excess thermal energy into tge night and given enough, into the day. Given intermintency of sun and clouds, solar thermal is best to augment another means of home heating. Given the simplicity of thermal lag engines, I wonder how well they might work as heat pumps. But because of their lower efficiency, Realisticly I suspect the challenges will be achieving a sufficient temperature difference and suitable cop.

[@JessWLStuart]

What are you using the pink tubes for? Is it a pink fluid in hoses for cooling?

[@myengines2443]

Yes, its cooling water and the pink color is from the antifreeze agent for conservation!

[@BrokenLifeCycle]

So... Have you considered a different way to apply the Brayton Cycle? I find that it's surprisingly tolerant of how you can input heat into the system, and it doesn't even have to be a gas turbine. The Brayton started off as a piston engine called the Brayton Ready Motor, so it can be built using commonly available parts from piston engines and air compressors. Nuclear jet engines demonstrate that it can run off of external heating. Heck, if it weren't for the wear and tear, you can run a turbocharger off of a barrel full of wood, as demonstrated by Turbo Burn Barrel videos. Given all of that, would it be possible to make an externally fired Brayton Ready Motor? It separates the dirty fuel and combustion products from the pistons and seals, improving longevity. Because it's made out of piston components, it may offset its inherent wear and tear through commonly available and easy to source parts. The reduced efficiency due to being externally heated may be offset by being capable of running off of a wide range of fuel and fuel quality.

[@myengines2443]

Sounds interesting, I will watch out for it. Thanks!

[@paradiselost9946]

you took the words from my mouth. i know of it as a "furnace gas engine", bit different to brayton. cayley? a stepped piston/oversized piston rod, small side compressing into a furnace, whilst the heated air acts on the other side of the same piston. constant pressure. power output being the difference in areas x pressure. then the piston returns, drawing in fresh air on the small side and exhausting hot gas on the other. its a bit of a head trip because on one hand, the large piston is expanding the total gas volume, whereas the smaller side is compressing it. the expansion wins, the exhaust is at a lower pressure than the intake. without any heat applied, mind you! at that point... its a jet engine with pistons rather than turbines. book even mentions the concept of turbines... 1912. only steam turbines at that point still.... valves were the issue, dealing with exhaust gases... so. i made a fireplace, two gas bottles inside one another, hopefully welded to deal with pressure! idea was a turbo burn barrel, external combustion. but the last few days ive been thinking of doing a furnace gas engine... poking around at bits of suitable scrap... the turbo? need a certain air speed, air mass... surface area, temperature rise, before it will even run. may be wasting my time... got a few small turbos, but yeah... go to the effort of plumbing up, only to find at self sustaining speeds i cant keep it hot enough to self sustain... meh. why bother? learn nothing! (i made ANOTHER one with twice the surface area, lol? i like making fireplaces...) whereas as soon as the check valves close and air has no escape, and must expand... the piston variety will produce force on the piston. as long as it has sufficient flywheel inertia, (or multiple cylinders?) to get past the return stroke, it will run... i sort of plan on documenting it, but yeah... my luck with videos and digital stuff... ahem. sealed, closed loop... you can pressurise the system. last thought... water will expand and contract with heat... ive wondered about if a striling could work filled with water... obviously the ratios have to be altered to suit the amount of volume change... rather than waste time with phase changes and all that nonsense....

[@OffGridInvestor]

I was thinking of alternative things. In the end a regular single cylinder generator for all the big power draws and solar for the small power draws has been fine for 13 years now. I have an overhead water tank that gets filled when I do the washing.

[@myengines2443]

you mean a conventional IC engine?

[@12prasad21]

Excellent work. Have you considered a simple alpha Stirling? That will be both powerful and long-lasting (Ic engines run for years without too much wear). Best wishes!

[@myengines2443]

The alpha engine seems to be the simplest stirling but has two pistons to seal and with an easy drive mechanism a lot of piston side forces. Thanks for your nice comment!

[@StanislavZachazevski]

Then one can go alphagamma way :) half or less of side force. Easy to balance. Mine first did run. Do have some technical limitations. But still first engines shell not run.

[@myengines2443]

The gamma configuration has some advantages. I think their thermodynamic drawbacks are insignificant!

[@StanislavZachazevski]

@@myengines2443 not gamma. Please google for alphagamma stirling. Its is mix of both of them.

[@Inventerius]

I would suggest a simple readily available internal combustion engine (inexpensive and easy to replace / spare parts 9n stock everywhere) and find a way to filter and clean up your gas.and add a noice enclosure

[@myengines2443]

I am not sure if I can clean the biogas so pure that the IC engine (especially a cheap one) will last for long, surely it would be the easy but also most boring way!

[@spod2011]

Look at an Arrow C-46 (natural gas oilfield​ engine) @@myengines2443

[@lolcaio]

How to convert the burn ring to electrical resistance?

[@lolcaio]

How much watts would it consume to achieve the best performance?

[@ThalassTKynn]

I think external combustion is definitely the way to go. I personally would probably choose a design that's easier to make/repair and make up for power limitations and reliability by having multiple cylinder pairs in one generator or multiple generators to give redundancy. But there would still be a minimum viable reliability. Man, you have set yourself a really difficult task!

[@myengines2443]

Thank you very much for your kind comment and your sympathy!

[@guytech7310]

Steam is a better option if your going to use a gas or biomass fuel. Best option for long term continuous operating would be a turbine since the only moving part is the rotor shaft & bearings. You can make the rotors using thin lamnations welded together to create simple impulse rotors.

[@myengines2443]

Steam still seams to be very poular as the mane y commentarys hers show, I will think about it!

[@DanielSilva-jj2lz]

I believe that the best option is a conventional diesel engine adapted to run on gas with a spark plug, with a piston and piston liner made of 316l stainless steel. This way we would have an idea of ​​whether it is viable to build an engine to burn LNG in combustion cars.

[@myengines2443]

Is it common practice to use stainless steel piston and cylinder liner in IC engines? I thought the sliding properties of stainless steel are to bad for this. A full stainless combustion chamber would be nice and could be the solution but I never heard of it!

[@Robbedoes2]

​@@myengines2443stainless steel is indeed known for seizing. I don't think it's gonna work.

[@zbarjevsky]

Did you try to use heat pump as heat source?

[@myengines2443]

No, I want to use my self produced biogas in a micro CHP.

[@ВасяВасин-ю7й]

Regarding steam engine I suppose it's worth considering the flash boiler scheme with small thick wall tube boiler with water injection "on demand", so it hasn't much pressured steam inside and needs less maintenance. It's not suitable for large powerful engines, but for small-scale power looks applicable, and was used in some steam engines in late "age of steam". I think in case of low grade fuel (e.g. wet and dirty biogas) steam engine is the best solution because of it's tolerance to fuel parameters flow by design.

[@myengines2443]

Yes, steam engines seam to be a big deal as I read in the many comments here about them. I will take a closer look upon them especially the monotube and flash boilers! Thanks!

[@OffGridInvestor]

I have a book on a guy that has used a cast iron hit bulb diesel weekly to charge his battery bank and heat water for him. He's seen other use wood fired steam but it's a VERY hands on set-up. Have to be at home while it runs and takes a while to get going. It works, but it's a fair bit of messing around. Personally I use solar for small draw things, and a generator for water pumps and washing machines and power tools, with a 600 litre overhead tank that runs my water during the week.

