In the environmental sense, what is the right weight for a product’s size? Would you, for example, expect that the ‘environmental weight’ of a microchip could be similar to that of a car?
Such is the somewhat surprising conclusion of a recent paper in Environmental Science and Technology [(2002) 36 (24), 5504]. According to researcher Eric D. Williams of United Nations University in Tokyo, Japan, who led the study, a single 2 g, 2 MB DRAM chip — such as that found in the memory of PCs — uses up 1700 g of fossil fuel and chemicals in its manufacture. “The environmental footprint of the device is much more substantial than its small physical size would suggest,” he says. If anything, this figure represents an underestimation of the true cost because of the uncertainties in determining the energy use associated with producing the input chemicals and packaging materials. The manufacture of a passenger car, however, eats up 1500–3000 kg of fossil fuel during manufacture. Much more than a single chip, you might say. But, argues Williams, a more illustrative figure is gained by comparing the weight of the final product with its fuel and chemical consumption. This ratio is about 2:1 for a car, but about 630:1 for a microchip. Another environmental disadvantage of computers is their short shelf life. In a ten year period, you might get away with buying one car, but you’re unlikely to make do with the same computer. If you buy five computers during a period of ten years, which is not so unlikely considering work and home requirements, the total energy to produce those computers would be surprisingly similar to that required for one car, says Williams.
“The public needs to be aware that technology is not free,” says Williams. “It also sends a clear signal,” he says, “that energy use in purification and processing of high-tech materials is much more important than generally perceived.” This argument is counter, says Williams, to the idea of dematerialization, whereby technological progress reduces the amount of material needed to produce goods and services. The microchip may not turn out to be such a good example of successful dematerialization if the use of secondary materials — fossil fuels and chemicals — during production are taken into account.
The interesting aspect of Williams’ work is this focus on the environmental impact during manufacture, rather than use. A comparison can be drawn with white goods, where it is relatively easy to determine which washer is most eco-friendly during use (in terms of energy and water consumption), but there is no such available comparison for the environmental cost of its manufacture.
And what of disposal after use? One of the driving forces in the automotive industry’s uptake of biocomposites, which are the focus of this issue, is the European Union’s directive that by 2015 vehicles need to be made of 95% recyclable materials. The right selection of materials has never been more crucial.