Solar Turbine – Project Manager Recruited

Solar electricity generation remains a hot priority for us – as one of the essential parts of the Global Village Construction Set. We are taking the solar turbine project to the next level – a working prototype, 3kW of electrical production at $3k in material costs.

If you read this post carefully, you will believe that this performance figure is achievable – utilizing proven technologies. At the very least, you’ll be introduced to this possibility even if you don’t believe it – as we are proposing an explicit implementation path.

We are talking of solar electricity via steam cycle and steam engine.

Nick Raaum, who is actually working at a coal power plant on their steam cycle – is stepping up as Project Manager for the Solar Turbine. His first task is to put together the Steam Engine Construction Set.

Here are conclusions from our past work.

  1. No other proven, long-lifetime (50+ years) reflector system is available outside of high-iron glass mirrors.
  2. No other proven, low-cost steam power technology beats the time-tested piston steam engine for cost and performance. The steam engine was the caused of the industrial devolution – and now it could be the key to a future of solar electricity.

We have examined bladed and bladeless turbines to near exhaustion. In the dozens of contacts that we made, we found no bladeless turbine higher than 60% reported efficiency (no data available presently) – and that was for a high-tech, non-open source version. The time-tested steam engine has 80-90% mechanical efficiency for basic, long-lifetime implementations. No long-term track record exists for bladeless turbines. Bladed turbines (such as automotive turbo chargers) may be similar to steam engine mechanical efficiency – but these are high-tech devices presently beyond the scope of replicability in small-scale workshops – due to dynamic balancing and precision machining issues.

We conclude that the turbine (after which the solar turbine project takes its name), may be a possible condidate for solar thermal electric concentrator systems of the future. However, for a proven solution for today, we are going with the steam engine.

We require only 5% overall cycle efficiency to reach our goals of $1/watt material costs as indicated above. Steam engines of 8% overall cycle efficiency have been around since the turn of the 19th century.

What else do we know from the solar turbine convergence at Factor e Farm back in August? We learned that for one-axis tracking, East-West running linear mirror arrays – flat mirror slats are the simplest design. Parabolic mirrors are not only more difficult (though not very difficult) to implement, but they suffer from defocusing on a stationary receiver tube as the solar angle changes throughout the day. At the end of the day, we were left with mere speculation regarding the heat engine of choice. We did not get to any implementations of a valving system for feedwater delivery. Note that we are considering valves because they are mechanically simpler to implement, and they require a small fraction of energy compared to feedwater pumps.

From our learnings, we propose these central features:

  • Absolute lowest cost structure for mirror mounting and tracking.
    • We have a design that costs $2k in materials for 60 kW of solar intercept. We built parts of this system, and our results show us that this is quite doable.
  • Tracking mechanism and actuator based on the Arduino electronics control package
  • In-house building of a 5 hp steam engine – $150 in parts
    • We are proposing a complete, open source tooling development to produce these engines
    • Basic, high performance lathe (1/1000 accuracy, 12″ lathe) – $486 for materials
    • Metal casting equipment – $400 in parts
    • Flash steam generator production for steam engine testing – $780 for tooling and first prototype
    • Adding digital fabrication control – $1200
    • Tooling total – $2866 up to digital fabrication
  • Optimize feedwater delivery and steam cycle
    • Valving – 200 psi electronic valves with open source Arduino control software
  • Optimization of power matching to generator head
    • open source generator head fabrication – $400 in winding equipment and $400 for oscilloscope
    • Open source controller for power matching
  • Adding oil heat storage for operation when the sun doesn’t shine, plus a backup burner, and overall integration into a combined heat and power system (CHP)

Our strategy is to overpower the system with solar capture, and live with a low overally cycle efficiency – to provide breakthrough cost predictions.

