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As the world strives to develop more sustainable technologies, a way of analysing their performance is necessary to avoid swapping one environmental problem for another. Life cycle assessment (LCA) offers a means of achieving this, and is being used by Eco-UV to analyse systems containing the new lamp and ballast technology. However, as with all simulations, the results are only as good as the data used to generate them.

Making sense of sustainability

The worldwide community is grappling with improving the lives of its current human population without compromising the planet’s ability to support life in the future. Sustainability is the watchword, but how can we be certain that one way of doing something is really more sustainable than another?

A frequently cited example is the use of paper hand towels versus hot air blowers for drying hands after washing. At first glance, it may seem obvious that paper hand towels are the greener approach: after all, hot air blowers need electricity to operate - probably derived from fossil fuels which produce carbon dioxide - as well as energy and metal or plastic for manufacturing. But hold on, you have to cut down trees to make the paper towels, which prevents them absorbing carbon dioxide from the atmosphere. No problem, just plant more trees. But what if, in order to keep up with demand, you plant fast-growing conifers in place of deciduous trees? That may reduce the biodiversity of the forests in question. And how about the large amounts of water, energy and chemicals (such as bleach) needed to make the paper towels from the trees? Furthermore, what to do with the used towels? Can they be recycled into other useful products or must they go to landfill? In the latter case, they put extra pressure on the already depleting sites for burying rubbish, and they may (eventually) break down in the ground to form methane – a far more potent greenhouse gas than carbon dioxide. Hmm, maybe hot air blowers aren’t so bad after all…

Balancing the myriad environmental impacts of even the simplest product or process is an exercise of sufficient complexity to make anyone wring their hands, wet or dry. However, it is essential if we are to design products with the lowest overall impact on the environment, or at least understand where the inevitable compromises have to be made. Everything has an environmental impact; what is needed is informed decision-making based on the full life cycle of a product or process. Life Cycle Assessment (LCA) is increasingly used by companies as the standard tool for answering the question: just how green is our “green” product?

Gundremmingen Nuclear Power Plant attrib 

LCA can help to tackle tricky questions such as: how environmentally sustainable is nuclear power?

Measure and analyse

The first step in a life cycle assessment is to define the system’s boundaries and assumptions: the functional unit of the analysis, how far upstream or downstream the analysis goes, and how impacts are assigned. For example, the functional unit of a building’s LCA would probably be a single building, while the analysis may quantify the impacts from the production of its materials, construction, use and maintenance, and demolition and disposal. If the system boundary is then extended to cover the potential for reuse of the building, or recycling of the materials after demolition, then the final assessment will be different. These scope definitions must be examined when comparing the results from different assessments to check that a like-for-like comparison is being made.

LCA diagram 

All the different stages of the product’s life cycle can be considered in an LCA

Once the goal and scope of the analysis are defined, a Life Cycle Inventory is collated. This describes and measures every flow in and out of the system being analysed: raw materials, energy, water, emissions, etc. This can be a complicated business as all related aspects within the system boundary may need to be considered, such as transportation of raw materials and final products, product maintenance, disposal, and so on. Compiling the inventory is critical to the validity of the entire assessment, and is often the most time-consuming step in the process.

Next, the inventory is analysed for its environmental impact, based on factors such as the depletion of non-renewable resources, pollution of water bodies, ozone depletion, etc. For example, if a process consumes a quantity of natural gas as determined in the inventory, the impact assessment calculates the resulting effect on global warming. This is the stage where current scientific knowledge can affect the result of the assessment and a degree of interpretation may be required. Sometimes the final “end-point” effects are simply unknown, which forces the LCA to be cut-off at a point further up the environmental impact chain. Effects on human health and ecosystem toxicity are particularly problematic. An LCA may calculate that a process leads to acidification of a body of water, for instance, but will probably stop short of stating how this will affect the populations of aquatic life in the water because this is not known with sufficient certainty.

Validating Eco-UV

The widespread acceptance of LCA as a measure of sustainability is not surprising when you think about it. Introducing a new product to market is risky enough at the best of times, but those that radically challenge the status quo are even more likely to fail due to customer inertia or restrictive industry standards. Anything that validates the claims that the manufacturer is making about the green credentials of a product will help, especially as the indications are that the influence of sustainability on consumer choice is growing.

For this reason, the Eco-UV consortium includes the Swedish Environmental Research Institute, IVL, an independent, non-profit organisation with many years of experience in performing life cycle assessments. IVL will use data from system demonstrators to perform a thorough assessment of the technology developed during Eco-UV, to compare its economic and environmental impact with that of current UV systems.

Know your limitations

LCA is a technique that is continuously being refined, both in terms of its actual practice and by the development of our knowledge of how human activities affect the environment. It is also a maturing process, with industry-wide standards and centralised databases helping to minimise disparities between different studies on the same product, often a source of criticism of LCA in the past. In making assumptions about future conditions, an LCA inevitably contains some degree of uncertainty, not to mention that it is often attempting to account for a huge number of variables. What LCA does provide is a means of comparing the impacts of different products or processes based on supporting data rather than mere assumptions, and guides us in selecting a way forward that offers the best compromise of the impacts.

Perhaps just as importantly, LCA raises our awareness of how everything we do affects the environment in some way, often unexpectedly or even counter-intuitively. The world of environmental sustainability contains many shades of green, an inconvenient and sometimes frustrating truth but one that we must face up to if we are to improve our stewardship of the planet and its resources. Something to think about next time you’re drying your hands…

 

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