Solar Fire Breakthrough

Ladies and gentlemen, we have a breakthrough on the Solar Turbine project. We are adopting the Solar Fire concentrator technology as our official solar energy platform. OSE and Solar Fire are entering into partnership – with a single purpose of creating a state-of-art, replicable, open source platform for solar concentrator power applied to electricity, space heating, and process heat. Prototyping done already by Solar Fire indicates that electrical production can be attained by such a system at a $0.5-$1 system materials cost per peak watt – if combined with a modern steam engine as the heat engine. This is about a factor of 10 lower than photovoltaics. See Eerik Wissenz, Solar Fire project leader, introduce the latest successful prototype of 32 square meter solar capture area:

Solar Fire is now officially adopted as the OSE pathway to the Solar Concentrator – one of the 50 technologies of the Global Village Construction Set (GVCS). Eerik is now the Project Leader for the OSE Solar Concentrator development. Solar Fire is bringing 3 key developments:

  1. Simple focusing mechanism for the individual mirrors (as seen in video)
  2. Computational program (open source) to calculate mirror alignment
  3. Low cost collector and reflector structure

OSE is bringing 3 key contributions to the table:

  1. Development of the modern steam engine as the heat engine for the solar concentrator, which is one of the 50 GVCS technologies
  2. Development of a solar tracking and mirror cleaning system for full automation of the device, as well as development of measures to protect against hail and heavy winds
  3. Media exposure to promote this idea worth spreading

We will be adding the solar concentrator to our Kickstarter offering on the Open Source Microfactory, which we are planning to deploy on June 1, 2011. Thus, it will be the Solar Microfactory. Now if we put the Distributive Enterprise concept into the core of our Kickstarter offering – then we might have to extend our offering to the Mobile Solar Microfactory- with an early release of the Civilization Starter Kit DVD v0.1 as one of the rewards. We are planning to build the Solar Fire P32 (as in the above video) with a modern steam engine in September, 2011 – during the first, major, one-month long Factor e Farm Convergence of 2011. If you have been following our work on the solar concentrator system – such as the initial prototyping work at Factor e Farm, you will note that Solar Fire is a departure from our former strategy of the Linear Solar Concentrator. The big point of the Linear Fresnel Type Concentrator, as discussed in Factor e Live Distillations – Part 8 – Solar Power Generator – is that the linear concentrator is inherently scalable. One can scale a linear array infinitely by lengthening it – thereby meeting the scalability criterion of OSE Specifications for Distributive Enterprise. The problem with dish concentrator systems is that they are not scalable. Structural costs become prohibitive for increasing dish size. It turns out that the Solar Fire system addresses the scalability question very well for 2 reasons. First – the Solar Fire system is a low-to-the-ground, flat array of mirrors – with inherently low structural costs (wind-loading is addressed by the low-to-the-ground profile). Second, the solar receiver is an extremely simple, low cost design: essentially an empty drum with a rounded front face – at a cost of about $100 in materials for the P32 system. To scale power, individual arrays with individual solar receivers can be replicated. For higher power applications, the receivers are simply linked via insulated interconnections. Because of the low cost of the receiver, the system cost scales linearly with added usable power – so the system is infinitely scalable. This means that a given community can build up its power-generating infrastructure on-demand, as it grows. So Eerik is a smart guy, and he has me totally convinced on the scalability issue – by his cost structure data for the system. We are expecting to put the entire P32 – with receiver for $2k in materials, and $2.5k in materials including a 5 hp uniflow, bump-valve steam engine. This is a psychological relief for me – as I admittedly had no practical clue as far as how to produce an effective, low-cost receiver if we went with the linear concentrator system. Industry standards show that this is possible, but that would have been an arduous up-hill battle if we were to succeed. At the same time – I can’t see any way to come up with a linear collector anywhere as low in cost as the Solar Fire point-receiver. We are building on the work of the Whitecliffs Solar Power Station – which has demonstrated exactly the simple bump-valve uniflow steam engine that we are pursuing in our prototype. They have run the steam engine successfully for thousands of hours, and attained 21% solar conversion efficiency to electricity. The parameters for the Solar Fire P32 indicate that we should attain a 15% efficiency with our system if we use the bump-valve uniflow steam engine design. This means 3kW peak of electrical power! We are enlisting the peer review of the Steam Automobile Club of America – a goldmine of talent. Ladies and gentleman – to sum up – solar power is coming to Factor e Farm this September – a welcome breakthrough, ahead of schedule. It looks like we’ll be testing our first steam engines in real life with the solar concentrator – which has the advantage of a ‘clean burn’ that does not require cleaning of the steam generator. This means no maintenance requirements, as opposed to the case when chemical fuels are burned. We have retired our 1-cylinder Lister diesel engine years ago when we received a donation of 2kW peak solar cells from Ersol. I’ve been anticipating the moment of going from solar panels (photovoltaic power) to solar concentrators (solar concentrator electric power) for years now. The former is still an eco-elite privilege, while the latter has the capacity to provide Power to the People. If you look at this issue from general principles – semiconductors will never be as cheap as mirrors. I stand in awe as the countdown to September continues, as we may break through the smoke and mirrors surrounding energy access for humanity. Share this far and wide and tweet this. This could be major news. It’s open source, so it may be coming to your rooftop or backyard next.

