Propane Refrigerators & Freezers
In most homes, the biggest energy user is the refrigerator. It follows, then, that a big chunk of energy savings can be had by adding a super-efficient fridge to your appliance mix, or by replacing the ol' electric cooler altogether. Enter the alternative energy fridge: one that runs on propane!
Originally designed for domiciles located far from a utility grid (such as hunting lodges, vacation cottages, or homes in the developing world), propane refrigerators and freezers can eliminate a major consumer of electricity in one fell swoop, while allowing for a lower cost solar or wind installation. Ironically, these types of refrigerators use the heat generated by propane to create the cold needed to store your food. According to How Stuff Works, a propane fridge operates like this (major components are italicized):
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Heat, produced by the burning propane (or, in some cases, kerosene), is applied to a generator in which resides a solution of water and ammonia.
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The ammonia/water solution is heated to the boiling point of the ammonia. At this point, the solution flows to a separator, where the water is separated from the ammonia gas.
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The ammonia gas flows up to a condenser. The condenser, which is constructed of metal coils and fins (think: car radiator), permits the ammonia gas to release heat, which causes it to condense into a liquid.
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From the condenser, the liquid ammonia travels to an evaporator, where it then mixes with hydrogen gas and evaporates. The evaporation process produces cold temperatures inside the refrigerator.
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Meanwhile, the ammonia and hydrogen gases flow to an absorber, where they mix with the water collected in the separator.
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Then, the ammonia makes like a nightclub DJ (sorry, couldn't resist) and remixes with the water to form the solution mentioned in step one (after releasing the hydrogen gas, which flows back to the evaporator). The cycle then repeats.
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Lehman's has a nice graphic which demonstrates the whole process here.
Who makes gas refrigerators? Here are some of the better-known manufacturers of propane/kerosene refrigerators on the market (by no means an exhaustive list): Dometic (also sold under the "Servel" name), Crystal Cold, Diamond, and Norcold. Danby, another large manufacturer, has apparently discontinued producing gas refrigerators.
If you are a dealer or individual looking to buy or sell a propane powered fridge, check out EcoSwap's alternative energy appliance listings.