3. Introduction to LCA, Danish Environmental Protection Agency

Input/Output analysis - Shortcuts to life cycle data?

3. Introduction to LCA

3.1	What is LCA?
3.2	Why use LCA?
3.2.1	LCA of a Television
3.2.2	LCA of the Danish recycling system for wine bottles
3.3	Conclusions
3.4	References

Marianne Wesnæs, 2.-0 LCA consultants

This is an introduction to LCA, presented at the Workshop on Life Cycle Assessment (LCA) and Input/Output-Analysis (IOA) 29^th September 2000, Copenhagen. The presentation gives a short introduction to the questions:

-	What is LCA?
-	Why use LCA?

3.1 What is LCA?

Life cycle assessment (LCA) is a method for evaluating the environmental impacts associated with a product or service from "cradle to grave". The LCA includes the entire life cycle of the product from extraction of raw materials, processing of these raw materials, manufacturing of the product, transport, distribution, use, re-use, maintenance, recycling and final disposal.

LCA is typically conducted in the following steps:

-	Goal and Scope definition (Description of the goal of the LCA, definition of the product or service, definition of the functional unit, geographical and temporal scope, definition of what to include and what to exclude etc.)
-	Inventory analysis (Collection of data for each step in the life cycle and addition of these. Data is typically consumption of energy and raw materials, emissions to air and water and amounts of waste. The results of the inventory analysis are presented in e.g. "kg CO₂").
-	Impact assessment (An evaluation of the environmental impacts – "kg CO₂" is calculated into "Global warming" and the environmental impacts are weighted in order to evaluate how serious the environmental impacts are).

In principle, all the processes affected by the life cycle of the products shall be included. For a wine bottle the processes in the life of the wine bottle are:

-	Extraction and processing of raw materials: Sand, limestone, soda etc.
-	Manufacturing the wine bottle at a glasswork
-	Filling of wine into the wine bottle and corking
-	Use (drinking the wine)
-	Recycling (rinsing and refilling) or recycling (remelting at a glasswork)
-	Use
-	Recycling….
-	Disposal as household waste (in Denmark it is mainly waste incineration)
-	Transport in between all these processes.

Furthermore, these processes demand a lot of other processes, e.g.:

-	Production of electricity and other energy types and extraction of raw materials for this
-	Production of water (for rinsing)
-	Production of chemicals for rinsing the wine bottles
-	Production of materials for all the suppliers of the glasswork, for the soda production etc.
-	Production of buildings, machines, trucks, tyres, roads etc. and production of materials for this (e.g. steel) – also for all the suppliers and for building the electricity work etc.

This list is endless. The glassworks has suppliers, and each of these suppliers has suppliers, and these suppliers also have suppliers……..

Hence, it is never possible to include all the processes in practice, because the work of collecting data would be enormous. It means that a LCA will never be "perfect", and when interpreting the results of an LCA it is very important not to believe or pretend that the results are "the whole truth".

3.2 Why use LCA?

LCA is the answer to questions like:

-	Are matches or lighters to prefer from an environmental point of view?
-	Which supplier should my company chose from an environmental point of view?
-	Does it give environmental benefits to collect more wine bottles for refilling within the existing collection system in Denmark?
-	What if the extra wine bottles cannot be sold in Denmark and has to be transported to wine producers in Spain? Does the extra transport counterbalance the environmental benefits?

There are two characteristics of LCA that are very different to the Input-Output Analysis (IOA):

-	The bottom-up approach in LCA gives information on minor details with large impact. In LCA, details are important!
-	By the use of LCA important aspects of the real systems are discovered. In LCA it is important that the results reflects realities – and that demands knowledge of the specific systems, not "average data".

This is illustrated by two examples.

3.2.1 LCA of a Television

The LCA of a Television from Bang & Olufsen showed that significant environmental improvements could be obtained by changing some of the components (Wenzel et al. 1997).

The LCA showed that the environmental impacts from a TV was closely related to the energy consumption - as is often the case in LCAs. Approximately 70% of the energy in the TVs life was consumed when the user watches TV and another 8 % when the TV was standby, waiting for the user to turn on the TV. Of course this result is very dependent on the exact TV and on the exact user of the TV (some people watch TV 4 hours a day leaving the TV at standby 20 hours, other people watch TV only twice a week. A TV uses more energy when turned on than in standby mode).

This energy consumption could be reduced considerable by choosing circuits, which use less power, by reducing the mains voltage and by changing to component types, which use less power. The energy consumption in the standby mode could be further reduced by using components specially designed for standby mode (e.g. a separate power supply – the power supply in a television will be designed to be able to handle the maximum power required in use).

Hence, it was possible to obtain considerable environmental benefits in a TVs life by focussing on a very little "details" – the components in the electronics.

3.2.2 LCA of the Danish recycling system for wine bottles

The LCA of the Danish recycling system for wine bottles showed that it is of environmentally importance that as few bottles as possible are crushed during the collection. In Denmark the wine bottles are rinsed and refilled, hence preventing new bottles from being produced (Nejrup and Wesnæs 2000).

During the work with the LCA we went "out in the real world" to see the system, to follow the wine bottles around the recycling system. In this process we realised that a lot of the wine bottles were crushed during the collection and handling – due to unnecessarily rough handling by some of the truck drivers that empties the cubes with recycled bottles. The truck drivers were paid "to empty the cubes" instead of "to bring back as many unbroken bottles as possible" – and this "detail of reality" was of significant importance for the environmental performance of the system.

3.3 Conclusions

It is clear that LCA is not "perfect" and not covering all the processes affected by a products life – as it in principle should. A possibility could be to "fill out the data gaps" with information from IOA. In many cases, this will be a very good idea. Adding information from IOA will give us a more total picture – but we shall keep in mind that neither LCA nor IOA can give us "the truth"!

I am not convinced that the overall conclusion in the above mentioned examples would have been changed significantly if an IOA had been added for filling out the data gaps. Hence, I believe that in some cases reasonable results can be obtained by performing simple LCAs combined with an estimate of the uncertainties and common sense!

3.4 References

Nejrup D, Wesnæs M. (2000). Genbrug af danske vinflasker. Vurdering af markedet og de miljømæssige effekter. København: Miljøstyrelsen (Miljøprojekt nr. 556, 2000).

Wenzel H, HauschildM, Alting L. (1997). Environmental Assessment of Products. London: Chapman & Hall.