Wardell Armstrong’s Luke Prazsky argues that whilst small-scale localised energy recovery facilities for residual waste may be viable and available, with the increasing adoption of the circular economy they may not be the most effective solution in the long run.
Large scale energy recovery facilities bring economies of scale and deliver cost effective alternatives for residual waste that would otherwise be disposed of in landfills. Often these facilities are clustered around the main population hubs in the UK, located to maximise their ‘zone of influence’. With this proliferation of ‘regional’ facilities the smaller populations on the periphery of these zones of influence will suffer considerably higher costs (from transport) in trying to divert waste from landfill.
Does this create opportunities for smaller scale facilities or alternative technologies with capacities of up to 30,000 tonnes per annum to plug the gap? And, with the circular economy ever more important, will we actually need them?
Wastes destined for energy recovery tend to be a mixed bag, whether they are from households or commercial and industrial wastes, especially given depressed prices for recyclates recovered from mixed waste streams. It goes without saying that any new facility needs to deliver a technology that can suitably treat these wastes. In terms of prices I think the market will only likely stand a price of circa £65/tonne in the long run, potentially a little higher, offset by the savings from reduced transport costs.
AD Is Proven, But Is It Always Suitable?
Anaerobic digestion facilities are proven at the required capacity, but they are not entirely suitable for the treatment of mixed wastes containing large quantities of non-organic wastes. The pre-treatment of mixed waste for an AD plant would effectively remove the majority of the waste stream and this material would still need treatment. Alternatively, the traditional moving grate technologies are very well suited to treating unsorted mixed waste streams but are only really financially viable with inputs significantly above the theoretical capacities needed.
Advanced Thermal Treatment (ATT) technologies offer another possible solution, primarily employing pyrolysis and/or gasification. Whilst these require a pre-prepared homogenous feedstock with a relatively stable calorific value to avoid thermal spiking in the treatment process, this can be produced relatively easily from mixed commercial and industrial wastes. In terms of capacity, pyrolysis plants tend to comprise several small modular units that can be added to if further capacity is required.
Small-scale pyrolysis facilities would therefore seem to be the answer. Regardless of this apparent solution it is important to acknowledge the challenges for developers to develop a financial model that has good profit projections and can secure the funding, let alone secure a decent site, obtain the planning consent and an environmental permit, all whilst delivering a competitive gate price.
And finally there are unintended consequences with every decision in a complex market. If we have too many of these small scale facilities springing up they could actually reduce the amount of waste going to the regional facilities which takes us dangerously close to replicating issues affecting our neighbours in northern Europe with excess capacity and the risk of white elephants.
One final thought – all the talk around the circular economy is actually likely to hold back further developments in energy recovery facilities which does not help us address the current issue. At the moment the low values for recyclates recovered from mixed waste streams means that there is an abundance of waste available but with much of it actually being theoretically recyclable will it be available in the future?
When the circular economy kicks in, the solution will be smarter and more effective recycling facilities coupled with improved segregation of materials at source which suggests that we shouldn’t be looking to add to the regional energy recovery capacity but to the local recycling opportunities.
Luke Prazsky is a waste resource management specialist at Wardell Armstrong