Manufacturing

products as directly competing with their new products and will continue to do so unless legislation is enacted or pricing differentials are introduced.

Three central components in the waste minimisation hierarchy are the 3Rs: reduce, re-use and recycle (see the Waste chapter). Following repair and remanufacturing to enable the re-use of products, recycling is a key step in the closed manufacturing system. This can support the use of the by-products of production processes, whilst also providing solutions in the substitution of inputs in manufacturing. The most important input substitution in the metals industry per se is the use of scrap in place of ore. In the US and Europe half or more of the carbon steel production is now based on scrap. Scrap is routinely sorted into grades, depending on the presence of contaminants. Research on ways to separate contaminant metals from the iron is needed, if only to facilitate recovery of the chromium, zinc, copper and so on. Yet, surprisingly, the recycling rate for iron and steel has dropped in recent years from a high of 60 per cent in 1980 to 35 per cent in 2006. The IEA projections assume that the decline will reverse and that a recycling rate of around 55 per cent will be achieved by 2050 (IEA 2009b). However, a significantly higher rate may be achieved by appropriate policy interventions, including measures to advance recyclability and design for dismantling.

Recycling is especially energy-efficient in the cases of aluminum and copper. Recycled aluminum requires only five per cent as much energy as primary production, but the recycled product, which often contains alloying elements, is not easy to roll into sheets or foil. Effective ways to purify the recycled metal (and to recover the alloying elements) would be very valuable. In the case of copper, a single tonne of metal requires the mining and processing of anywhere from 100 to 300 tonnes of ore (depending on the country), so the recycled copper requires much less energy than the virgin metal from ore (Ayres et al. 2003).

One of the most important (and under-exploited) near- term opportunities for improving energy efficiency in industrial processes lies in recycling high-temperature

waste heat from processes such as coke ovens, blast furnaces, electric furnaces and cement kilns, especially for electric power generation using combined heat and power (decentralised CHP). Virtually all of these examples are technically suitable for small combined heat and power plants with paybacks of the order of four years, providing only that the power can be utilised locally.4

The

pulp and paper industry has reported heavy investment in CHP technology to reduce energy consumption, noting that CHP installations allow savings of between 30–35 per cent of primary energy (UNEP 2006). Where CHP is not an option, the next example of input substitution is the use of waste fuel, such as biomass or municipal waste.

On the demand side, numerous measures can reduce absolute water use through efficiency and recycling measures. Recycling waste water from a variety of industrial processes is increasingly important because of the scarcity of fresh water in conjunction with growing demand for water in many parts of the developing world, such as northern China and India. The world market for water treatment in 2008 was US$ 374 billion, of which US$ 70 billion was in the US alone. Half of this market could be served by new modular systems using magnetic separation technology, which has been successfully applied to mining and industrial wastes as well as municipal wastewater (Kolm et al.1975; Svoboda 2004).

Water used in chemical wood pulping is mostly recycled internally to recycle the chemicals. Metallurgical, chemical, textile and other surface-finishing operations generate polluted wastewater that must be treated before it can be re-used. In the longer term, there are numerous possibilities for reducing the need for water treatment after use by making the processes more efficient or cleaner. In particular, the need for industrial cooling water can and should be reduced dramatically by introducing co-generation of electricity to take advantage of high- temperature heat that is currently wasted.

4. Under current rules in most countries, only electric power companies can sell electricity. This means that the utilities are also monopolist buyers. The price at which they are willing to buy electricity from other producers is often too low to make the investment worthwhile.

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