Open source, and coming to your backyard next.

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41 Comments »

  1. Insidious said,

    May 8, 2011 @ 7:35 am

    This seems like a great direction to go in..

    With the solar concentrator, your only output is electricity.

    With this model you can have electricity or heat, and other methods/fuels can be used to generate electricity/heat when solar isn’t avaialable (backups).

    This would also allow for methods other than batteries to be used for energy ‘storage’, such as thermal salts.

  2. gregor said,

    May 8, 2011 @ 7:50 am

    It’s all very interesting and I hope it works, but for electricity only I don’t know if steam makes that much sense.

    Free piston stirling engines are already developed and are totally maintenance free. Have they been given a fair shake here? A nitrogen charged one will get you your 21% pretty easily, and pressurization keeps it reasonably small.

    Sunpower knows how to make engines that will last 20 years maintenance free. They have a nice library of stuff, and there are scientific docs elsewhere that I have seen that describe how to make them last in this way, the only sticking point is the planar spring, which is just spring steel, but it has to be shaped just right to keep the material stresses below the fatigue limit. Do that and they last almost forever.

    None of the parts touch at all, so no need for lubricants and no wear. And I say that having read what is said on the blog and the wiki and the forum about the steam engine. I recently posted my notes in the forum on the steam engine.

    I agree that it is possible to make a maintenance free steam engine, but I think they do not make that much sense if you don’t need either shaft power or high power density/weight ratio, or high efficiency of a turbine maybe.

    He can get you like 36% overall heat to electric with 650 deg c input and 30 deg c output. But it is no good to OSE because it is not available in the environment.

    Neon might be a good compromise, available from the air, inert close to ideal gas, and 25% lighter than n2. Presumably not used in industry because it is no cheaper than He, but that doesn’t apply here.

    One more redeeming feature of steam may be that it can be used in a variety of situations reasonably well with variable compression ratio. That might be worthwhile, but by the sound of it you’re just talking electricity. Now that you are talking dish collector maybe it is time to give FPSEs a second look?

  3. Abe said,

    May 8, 2011 @ 9:21 am

    I have been awaiting development on this project for quite some time. It will be interesting to see how you will be able to make the steam engine and keep it running with low maintenance (to be able to compete with solar PV)

    Solar PV is currently available at around $1.6 – $2.5/watt, and the price has come down considerably since I bought my first panels ($5/watt) in 2001.

    Could some of the waste heat form this system be used somewhere else? Like a mini co-generation unit? Possibly to heat a house, water, or to make some ethanol?

  4. benk said,

    May 8, 2011 @ 11:43 am

    Because it seems important, ‘infinitely’ scalable should not be used in the description. Put some bounds on it, for surely there are bounds. Scalable up to…?

  5. Natem said,

    May 8, 2011 @ 6:59 pm

    Awesome work guys, this seriously looks great!

    I’m not very skilled at this (more like fascinated by cheap and clean energy), but I wanted to ask, why not use a closed loop system instead of the steam engine + compressor.

    Wouldn’t something like a Stirling engine at the top of the tower be better?

    Like, the steam provides power by rotating a flywheel, but instead of exiting as exhaust, it could go through a radiator that would cool it just below boiling point (turn it back into liquid), and the pressure of the steam itself would push it back into the boiler. Eliminate all the middle men, so to speak.

    I hope you understand what I meant…

  6. Mike said,

    May 9, 2011 @ 11:42 am

    Very exciting. What is the best way to follow this progress as it develops? The development wiki (specifically the steam and solar sections of the site)? Why wait until september to deploy?

