Some concepts just make sense- like when the developer of a solar powered pontoon boat pointed out-"Since most recreational boating is done when the weather is nice, solar power is particularly well adapted to the task." We were thinking that way while looking for a solar powered air conditioner- when do you need it? When it is hot and sunny. We looked at Justin's SolCool but we knew that natural gas fired AC units or propane fridges existed and thought heat is heat- there must be one somewhere, and put google to work. This is the first of a series- the Direct-Fired Absorption system.(DFA)
Gas fired air conditioners work on the absorption principle. "The distinguishing characteristic of absorption cooling equipment is that it produces cooling by using heat energy as an input, rather than by using mechanical energy. For this reason, absorption chillers were once common in facilities that had large boiler plants with excess capacity during the cooling season. Unfortunately, absorption cooling is inefficient, and absorption chillers appeared destined for extinction." ...In large absorption machines, the actual refrigerant is water at very low pressure. An absorber, usually the salt lithium bromide, is used to move water vapor through the system. Crystallization of the salt is a major operating problem that the design of an absorption chiller seeks to avoid."
Direct Absorption (DFA) was developed in Japan in the 60's and now the world's largest maufacturer is Broad Air Conditioning in China. "To power our absorption cycles, BROAD absorption chillers use a wide range of energy sources: oil, gas, as well as solar power, steam, hot water and exhaust. As our chillers do not use electricity as an energy source, they have the potential to dramatically reduce investment in electricity infrastructure in both public and private sectors." They now appear to be extremely efficient and save lots of electricity.
Finally, we find on their site:
"BROAD strives to be like our ancestors that mastered the miracle of fire, like James Watt who harnessed the power of steam, like Thomas Edison with his devotion to testing and retesting. Our goal is to limit the use of fossil fuels and exploit the use of renewable energies such as solar energy to provide cooling and heating needs.
Two years ago, BROAD provided an American customer with our first solar energy powered air conditioning system. This system has performed exceptionally well to date. BROAD's solar energy engineers and salespeople have drafted an ambitious plan to commercialize the solar energy air conditioning system worldwide."
We did not find the home-sized unit we were looking for, but the peak loads in North America are driven by air conditioning in summer- this looks like a good way of taking much of that off the grid. Visit the surprisingly complete and thorough website at ::Broad Air Conditioning and read their ::environmental manifesto here