Hi James When I pull a silicon crystal the melt is sitting at ~1450 deg C so I have some feel for the problems you are hinting at without ever having touched a stirling engine. The point I was going for was that diversity is key. One of my friends who is off grid has no problem producing more energy (in different forms) at different times than he needs, but what is really needed is a good all purpose storage system so that the production peaks and valleys can be leveled out versus usage peaks and valleys. One also needs to consider the options for usage. For example there are more options for the usage and storage of energy in an electrical form than thermal although I cannot ignore that nature found the most parsimony in the humble carbon bond. Electricity when used wisely offers high efficiency as well but in terms of solar conversion thermal is king. It will be a long time indeed before we hit a quantum efficiency in PV anywhere near 60% I think although nanomaterials look promising. One of the most interesting storage systems I have come across is the vanadium redox cell which has a virtually infinite shelf life with its zero self discharge characteristic. High current capability in both charge and discharge as well made it look very attractive for any non mobile usage scenario. A great BIG battery. I haven't heard much from VRB power systems lately so I assume there is a catch somewhere with that technology but it sure sounded promising when I studied it. Link here: http://en.wikipedia.org/wiki/Vanadium_redox_battery If you have any reality to share on it I'd appreciate hearing. Things have also gone very quiet with solarmission and the solar updraft tower, I don't know if you are aware of that one here's a link http://en.wikipedia.org/wiki/Solar_updraft_tower. <http://en.wikipedia.org/wiki/Solar_updraft_tower> Both of these ideas address the load leveling issue although with the updraft tower I think it came as a pleasant surprise to its designers!
Joe James Quaid wrote: >Joe, > >Stirlings aren't ready for prime time. They are still having seal and >ring issues. However, I hope to have an update on some new units that >may have that problem solved. The magic 10,000 hrs MTBF (diesel) >rating is the goal. BTW that was with land fill gas not solar. That is >another can of worms. Getting all 1000 C plus in the right place is not >a trivial procedure. Typically, a Stirling working fluid is ~ 850 C. >Things tend to melt and catch fire if you're not spot on. You can turn >insulation material into glass with this kind of heat. > >Overall, a trough plant is the most bang for the buck. The older units >are 40 + years now and are pretty bullet proof. Heat transfer / >storage technologies from the nuke power side may hold promise for >serious thermal storage at 1000 F temps. But, that too is not in >production yet. > >In 2005 all PV mfg's cut the thickness of their cells in half. I have a >friend that has older mono crystalline panels. They are twice as heavy >as today's panels. However, none of these thinner celled panels have >made it 25 years. PV panels are amazingly bullet proof. Weak panels >appear under high stress conditions. So, if these thinner cell PV >panels are going to have problems, they'll show up in the Desert SW >first. > >There are a few promising small solar thermal units that are being >tested (Stirlings / Turbines). I wouldn't touch any of them until >they've run for five years with descent MTBF. Plus, with any alt energy >system, demand a serious end to end guarantee. Also, solar thermal >units are not fire and forget like PV. You would have to be a competent >electro / mechanical type to own one. But, if you can do a valve job a >car and wire a 220 VAC outlet, working on solar thermal would not be a >stretch. > >But, the absolute best small alt eng solution is hydro. Small hydro >rocks. Find a stream with some flow and you are set. > > -------------- next part -------------- An HTML attachment was scrubbed... URL: /pipermail/attachments/20110105/9ff6e19f/attachment.html _______________________________________________ Biofuel mailing list Biofuel@sustainablelists.org http://sustainablelists.org/mailman/listinfo/sustainablelorgbiofuel Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Search the combined Biofuel and Biofuels-biz list archives (70,000 messages): http://www.mail-archive.com/biofuel@sustainablelists.org/
