Revised 24 May 2019

Emergy is the total energy used or embodied in the life cycle of a product in terms of the available energy of one kind that has to be used directly and indirectly to make a product or service. Emergy is measured in units of emjoules or emcalories, units that refer to the available energy consumed in transformations. The type of energy is arbitrary and Emergy can be measured in terms of fossil fuel equivalents (FFE), electrical energy (MJe), or Solar Energy (seJ). Different products and processes make use of different forms of energy, each of which give rise to different levels of CO2 contributions to the atmosphere. Use of Emergy alone is therefore inadequate for making true comparisons of the environmental impact of different products. The same applies for Exergy.