The specific energy consumption of six different microwave-driven processes and equipments has been studied and it was found that the scale used dramatically affects it. Increasing the amount of sample employed from 5 to 100 g leads to a reduction in the specific energy consumption of 90–95%. When the amount of sample is 200 g or higher, the specific energy consumption remains practically constant. This means that to assess the real energy efficiency of a microwave-driven process a minimum mass of about 200 g needs to be used. The energy results can then be easily extrapolated to larger scales. Otherwise, a correlation should be used to avoid overestimated energy values and inaccurate energy efficiencies.The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement no. 311815 (SYNPOL project). D.B. and N.R.R. are also grateful to FICYT of the Government of Principado de Asturias (Spain) and the Ministry of Economy and Competitiveness of Spain (under Project MAT2011-23733), respectively, for their predoctoral research grants. The help of Xerolutions S.L. in providing experimental data is also acknowledged.Peer reviewe
