EmergySynthese

Emergy synthesis, or Emergy-Synthese in German, is a methodological step in emergy analysis that aggregates diverse inputs of emergy into a single comparable measure for a system, product, or service. Emergy, introduced by H. T. Odum, represents the amount of energy memory embodied in resources and processes, quantified in solar emjoules (seJ). An emergy synthesis combines flows from natural and human-made sources by applying transformities—the emergy per unit of energy—for each input, converting everything to a common unit before summation. By summing the emergy inputs across the system boundary, the approach yields the total emergy yield or emergy cost, allowing comparisons of efficiency, sustainability, or ecological footprints.

Process: define system boundaries, inventory energy flows, assign transformities, and compute totals. The result provides a single metric to assess the up-front energy invested and the energy support required to deliver a product or service. Emergy synthesis is used in ecological economics, energy accounting, and life-cycle thinking, often alongside other sustainability indicators. It supports analyses such as the relative importance of renewable versus nonrenewable inputs, the dependency on ecosystem services, and the emergy return ratios.

Critiques note sensitivity to boundary selection, data availability, and the estimation of transformities, which can affect comparability. Despite limitations, emergy synthesis remains a structured framework for evaluating energy memory and systemic sustainability in complex socio-ecological systems.