  7. Interesting Reading #747 – Printing Parts for Airplanes, Peugeot EX1, Cheap solar power and much more! – The Blogs at HowStuffWorks said,

    May 9, 2011 @ 7:57 pm

    [...] Solar Fire Breakthrough – “We are adopting the Solar Fire concentrator technology as our official solar energy platform. OSE and Solar Fire are entering into partnership – with a single purpose of creating a state-of-art, replicable, open source platform for solar concentrator power applied to electricity, space heating, and process heat. Prototyping done already by Solar Fire indicates that electrical production can be attained by such a system at a $0.5-$1 system materials cost per peak watt – if combined with a modern steam engine as the heat engine. This is about a factor of 10 lower than photovoltaics….” [...]

  8. Steveon Walker said,

    May 9, 2011 @ 11:18 pm

    I was just wondering, could you use the steam engine to turn the waste steam into Oxygen and Hydrogen from the power made for later use? I was looking at wikipedia and ran across High temperature Electrolysis article.

    http://en.wikipedia.org/wiki/High-temperature_electrolysis

    and the Dept. of Energy pdf on the topic

    http://www1.eere.energy.gov/solar/pdfs/doctor.pdf

    I was thinking, you could use the Hydrogen as is or use the gases later in a fuel cell.

    Thoughts?

  9. Miquel said,

    May 10, 2011 @ 12:21 am

    Wow, this is really big, specially for developing countries located in the “South”.

    Nice demonstration video and clever mirror curving technique!

    There is no way, however, this is going to work for north east US or most of Europe, which makes them into the most energy-poor, highest energy consuming regions in the world.

    I do expect Solar Fire to work further to the North than the Parabolic Through power plants SolarMillenium is deploying in Spain and elsewhere.

    Web: http://www.solarmillennium.de/english/technology/parabolic-trough-power-plants/index.html

    Animated Technology Diagram: http://www.solarmillennium.de/upload/Animationen/andasol_blue_engl.swf

    Has the Eerik team done calculations on what latitudes will this technology be feasible?

    Could you at least envision northern communities employing such a power plant for mainly summer use? What about cloudy/rainy/monsoon months?

    These concerns are motivated by thinking about the problems Climate Change may cause by forcing mass migrations to the north.

  10. Anonymous said,

    May 10, 2011 @ 12:23 am

    This is amazing work being done for the betterment of all humankind. My only regret is that this wasn’t finished yesterday. The world of the future needs the GVCS.

  11. Marcin said,

    May 10, 2011 @ 12:45 pm

    If you would like it to be finished yesterday, please subscribe to the True Fans.

  12. Marcin said,

    May 10, 2011 @ 12:48 pm

    There are no a-priori reasons why this does not work in the US northeast or most of Europe. True, they get less sunlight, but feasibility is a function of performance/cost ratio. In the limit of zero cost, this is feasible where there is no sun at all:)

  13. Marcin said,

    May 10, 2011 @ 12:52 pm

    Does anyone else share this critique? The only bounds I see are the bounds of sufficiency.

  14. Marcin said,

    May 10, 2011 @ 12:54 pm

    Abe, show us a reference to the PV prices that you’re referring to.

  15. Miquel said,

    May 10, 2011 @ 1:30 pm

    Mmm, it seams that the comments got mixed up.
    Anyway.

    In the limit of zero cost, this is feasible where there is no sun at all:)

    You are right (and it is what I hope) up to a point. There is no such thing as zero cost (free lunch). Even if the technology is open source, it is automated, and you get materials from your region, there is only so much human effort/attention, and so much available land surface.

    But that is not what I meant. At some latitude, you won’t be able to reach the minimum required temperature to create steam with a “reasonable” amount of collector surface in any month other than June/July.

    I asked because Eerik will surely know a ballpark answer, or may even have calculated it already.

  16. Miquel said,

    May 10, 2011 @ 1:47 pm

    Does anyone else share this critique? The only bounds I see are the bounds of sufficiency.

    I think he has a point, though the nuclear physicist/optimist in you may not be able to see it ;-)

    The system does seem like it would be “infinitely” scalable. But that is theoretically. In reality, limits other than the theoretical design kick in, because it is just not practical.

    In general in OSE, I would avoid saying something is “infinitely” scalable, because it reminds too much of technofix-talk.

  17. Marcin said,

    May 11, 2011 @ 12:39 pm

    Eerik, comments?

