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Study Charts a Future for Waste-Derived Fuels

Pointers to possible future EU policy initiatives to give co-incineration facilities burning waste-derived fuels a strategic role in waste management have emerged in a study for the European Commission.1 The report suggests a policy focus on promoting source separation of municipal wastes, active discouragement of mass burn incinerators, and a levelling of the regulatory playing-field for incineration and co-incineration.

The European market for waste-derived fuels is undergoing rapid change, stimulated by complex - and not always well integrated - policies on waste, energy and climate change. A growing diversity of wastes is being burned in a wide range of industrial 'co-incineration' facilities as well as dedicated incinerators.

The trend has not been universally welcomed. Hazardous waste incineration businesses have complained that the less stringent emission limits applied to co-incineration facilities give them an unfair advantage. The move towards combustion has also provoked concern that wastes may be diverted from recycling and other options higher up the waste management hierarchy.

Defenders of co-incineration have countered that the use of waste-based fuels to replace fossil fuels in more energy-efficient plant than dedicated incinerators offers substantial benefits in reducing greenhouse gas emissions - while cement businesses contend that their facilities are superior in destroying organic wastes and lock heavy metals away in cement clinker.

The new study, carried out for the Commission by a consortium which included British consultancies WRc, Ecotec and Eunomia, comprised a survey of the market for waste-derived fuels, a review of the legal and policy background, and environmental and economic assessments of waste-derived fuels.

Market trends: The consultants put current production of fuel from municipal waste across the EU at about three million tonnes per year, with planned facilities set to increase this (see table). The highest levels of activity are in Austria, Germany and the Netherlands, where source separation of municipal waste is highly developed and produces a non-recyclable residue with a high calorific value suitable for refuse-derived fuel (RDF) production.

About 70% of RDF production is co-incinerated - mainly in multi-fuel district heating plants, paper mills and a few cement kilns.

A wide range of industrial wastes are also processed for co-incineration in industrial facilities. They include packaging, tyres, textiles, automotive shredder residues, solvents and other hazardous wastes, and biomass wastes such as straw, wood and sewage sludge.

The industrial co-incineration business is dominated by the cement sector, with 105 kilns burning about 2.6 million tonnes of waste per year. A recent addition to its fuel mix has been meat and bone meal, with kilns in Austria, Belgium and Finland burning some 0.35 million tonnes per year.

Other facilities burning wastes include power stations, lime kilns, blast furnaces and brickworks. Co-firing of biomass residues in coal-fired power stations has lately been given a spur by support mechanisms for renewable energy.

Environmental assessment: The exercise conducted by the consultants was not a comprehensive overview of waste combustion options. It compared the environmental effects of a narrow range of waste-based fuels when burned in power plants fired by hard coal and brown coal, a cement kiln and a municipal incinerator. The fuel substitution ratio was set at 5% for the power stations and a high 50% for the cement kiln. The technology of each plant was assumed to be average or better, so that the incinerator complied with the emission controls set by the 2000 EU waste incineration Directive, while the other facilities might do so depending on the type of fuel used.

No technology was found to have an overwhelming advantage. The co-incineration options were superior on emissions of several pollutants because of the substitution of fossil fuels with waste. However, the cement kiln had higher emissions of mercury and the brown coal plant higher emissions of cadmium than the incinerator - though the impact on ambient air was predicted to be comfortably within air quality guidelines.

The most difficult part of the assessment concerned the impact of co-incineration on contaminant loads in the solid products and by-products, such as cement clinker and power station gypsum and fly ash. Levels of chloride, lead, cadmium, zinc and copper all increased substantially, though with automotive shredder residues producing a much greater toxic loading than, for example, RDF made from municipal waste.

Many of these materials are used in construction products, 'so an increase in toxic loading is of concern for the environment and health,' the report notes. However, the study did not consider how effectively toxic metals are locked into combustion residues or their bioavailability or leachability.

Legal background: Several EU Directives are shaping the market for waste-derived fuels, as may the case law of the European Court of Justice.

Two recent ECJ decisions are of particular importance. One ruled that use of waste in cement kilns is 'recovery' rather than disposal where excess heat is generated for use in the process. The second ruled that burning waste in a municipal incinerator, whether or not it reclaimed energy, is 'disposal'.

The latter decision implies that burning packaging waste or automotive shredder residues in municipal incinerators does not count towards the recovery targets set in EU legislation, and may have the effect of diverting more of these wastes to co-incineration.

Another key element in the legal mix is the 2000 waste incineration Directive, which applies to existing plants from the end of 2005. Although it has narrowed the differences in emission limits between incinerators and co-incineration plants, some divergences still remain. In particular, limits for particulates, nitrogen oxides and sulphur dioxide are much less stringent for co-incineration.

The Directive has also left some unfinished business. It provides that, where 'untreated' municipal waste is co-incinerated, the less stringent emission limits for co-incineration do not apply. However, 'untreated' is not defined - and the report suggests that this could be environmentally counter-productive as Member States gear up to meet the targets for reducing landfilling of biodegradable waste set by the 1999 landfill Directive.

'Some countries,' it warns, 'could apply a lax interpretation of the term 'treated'... If minimal treatment (such as low-level source separation) were to be considered as 'treatment', large quantities of MSW could be considered as 'treated', and thus suitable for combustion in co-generation facilities with lower emissions standards than MSW incinerators. Such an approach could easily be a cost-minimising solution to the landfill Directive, though far from desirable from an environmental perspective.'

The report points to another undesirable scenario which may unfold in such circumstances. In countries beginning the process of diverting waste from landfill, incinerator operators are likely to react to competition from co-incineration facilities by cutting their gate fees - potentially entrenching existing low rates of composting and recycling unless other instruments to promote them are in place.

The report's conclusion is that the 'spotlight of policy development' should fall on promoting high rates of source separation and minimisation for household and commercial waste through higher disposal fees, variable charging or sectoral agreements.

Equally, policy should not seek to promote a guaranteed future for incinerators, the report argues. On the contrary, the inflexibility of incinerators should be 'actively discouraged', making room for flexible strategies based on modular mechanical/biological treatment plants and RDF production feeding co-incineration facilities.

In addition to this general policy prescription, the report suggests several further elements of a strategy in which waste-derived fuels could play an integral role:

  • A legal definition of 'treated' and 'untreated' waste in the incineration Directive.
  • Further alignment of emission limits between incineration and co-incineration plants.
  • Measures to reduce mercury emissions from co-incineration facilities - whether through permit changes, amendment of the incineration Directive, or quality standards for waste-derived fuels.
  • Investigation of toxic elements in solid residues from co-incineration to ensure that they do not pose health or environmental hazards.

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