Energy From Waste - The Concept

There is now a real focus both on reducing waste and on recycling and recovering useful materials from waste, but, despite the best efforts of all concerned, there will still be a residue that has to be dealt with.  This residual waste is a valuable source of energy – indeed, enough energy to generate 17% of the UK’s electricity requirements.

Only the waste arising from non-fossil fuels, about 65 % of municipal solid waste, is eligible for Renewable Obligation Certificates (ROCs).  Although this is an important consideration in the economics of EfW Plants, it is irrelevant in terms of policy making – the conversion of all of the residual waste to heat and power, whether eligible or not, will facilitate a significant reduction in the consumption of primary fossil fuels.

EfW plants are now commercially viable at a relatively small scale – 30,000 tonnes of waste per annum.  Their use of advanced thermal technologies means that EfW plants can safely handle not only municipal wastes but also agricultural and veterinary wastes, clinical wastes from hospitals and nursing homes, commercial and industrial wastes and contaminated oils.  They are thus ideally suited to providing local solutions for waste management without the need for costly transport to distant facilities.

Advanced thermal technologies achieve very high standards of emissions and produce a solid residue which is virtually carbon free and can go to landfill as an inert waste.  In some circumstances, these some of these solid residues can be used for commercial purposes, but, even if all of it has to go to landfill, the quantities will have been reduced by a factor of six or seven – a real benefit for Local Authorities struggling to meet the requirements of the Landfill Diversion Directive.

Of course, local populations will have some concerns, but our experience is that once they have a clear understanding of how the technology works and practices designed to minimise visual and odour impacts, they see that EfW plants are quite different from municipal incinerators and regard them as acceptable solutions to the problem of waste.  As proof of this, we have secured full planning consent for an EfW plant in Dumfriesshire.

The concept promoted by the company is as per Figure 1.

The Benefits

As well as their potential for generating electricity, EfW plants produce heat in the form of steam or hot water that can be used for by industrial operations and as a low cost source of heating for commercial and residential developments.

EfW plants can be fully integrated with other initiatives to reduce waste and increase recycling and indeed can offer great economic benefits to the whole recycling process.  Metals can be recovered from the ash residue in a clean, non-contaminated form, which means that metal recycling can be increased to virtually 100% without any need for expensive separation and collection procedures.

Mechanical Biological Treatments of municipal waste are unnecessary because EfW plants can take waste direct from collection vehicles and avoid the problems of composting where the quality of the product cannot be assured and is often unsuitable for uses beyond landfill restoration.

The small scale viability of EfW plants obviates the need for large scale, centralized solutions to the waste problem, reducing the need to transport waste unnecessarily around the countryside – especially important in reducing the potential for accidental spillage during the transport of hazardous wastes.  A regional network of EfW sites also provides a back up in the event of any unforeseen operational difficulties with any particular plant.  Such a network would also provide sufficient capacity to cope with any interruption of  the recycling chain.