[@VEC7ORlt]

Not sure how deep the rabbit hole goes, but my vote is for free piston engine - seems the best from manufacturability point of view - most if not all parts only require lathe work, spring stacks can be lasered or etched, the generator is basically a loudspeaker motor in reverse. I'm not entirely sure about the parts where you apply heating and cooling.

[@myengines2443]

Yes the free piston Stirling is very nice but has also issues with wear and mechanical friction like the rhombic Stirling. So maybe a TMG like low tech version with rubber diaphragm and increases stroke may be possible? The heat exchangers in a conventional free piston engine are the same, only a TMG style can make use of the big diameter an can use plain ones.

[@VEC7ORlt]

@@myengines2443 gave TMG a closer look - very impressive indeed, I wonder why it didn't take off? Or are the cryogenic pumps of today a reflection of that design?

[@Silberschweifer]

What about Fluid Stirling Engine? I think they are for you the best choice

[@myengines2443]

I think they have very low power. But if you know a powerful design it would be very interesting...

[@skyw4278]

Is there a way to have a capacitor included somehow?. Give the weak input a boost?

[@myengines2443]

I don't understand what you mean, can you explain it please?

[@skyw4278]

@@myengines2443 I'm not sure if I can get anymore technical...sorry.

[@orpheuscreativeco9236]

Is it super cold where you live? If not, there are plenty of other ways to extract heat from the earth beneath the ground, in conjunction with running black garden hose through enclosed solar still type boxes. Run PEX pipe through the subfloor of your home (as well as high R-value insulation), circulating the warm water with small inline pumps, and you will never be cold. You can even install inline heaters just incase you need a little more heat. Heat rises up from the floor, warming your feet on the way into the house, which will keep you toasty in just about any climate. I helped install a similar heating system here in the USA, at the same latitude as Berlin. Just a thought. Very cool engineering though! I don't mean to detract from your efforts. I really appreciate the time and thought that you have put into your engine designs 🙏 Thank you for sharing ✌️✨

[@myengines2443]

In first place I want to generate electricity, heating is a byproduct and even not a big problem as we have enough firewood! Thanks for your nice comment!

[@orpheuscreativeco9236]

@@myengines2443 Ohh! I see 🙏 In that case, the Stirling is a great choice 👍✨

[@j78513]

I would want to know, what are you using for lubrication? I don't see any kind of oiling system on any of the rods or bearings.

[@myengines2443]

Yes that's the problem with the Stirling, any lubricant in the working space will contaminate the heat exchangers, especially the regenerator. This makes things much more complicated and is the reason to use the 'bulky' Rhombic drive which has no piston side forces!

[@j78513]

@@myengines2443 could the gears in the crankcase be coated with a solid lubricant like MoS2? The piston itself seems to be a solid piece of material. Could the issue with the piston be thermal expansion of the metal as it heats up?

[@myengines2443]

I lubricated the gears with a bit adhesive grease as you can see in detail in my older videos a few weeks ago. The piston gets hotter than the cooled cylinder and that causes seizing problems. I am not sure how to deal with it because I think the way to go is close tolerances without piston rings!

[@Pystro]

@@myengines2443 Wouldn't you run into the same problem with the other Stirling engine types? They all(*) use a cylinder for which you have to decide between "guessing" tolerances and using lubrication. And they all have regenerators that would get contaminated by the lubrication. Or do they allow you to use lipophobic regenerators? If your lubrication can't condense or gather on the regenerators, then you wouldn't have any problem. (*) except for the thermoacoustic Stirling.

[@RustyInventions-wz6ir]

Very interesting. Nice work

[@myengines2443]

Thanks!

[@travismoore7849]

I suggest you use a thermal acoustic pipe that will make a high pitched sound to make power by vibrating piezo electric elements to make power. Where you only need to harvest the energy with a diode bridge and maybe capacitors that dump power into a battery bank once the capacitors are charged.

[@myengines2443]

At the moment I am building a thermoacoustic prototype model to get familiar with the principle. I hope to report a new video about it soon!

[@arandjeljovicic5031]

I suggest 2st option TMG style even though you probably wont make enough power from one unit you can always stack more of them. Most important thing is that they are efficent, reliable, no maintance, versitaile (many fuel choices) that is more important for offgrid system if you ask me.

[@myengines2443]

The TMG is a very elegant concept but the design is really hard I think. But the reliability is really an argument!

[@Geri_crs]

what is with a Rhombic Stirling engine with extremly thin oil wich in constantly filtered with a small electric gear pump to provent clogging ?

[@myengines2443]

This will not work with the high temperatures in the heat exchangers.

[@Geri_crs]

@@myengines2443 you right the highest temp oil i found is ratet for constant 200C and short time 450+C, i also dont think that will work. But if you use bigger surface heat exchangers and dont go over 500C outside the heater do you think this wille be efficent enouth ? Oil has a higher thermal conductivety than air or helium so i think oil film or little oil wettyness on the heatexchanger will not matter but the temp thing. sry for my bad english

[@Geri_crs]

*to provent clogging from wear particles form bearings, seals, moving marts and small amounts of coaled degraded oil

[@ScaryJ1701]

I would love to hear your thoughts on a large(ish) alpha Stirling, specifically one using a Ross yoke

[@myengines2443]

Yes that is still one option the Ross yoke is really nice, thanks!

[@oddzc]

You can buy free piston stirling coolers, they arent cheap but id be interested to know if they could be adapted for power generation

[@myengines2443]

They can't because the heat exchangers are made for the different temperatures. Also the are build quite different and are expensive.

[@briangrundeman3732]

I would like 2 try a radial engine of sterlings ganged to gather and ran with hot air. The hot air from hot water heated with gas or solar and stored in a insulated storage. Give that some thought.

[@myengines2443]

Which radial engine you mean? The temperature difference has to be as high as possible for good efficiency and power, boiling water is not hot enough for a small engine.

[@samsawesomeminecraft]

perhaps a fuel cell can run on mixed fuel gas like biogas? On one hand I heard fuel cells are very picky about their fuel supply, but if it works, it could be very effective.

[@myengines2443]

Can they run on biogas and produce electricity directly or have they first be converted in hydrogen?

[@sierraecho884]

Since I saw your first videos with the rhombic configuration I thought "damn this dude is really proficient but why does he use this design ? So much potential here" I just wanted to propose a 4 cylinder engine with double acting pistons BUT YOU HAVE INCLUDED THIS ONE ALREADY. I am really pleased to see that, well done mate =) I can´t wait for the next design and I couldn´t agree more on the design choices. Now I am really eager to see how you will rank the design choices, maybe through a pugh analysis ? Considering the "semi hobby like" nature of this projects (no offense you are a professional but you don´t have the means to develop a new engine with a team of engineers), my favorite would be the 4 cylinder engine. It´s probably the biggest and heaviest option but in this stationary application it should be no problem besides it´s most likely the simplest and cheapest to produce. Also probably easy to service and you should be able to use many standard parts like a cylinder block and pistons from an existing engine for example. However the thermoacoustic engine interests me very much as well but it´s probably more of an interesting though than a practical engine has you would need to do so much more R&D on that one. I mean it would probably be the best theoretical contender but for it´s lack of moving parts and overall simplicity but again I feel like it´s way more complex to produce a really well made one.

