Solar Turbine – Commentary on Results

Friends, the latest developments on the Solar Turbine project, outside of the documentation clips in Factor e Live 6 and Factor e Live 7, are ambitious. We are presently leaning to mirrors and a modern, high-recirculation ratio uniflow steam engine as the heat engine of choice. The long-term motivation for the latter is to not rely on industrial detritus – such as some turbine from another application or non-modern steam engine from other suppliers. The long-term supply of the former is uncertain, and performance and cost of the latter are in question.

The results of the Solar Turbine convergence are promising. We got hands-on insight into what may or may not work – and that is what informs our direction. We still have a promise on the whiteboard – of $3/W as Milestone 1 with a 5% efficient heat engine – and $1.5/W as Milestone 2 with a 10% efficient heat engine. Talk to me or join the Solar Turbine google group if you are interested in understanding these cost predictions deeply.

Here’s the good part. The above predictions rely on off-shelf mirrors at $2/sq foot. In the long term, we have to replace this cost, which now constitutes over 50% of the cost in our design, with industrial swadeshi mirrors. I predict a mirror cost of 50 cents per square foot in this scenario. Critics, of course, say that we can never beat commodity production costs for mirrors – but I think open source production can, given that sand or glass cullet feedstock is readily available – and the commodity production process is fraught with inefficiencies of global supply chains. Plus, mirror production is old technology – we’re not talking about rocket science.

In short, we will pursue mirror fabrication and high-recirculation ratio uniflow steam engine fabrication in house. If you know anything about these topics or know people that do – help us with the engineering. Here we have great opportunity for open source engineering – on a topic of huge relevance to societal well-being. Concentrator solar power is in vogue – read the commentary in the next post.


  1. Richard Schulte

    exciting to hear! Though i think you mean $3/1.5 a W not kW, right? 1500 for a KW would be amazing and would very easily rival solar PV, and local production for concentrators are much more feasible as well. This is an impressive feat and I will be glad to tell folks about it at the OSN conference in san francisco.

  2. Abe

    Here’s another off-the-shelf steam system… this time from India. I am sure you have heard of them before, but just in case:

    Their prices don’t seem to bad, who knows about shipping, but it does include the generator, boiler and engine.