  18. gregor said,

    May 11, 2011 @ 10:54 pm

    “does anyone else share this critique?”
    I sort of do. I may sign up on the wiki as a collaborator when I get around to it, and I can volunteer to do a time step simulation in calc if I can get the relevant data table for efficiency vs. input temperatures etc. or better insolation vs. efficiency for the engine it is easy to take weather data (includes insolation measures) from NOAA or elsewhere and produce a time step simulator to determine the detailed anticipated kwh output on an hourly basis for a whole year (or multiple real years even). This can then be compared with other systems in the same way.

    What the ideal way to do things is to do the simulation (hypothetically to very high accuracy but the weather data is only hourly anyway and that’s not bad) then compare to what’s called a “demand pattern” to represent the demand, and compare them for different systems. Thus inching closer to total system optimization.

    Also Abe is right about the solar prices. Here is a reference:
    links removed, see bottom of comment

    The first one has them supposedly at $1.2 per watt. Also I posted a comment on this blog already linking to an idea to get roughly twice to 2.5 maybe more energy per day out of a solar panel with the use of a variable concentration ratio solar collector. By my reckoning the cost maybe reduced by 80% or so after the cost of the collector. This is drawn from time step simulations in calc, you can download an view the spreadsheet and verify this if you wish:
    links remo ved

    The sunlight is substantially less intense here, and unlike for solar panels, the output of a heat engine system goes down faster than the solar input does (less efficient at lower insolation) which is less of a problem for solar panels.

    By the way the reprapmetallica people are looking into producing their own thin film panels with a vacuum chamber at home. I don’t know if this can be done without rare metals though.

    So if this system is to compete on the open market it will have fierce competition… I posted in the forum about linear free piston engines. Infinia is now competing with solar panels successfully with LFPS engines and dishes so there may still be hope for solar thermal electric if done cleverly, but I am very skeptical if this solar fire system as it stands, with low efficiency steam and relatively expensive collector will work out well.

    Funny everyone thinks of different way to do it and there must be an enormous amount of thought put into this problem, but because they rarely record or share their thoughts it does no good. One of the perks of open source comes from documenting the development of the project itself so people can follow the lines of reasoning to see if method x makes as much sense as it seems or not, or if it has not been previously considered and therefore may be worth doing so. As far as I can tell, none of the above has really been considered yet here.

    BTW I submitted this before but it was gettign in the spam filter I think probably due to the links, check the spam bin for them.

  19. neodynos said,

    May 12, 2011 @ 3:32 pm

    Folks, I definitely like that the Solar Fire design is “doable”, in the sense of producing it with relatively low tech means by ourselves. That’s something that cannot be said of monocrystalline silicon currently, to my knowledge …

    Also, it’s great that OSE does so many collaborations with other groups now, globally. That’s the upside of globalization :)

  20. LucasG said,

    May 13, 2011 @ 1:39 pm

    Not sure we want to optimise for efficiency. More for a combination of efficiency and resilience.

    .002 cents

  21. Lorin said,

    May 13, 2011 @ 5:33 pm

    Marcin I’ve got a ballpark latitude for you. I haven’t worked with the P32 yet but have used similar systems.
    anything inside the tropics should be able to sustain decent (6hrs+ a day) year round performance
    I just spent the winter at 30degN in Mexico working on solar concentrators for domestic cooking and in December January the performance was barely there… 650W/m2 as opposed to 900W/m2 three months later

    as for limits of scalability, yes, the limit of sufficiency sounds good to me :)

  22. Solar Fire and Open Source Ecology « Symington Solar Fire said,

    May 13, 2011 @ 7:08 pm

    [...] Eerik has teamed up with Open Source Ecology. As OSE founder Marcin Jakubowski says in his blog post:  Solar Fire is now officially adopted as the OSE pathway to the Solar Concentrator – one of [...]

  23. Joel said,

    May 13, 2011 @ 7:17 pm

    If you have a solar concentrator, and want hydrogen and oxygen, you might look into photocatalysis.

    Most photocatalysts are designed to split water, but they also make some that split CO2 into CO and O2.

    Good work has been done on this topic for many years, but recently it became famous with headlines like “artificial leaf”.

  24. root said,

    May 14, 2011 @ 4:26 am

    Hi, i agree with Gregor, free piston stirling engines have 3 advantages in front of steam engines:
    1) Less maintenance
    2) More efficiency translating heat into energy
    3) Don’t waste water
    I think the third is a very big advantage (not mentioned yet) specially in regions (like mine) where water is a rare resource.
    I live in Spain and in the local chapter of the ZM here we are in the early phase of developing a system also using solar fire concentrators to produce electricity. We also want to refrigerate the radiator of the motor with water, in this way we can also produce hot water for home uses.
    There is a company from Italy starting to commercialize a solar dish concentrator with a stirling engine to produce 1,5Kw of electricity and 4Kw of hot water for home use.