[@myengines2443]

Thanks, I will put that in my consideration!

[@borium]

Great video ,have you tried a vacuum engine or also called a flame eater ,a type of heat engine .the main problem with heat engines is when you size them up they are less efficient, so why not use more than one smaller engine .cheers

[@myengines2443]

I never heared of a powerful flame eater engine, does you are anybody else?

[@borium]

I never heard of them before either ,I found one at an antique store and had to research it to find out what it was ,it turned out to be a solar 3 from pm research ,it seems to have a lot of tork for the size of it ,I have seen larger size ones on KZbin that may produce more power ,I am still experimenting with mine ,I plan to run a small generator from it and see how long I can run it at one time.

[@sigmawarrior.fokeryou]

I saw something about using the flame to heat a sodium mass that will emit a tuned light wave to be collected by a tuned solar panel that will have much more efficiency

[@myengines2443]

Do you know at which temperatures this works?

[@burnologist229]

Tesla turbine, with steam setup, Charlie solis has a bunch of videos and research on the matter. Tesla turbine are quite simple and cheap to manufacture, the only concern would be the boiler for steam.

[@myengines2443]

That are also my thoughts, in an other comment threat here is a discussion about monotube boilers, maybe this is a solution?

[@yeahright3348]

@@myengines2443 I'm curious about actual results from tesla turbines, i can't find any diy projects with any meaningful results. Some of the people seem a bit iffy to me, i would love to see somebody i trust investigate tesla turbines and let us know if there is any future in them.

[@burnologist229]

Have you considered nitinol heat engines?

[@myengines2443]

Do the exist for higher powers?

[@burnologist229]

​@@myengines2443 YES, they do exist for higher powers, in my experience messing about with nitinol engines the most promising are the linear motion engines. 1 square inch of nitinol exerts a force of 25,000PSi. linear motion Nitinol engines "work best" when treated as a "burst system", In other words they create Large amounts of energy at once. They can be coupled with linear Stirling engines to greatly increase performance and thermal efficiency. Nitinol when compressed/bent stores heat energy, and when decompressed gets rid of it, the temperature difference can be around 15-20C. See where I'm going with this? you can have an active passive regenerative cooling system integrated into a Stirling engines design, with the benefits of increased torque generated by the hybrid system.

[@DeanLogan]

I have no suggestions, but I am definitely curious as to what you figure out. Good luck! Is the biogas engine on the same level as a gasifier as far as your worry about wear and tear due to the fuel not being clean enough? I am guessing that attempting to purify the biogas more would just lead to higher energy requirements and defeat the purpose.

[@DeanLogan]

I realized later that you probably wouldn't want to do a gasifier due to lack of sufficient inputs, compared to a biodigester.

[@myengines2443]

I want to use a wood gasifier as a backup in winter when the biogas has ran out also. So the engine has to be robust because its not easy to clean wood gas and biogas so pure that they don't take damage!

[@PatrickKQ4HBD]

If your current rhombic produces 300 W, can you not put six or seven in series on a common crankshaft? Perhaps it then becomes a question of producing enough biogas to feed them? Perhaps you could explain better what you mean by service interval? Do you mean refueling? Cleaning out? Replacing parts? These are very differing levels of concern.

[@myengines2443]

By service intervals I mean replacing or repairing worn out parts like the piston rings, the cylinder surfaces and bearings. This is quite work intensive. The engine is simply too complex and expensive to build multiple of them!

[@felipealmuna4336]

Why not use TEG?

[@myengines2443]

You mean Peltier elements (Seebeck effect) ? Its my last candidate if you look the video to the end.

[@CNCmachiningisfun]

Talking of woodgas for an IC engine, you'll be surprised at how clean it is :) . Even after thousands of hours of operation, corrosion of my engine's internal parts is simply not an issue.

[@myengines2443]

You have a very big IC engine I think? Mine would only have a very low output and would therefore be much more vulnerable?

[@CNCmachiningisfun]

@@myengines2443 My first system had a car engine on it, but I went with much smaller engines after that. I use the working parts of portable 2KW generators, that I have taken out of their frames, and installed on the cart, with the gasifier. Corrosion is not an issue with these, but they do start to wear out, after about 1000 hours, because they are rather cheap engines.

[@robertpoynton9923]

Will you be updating any videos on you set up?? I would be very interested in this. I'm still in the building phase but still needing ideas on how to set up and process the woodchuck like you have in your wood pallet video. Cheers from Australia

[@CNCmachiningisfun]

@@robertpoynton9923 Sorry, I have been inactive in that area for a while, as I am in the process of moving to a new farm, and building a new machine shop. Still though, we may be able to swap some notes, to help get your new project started :) .

[@robertpoynton9923]

@@CNCmachiningisfun sounds good mate! I'd love to pick your brain

[@BuckarooBanzaiMsm]

I've been getting an itch to build a rhombic drive and I decided to watch all your videos from the beginning to in sequence. It seems you had put so much effort into getting this to work and I thought you where making progress. It's a bit of a bummer that you're thinking about moving in a different directions. You mentioned your primary reason for abandoning your design was over reliability issues. I understand that part of your constraint is the diy aspect of this with the equipment you have. The question that I ask myself, was did the original phillips engine also suffer from these issues as well. If equipment, time and money, where not the constraint, how would you solve this problem. I don't know if this could be a solution or not but it seems to be that the lower portion of the drive, the linkages, gears etc should be bathed in oil. You mentioned that you needed to keep oil out of the compression area because it would foul up the regenerator. Would there be a way to have a oil sump isolated from the piston/displacer (Bellows perhaps)? Fwiw.. I don't exactly understand how your regenerator works. I saw a couple other designs where the displacer was also the regenerator, which is not the case in your design.... Was there a video where you talked about your regenerator and I just missed it? It sounded like you had many technical challenges with the compression cylinder.... How do the big boys do it.. It sounds like you might be moving to a free piston design, would those piston issues carry over to that design as well?

[@myengines2443]

I will still develop the Rhombic engine further, I just need something new now for a time! The Problem with it is that the Rhombic Stirling is too complex and therefore it would be ridicoulus expensive. So I have to make it simpler, more powerful and also less maintenance intensive which is a big task. The Philips Rhombic engines were succesful but also too expensive for the market to compete with other engines. If you want to use oil in the crankcase and/or on the power piston you need a oil scraper ring which is also quite complex. The regenerator is a very fine wire mesh and stores the heat between hot and cold and raises efficiency. I think you can see at least a part of it in the video "development of the rhombic Stirling engine" a few years ago. I did not decided which concept will be next as I got so many suggestions here that I first have to sort everything. Greetings

[@alimardani-t8z]

You are real scientist. Can you test the reflection dish for heat source and find the best mechanism for that

[@johnwyman6126]

For what it's worth, if you choose to go with a conventional I/C engine, you can add automotive water injection in order to control and eliminate the by-products of the dirty fuel, along with adding power and efficiency due to the mist flashing into steam. If you want to try an easy turbine style look into the Tesla turbine which uses no complex blades, and is quite easy to machine. For a large, inexpensive diaphragm, they can be found used in large truck brake canisters. If adding a generator to a battery based Renewable Energy System, for best efficiency, match the generator/charger output to the ability of the battery to accept the charge. For example, if you have a Lead Acid battery, they have a C/10 best charging rate. Therefore if you have a 1000 Amp hour battery you should charge at a maximum of 1000Ah÷10=100Amps. Different battery chemistries have different optimal charge rates. Thank you for sharing your experiments with us, it is very interesting. I have not seen all of your videos, and I'm curious what excessive maintenance is causing you to abandon this project to charge your system?

