ClientEarth commissioned Eunomia to assess the greenhouse gas and air quality impacts of managing residual municipal solid waste (MSW) through Energy from Waste (EfW) and landfill in the UK.

Carbon considerations are becoming increasingly prominent in how we think about waste. In the UK, the government has committed to reaching net zero carbon emissions by 2050. In addition, 74% of local authorities have declared local net zero targets, often with challenging timeframes in the 2030s. The vast majority of those authorities now treat their residual waste via incineration: Defra’s latest statistics show that in 2019-20, 44.8% of local authority collected waste was incinerated and just 8.5% was landfilled. Businesses, too, wish to reduce emissions. This makes it essential to understand the methods to reduce net emissions from residual waste management.

Both the characteristics of waste treatment infrastructure and the composition of waste differ from country to country. Our analysis was specific to the UK context and caution should therefore be exercised in applying the report’s conclusions outside the UK context.

  • Within the UK, approximately 50% of residual waste is treated via EfW. This figure is set to increase as more EfW capacity comes on stream, which will divert residual waste out of landfill.
  • In the UK, most EfW facilities are “electricity-only” – they are optimised to generate electricity and do not make significant beneficial use of the surplus heat they generate. Elsewhere in Europe, “combined heat and power” or “CHP” facilities are more common. CHP facilities supply their surplus heat to industrial or residential users through heat networks, allowing them to achieve higher overall energy efficiency than “electricity-only” facilities.
  • Waste collection systems and residual waste composition differ across Europe.

The report finds that:

  • Currently, EfW provides significant carbon benefits over landfill, which sits at the bottom of the waste hierarchy. Investments in EfW have been made on this basis.
  • Benefits today are largely because residual waste is partly biogenic (e.g. paper, card, food), the emissions from which are generally disregarded in carbon analyses; and because the electricity generated from treating residual waste avoids the need for electricity to be produced elsewhere on the grid – some of which will be from fossil fuel sources, such as natural gas.
  • The analysis shows that removing more plastics from the residual MSW stream makes a profound difference to carbon emissions, regardless of the stage at which it happens: whether through kerbside recycling collections, or through mechanical pre-treatment of residual waste. In our modelling, the addition of pre-treatment to remove further plastics from the residual stream changes EfW from being a net contributor of emissions in 2035 to having a net benefit. EfW operators should therefore consider implementing pre-treatment to remove plastics from residual waste so that it can be recycled.
  • The analysis also shows EfW plants operating as CHP perform better than “electricity only” plants, provided that a significant proportion of the heat can be utilised. This is because heat is harder to decarbonise than electricity. Heat networks should be developed to maximise the benefit of energy generated at EfW facilities.
  • In the longer-term carbon capture and storage (CCS) may have a role to play, but this technology is still under development and would have greater capital costs than pre-treatment. CCS solutions should be considered as a potential longer-term solution, whilst recognising this would require further technology developments and a supportive policy framework to make it viable.

As the UK’s energy systems continue to decarbonise, the importance of reducing the plastics content of residual waste to tackle EfW emissions is clear. The EfW industry is relatively well placed to tackle its emissions. Technologies and techniques already exist to improve emissions performance, and implementing them represents a significant opportunity for the sector, as the necessary improvements are likely to involve additional investment. The report shows investment in advanced pre-treatment systems in the UK could play a significant role in substantially reducing carbon emissions, while also contributing to improved recycling rates.

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