4 Residual Waste Management Options
What are the options for managing residual waste?
4.1 Feasibility Of Options
The capacity analysis (Section 3) noted the need for careful consideration of waste management options to overcome a short-term capacity gap as well as management options to mitigate risks to overcapacity in the medium to long-term.
In considering the feasibility of waste management options in Scotland, the vast majority of stakeholders noted that waste prevention and recycling should be prioritised. Zero Waste Scotland notes that around 60% of residual waste is recyclable. There will be greater carbon and environmental benefits to reducing and recycling this waste compared to residual waste treatment.
Where materials do become residual waste, the Review's analysis suggests that incineration and landfill are both feasible options for its medium to long-term management . However, for BMW streams, landfilling in Scotland will not be an option after 2025.
Analysis suggests that biostabilisation is unlikely to be a feasible option for the short or medium-term management for residual waste treatment in Scotland. It seems to be technically feasible to stabilise waste to achieve the landfill ban criteria, using an MBT plant with in-vessel composting as a biological treatment step, and this may be lower carbon than other options (see Section 7.1). However, the evidence also suggests the UK market is moving away from MBT and the reported technical difficulties associated with MBT facilities are unlikely to make this technology appealing to investors. MBT also appears to require stable feedstocks to achieve consistent performance and Scottish Government policies are seeking to change the nature of residual waste. Therefore, there appears to be similar risks of lock-in effects or stranded assets (see Section 3.5).
It is difficult to compare the cost of MBT and other treatment options, however, from the available evidence MBT appears to be a costly treatment option for local authorities. It is also worth noting that another economic barrier to biostabilisation is likely to be the exclusion of biostabilised waste from the list of wastes that incur the lower rate of Scottish Landfill Tax (currently £3.15/t). Biostabilised wastes would therefore be subject to the standard rate (currently £98.60/t).
For the short-term management of residual waste, for example to fill the immediate capacity gap identified in the analysis, the export of waste appears to be the most feasible option. This could include export of waste to England for landfill or export of RDF or SRF for energy recovery to England or further afield. Scotland has two significant MBT facilities, which both produce RDF (though one supplies only the co-located gasification plant). As noted above, MBT appears to be a costly waste management option, so export of waste is likely to only be desirable as a temporary measure.
One potential benefit of MBT facilities is that they can be designed to remove recyclable waste from the residual waste stream. Similarly, some incineration facilities in Scotland have sorting facilities which can remove recyclable materials. However, as some stakeholders note, due to the poor quality of the materials produced it is often difficult to find suitable outlets for them at this time, meaning incineration or landfill can be the most economically favourable option. This often results in only metals being recovered from the residual waste stream in the UK.
Some emerging technologies which are in pilot and demonstration stages were highlighted by the analysis. These include waste to hydrogen technology and hydrothermal liquefaction. While these are unlikely to provide short-term options, these or other emerging technologies may provide medium to long-term options as they develop.
4.2 Conclusion On Options
In conclusion, the Review considers that overall, incineration's place in the waste hierarchy is appropriate. Incineration in a properly regulated and operated facility remains the most appropriate treatment route for residual biogenic and BMW, especially once everything that can be extracted for recycling has been taken out and where waste prevention and reuse have been maximised.
Recommendation 7 The most feasible treatment options to manage Scotland's residual waste are incineration, landfill and export of waste. Scottish Government should work with local authorities to ensure they have a solution to manage their residual waste in 2025 based on this.
- This may involve shorter term solutions such as export of waste to bridge an expected capacity gap in 2025.
- Following the introduction of the BMW ban, landfill should be considered as a specialised waste treatment option only, where it provides the best environmental outcome and not for the routine disposal of active waste.
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