[@myengines2443]

Thanks for your many suggestions! I do not abandon the work on the Rhombic Stirling, I just want to try something new now, mainly for motivation. The Rhombic engine is very complex and therefore too expensive and maintenance intensive to really reasonable produce some energy for household use. It has to be made much simpler for rational use but first I want to investigate if something different may be more easy!

[@maranmarantakeiteazie]

I note that you have taken down your earlier acoustic engine video from 10 days ago. Any reason for this?

[@myengines2443]

I have to change pictures in the video, it will be back online in a few days!

[@maranmarantakeiteazie]

@@myengines2443 Excellent!

[@Ezio-Auditore94]

Can't the biogas be filtered and clean to a degree that the ICE won't degrade? If not I think the free piston engine is the go-to. Good luck with the project

[@myengines2443]

I am not sure if I can filter it enough to not damage an IC engine. Thanks!

[@MrHerhor67]

I am a fan of steam power, with some lubrications the pistons will probably outlive everything... The rubber in stirlings will wear out too, if you are worried about wear...

[@myengines2443]

You are right, rubber will also wear but can be replaced very cheap and easy. Steam power is really not dead as I thought...

[@LexYeen]

I'd suggest avoiding thermoelectrics, they're inefficient and fragile both physically and thermally. Have you given any thought to beta stirling engines? They're relatively compact, there's only one cylinder to worry about sealing, and if you want expansion capability you may be able to link them in an inline configuration that allows for shared heating or cooling. Edit: Also, consider your electricity generation method. I've seen a few tinkerers on youtube getting impressive results with axial flux designs, and I feel they have promise due to the design's stackability.

[@myengines2443]

The Rhombic Stirling is a beta design. The cheap thermoelectric elements are really not suitable. But maybe self made high temperature ones made with magnesium and other new discovered materials may be possible? The axial flux generator is a good choice if you have a rotating crankshaft!

[@LexYeen]

​​@@myengines2443Rhombic is a fascinating design, but it incurs gear losses instead of just bearing friction losses, yeah? And it certainly looks easier to make and maintain a beta than a free piston. Maybe it's my love for simplicity biasing me! 😅 Edit: As for thermoelectrics, I wouldn't hold my breath waiting for improvements to trickle out of labs. Instead, maybe augment your biogas with HHO mix from a small low-output water electrolysis cell? It's no infinite energy glitch, nothing is, but adding a mix of 2:1 hydrogen and oxygen gas would likely improve combustion efficiency.

[@crestfallensunbro6001]

imo the oversized alpha is the best option, constant running is a very restrictive requirement and if you are charging batteries is unnecessary.

[@myengines2443]

The problem is that high power levels are difficult to achieve with these engines!

[@crestfallensunbro6001]

@@myengines2443 an idea worth considering would be having multiple units slaved together which would give 2 layers of downtime compensation, firstly they wouldn't have to run 24/7 and secondly if you make one or two more than the minimum needed you could swap out units for maintenance.

[@zthihasan5169]

Since old vidoes my pick is still alpha and it can be use with engine oil like 4 strokes engine to reduce wear.

[@myengines2443]

Oil will contaminate the heat exchangers and can only be used without a regenerator and very low temperatures or the hot space will also be clogged!

[@wayne851]

Is relative anonymity important to you, or could you elaborate on how you came to your cutting-edge hobby?

[@myengines2443]

In my late childhood I came in contact with the Stirling engine and since then I was addicted to it! I find the possibility of generating electricity from just heat very fascinating till today! Also my constant progress is also very motivating, even if there are always massive setbacks. Now I am in a position to really produce our own energy besides the solar plant and can try to make it simpler and cheaper that also others can use this fascinating technology!

[@wayne851]

@@myengines2443 Thanks

[@tomlearnmakelive]

My first experience with thermoacoustic engines are that it is a little work to calibrate every parameter right for best output. Probably this could be automatic done by some sensors and an simple algorithm. Alpha Engine seems good for a bigger power output.

[@myengines2443]

Did you experiment with a traveling wave thermoacoustic engine? A little work to calibrate sounds very promising, I thought of VERY much work to even get it to run!

[@tomlearnmakelive]

@@myengines2443 I tried standing wave and traveling wave configurations but only with a speaker and no heat source as heat pump. so it was easy to setup with some pluggable pipes from the hardware store. the traveling wave engine was a little easier to get running. but still work in progress. i made 3 regenerators from steel wool, plastic straws and a 3 printed stack of layers. next step for me will be to get a microphone and some thermal sensor. so i can get the max amplitude and the resulting temperature difference. for the amplitude i bought some 30$ oscilloscope online.

[@avto4464]

Thermoelectric generators are generally extremely inefficient, but you could actually make use of a particular thermogenerator that operates at the same temperature that the methane in your biogas would burn (given a high enough purity). See “Thermophotovoltaic efficiency of 40%” by LaPotin, A. et al. It’s a feasible build. Good luck!

[@myengines2443]

Thanks, I will look out for it!

[@McRootbeer]

Thermal lag or free piston seem like the best options to me.

[@myengines2443]

Yes that are also my thoughts!

[@McRootbeer]

@@myengines2443 have you read Stirling and thermal lag engines motive power without the c02?

[@McRootbeer]

@@myengines2443 In it, Dr. Organ designs his engine for solar, designing to use a fresnel lens and quartz glass to heat the engine internally. Do you think something similar could be achieved with a biogas powered engine by incorporating a burn chamber inside the hot end? Something like a pipe that runs through the hot section, with inlets for gas and air, an igniter, and an outlet for c02. Could there be an advantage to an internal burner system?

[@myengines2443]

I am very familiar with the work of Allan Organ and he kindly helped me several times with my engines. I have also the book and I know the engine you mean. My 4 bar link engine is built according to it without the quartz window, look at my older video about it. The aim of his design is to get a higher temperature difference inside the engine but for me its not possible to deal with these high temperatures although it is quite interesting! For me its hard enough to deal with the 'normal' temperatures inside my engines. If you can handle it it has surely a great potential.

[@McRootbeer]

@@myengines2443I'll go back and look at those videos for sure👍. But what I was thinking wasn't increasing the engine temperature, but improving heat transfer to the hot end. If the burner is in the hot end, all the heat has to radiate out... Into the hot end working fluid, minimizing heat loss to the environment, reducing the fuel required to maintain engine temperature, and simplifying burner construction. Plus, you could insulate the hot end to further prevent heat loss from the hot end.

[@Huntloserpyrotechnik]

Have you ever Heard about the ST05G? A 500W Alpha Stirling building kit with integrated Generator? For a few your ago, you can buy this building kit in germany.

[@myengines2443]

Yes of course, I brought the plans years ago and studied them!

