A key determinant of the tonnage capacity of an EfW facility is the calorific value of the waste treated at the facility. The higher the calorific value of the waste, the lower the tonnage throughput of the facility. Variations in the calorific value of Contract Waste therefore raise significant operational and commercial issues.
The facility will be designed around an assumed calorific value (the design calorific value) that is typically around 10MJ/Kg for a facility treating unprocessed MSW and will be higher for pre-treated MSW with the highest calorific values being obtained for more refined pre-treatment processes. The assumed calorific value should be based on an assessment of the current composition of the waste stream (using data provided by the Authority) and an assessment of the foreseeable changes likely to occur due to additional upstream recycling efforts.
Bidders should thus be able to propose an upper and lower calorific value range as the operating parameters of the facility. When bidding the Unprocessed Landfill Performance Target22 (as a percentage of Contract Waste) bidders will have to take account of factors that will affect the capacity of the plant, including facility downtime and calorific value variability. Bidders may also request that the Payment Mechanism includes a mechanism to change the price per tonne (used to calculate the Base Payment) if the calorific value of Contract Waste falls outside such parameters.
The Authority23 should ensure that the calorific value assumed in the bidders' proposals reflect the likely calorific value for the Authority's Contract Waste and allow sufficient flexibility for any potential future changes. In making this assessment the Authority should consider the impact of any proposed or likely changes to the recycling services as this is likely to impact on the calorific value of the residual waste stream. In principle, if this approach is followed, there should be no need for the Authority to agree changes to the Payment Mechanism pricing for calorific value variability within a specified calorific value range.
Authorities may consider value for money arguments for agreeing some protection for calorific value changes that fall outside the specified range though it should be noted that in some contracts such protection has not been sought or given. It should also be noted that in the first case the issue will be how to match the characteristics of the Contract Waste being processed with the design capabilities of the facility. This may involve varying the blend of wastes being processed and/or amending or upgrading the technologies used (where practical). Ultimately, the project is unsustainable if the Contract Waste calorific value is not compatible with the facility's design capabilities
and the parties should focus on the actual capability of the proposed technical solutions as well as contractual provisions.
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22 Set out in Appendix 3 of Part II of this Module 4.
23 The issues relating to the calorific value of the waste are highly technical and before initiating a procurement the Authority should consider the need for specialist external advice in relation to this area.