A Systematic Approach to Explorative Scenario Analysis in Emergy Assessment with Emphasis on Resilience

Fossil energy depletion (specifically peak oil) and climate change are imagined to profoundly affect human civilisation. This motivates assessment of resilience, a concept associated with the ability to persist and maintain function. Explorative scenarios may be used to cast light on what the future may bring.

We develop a systematic approach to explorative scenario analysis and attempt to quantify aspects of resilience specifically for emergy assessment (EmA) of production systems. We group system inputs into five categories: (1) fossil fuels, their derivatives, metals and minerals, (2) on-site renewable inputs, (3) slowly renewable inputs, (4) direct labour and (5) indirect labour.

We consider the existing EmA indicators of biophysical efficiency (the unit emergy value, UEV), the degree of dependence on free, renewable, natural flows of energy (%R) and the degree of dependence on local inputs (%Local) as relevant resilience indicators in EmA. Formulas to calculate the corresponding indicators for the outputs in future scenarios are provided, e.g. the resulting adjustment factor for the UEV.

We demonstrate our approach by parameterising four conceivable energy descent scenarios described by corresponding narratives. We analyse the aggregated effect on UEVs of these scenarios for production systems that differ with respect to how the emergy flow is distributed among the five input categories.

We find that for most production systems, scenario conditions significantly affect the UEV. The production systems that rely primarily on on-site renewable resources appear less sensitive to societal changes. The significance of labour inputs varies among scenarios, and a higher percentage of labour inputs leads to increasing UEV in a Green Tech scenario but lower UEV in more radical energy decent scenarios.

A comparison of two specific production systems showed that different expectations of the future lead to contrasting conclusions regarding prioritisation. We use the insight gained in the study to suggest venues for sustainable development under changing societal conditions.