[@Huntloserpyrotechnik]

@@myengines2443 ahh great, These Engine are really good. We have one of these in our laboratory in the university in Bremen (Germany). But we lost the plans of these Engine. Where are you from?

[@DeeP_BosE]

French EURODISH is an alpha type with pressurized He, reaching thermal to mechanical power conversion ratios at 40%

[@plinble]

Yes, use He to make manufacturing in volume quantities impossible. How about propane, methane, ethane, or butane?

[@davidfleischer4407]

This is probably a case of experimenting and measuring which engine is more effective in practice

[@myengines2443]

Yes and I want to investigate which concept I will try first for a study model first. At the moment I prefer the Thermoacoustic Stirling but I get so many good suggestions here on KZbin now that I really have to evaluate all these ideas!

[@davidfleischer4407]

@@myengines2443 perhaps we can collaborate on the design. How do I get in touch?

[@myengines2443]

@@davidfleischer4407 best way is here in the comments here on KZbin!

[@davidfleischer4407]

@@myengines2443 very well. It seems the free piston design is the best candidate. I would target a small model with modest output, but that can be measured reliably. Less than a commercial model, but more than one of the hobby diy designs.

[@ollimacp]

There is a open source nasa diy stirling engine and Robert Murray Smith did a Video on that! Really low tech but efficient and could be maybe scalable. if you run multiple machines simultaniously and due to modularity you've only had to change the ones failing. Could be a cool concept

[@myengines2443]

I think I know which engine you mean, it really has low power. But I will look at it maybe its an option, thanks!

[@mikenorfleet2235]

Honestly, the best analysis starts with your lifestyles and energy use....like most people tend to like to have hot water on tap, so keep the bio-gas energy as thermals as a simple water heater and it can be consumed immediately in the design of on demand hotwater heaters or in a tank storage with reasonable insulation (usually only loosing about a degree C/day stored). This will keep the number of energy transformations low in your house "system". Think how can I get the energy to where I can use it fastest onsite from my generation sources? Solar panels are very useful in this category since most modern amenities rely on electricity as an energy form and it doesn't need to be transformed. Since you have biogas digester, then burn it for thermal energy loads in your house, like water heating. Ask yourself if your hot water consumption will be lower or higher than the amount of Therms you can get from biogas generated onsite? This is the best approach energy wise...but stirling engines are so attractive to engineers and tinkerers. I dream of the day when I have two gigantic thermal reserviors burried under my house, one for cold store and one for hot store that I can just run through my heat engine for on demand power forever!!!! I have to calm myself down and ask where am I getting all this untold energy from? Your resources (sun, bio-gas, geothermal, local utilities) available to you will dictate the best engineering design for your house.

[@myengines2443]

The generator has to run as a cogeneration unit. All these very small engines have small efficiencies and all 'wasted' energy is used for heating and hot water. Thanks for your ideas!

[@Hydrogenblonde]

The standard piston engine. It will probably make the most power and hence reduce the running time. Have a spare cylinder head you can swap at a set interval and clean and refurbish the other head while the first one is in use. Accept the need for maintenance.

[@myengines2443]

I don't want to accept too much maintenance as long there are better possibilities like the ones I am searching for... But surely the IC engine is the easy way!

[@fredbloggs4829]

I remember when electric cars first came out and I discovered that they were basically 1000's and 1000's of 18650 style batteries. I was shocked. Not really high tech, just throw enough of the little ones at the job to get it done. And it worked. I think a small investigation into Peltier devices might be worth it. No moving parts at all makes for compelling motivation.

[@myengines2443]

Yes it would be very easy but many here advised me against it to use the cheap elements. But maybe self made high temperature modules with magnesium etc. may be possible?

[@contentontherock1958]

Great comment! I like to build stuff as much as the next man, but after being off grid energy wise for 8 years now even I can see that the solution for me at least is a simple PV system. Solar panels are cheap and we are awash with cheap lithium storage, I’ve gone for years with used 18650’s, now with Lifepo4. The fun is in the journey not the destination, I’m going down the sand battery rabbit hole now to try and get me off the wood stove thanks to inexpensive PV. Hard to beat cheap brute force but I still have a soft spot for gasifies, turbines and sterling engines.

[@olafberend8837]

Ein Agregat ist immer noch sehr günstig in der Gestehung. Da lohnt sich schon noch der Aufwand, einen besonderen Schalldämpfer und Einkapselung mit Belüftung zu bauen. Das Biogas muss ordentlich mit Stahlwolle entschwefelt werden und mit Betonit (Katzenstreu) entfeuchtet werden. Bei 1000h Haltbarkeit kommst du mit diesem pragmatischen Ansatz noch am besten weg. Auch wenn ich den thermomechanischen Sterling immer noch für den Haltbarsten halte, aber auch 700h+ Entwicklung und Bau kostet. Wann willst du Ertrag sehen???

[@myengines2443]

Es ist schon ein Hobby, darum kommte es auf die Zeit nicht so an. Und 1000h sind nur gut ein Monat im Dauerlauf! Ich gebe mir schon große Mühe mit der Biogasssäuberung aber richtig rein wird es nie...

[@olafberend8837]

@@myengines2443 Einen Honda mit knapp 2kW Nennleistung auf Gas und dann mit ca. 50% mit Biogas. Bei 1000h sind das 1MWh el. Meinen 15kWh Speicher macht man damit recht schnell voll. Mit ner WP im Abwärmestrom der Kapselung kann man aber so einige Winter durchkommen... Und Reinigen mit zwei Säcken Aktivkohle aus dem Aquariumbedarf sollte auch ca. 2 Jahre halten für die Reinigung. Wenn du vorher mit Stahlwolle und Bentonit vorfilterst. Wenn das nicht blau brennt, komme ich vorbei...

[@BasementEngineer]

No matter how you slice it, to produce electric power one needs mechanical motion. There is one exception to this but the extreme temperatures required preclude domestic use. I firmly believe that a rhombic drive Stirling engine can be built with minimal maintenance requirements. Consider industrial Diesel engines that run thousands of hours without extensive maintenance. I know that with modern coatings sliding surfaces may operate with minimal or no lubrication. Any Stirling engine for a given power output and efficiency will encounter similar complexities, namely the heat exchanger design and manufacture. For my money I'd design and build a milling machine that mills the internal fins on the hot cap. With a bore of 6 to 7.5 cm that would not be a problem and it would be much faster than EDM or slotting. An alternative I had considered is to machine external fins onto a liner sleeve that fits into the hot cap. These fins would then be nickel brazed into the hot cap. This also has the advantage of a well defined gas flow passage when the displacer piston is moving towards minimum displacement. If you have much free fire wood available I'd go with a wood gasification plant. During WWII many vehicles were powered with this arrangement and much experience acquired as to scrubbing and filtering requirements. KZbin has a number of channels with promising designs. Good luck with your endeavours! Greetings from Canada.

[@myengines2443]

I tried many ways to manufacture the heat exchanger fins (including milling and sawing on my milling machine!) and the EDM method is by far the most comfortable. The heat exchangers of the thermoacoustic engine are very simple to make in comparison, that's one reason why I favor it! I will use wood gas when I haven't enough biogas in winter. Thanks and best wishes!

