LAWR

EfW and recycling The above calculations only show part of the picture because not all the waste in Figure 2 would be available for EfW. Already around 45% of the material is currently taken out for recycling, composting or anaerobic digestion and there are national and EU-wide targets that both call for a recycling/ composting rate of 50% by 2020. When taking account of recycling we need to look at both the amount of rMSW available for EfW and its calorific value. The quantity of rMSW is not a problem as long as recycling is taken into account when the EfW facility is designed. For example, if a local authority knows that its residents produce around 400,000 tonnes of MSW a year and intends to use EfW for the rMSW, as long as the capacity of its EfW is around 200,000 tonnes a year, there is no conflict between EfW and recycling. The same authority could even budget for waste reduction of (say) 20,000 tonnes per year and opt for 180,000 tonnes per year of EfW capacity. On the face of it, predicting the impact of recycling on calorific value is more difficult because removing the high calorific value plastic from the rMSW will have a very differ- ent effect from removing low calorific value organic waste. However, if we take the detailed waste composition from 2005 it is possible to investigate the effect of a number of recycling scenarios on the amount of rMSW and its calorific value. This is shown in Table 1 below for the maximum pos- sible recycling and composting rates and for a scenario that just achieves the 2020 recycling/composting target. (Please note that for this analysis ignores recycling from household waste recycling centres so, in reality, the recycling figures would be higher than these when HWRC waste is taken into account) Table 1 tells us that, in all cases, the calorific value will still be acceptable for the EfW process. For the 50% recycling scenario, which is based on dry and organic material collec- tions, the calorific value (and income from power sales per tonne of rMSW burned) has increased. In summary, having an extensive recycling scheme has little effect on the quality of rMSW as a feedstock - table 1 is good news for both the recycling and EfW communities. Future feedstock changes At this point, our thinking has to become more speculative, but let's imagine a future where: the proposed plastic bag tax reduces their use by 80%, the use of tablet computers, smart phones, eReaders reduce newspaper consumption by 50%, the growth in online retailing increases waste cardboard gen- eration by 10%, waste reduction initiatives and the introduc- tion of 'pay as you throw', where householders waste costs are based on the amount they produce, reduces overall waste generation by 20%. Of course, all these points are debatable and the current coalition Government is deeply opposed to pay as you throw, but this does not mean that a future Government (of whatever political composition) would still hold to this view. If the above changes came into being, the waste manage- ment industry would face a number of challenges and oppor- tunities. The overall quantity of MSW would fall to around 75% of its current level of 22.6 million tonnes per year (Mt/y). To meet the recycling targets this implies a recycling/com- posting collection capacity of around 8.5 MT/y (compared with the current figure of 9.8 MT/y) leaving 8.5 MT/y of rMSW which is very close to England's current and under- construction EfW capacity. This could result in EfW capacity taking a greater propor- tion of commercial and industrial waste, long-distance trans- port of rMSW to existing EfW plant and the development of smaller EfW facilities (possibly using advanced thermal processing technologies). Of course, this is an extreme picture; it is possible that in the next few years MSW generation returns to its pre-reces- sion level and waste reduction strategies turn out to be largely ineffective. However, it does demonstrate some of the issues that we may face in the future. All in all, I have shown that historic changes in MSW com- position have had little effect on its calorific value. Similarly, an extensive recycling and composting/AD collection scheme has little effect on the quality of rMSW as an EfW feedstock. Possible future changes in the production of waste plastic bags and newspaper are also unlikely to have an impact on the quality of EfW feedstock. However, a combination of a 20% reduction in waste generation and high recycling rates would require a change in the nation's use of EfW technology. Dr Stephen Burnley is a senior lecturer in the Faculty of Mathematics, Computing and Technology at The Open University. He will be speaking at the RWM show at the energy from waste theatre on 17 September from 12.30- 13.15pm. August 2014 Local Authority Waste & Recycling 23 RWM WITH CIWM 2014 PREVIEW Figure 2 - Comparison of 1980 and 2005 Table 1 - Effect of recycling on calorific value

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