  25. Marcin said,

    May 14, 2011 @ 12:33 pm

    Solar panel prices: http://www.ecobusinesslinks.com/solar_panels.htm

  26. Marcin said,

    May 14, 2011 @ 12:39 pm

    Resilience is included is the core of the design. An enabling component is efficiency.

  27. Marcin said,

    May 14, 2011 @ 12:48 pm

    Regarding your points:

    1) The Whitecliffs Solar Project report has examined the heat engine choice in detail and concluded that maintenance was one of the issues for not choosing the Stirling. See more here.
    3) Closed loop water systems are one option.

    I’d like to see cost of the system you mention. Stirlings are generally much more demanding to fabricate.

  28. Mike said,

    May 14, 2011 @ 5:27 pm

    On stirling vs. steam: Why argue? Why not build both as part of the gvcs? Obviously there are not unlimited funds available to explore the different options within the operation that you are running Marcin, but there is likely plenty of interest in stirling to support some research outside of factorefarm.

    This is something i’ve been kicking around in my head for a while. Why limit the GVCS to just 50 tools? Would it make sense to use openfarmtech as a convocation of sorts, and an organizational structure for self-funded, but still relevant and potentially useful open-source hardware projects? If one of the key goals for the GVCS is modularity, why not support a multitude of solutions for disparate environments and local resource availability?

  29. Abe said,

    May 15, 2011 @ 8:57 am

    it might be a good idea to work on the steam engine design first, using biomass or wood to drive a simple boiler. Once the design is worked out, you can play with concentrator designs…

  30. root said,

    May 15, 2011 @ 3:07 pm

    Hi Marcin
    Also regarding your points:
    1) I’ve read everything i found online (including the links on the page you provide) about the Whitecliffs Solar Project and i haven’t found a word about the stirling engines with the exception of an error in the article of Oze Parrot. He writes “Two rows of seven parabolic heliostat dishes were erected to collect the sun’s rays, and focus them on an apparatus to generate steam that drove a Stirling piston engine” but this is obviously wrong, in truth they applied an steam engine). As far as i understand they only thought from the beginning in the application of a steam engine in the project. They never even contemplate use stirling engines and of course they never did any test with stirling engines.
    I must say maintenance in long term in steam engines must have more troubles than stirling engines for a couple of reasons:
    a) Corrosion of the components. Steam is corrosive to any metal at long term.
    b) New water means new sediment, although you get a closed loop design you will need a little amount of water to supply the output of the security valves when the pressure of the system exceed the max operation pressure in very hot days. Sediment is a big trouble at long term.
    3) Yes, “Closed loop water systems are one option” but this complicates a lot the design, you may need a system to de-pressure the exhaust, that means some big and sealed chambers with heat exchangers inside or something similar. Much more complicated than a free piston stirling engine.

    >> Stirlings are generally much more demanding to fabricate.
    Well, this is perhaps if you want a high tech engine that works close to the max theoretical efficiency. You can build a simple but robust stirling engine using recycled pieces from combustion engines for example. You can recycle the pistons, the camshaft and the piston rods of an old gasoline engine an put it in a big piece of iron with holes acting as cylinders at the same time than heat collector of the mirror focus. We are going to build it and then you can be sure we will share all the information not only about cost but about power produced, materials, design, etc…
    Is an entirely open source hardware project.

    Moreover i want to say i admire all the projects you are developing and although there is a lot of miles between us i send you a hug.

  31. Marcin said,

    May 15, 2011 @ 10:14 pm

    If someone can join and stand with full commitment to develop more items, I’m all for it.

  32. Marcin said,

    May 15, 2011 @ 10:17 pm

    The Solar Fire steam generator is the simplest steam generator which has been demonstrated in the open source world. An open source biomass steam generator is yet to be developed.

  33. Rick Gandenberger said,

    May 17, 2011 @ 10:00 pm

    Sandia Labs did extensive solar collector and solar heat system research, reported in 1983.
    Linear solar collectors created from linear thirds of oil drums lined with (self adhesive aluminized vinyl) reflective surface using cast iron pipe as receiver and peanut oil as a medium produced 500F+ media temperatures with thermodynamic circulation. The accumulator was periodically tapped for energy use, but sized to permit cooking temperatures (using fluid coils in a modified oven as if they were electric heating elements) at night and water heating for bathing in the morning. Household energy was the design paradigm.
    Related findings are mentioned in
    http://www.powerfromthesun.net/Book/chapter09/chapter09.html

  34. Henrik said,

    June 2, 2011 @ 6:56 am

    Marcin, here’s a dumb idea for weather protection:

    Place the reflector array on a rail, which leads inside the south facing end of a building that can house the entire array.