[@nigelwilliams7920]

I would add Thermoelectric generators to your list as a way to use the low-quality heat you have there. With your expertise in making hot ends for your Stirling engines I'm sure you could get the most out of the gas supply. Low efficiency maybe, but the ultimate in 'simple' and zero maintenance. Also, ask yourself what type of energy do you need? Would the gas be better used to heat water that could be used for space heating and other domestic uses, and for direct heat for cooking, reserving the solar electricity for things that need electricity? You could also use the gas to heat a rock or sand store to higher than 100C provided you do the insulation very well; thus giving yourself a multi-day energy store. What do you actually need: mechanical energy (reciprocating, rotating et al), heat or electricity or compressed air? Are your energy needs and available energy seasonal? Does your digester work better when heated (I'm sure it would) especially to increase production of gas when your solar energy output is low in winter. If the Atlantic meridional overturning circulation (AMOC) slows you will need all the warmth you can get!!!

[@myengines2443]

Surely I want to use the 'wasted' heat from the generator completely to heat the digester, heat water and warm our home. In winter the solar plant unfortunately produces very low energy.

[@martin09091989]

The most efficient and reliable solution would be also the most boring one.... Internal combustion engine! But the fun part with that would be to optimize the shitt out of it! 😁 I would suggest to use a bike engine instead of a stationary equipment engine. Those lawnmower engines are cheaply build and very inefficient to start with. For example the engine from an old Honda CB125 or 250 would be perfect. Those engines are absolutely bullet prove! You could increase the compression ratio slightly and optimize valve and ignition timing for lower rpm. And the bio gas should not be a problem at all, just filter it through a bubbler to get rid of solid particles. The moisture is perfectly fine for an IC. You might even could experiment with water injection, especially on the hot burning methane gas. 🤔

[@myengines2443]

If everything else fails I will try an IC engine, not before. But many thanks for your suggestions!

[@plinble]

Phase change organic Rankine Cycle Engine with bearing free, near friction free, magnetically mounted turbine? Two drops of oil every week isn't too much? Are you confident to have butane as a working fluid? Diamond or saphire bearings might be much more better than oiled steel. They worked this out about 300 years ago when making watches.

[@martinmaerzinger3400]

I will make a Lage Alpha Stirling configuration, because a V-Engine from a Twin V-Air compressor is very cheap. And with a big cylinder volume your heatexcangers are in relation smaller, so the death-volume is lower.

[@myengines2443]

The V configuration is very easy but also involves heavy piston side forces without crossheads! Small dead volume is good but you need as much heat exchanger surface as possible!

[@BokoMoko65]

What about a small microturbine, or a pair of microturbine, the kind used in RC models, burning the biogas in optimized RPM for burning such gas. The microturbines are coupled to alternators also optimized for that particular RPM regime of the turbines. These turbines aren't expensive and there are some turboshaft models already available.

[@myengines2443]

Do you think they have a reasonable efficiency?

[@BokoMoko65]

@@myengines2443 Turbines are the most efficient way to convert chemical energy in mechanical energy. The problem with turbines is that they don't have much torque at lower RPM and they are expensive. So, some engineering is needed to couple a turbine to generator so solve the former. The issue of cost is solved by mass production of a consumer (?) item like RC model aircraft. Maybe. I think it's worth the investigation. One of the main advantages of turbines is that they can easily me configured to burn different fuels and mixes of those fuels.

[@oscarverwey]

What i did is modify a old diesel engine to run on woodgas I have a tar free gasiffier design to so the thing is spotless it produces 5 kw/h (derating is 20%)

[@myengines2443]

I would mainly use biogas from my micro diy digester and it is not easy to completely clean the gas so it does not destroys the IC engine really quickly I think!

[@oscarverwey]

@myengines2443 cleaning wood gas is most often a bigger problem than for biogas. first, make it dry. Then filter the dust with rockwool en after letting the acidic stuff do its thing to something like a steel wool filter , then its perfectly fine to burn it in an engine , I recommend making it a 2 stage system so let a Stirling engine run of the exhaust gasses of the otto engine you can Get 35/40% thermal efficiency mevy more 😀

[@atntaltd]

really nice , your efforts will payoff

[@myengines2443]

Thanks!

[@jds1275]

Why not use a sand based thermal battery to power the Stirling engine, then heat the sand with biogas or the concentrated sunlight like those cheap solar furnace projects. If you can remove the Stirling engine from the original heat source, you can change up how you produce the heat and remove the need to constantly feed fuel into it. From what I understand, large sand batteries can retain heat for quite a while once it's heated.

[@edwinbruckner4752]

Why not a cheap ( possibly even Chinese ) IC generator with a gas carburetor ? If you can bring your gas to certain amount of pressure I see no problems at all. Gas compressors tend to be expensive though, but with it you have much more options and control.

[@myengines2443]

I think especially a cheap IC engine will not work long with 'dirty' biogas!

[@edwinbruckner4752]

@@myengines2443 Meh, I think you'll be suprised. Anyway, first testing this out with a cheap engine seems logical to me, seems the most easy way at least. But again, compressing and storing the gas is probably going to be expensive. Especially compressing it, but gives you much more options to try things out. And that way you can store the gas compact for later use. Anyway, that's what I think :)

[@stephenroot1012]

In theory the bio gas can be filtered the same way coal and producer gas is using iron on the sulfur and either water or sawdust filter for the tar.

[@myengines2443]

I do filter the biogas as you can see in my biogas video but it never gets really clean to not damage the IC engine I think.

[@giovannicesaramorim9adigan961]

there is no need for a big boiler for a steam turbine. Monotube boilers can be made compact and efficient (using 20-30m of 8mm 304 tubes), with a probable total system efficiency of 30% using a tesla turbine, which is compact and efficient. Any burst will only generate a single pinhole leak, and can be entirely avoided with electric controllers, like an arduino, and a safety valve at 350psi

[@myengines2443]

Ok, monotube boiler sounds really interesting. Is a tesla turbine able to compete with a conventional steam turbine or steam engine with regard to efficiency? Thanks for your suggestions!

[@nilnailscrew4784]

If steam boilers aren't as problematic as we thought, does that not open up the ability to use a turbocharger as a turbine instead of a Tesla turbine I figure some slight modifications to a vehicle turbo would work great for producing steam power

[@nilnailscrew4784]

also I imagine the high pitched whirring sound of a turbine would be pretty simple to insulate since high pitched sounds dont travel very far/through objects

[@giovannicesaramorim9adigan961]

@@myengines2443 Depending on the design, it can reach 37% efficiency single stage to 63% efficiency max with multiple stages. It is somewhat simpler to build than normal turbines (which blades need to be very precisely built to not have balancing issues, and have peculiar geometries, while the tesla turbine is a set of simple disks, which have a single hole in the middle, and either a star shaped separator in the middle, bumps in the outer diameter, or 2mm shafts with separators in the outer diameter, which also serve as a torque increaser). The most difficult part is the shaft sealing, nozzle, and casing, which any turbine needs to have.

[@giovannicesaramorim9adigan961]

@@nilnailscrew4784 You'd need to either separate them and use a single turbine, or use both, with one acting as an exhaust pump. I also think that it is designed specifically for high flow low pressure systems, which is mostly detrimental to steam efficiency (huge amount of water use, no temperature efficiency increase).

