Fig. 3. Cost and TEWI comparison of different refrigeration systems (modified
after Zoontjens et al., 2005). TEWI—total equivalent warming impact is the sum of
the direct (chemical emissions) and indirect (energy use) emissions of greenhouse
gases. (AMR—active magnetic regenerator, M.Hyd—metal hydride systems, TAR—
thermoacoustic refrigeration, TEC—thermoelectric cooler, VAR—vapor absorption
refrigeration, VCR—vapor compression refrigeration).