What do we mean by the term “life cycle analysis”?
Life cycle analysis means, when we try to assess some product’s environmental or health impact, then we do not stop at the analysis of the immediate effects of the product itself but include its whole life cycle and environmental burden. In the case of petrol (gasoline) that would entail the full spectrum from oil drilling, transportation, production stages at the refinery, transportation to service stations, contamination of ground water from the tanks of service stations, to the health effects of petrol itself when handled at the service station, and finally incorporating the environmental and health effects of exhaust gases.
Life cycle analysis is useful in that it may reveal the environmental or health impact of the whole chain of activities compared with a totally different solution to achieve the same purpose (e.g. transportation using electric-powered trains). On the other hand, a life cycle analysis is a very ambitious and demanding exercise that can be used only to illustrate very large and relatively clear chains of events.
One of the most useful benefits of life cycle analysis is that it can reveal internal inconsistencies in processes or administration. For example, risk management by sectors can lead to a situation that one sector is very finicky in some aspects that are after all not very important to the total risk which depends on decisions in some other sector. One example is the tight dioxin limit values set for contaminated soils when in fact the dioxin exposure of population depends to a large part on their intake from food, especially from fish, meat and dairy products. These depend mostly on airborne fallout. In such a case, investigation of the comprehensive life-cycle of dioxins from the emissions of industries, energy production and waste incineration through the different intermediate stages to the most important medium, food, provides a realistic picture also of the relative importance of the intermediate parts of the chain for exposure.
Important in evaluating energy alternatives
Another kind of example is energy production. When comparing the benefits and problems of energy production, one mostly takes into consideration only those impacts during the production stage with both the early and the late impacts being overlooked. In this way one can claim that certain ways of generating power e.g. wind, hydroelectric and nuclear energy have no emissions during normal operation as compared with natural gas, oil or coal. In fact before one can construct these power plants both materials and energy are needed, and it depends on their amounts and ways of production, what kind of emissions will be produced. Moreover one has to calculate material and energy consumed per unit of energy produced in order to make comparisons relevant.
As a result, one may consider wind energy and natural gas as extremes in different directions. The investment is relatively heavy in the case of wind power when calculated per kilowatt hours of energy produced. In other words, relatively large amounts of metal, plastic and concrete are needed, and energy is used in their transportation and the land restructuring before the power plant will produce one kilowatt hour of energy. Thus the construction stage will produce high emissions of carbon dioxide, nitrogen oxides, particulate matter, chromium and plastic monomers. Whereas there are no major emissions during the operation itself, the crucial question is whether the power plant will operate for ten years or hundreds of years. If the operational time is long, the investment is divided over a long-lasting production of many kilowatt hours and the unit impact per kilowatt hour is small.
A power plant burning natural gas requires relatively simple and light investment when compared with the amount of energy produced. Therefore the most critical factor is how much emissions are caused by the normal activity calculated from the production of gas at the gas field, its transportation to the power plant and its combustion in the power plant. These two very different methods of energy production (wind-power and natural gas) cannot be compared unless the whole life cycle in considered.
Life cycle analysis aims at obtaining a comprehensive evaluation of the whole chain of activities with all direct and indirect impacts.
One level up: Here a risk, there a risk, everywhere risks, risks!
Previous chapter: Why are people afraid of dental amalgam?
Next chapter: The precautionary principle – better safe than sorry?