At SELCHP, we help to sustain the quality of life for those living in the local urban region, and also for the wider community. The major part that we play is through our contribution to national electrical energy generation, by recovering energy from residual waste, which is that part of waste that cannot be effectively reused or recycled.
This fraction is roughly half of the total waste and it contains about one third of the energy of a similar weight of coal or oil. Since each household produces approximately one tonne of waste per year, it contains enough energy to supply about 10% of our household electrical needs and thus replaces the fuel that would be needed in a conventional power station. Furthermore, since most of the energy in residual waste is from biomass, the carbon dioxide emitted is simply returning to the atmosphere the carbon dioxide that was originally harvested from the atmosphere by the plants that grew the biomass. It is therefore quite environmentally friendly.
The first plants to burn waste on a large scale were operating in 1870, but did not utilise the energy available. Modern plants recover some of the energy as electricity and in some cases (such as the Sheffield plant) also recover the vast amount of available low grade heat for district heating. The growing need to divert wastes from landfill has led to rapid growth in the number of energy-from-waste plants and there are well over 400 plants now operating in Europe. The UK is lagging behind most other European countries where 38% of their waste is now burned in energy-from-waste plants. At present we have only 20 plants operating, but this number is increasing rapidly and will soon double, as local authorities move quickly to avoid the growing cost of landfill and the associated environmental damage.
SELCHP, which we continue to show with pride to our many visitors, was built in 1994 and has long been regarded as the leading plant in the country. It is interesting to observe that plants constructed recently often have a striking architecture, as illustrated by the new plant at Southampton, which is illustrated below. Nevertheless, they operate on the same principles and at similar efficiencies to SELCHP, and they are required to conform to the same tight regulations.
In view of the global warming problem, the power industry and academia are already investigating advanced technologies that will carry us into the more distant future. Among other options, the carbon dioxide can be buried (i.e. landfilled!) in the deep wells from which oil and gas have been removed. This would mean that chimneys would no longer be required on power stations, but inevitably the additional costs will have to be covered directly or indirectly by the consumer. Incorporating such concepts in an energy-from-waste plant leads to the novel observation that such an installation would actually result in the net removal of carbon dioxide from the atmosphere. I leave you to ponder such intriguing thoughts about the world our children will inherit!
Professor Jim Swithenbank
BSc, PhD, FREng, FInstE, FIChemE