Cool in the Hurricane: Dual-Fuel Refrigerator/Freezers

Pictured is a combination 12V DC/120V AC/natural gas powered absorption refrigerator/freezer by Norcold. There's no traditional compressor, and it makes barely a hiss. When a violent storm takes out the grid, you have the option of changing to 12V solar (or wind) locally sourced electricity, for example. If the 12V supply becomes insufficient, you can then switch to gas or kerosene power. Check out the Norcold website for a wide range of sizes, styles, and power options. In the US these are commonly found in RV's, boats, or yachts. TreeHugger thought such appliances might be just what the weatherman ordered for preventing loss of your food in an outage, or for evacuating with some food. But what about efficiency and air emissions? No point if its just more "stuff" that pollutes.Here's the answer. All models discussed in this post are based on absorption chilling technology, which involves an hermetically sealed ammonia solution, a heat source, condenser, heat exchange tubes, and no moving parts. Although the technology has been around for many decades, these new models are considerably more refined and lighter than earlier versions.

The samples we selected for TreeHugger are basic: lacking some digital "stuff" and absent, too, the price tag more befitting a yacht owner.

The environmental advantages of absorption chilling are several. Needing no compressor, they are extremely quiet and reliable: you might reasonably hope for a long, pleasant design life in other words.

There are absolutely no CFC's, HCFC's, or HFC's present. When the warmed up, ammonia gas is driven out of solution, after which it rises to a plenum where heat is absorbed as it re-condenses and goes back into solution: the opposite of other gaseous refrigerants.

Absorption chilling what msome grocery stores and most ice rinks use. It is widely found in domestic refrigeration units in developing nations. Yes, a rapid ammonia leak would be unpleasant and potentially hazardous to a nearby person. But, leaks are rare and the amount of ammonia is low.

When electricity is applied as the "fuel" no local emissions result. However, when natural gas or kerosene provide the heat to evaporate the sealed ammonia, combustion emissions originate from the appliance, instead of the power plant. Because the power is from a "distributed" source, there is no associated line loss of electricity to account for (typically in the 3 to 9 percent range). Hence, the direct use of fuel in the unit is an efficiency boost.

If you live in an apartment building that allows gas appliances you're probably OK to have a gas tank or kerosene tank in the kitchen or pantry. Check with the super and the fire department as well as the supplier about ventilation.

If building rules, zoning codes, or local ventilation avenues present an obstacle, you can always get one of the smaller 12V DC models and hitch it to a few solar charged 12V DC batteries when at home, or screw in a butane camping cylinder when on the road.

Regardless of size, the chest style refrigerator/freezer is always the most efficient design, followed by the "drawer" style upright style in second place. All open-shelf, upright refrigerators are relatively wasteful of energy, as when the door is opened, most of the cold air spills out and is replaced with warm humid air. There's no way around that.

To save money and do the best thing for the environment, as well as have dual fuel flexibility for electricty outages, then, TreeHugger suggests you have a look at the Dometic kerosene/electric chest freezer/refrigerator. The pictured one's got lots of space and runs off 120V AC, 240V AC, or kerosene. This would be ideal for a back porch or shaded pantry with feasibility of ventilation. Kero might present less of a worry than natural gas in the unit, given the potential for storm damage to the kitchen; again, check with the fire marshall and building super first.

Dometic also has a combination natural gas and electric chest freezer if that works better for you.

TreeHugger views these appliances as future-adaptive: adaptive for hurricanes, to make practical the use of distributed solar power, for coping with grid outages due to excess demand, for Peak oil, and so on.