  • 60 kW incoming radiation capture at a baseline of $2/sq ft mirror costs – $1200 total
  • Balance of system – $800 for structure
  • Steam engine – $150, Generator – $150
  • Collector tube – $700
  • Total -$3k

In summary, to do the Solar Turbine correctly – we need to develop the capacity to build each of the system components in-house. Add materials cost, tooling cost, plus a $1500 storage cistern and heat exchanger, and the total Steam Turbine project has a basic budget of $7366. Not a bad cost for changing the world’s energy system. If you donate, send us an email that you’d like to contribute to the Solar Turbine project. We are beginning to parallel our project development, and will be setting up separate donation sites for each project. Right now we have the CEB Project, Solar Turbine, and tomorrow I’ll blog about the Sawmill. We found a project manager for that. If you’d like to become a project manager, examine our product list and drop us an email.

Here are some links to other Solar Turbine material –


  1. Nick Raaum

    Hi Marcen,
    Just wanted to try to clarify some potential confusion concerning efficiencies, the 60% for a bladeless turbine and the 80-90% efficiency for conventional turbines are reffering to mechanical efficiencies. That is how much of the cycles available energy was converted to mechanical energy. The 8% figure used for the steam engine is the cyle efficiency which is how much of the energy in the steam ultimately was ouput at the steam engine crank. Typical steam turbine cycle efficiences run around 35%, this is much greater than the steam engines average of 10%-15% much of this is just due to the lower steam pressures and temps typically used on a steam engine cycle. Mechanical efficiencies however for a steam engine however are close to the turbines and run 85% or better. See this book for more details: efficiency of steam engine&source=bl&ots=y1QoUKMj0k&sig=NgyJ2vPqilYNIWwwLKXrmvGtZas&hl=en&sa=X&oi=book_result&resnum=1&ct=result#PPA167,M1

    In any case I’m excited to start work on this project and expect to start posting more in the next couple of weeks.

  2. Richard Schulte

    $1500 storage cistern? for hot water/liquid, im guessing? Because if you want to avoid high metal costs, use ferrocement. Ferrocement, ferrocement, the appropriate tank maker.

  3. Jock Gill


    I wonder if burning biomass, recent sun light, at night might be a possible alternative. Perhaps simpler?


  4. Marcin

    Burning biomass – or recently captured sunlight – is generally a good idea. It is not as exotic as heat storage, but it may turn out to be the option of choice from the feasibility perspective. We will evaluate and compare both options, side by side.

    Also, I need to add an update – which you may study further at

    The total cost, with foundation, steam engine, and generator – is $3066 for the first prototype. That would meet the $1/watt prototype prediction (5% efficiency), and once we optimize the system to overall 10% performance, we are expecting $1/watt for complete systems produced via flexible fabrication for outside markets.

    Furthermore, the recurring comment that we get is the use of parabolic mirrors. We believe that the low cost and simplicity that we specify is more difficult to attain with parabolic mirrors, for three reasons.

    1. It is more difficult to fabricate curved mirror systems, especially in low-tech applications.
    2. Parabolic mirrors, in the one-axis tracking scenario of interest, with length running in the East-West orientation, suffer from defocusing as the angle of the sun changes from high noon. There are about 20% losses associated with this.
    3. There is no need for added complexity if flat mirrors are good enough.

    If we see that the flat mirror design is insufficient, we’ll reconsider. While we are aware that parabolic mirrors are the industry standard for large (MW-scale), solar power plants such as those produced by Ausra, we don’t believe that we need to go that route in smaller (kW-scale) distributed production facilities.

  5. […] Please study the drawings and comment here or at the wiki. Please pass this on to others who may be knowledgeable about the topic.  A discussion of some of the features of the design are found in a past blog post. […]

  6. Ted

    Hey Factor E Farm Folks,

    I was thinking about the concept of a steam engine. From what I understand it basicly it takes the energy of the expanding gas (water vapor) to cause the piston to move. What if some other gas was used? Something like freon or other gas with a low boiling point. Rather than using a heat exchanger like most air conditioning units, you could bury the pipe in ground and use the earth to cool the gas back into a liquid state. What I am saying is just a concept but I heard of others using this principle to cool their houses without using a traditional heat exchanger and fan. Who knows, this might work!

  7. glassdarkly

    How about the Deluge heat engine as an option?

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