[@gsestream]

if you mostly use the biogas directly in an open burner (rocket stove) then it produces direct heat like wood/alcohol stoves without having issues of contaminations. then part of the heat can be used in peltier TEG or steam engines to generate electricity, and rest of the heat is also captured and transferred directly or to water/sand heat storage. by capture I mean that the steam/stirling engine is in the same hot air/water ventilation/pipe room, as the generating engine, so that the hot air/steam output to the steam output is directly outputted to the heat transfer system. how about tesla disc turbine generator for steam, and direct hot burn air and steam water directly as heat output. small tesla turbines are easy to make and maintain. you might also be able to use tesla disc turbine as the burner at the same time as the generator. ie tesla disc turbine is a simpler maintained and made type of the conventional turbine generator burner. you could also gasify wood gas or filter pyrolysis gas or just clean up the methane natural gas. the tesla disc turbine also outputs very cold liquid or ice, so its a compressor heat pump also.

[@rekinek1111]

Im scared that an alpha stirling engine of sufficient power would need to be the size of a fridge. I saw 400 w low rpm stirlings on yt and they are the size of a fridge so even if you could push the rpm to like 2000 - 3000, it still will be a very big and therefore hard to make contraption. Perhaps a windmill would do the trick but it depends on your location.

[@myengines2443]

You are right, a 2000 watts Stirling is a challenge. With a wind turbine you are again dependent on the weather, the generator is supposed to buffer the times of low sunshine!

[@rekinek1111]

@@myengines2443 Im guessing you dont have any rivers nearby, right? Water wheel would be a great sollution at providing constant, reliable power. You could make it work of rain water but that would by terribly unpractical and unreliable power source though it would be a fun project.

[@myengines2443]

Funny enough I have a big river ob my property but is flows very slow.

[@thomass7880]

I have a nother suggestion for you the Stelzer Motor in english Stelzer Engine, it is a kind of a two Cycle Engine but the only moving part is the Piston it is a Freepistonengine and it is relatively simple. I heart from the Engine about twenty Years ago and i find it simply an genius. It has a wikipedia page for the engine.

[@myengines2443]

But can it deal with 'dirty' biogas?

[@thomass7880]

@@myengines2443 i think so, the material for the piston and the engine housing must be resistant and then its i think no problem, the Inventor says the engine run on Gasoline, diesel, natural gas and ethanol

[@myengines2443]

The parts in direct contact with the combustion are the endangered, sulphur and tar are quite aggressive ! Stainless steel grades are normally not suitable for running surfaces in IC engines.

[@GeorgeJFW]

Why not use a steam engine? Then you can scavenge the exhaust and have hot potable water?

[@GeorgeJFW]

I see you address the issues, I still think it would be a good option maybe with a Tesla turbine very small and easy to manufacture and service

[@myengines2443]

As I can read from the many comments here, there really is still a lot of interest in steam power!

[@casperyourfriendlyghost7552]

I just bought 12kw of solar panels for $3100 shipped.

[@myengines2443]

I have 5 KW peak panels but also your 12 KW panels are not enough if the sun is not shining. I need something for backup for dark times!

[@mikehughesdesigns]

A free piston two cycle IC engine with integrated linear generator...

[@myengines2443]

Its a nice design but will also have problems with 'dirty' biogas I think?

[@paradiselost9946]

linear generators are far harder to make than they first appear. once you start delving into flux density, current density, turns ratio, reluctance of magnetic paths, air gaps... more to it than "wave magnet past wire make voltage"

[@VEC7ORlt]

Eh, those seem like loudspeaker motors in reverse, and there is plenty info on those.

[@radomirfilip8741]

I like the idea of the gas turbine. It shouldn't be so complicated to repurpose an old turbo from car.

[@myengines2443]

Isn't it really rocket science to build a reliable gas turbine?

[@radomirfilip8741]

@@myengines2443 It is for sure challenging. I would say that the majority of the off-grid systems that are using gas as a heat source, include always some sort of micro turbine to harness the power. Either with Organic rankine cycle or Brayton with heat recuparation.

[@plinble]

A large volume of solar heated water e.g 30C is reasonable easy to make, can even use aerobic digestion for the warmth. Getting electricity efficiently from it isn't quite so simple. Might have to vary the pressure of the working fluid to optimise efficiency, and have more than one stage? See what they were doing in the 1950's to 1970's?

[@Berkana]

Would you be interested in considering two alternative reciprocating steam engine concepts that might work? I can email you; it's hard to explain adequately without some graphics.

[@myengines2443]

Sure, you can find my e-mail on my channel page!

[@ACTSRevolution]

BAM-TiB is nearly as hard as carbide or diamond and is the slipperiest mechanical material of all. Couldn't you beat the corrosion problem with this and just go with a low-compression IC?

[@myengines2443]

I will look out for it, never heard of BAM-TIB. Thanks!

[@myengines2443]

Aluminium magnesium boride or Al3Mg3B56, colloquially known as BAM, is a chemical compound of aluminium, magnesium and boron. It is a ceramic alloy that is highly resistive to wear and has an extremely low coefficient of sliding friction. BAM films can be coated on silicon or metals by pulsed laser deposition, using AlMgB14 powder as a target, whereas bulk samples are obtained by sintering the powder. The properties sound really nice but it is really high tech. If it is commonly made for a reasonable price in specialized workshops it may be an option. Do you know what it may cost to coat a custom cylinder or piston?

[@ACTSRevolution]

@@myengines2443 Wiki updated their article, i see, with very helpful process specs. I'm glad I looked that up again!

[@lanceramshur9124]

Thermoelectric could work but expensive to get enough to have a reasonable output. What is interesting about them that ppl don’t talk about is the lower the voltage the more efficient they become even if you lose effective pumping capacity. For example 12v TEs at 2v 1amp and you have COP of 4.3 which is on par with ac compressors. So you could get 600 or so and when on let hot side heat a water storage tank and cold side chill another tank. When you want some power back off the system the same modules can generate electricity from that temperature difference. 600 12v modules 320gallon hot tank heated to 140f and another chilled to 32f would allow you to pull 1000watts for about 160ish hrs. This is still a bit impractical of course but interesting nonetheless. I mean IBC containers are free if you could source them and TE modules bulk ordered from manufacturer can be about $.90 each so it’s not impossible. Prob need 8inch or so closed cell foam also. So I mean if incorporating it into your homes heating and cooling system I suppose it would work well. Even the cheap modules should hold up running them at that low of a voltage. Just pump the cold water through some liquid to air heat exchangers in your home for AC and hot water tank for hot water needs and heating via same exchangers. Idk maybe worth thinking into. If you’re interested let me know and I will send you the math used to come up with the output and pumping capacity. Oh and the reason they work better at lower voltages is that when at 12v for example they generate heat while trying to pump heat so they work against themselves really. The sweet spot for a 12v module is about 2v from my research and few test.

[@myengines2443]

Whats with diy element made of magnesium and other metals? The use of higher temperatures will improve efficiency and power, and the durability will also be much better? Thanks for your thoughts I will think about it!

