Solar Turbine Brochure – Community Supported Manufacturing

We are taking the Solar Turbine project to the next level. Nick Raaum is our Project Manager, and he will be arriving here in about 2 weeks. He has put in his 2 week’s notice for leaving his post as a performance engineer in a coal-fired power plant.

Here is a brochure on the Solar Turbine:

We are serious about the first link in this brochure. Http:// links to a working paper for developing the Solar Turbine, under a Community Supported Manufacturing model. This is OSE Working Paper #1. It is on the OSE wiki – so you can review, edit, and comment. We are making some heavy claims there – so we invite you to poke holes in any of the arguments.

Here’s how you can get involved.

  • Print a copy of the brochure above and pass it to your friends and networks. You can dowload a high resolution version and source files here. Let us know if you can help us with at-cost color printing or bulk mailing by email.
  • Review and comment on the technical aspects of the proposal at the wiki
  • Donate to the Solar Turbine Project

Let others know about this project. Together, we can make Solar Thermal Concentrator (STC) electric generation a viable decentralization technology.


  1. Nick

    I’m a bit busy with leaving my position as performance engineer (not manager), but do plan to get a project schedule and prelimary system drawings and plans posted in 3 weeks. We are making pretty big claims, but then I know of no one who has really pursued coupling a large simple efficient solar concentrator collector with a simple robust steam engine. The system will be true to OSE philosophy, simple, replicable and at $1000/kW downright revolutionary.

  2. Abe

    Everything I have read on steam, including your references, like the Otherpower Steam engine and Mike Brown, have said that steam is:
    1. Dangerous – a leak can cut an arm off
    2. Not a “leave alone” system – requires periodic attention, meaning checking on it every hour or two
    3. Requires high temperatures – this is a problem because higher costs in materials to hold these higher temps, plus tracking king mechanisms and more technology to keep the thing running well.

    So, in conclusion, I am strongly suggesting you go with a working fluid that boils at a lower temperature, maybe 50 C or lower. This would greatly reduce the cost of your collector, and you could avoid needing tracking or concentrators. Also, at these lower temps, you don’t have such a high risk of failure, so constant attention is not necessary.

    Go for low cost, lower temperatures. Yes, it will mean lower efficiency, but space is relatively cheap, arms are not! 🙂

  3. Nick

    Your first two points are good ones, steam is definetely dangerous. However I think OSE sits at a unique point in time to start constructing these low tech decentralized technologies, mainly because in many cases we can piggy back off of the large centralized technologies. In the case of working with steam we know exactly what works and what the rules for constructing steam pressure vessels and piping are. This was worked out, often in great failures, for us over the last 100 years and is recorded in power engineering literature everywhere. Furthermore our target temps and pressures are very tame compared to the state of modern steam plants, the plants that are probably powering the computers we are working on.

    Regarding how much operator care the system will need, I guess I just don’t know yet. I was envisioning a daily maintenance check that would cover feedwater levels, governor operation, piping walk down and other items. There would also need to be quarterly check ups on important items like relief valves.

    If we went to a very low temp and an a different fluid I’m afraid we have a real rough time making our goal of $1000/kW due to the increased space. The steam cycle is time tested and the main driver of our electrical grid. Given that we are proposing relatively modest temps and pressures I believe we can make this work.

  4. rtw


    1. Can we use Convex lens in addition/instead of mirrors?

    2. Shape of mirrors is important. Off my head I think parabolic mirrors might work better. I may be way off though

    3. Can the system be coupled with other sources like wind?

    More later!

  5. Abe

    I do think you guys can make it work, and if anyone can, you will. The only thing is for the rest of us, especially those of us in the developing world, constant attention and inherent dangers are very big issues. I do understand you guys have excellent access to information from current technologies.

    It seems to me that space would not be the biggest factor in cost, but maybe I am wrong. Looking over the system, it seems like the tracking concentrator is the main cost, and you only need that sort of system if you want to get over 200 degrees F. With a lower boiling point, it opens up options for cheap flat plat collectors, which are little more than black pipe. Or even asphalt roads might work. Tracking adds to cost, as does reflectors.

