The Surplus Cost Method | Introduction

As society is demanding more fossil fuels and metals, there is an increasing concern about resource depletion

By Tommie Ponsioen on March 15, 2013

Resource depletion has therefore been an important part of LCA, next to ecosystems quality and human health. However, there is little consensus on how to calculate the impact of resource use on resource depletion. For example, the total fossil resource use expressed in heating value has often been used as an indicator, even though it does not have any meaning in terms of depletion. Another often used approach is to implement the use-to-stock ratio, in which a resource that is intensively used and is close to depletion has a high factor. However, while the total available future resources is an important factor for this approach, it is highly uncertain and its efficacy depends on how it is defined. Moreover, stakeholders (manufacturers, policy makers, consumers) are actually more concerned about resource scarcity rather than resource depletion.


The approach that PRé developed gives an indication of resource scarcity for different types of abiotic resources by modelling the consequences of future resource use in terms of surplus cost. Surplus cost is defined as the total additional future cost to the global society due to the production of one unit of resource, and is related to a certain future global production volume. Resource extraction cost increases due to changes in techniques, or dependency on ore grade and recycling rate. Future global production is very uncertain, but different scenarios were used from an internationally recognised study, by the climate change panel of the UN, to assess the model’s sensitivity.


The presentation will focus on the results of fossil resources, which are fully completed. The main finding was that crude oil use has a much higher impact per MJ than the use of natural gas, and that coal use has a minor impact. This means that improving crude oil use efficiency has much more effect than for other fossil fuels. And, where possible, lower impact fuels should replace the higher impact fuels. It must be noted, however, that for the damage categories ecosystems quality and human health, coal use has a much higher impact because of the larger amounts of CO2 emissions per MJ.


By integrating the method in a multi-impact LCA, the authors believe that it is appropriate for assessing resource scarcity, as it captures the issues of concern (rising resource extraction costs) and combines it with future production scenarios.


Tommie Ponsioen
LCA Consultant for PRé



Want to know more?

A paper is being prepared for publication in a scientific journal:
The presentation will be given during the CILCA conference (Mendoza, Argentina, 24-27 March).

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