    This means the protection is stationary and can be built as sturdily as you want it from wooden barn for heavy rain/hail/snow areas to heavy duty CEB bunker for tornado/hurricane areas.

    So why not just wheels on the array to move it around freely? Rail tracks mean that you don’t need to re-adjust the mirrors as the tracks don’t change direction in relation to the sun, and exact position of the array on the track is not critical, since there is only a forward/back motion.

    It also means that one person can pull the array out and push it back in, possibly in less than 2 minutes, in case of weather emergency. An automated mechanism for push/pull would be easy to add to the track wheels, if necessary.

    The housing could double as maintenance facility which protects the worker from solar reflection accidents, plus double as housing for the steam engine.

    Having extensible tracks, means that you could place multiple arrays after each other on the same track with identical adjustments. Just make the track and the housing longer. Possibly serially connect arrays for more performance on one steam engine, although, this is not something I know about.

    A south facing wall for the northern hemisphere would also not shadow the array, neither in the summer, nor winter.

    Steam engine hook up would have to be flexible, though, and the whole thing will take up a lot of space, plus tracks must be clear of snow in the winter time.

  35. Open Source Solar Concentrator Shows Promise | EarthTechling said,

    June 21, 2011 @ 12:30 pm

    [...] Denison, June 21st, 2011Eerik Wissenz is a rather industrious fellow who has created his very own open source, solar concentrating device and he claims it can deliver power that comes in about 10 times cheaper than that of photovoltaics [...]

  36. Open Source Solar Concentrator Shows Promise | Product Sourcing - Industrial News said,

    June 21, 2011 @ 10:21 pm

    [...] Wissenz is a rather industrious fellow who has created his very own open source, solar concentrating device and he claims it can deliver power that comes in about 10 times cheaper than that of photovoltaics [...]

  37. SUNfiltered said,

    June 28, 2011 @ 11:45 am

    [...] open-source solar concentrator: Designer Eerik Wissenz claims that his Solar Fire open source solar concentrator concept can harvest power at ten times cheaper than photovoltaics. Check it out in the video above… [...]

  38. Max K said,

    July 6, 2011 @ 9:10 am

    Good reasonable design and have been collecting materials for something similar using stainless plate scavenged from discarded sinks etc. Cut to size (I’m using 3″x12″ to maximize # of strips from a discarded sink), drill a small hole in the centre for your mounting bolt (you don’t loose a lot of reflective capacity) and secure the 2 ends in a frame. By tightening or loosening the bolt you can focus the light. Stainless chosen due to availability of scrap, durability, flexibility without brittleness, weather resistance and it can be polished to a good shine. Since I live in NE Ontario need to consider snow loads and wind protection so am working on how to protect against these potential problems.

  39. Max K said,

    July 6, 2011 @ 9:16 am

    With respect to the stirling vs steam engine; the ease of construction and universality of small convertible ICE engines makes steam a far better choice. Stirlings of any significant power require very precise machining or are extremely expensive thus taking them out of the realm of universality. High power stirlings will remain a specialty item for those with LOTS of money!

  40. zawy said,

    August 2, 2011 @ 3:28 pm

    I’m concerned that Solar Fire is a design that makes tracking too difficult. It appears to be a modified parabolic dish. The only reason I can think that it is not shaped like a dish is so that they could make it flatter. Making it flat appears to be why they needed 6 different angle adjustments (4 quarter sections, and it appears to still need azimuth and altitude). If it was in a standard parabolic shape, you could get tracking down to 1 axis based on a 24 hour clock (no electronic calculation needed) by putting the light receiver bucket on a latitude-tilt axis (like tracking telescopes) that is adjusted once every few days. Supports would come from this axis to support the dish, so that the focus does not move, except for maybe when adjusting the tilt. This would be a lot taller at times, but allows more light capture in morning and afternoon.

  41. Lorin said,

    August 4, 2011 @ 9:59 pm

    Zawy, Solar Fire concentrators can be mounted on equatorial mounts as you describe. You’re right that it makes tracking easier. However, as far as I can see it becomes structurally challenging to do with 350sq ft concentrators. An advantage of a design like a P32 is the simplicity of the construction.

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