    Again, I am not saying you guys can’t do it, because I truly believe you will. I am looking at it from my standpoint in rural Mexico in terms of replicating a similar system. Space here is available, but tracking mechanisms might be difficult to come by. So, in our case, we are looking at lower temperatures BECAUSE we feel it might be cheaper and easy to replicate. If you add safety and constant attention, it begins to look harder for us to replicate.

    In any case, I am eager to see how your system turns out!

  6. Marcin

    Please view the conceptual drawings at

    and let us know if you can conceptualize a flat pane system that will be cheaper. Flat panes sound good, but I think that if you go through the numbers, you’ll discover that the cost begins to add up. We’ve thought about flat panes, and concluded that it’s significantly cheaper to implement concentration rather than flat panes – because with flat panes, you are talking of large, fluid-tight containers. These are not as cheap to build as you suggest.

    Moreover, based on safety, ecological considerations, toxicity, availability, and cost, we cannot think of a better working fluid that water. Can you?

    We stand to be corrected, so please provide any evidence to the contrary on both points.

  7. Mike

    I also agree with Abe in that it might be a good idea to go with a fluid that boils at a lower temp. This is especially important due to your all’s location in Missouri, where the irradiance is not terribly high. In my research, it seems that is very important for applications like this that will be using the Rankine Cycle (or the Organic equivalent).

    Also, these links from the brochure do not go anywhere.
    Do you have suggestions on a benign, lower boiling temperature fluid that we should use?

    I corrected the links. They now work with capital and small letters – Donate.html and donate.html.

  8. […] a historic convergence of December, 2008 – Solar Turbine work of OSE merged with a UK linear concentrator development team. Both teams have arrived at essentially the […]

  9. Dan Jackson

    Propane is the answer.
    1.It is cheap
    2.We can keep it a liquid at roughly 73psi (Room Temp)
    3.It will work as a lubricant

    Propane boils at -44° F but at 73psi at room temperature it will remain a liquid. By controlling the pressure we can allow propane to boil at any temperature. Vaporised Propane is 270 times the original liquid volume. Even PVC pipe up to 2” schedule 40 is rated roughly at 280psi at room temperature. I would recommend using copper or steel.

    I live in Madison Wisconsin and it snows here! I don’t want to have to go out everyday and try to de-ice my electrical system. Vacuum tubes have proven to produce heated water even under snow. 1” of vacuum equals roughly 100 R value. I have found Borosilicate 33 glass (106mm x 2000mm with wall thickness 4.6mm) for $50/pc without shipping. Think a 2” copper pipe inside a glass pipe (vacuum) with a large reflector. That would protect from heat loss.

    Where is the economizer in the design? Think Sterling Engine they have a economizer which is a glorified heat exchanger to regain some of the heat lost in the cycle.

  10. mimarob

    What is the advantage of propane compared to a safe working medium, such as CO2 or helium?

    Can’t help it, but the thought of putting a solar “torch” to a propane tube gives me the creeps 🙂

    How much working gas would one need per hp of engine?

  11. Jeb

    I’m not sure I like propane either, but for a different reason: I don’t know how to make propane myself and therefore would depend on global supply chains to maintain this. With that said, (and in case I’m wrong on the above point), I’ve heard from a friend that propane is used as a refrigerant in some countries, where it performs efficiently. As a turbine drive fluid, you don’t have to put a torch to the piping, just use a heat exchanger with another hot collector fluid — ideally something like motor oil with a high boiling temperature, and low freezing temperature. On the other hand, there is an existing project that takes this approach — (Unfortunately, they aren’t open source.)

    Another concern about using water as both the collection and turbine fluid is freezing and breaking of pipes in cold weather. Perhaps Ethanol would work in a closed loop, having a slightly lower boiling temperature than water and much lower freezing temperature? Shouldn’t be much more dangerous that on-farm distillation anyway.

  12. Ron Pryhorocki

    Why not use steam to compress air, then use air to drive the steam engine. That way you can run the steam (air) engine 24/7 to include no sun days. All you need then is a large enough compressed air storage bank to cover the number of hours needed. Propane tanks are available in varying sizes and could be ganged to provide the desired storage.