6.2 Life Cycle Assessment and Impact Assessments

One of the 8 Grand Challenges relates to Life Cycle Assessments (LCAs), where the emissions and resource consumption of a product is analysed across its entire lifecycle. This lesson will describe the process of an LCA and how it might be used to make informed decisions by engineers and businesses alike.

An LCA is a necessary part of sustainable engineering in that it allows the engineer to consider the total environmental cost of a product or process. All of the consumptions and emissions of a product through its life-cycle are evaluated, from the manufacture through to use and disposal, or the “cradle-to-grave” journey.

All aspects of an LCA are considered in terms of the potential environmental impacts, whether that be the consumption of non-renewable resources like land and fossil fuels, or the emissions resulting in global warming or ozone depletion. Every single stage of the process is considered, where each stage has detailed components.

An LCA quantifies emissions and consumption on a “per unit” basis, where the global warming potential of a product will be considered as the amount of carbon dioxide emitted in order to produce 1 item.

The quantification of emissions is simplified to a select few substances. Global warming potential is measured in the emission of \(\ce{CO2}\) equivalent (\(\ce{CO2} \, _\text{eq.}\)) whilst the impacts of global warming are in reality a combination of many other substances, such as methane (\(\ce{CH4}\)) and nitrous oxide (\(\ce{N2O}\)).