An Analysis of Off-Grid Residential Refrigerator Energy Usage- Absorption vs. Electric?
Stephen J. Treado

This paper describes a detailed analysis of off-grid residential refrigeration energy usage, specifically comparing the energy performance of electric and propane-fired refrigerators. Off-grid electric power systems frequently incorporate a renewable source such as wind or solar photovoltaic (PV) with a back-up propane fueled motor/generator. Residential consumers face the choice of employing an electric refrigerator with a conventional vapor compression refrigeration system, or a fuel-fired refrigerator operating as an absorption refrigeration system. The essential question is whether it is more advantageous to use electricity to run the refrigerator, which might be provided by some combination of the PV and propane motor/generator, thereby taking advantage of the relatively higher electric refrigerator Coefficient of Performance (COP) and free solar energy but having to accept a low electrical conversion efficiency of the motor/generator, or use thermal energy from the combustion of propane to produce the refrigeration effect via an absorption system, albeit with a much lower COP. The analysis is complicated by the fact that most off-grid renewable electrical power systems utilize a battery bank to provide electrical power when it is not available from the wind turbine or PV system, so the state of charge of the battery bank will have a noticeable impact on what energy source is required. The bottom line energy usage and fuel input depend strongly on the ability to make use of the renewable sources in real time to avoid battery bank conversion losses, as well as to have sufficient battery storage capacity to minimize the need for operation of the motor/generator to meet electric loads.

Full Text: PDF     DOI: 10.15640/jea.v3n1a2