Solar Icemakers

Here's a "cool," low-tech, small-scale construction project: a solar icemaker, for your off-grid house, or perhaps for a remote village to help refrigerate food or medicine.

It turns out you can contrive some simple plumbing, a reflector and ammonia into a passive icemaker -- no electricity or gas needed. (There are other approaches, too -- photovoltaic cells and a high-efficiency DC refrigerator, for instance -- but that's cool in a high-tech way, instead of low-tech.)

You can buy these ready-to-assemble from Energy Concepts Company (and even pay to get them assembled), or you can DIY. For the true tinkerer, you might go a little further and scale up to a Szilard/Einstein-cycle single pressure refrigeration unit.

Here are relevant links.

Energy Concepts Co. makes their Intermittent Solar Ammonia Absorption Cycle (ISAAC) models and sells them through distributors like these:


 * http://www.realgoods.com/renew/shop/product.cfm?dp=3100&sd=3104&ts=1062532
 * http://www.jademountain.com/appliances/refrigeration/isaac.html

Here's a case study of an ISAAC installed to refrigerate the catch at a fishing village in Mexico, saving the village US$16,000 per year in transportation costs (they bring the fish to market weekly now instead of daily) and increasing their profit US$16,000 a year (they can bargain more efficiently with the wholesaler when they don't have to sell on the day they catch):


 * http://www.caddet-re.org/html/body_397art2.htm

From Home Power magazine, here is a description of the STEVEN (Solar Technology and Energy for Vital Economic Needs) Foundation icemaker:


 * http://www.humboldt1.com/~michael.welch/extras/solarice.pdf

For his Ph D dissertation at Georgia Tech, Andy Delano did a "Design Analysis of the Einstein Refrigeration Cycle," including a working model. This doesn't include a solar heating element, but the refrigeration cycle (and the bubble pump!) is interesting, and Delano did a fair amount of optimization modeling that I'm sure would be useful groundwork:


 * http://www.me.gatech.edu/energy/andy_phd/

Some descriptions of other related design work:


 * http://www.pacificsites.com/~sps/refrigeration.html
 * http://www.hku.hk/bse/e-conf/b/index.htm
 * http://www.napa.ufl.edu/2001news/solar.htm

Pete, something tells me you might find Gaviotas' technology (and in general) interesting: http://www.dharma-haven.org/five-havens/gaviotas.htm --John Abbe