Energy, environmental issues and recycling -- or how to tie yourself in knots

摘要

Many of us, as individuals, are concerned about the environment and want to do the 'right thing' with respect to saving energy and responsible use of materials. Similarly industries are doing the same thing but are having difficulty to know what is the 'right thing'. For example in the UK one supermarket chain, as a positive environmental initiative, changed to using biodegradable carrier bags. They were immediately criticised because this was seen as an encouragement for their customers not to recycle but to continue to throw the bags away. A short time afterwards the same supermarket chain switched back to non-biodegradable bags and using publicity tried to get customers to re-use their carrier bags. The pressures are on to minimise packaging some of which are based on political dogma rather than good science. There is a tendency to take a good idea and extrapolate it beyond the practical or useful. It is pointless to minimise the packaging to the point where the food is spoiled because then everything is wasted. Biodegradable polymers can look attractive but there are competing demands that may make this technology look less attractive. Vacuum coating has some benefits but it is also immensely wasteful of energy and material. Only approximately one third of the power into the evaporation boats ends up as evaporating the aluminium and when the aluminium is evaporated only approximately 50 percent reaches the substrate. There are some ways of saving energy that can be take quite easily and others that could be worked on to improve the vacuum deposition energy consumption for the future. In this paper I hope to highlight some of the issues involved in this latest packaging minefield.