Talk:Medium and Small Scale Concentrated Solar Thermal Power Platform
Interesting projects - wish I would have seen this 2 years ago when I first considered developing small scale solar thermal electricity gen - decided there was too much work for one person and I had other projects. A few quick notes:
1. I did not see Sopogy mentioned on your site but they are the only small (rooftop) scale producer I am aware of. Regarding heat-engine/generator coupling, I believe they use small scale geothermal units off the shelf. I'm sure they looked at different options before arriving at this as a semi-optimal solution. It might be helpful to get one of the small geothermal units and deconstruct it to see how it functions. The gen part seems easy, but there are many permutations for the heat engine portion.
2. The small section on Stirling engines mentions the Sunpower units, but I do not believe these designs have helium/hydrogen as a working fluid and most of the serious Stirling engines have this (for efficiency). Although, despite looking, I am not aware of a cheap source for these engines to tinker with (or any diy designs). I would guess the seals are difficult to get right.
3. Some of your efficiency numbers seemed off for solar thermal relative to N_Gas/Coal generation but perhaps I followed the numbers incorrectly. It is generally helpful to put such things in a table (maybe google spreadsheet?) to evaluate how the components add up (reflective film eats n%, thermal losses eat n%, total net loss~).
4. This may be a non viable concept, but here it is: I wondered if a reflective surface (e.g. reflectech) could be applied to a large piece of canvas that had a few guide wire attachments along the back side actuated by spool/motor/encoder (like a sail on a boat) in a feed back loop with a sun tracker (or % temp rise in working fluid). What it would lack in some reduced efficiency could be countered with much lower cost and thus larger surface areas, plus greater portability since the whole unit could be portable and simply staked into the ground - the fabric could also be furled/unfurled during high winds, dust, rain, etc. and even drawn through a squeegee during furling/unfurling to ensure the reflective surface was clean. Another option might be an inflatable reflective structure.
5. For glass/mirror/metal molds Geoploymers w/ various additives (aluminum powder, etc) might be of consideration since with a reprap (additive) or CNC mill/lathe (subtractive) a part could be printed from a CAD file in a cheap material (e.g. plastic) and then a mold constructed from relatively cheap geopolymer components to cast glass/metal, etc. - it won't have the longevity of a Nickel mold, but it will be cheaper and easier to construct diy