[@lanceramshur9124]

Any two metals with dissimilar thermal conductivity can work but only are few are worth the effort. I’ve never tried copper oxide and copper before but that would be a easy one to test. Not sure if a diy version can get as compact as the bought ones but from your videos I’m confident you could do it. Other metals are bismuth telluride which they are normally made with if I’m not mistaken..Silicon-germanium…magnesium silicide and even a polymer that can do it but I would have to look that one up to tell you the name. As for improving efficiency and power yes the higher the temperature the better long as modules can handle that temperature. Another way to think of it is the greater the temperature difference the better. Like in my dual tank example the cold thermal storage is near freezing. Could go on below freezing if inclined to of course. I’m pretty sure the cheap TE modules that are normally in coolers and such can’t handle much above 150f. Would need to look up specific model to know for sure. Let me know your thoughts I would be happy to help in anyway I can. In fact I will check that copper and copper oxide junction and let you know the results.

[@lanceramshur9124]

Copper oxide is garbage for it..haha magnesium seems to be the way to go as you suggested. Robbery Murray has a few videos on the topic that are worth taking a look at.

[@lanceramshur9124]

I do have another type stirling engine I designed a couple years back that I have yet to see anything like it anywhere. Would take a while to type it out but its much simpler to build with the only drawback being size. Like it will have to be rather large to get any useful output. If interested let me know where I can send you some pics and further explain it.

[@realdbcooper3423]

Hear me out, What if you used an atmospheric heat engine Advantages: -Quiet -Extremely low maintenance -resilient -low complxity -easy to manufacture -cheaper -ver minimal moving parts -easily runs on dirty natural gas -no more looking for stirling engines and going into water or compressed air turbines ( better i think) For this engine you basically using low pressure steam, but you are able to pump water to a raised reservoir, then this water will come down into a turbine generating power and turbines are god like in this respect. The water returns to a lower reservoir and the cycle continues. So if you actually improve this old technolodgy with advanced technolodgy, think it would be simpler. you wouldn't need to worry about the complexity of the system, you will just be analysing and improving the turbine and the fluid system. So i think thats the best place to put your dirty natural gas into. If your not interested in water dynamics why not turn it into a compressing pump. I think it could be highly efficient with the improvements of todays technolodgy, AND its extremely low difficulty in maintenance and quiet. I think its a perfect contender. What do you think? Love the VIDEOs!

[@myengines2443]

Thanks, I have to think about this!

[@RingingResonance]

Those cheap little thermoelectric peliter devices have a service life dependent on how often you thermal cycle them, how hot you get them, and how much current is passing through them. I've had bad luck with reliability and quality. They seem to vary quite a bit if you buy the cheap ones in bulk, but they are cheap! From my experiments over a decade ago, staging two high seems to work the best, but you need to cull them out and find the most efficient ones from each batch. As for repair ability, they are repairable as far as you can replace them. Once they are damaged, they are as good as delicate, ugly ceramic tiles. Why not add a small mount of PAG oil to your existing engine and then run it upside down. The action of the pistons moving, and the heat from the heat exchanger should make it evaporate and condense in the crank case where it should then make it's way back down. It's a closed system, so as long as you are pressurizing it with clean dry air it should be fine for a long time as long as the heat doesn't break the oil down. Give it a shot! It might just work.

[@myengines2443]

Do you know something of self making high temperature TEG's (with magnesium?) for a better efficiency? Oil in the Stirling engine will contaminate the heat exchangers and especially the regenerator so this will not work. Thanks for your nice thoughts!

[@RingingResonance]

@@myengines2443 I do not. I figured it would make for a good experiment. Say you loose 10%-20% of your efficiency but it lasts years of running vs hours. Would that be worth it? This is just my cave-man thoughts on the idea. I see friction and wear, I put oil. Keep it simple ya know?

[@JocelynFarmer-kf7xy]

Use the sterling cycle to drive a mag wheel.

[@myengines2443]

The crankcase is already sealed very good with little friction so I don't need a mag wheel!

[@JocelynFarmer-kf7xy]

Throw the whole assembly in a vacuum chamber instead of flame wicking the heat exchanger

[@JocelynFarmer-kf7xy]

Solar tubes instead of flame wicking

[@myengines2443]

How hot do they can become? To achieve a good efficiency and power the temperature difference has to be as big as possible!

[@scurvofpcp]

I've been tinkering with using solar power to compress methane, but I'm on a quest for long term energy storage.

[@myengines2443]

The storage of the summer methane for the winter is another problem! Do you foud any good solutions?

[@mykolapliashechnykov8701]

@@myengines2443 The best way to store methane is probably to convert it to methanol which has infinitely better volumetric energy density. I'd pay to see someone creating a catalytic reforming column to do this...

[@GiesbertNijhuis]

A "cold" steam Tesla turbine (running at very low pressure, therefore the boiling temperature is reduced).

[@myengines2443]

Can it reach reasonable efficiencies?

[@Infinion]

@@myengines2443 Yes, Look up the videos of Charlie Solis (TesTur Energy) where you can see power being made and learn about the Tesla Turbine. He makes 4.5" turbines as a kit. Jeremiah Ferwerda (My Tesla Power) is doing the same thing with titanium blades to handle corrosive gasses. In his case, he has cad files available for subscribers.

[@pedroneto1313]

Resgatem esses excelentes motores Stirling, usando queimadores à óleo suado, que está virando febre no mundo todo, pra uso em cozinhas, tanto doméstica quanto industrial. São fogões com excelente custo benefício, já que são simples de confeccionar e o combustível, que é o óleo lubrificante usado, que é abundante no nosso planeta. Consiste apenas numa câmera de combustão, uma queimador e um soprador, controlado por uma pwm. Só assim, o Stirling será muito promissor.

[@ravelkoff3549]

I would think about a steam engine. More power, simpler and a free selectable heat source which isn't involved in the engine process anyway.

[@myengines2443]

The steam engine still seems to be very popular, as many people write in the comments here. Thanks!

[@ravelkoff3549]

@@myengines2443 Indeed. It is proven, robust, valuable and reliable technic. If we go for off grid appliances - I would recommend to avoid as much digitality as possible. Further you'll have to look for the most available heat source off grid. A steam engine doesn't need more than steam and oil to operate.

[@aselagunawardana1032]

Free piston nasa version also helium as working gas

[@myengines2443]

You mean the very simple or the very complex NASA Free Piston engine?

[@katfrancis7989]

Maybe a tesla turbine instead of traditional turbine?

[@myengines2443]

Whats with the efficiency of a steam Tesla turbine?

[@hoola9224]

intenal combustion egine running on gas fumes or gas vapor. low fumes, last longer. make a gas vapor carburator.

[@myengines2443]

I am not sure if I can clean the biogas so much that it will not destroy the IC engine very fast!

[@oneplaneteer1708]

I need your help. I'm working on a project to develop a biological solar panel that is part of a whole house resource recycler. I've been tinkering with this for the last decade. There is no new tech needed. Take hold of all of your utilities, water, sewage, electricity and heat, Year round. Grow biomass than is naturally sequester-able. I have my own YT channel and a Patreon if you want to hear more. I don't have any faith for the US government or most govt to do enough. Take matters into your own hand. Keep your fridge running in every rolling blackout, blizzard, and hurricane. Stabilize and recession proof your utility bill.

[@kevinsjoebeck82]

Try a fluidyne engine :)

[@myengines2443]

Nice concept but low power!

[@JocelynFarmer-kf7xy]

Stirling cycles mag wheel swap out the armature for a turbine and levitate it between your perm magnets for almost no torque