1. INCINERATION DIRECTIVES

The draft waste incineration directives (89/429/EEC and 89/369/EEC) were effective as of 1996 and aimed to reduce as far as possible the negative effects on the air, soil, surface and groundwater caused by emissions from waste-to-energy plants. To all thermal conversion plants it meant that either they install an efficient cleanup system for their flue gases or they close. Most closed. Only the plants built after 1989 which were expecting the emission controls or those who could afford the expensive refit remained.

A further proposed directive has been formulated and is expected to be given a second reading in the European parliament in January 2000. The existing and proposed limits and typical plant emissions are shown:

Table 1: Emission Limits For Energy-From-Waste Plants:

As can be seen the proposed directive will have the effect that all UK plants will now have to install de-NOx equipment in order to meet the limits.

The major public concern of recent times has been with Dioxins. The group of chemical compounds 'Polychlorinated dibenzo-paradioxins' and 'Polychlorinated dibenzofurans' are grouped and given the abbreviation dioxins. A presence of chlorine and temperatures in the system of between 200 and 400°C are conducive to dioxin formation. They may also be formed at lower concentrations in system temperatures of between 800 and 1200°C, but higher temperatures will destroy them. They can either be deposited on fruit and vegetables which go directly into human food chain or on plants which are eaten by farm animals intended for human consumption, otherwise they can enter the food chain through diary products. Dioxins are fat soluble and retained for long periods. Excessive exposure to dioxins can cause weight loss, liver problems, or chloracne (a severe skin condition). Presently in the UK an average dietary intake is estimated to be about 0.19ng TEQ/day/kg body weight. This compares satisfactorily with the tolerable daily intake of 100ng TEQ/day/kg body weight. The toxins have not been shown to be a notable risk to human health, and emissions from energy-from-waste plants produce minimal amounts compared to other sources (other industry, traffic and cigarettes). Future plants will however be required to periodically monitor for dioxins.

2. LANDFILL DIRECTIVE

The Landfill Directive requires a diversion away from landfilling with compliance to set standards by 2010 for the UK. It will mean there will have to be a development in UK Waste-to-Energy in order to reduce the amount of material being sent to landfill. There is also the aim to increase recycling and composting for a more sustainable waste management strategy. Further to this though, it has to be realised that recycling and composting may not be as successful in the quantity of their diversion as is hoped in order to meet the required targets. Figure 1 shows what the recycling and composting targets hope to achieve and what will have to be left to Waste-to-Energy in order to satisfy the targets emanating from the landfill directive.

Figure 1: Future Trends In Municipal Waste Handling

The UK will by 2015 be legally obliged to divert from landfill somewhere in the region of 30 million tonnes. If the composting and recycling targets laid down in Waste Strategy 2000 are reached then 15 million tonnes will have to be treated by Waste-to-Energy. This can quickly be translated into the number of thermal conversion plants required to deal with this waste. Assuming 200,000 tonnes per facility there will need to be by 2015 about 75 thermal conversion plants across the UK.

Also, it should be noted that industrial and commercial waste is not included in the Landfill Directive and this waste could easily be used in the same waste-to-energy operations. This would make good use of a valuable energy resource, and would also help achieve the desired result of reducing landfill gas emissions. However, it would require extra waste-to-energy plants on top of the ones required to satisfy the landfill directive.