Pure and Applied Chemistry

Abstract: In order to sensibly design green policy, at least three separate disciplines need to be involved. Clearly, technology will be required to design new processes and redesign old ones. Government policy makers will need to ensure that new regulatory structures adapt and reflect societal goals of decreasing our impact on the planet. Lastly, we need to hear from the economists to make certain that our efforts to develop green processes actually have a net positive effect. This last point is not as obvious as it might appear. James Watt’s invention of the external condenser for steam engines, which he patented in 1769, dramatically reduced coal requirements for a unit of output. Not surprisingly, demand for coal dropped as new steam engines incorporating that design became common after the patent expired in 1794. However, in the period 1830–1860 coal use in England actually increased by an order of magnitude. This is the efficiency paradox. As the effective cost of the product falls because more can be produced from the same raw materials, demand increases. The net result is higher overall consumption. While the focus of green chemistry is the effect emissions are having on the environment, to date we have tended to concentrate on inputs and processes, and not the emissions themselves. In designing policy and new processes, we need to keep phenomena such as the efficiency paradox in mind to ensure that our efforts to improve the environment actually have that effect in practice.