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Life cycle assessment

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A Life Cycle Assessment (LCA) is a full assessment of the environmental impact of a process or product - as the title suggests, this assessment is over a product's entire life cycle. It is often poetically termed a "cradle-to-grave" assessment, with cradle and grave being euphemisms for digging the raw materials out of the ground and burying them in a landfill, respectively.

Method[edit]

LCA takes into account every process that goes into a product - and we mean every. This makes it one of the most powerful ways to assess the true environmental impact of something. They are often presented as flow diagrams. Each block forms an individual "process" and each process is listed with the resources it consumes and the waste it generates; these can be simplified or made more complex as necessary, for example, you could have "packaging" as a single block or you could split it into "printing", "making cardboard", "making glue" and so on. The individual processes are linked by arrows in the direction the life of the product flows and these arrows usually represent transport. These transport sections are one of the key components of LCA, as many people underestimate the environmental impact of a product until they count transport. Some LCAs made by companies even include the environmental cost of their employees driving to work to make the product, although in practice most don't quite go this deep.

At the end of the assessment, the consumed resources and waste generated are added up. This is then the true environmental impact of a product or process, which can then be quantitatively compared with a rival. The best choice, therefore, is one that has the least impact over its entire life cycle, not just small individual sections of its life, such as how it degrades in a landfill.

Example[edit]

The following is a fairly simple LCA of a hypothetical "goat burger". It doesn't include everything that it should do, however. Transport costs are omitted and some sections are highly simplified for reasons of space - it could be much, much larger and much more thorough.

LCA.PNG

This is merely a qualitative illustration, but it can be quickly seen that the packaging for the example goat burger and, well, everything that isn't the actual burger itself, seems to dominate the assessment. There are also at least 9 points shown where the product has to be transported, i.e., from one factory to another, although some might do it all on one smaller site, and minimise this problem. Each section of transport consumes fuel and emits carbon dioxide, among other pollutants.

Comparative assessment[edit]

The primary purpose of LCA is to compare processes to find the true environmental cost and which is better. For instance, imagine wanting to change your old, crapped out car for a brand new one with a massively efficient engine. Sounds like a good idea, right? LCA can assist in the decision making.

Firstly, the life-cycles of both options need to be compared. In the first case, the expected remaining life time of the old car needs to be multiplied by its fuel consumption, emissions and amount it is used followed by the cost of scrapping it. This is simple to do. However, this needs to be compared with not only the fuel consumption, emissions and use of the new car, but also with its construction and transport costs - which may be very significant. If the efficiencies of the new car over the old car can't offset the construction cost over the expected time it will be used for, keeping the old, crap car is actually the best option.

Environmental impact[edit]

From an LCA, we can look at the environmental impact of two processes. Consider an example where you need to print off several dozen to a few hundred pages of text for one reason or another - you're self-publishing your James Randi slash fiction, or you're writing an epic piece of music and need to distribute it to performers. What is better, then: printing, or using an eReader? A naive view would state that the eReader option is clearly the best because it saves trees. Often enough, it's these large and easily visualised areas that dominate peoples' thinking - yet usually take only a minute fraction of the true impact.

When considering an eReader, the following needs to be taken into account:

  • Mining for precious metals for computer parts.
  • Refining plastic for the casing.
  • Dyes for the electronic-ink sheet.
  • Power consumption (although minimal for most eReaders, there's the computers you need to boot up to load your PDFs onto them)
  • Shipping from the factory, and packaging.

Looking at this, the printing option actually becomes considerably more environmentally friendly! Especially when using a sustainable source for paper, where every felled tree is replaced by one or more new saplings, the trees component disappears. However, what if everyone you need to distribute your document to owns an eReader anyway? As they would have this equipment regardless of the publishing option you take, you can remove it from the assessment, and so the marginal cost of loading an electronic document is considerably less than the printing, which would involve the following:

  • Felling and transport of trees.
  • Processing and pulping of wood.
  • Water consumption in paper manufacture.
  • Bleaching of the final product (perhaps the largest environmental impact of paper manufacture)
  • Compressing and drying.
  • Transport and packaging of the final product.
  • Printing: electricity, printer manufacture, ink consumption, pollutants associated with printer ink.

A quantitative LCA would show how many sheets of paper it would take before building an eReader, and the marginal cost of loading up documents onto it, would be the preferable option. It's a bit more complicated than how many trees you save.

See also[edit]