Electricity generation on the Moon

>>>>>Does anyone know much about solar thermal generators? Presumably the
collectors would be easier for a robot to make than PV cells, but I have
no idea what kind of tolerances are needed for the generator and heat
exchangers. I was thinking of something like a Sterling engine, but
isn't there also a way to generate electricity using a high temperature
difference across a pair of metals? Can any in-situ resources be used as
the working fluid?
Even if we can't robotically build the generators, we could ship one
or more and build the rest in place.

While the efficiency may be lower, the easier construction
requirements might make something like this a valid tradeoff.

Andrew
bleyddyn@...

In order to get a reasonable efficiency with a Sterling engine, it must be
engineered to extremely high tolerances. This makes it near impossible for
robotic production on the moon, in the beginning at least. Sterling engines are
favoured for use in space, due to their high reliability. The abandoned NASA SDG
project worked on a Brayton, gas turbine type cycle. I don't see how it will be
possible to produce gas turbines on the moon. The tolerances have to be very
high, and each blade must be grown from an individual crystal.