OPINION: ‘How to effectively decarbonise UK’s crucial energy from waste sector’

BBC’s report stating that energy from waste (EfW) produced “the same amount of greenhouse gases for each unit of energy as coal power” has prompted considerable debate about the study itself, the technology and how we manage our non-recyclable waste. Synergie Environ sector director Gavin Ramsey says that while it is clear that EfW will continue to play a significant role in the UK’s capacity to deal with residual household waste, it is now more likely than ever that the UK government will introduce some form of mechanism to incentivise the sector to reduce its carbon emissions.

Bans on the construction of new EfW facilities in Wales and Scotland are already in place, and there have been calls from both academics and environmental groups, including the UK Climate Change Committee, for similar steps to be taken in England and Northern Ireland.

The industry’s trade association, the Environmental Services Association (ESA), was quick to respond, challenging the BBC’s findings and saying that it was not correct to directly compare EfW greenhouse gas (GHG) emissions without taking account of the greater quantity of GHGs that the same waste would produce if it were disposed of in landfill. It also pointed out the role EfW plays in dealing with residual waste from recycling.

The question surrounding the need for these plants and the emissions impact they have is complex. On one hand, the residual waste feedstock used as fuel in the UK’s existing EfW fleet contains a significant amount of plastic (produced from fossil-fuel-derived hydrocarbons), which when burned, produces “fossil” carbon dioxide that contributes to atmospheric CO2. The continued growth of these plants will undoubtedly further contribute to this.

Residual waste arisings from households and businesses are likely to remain a problem (certainly for parts of the country), given that the average UK household waste recycling rate in 2022 was 44.1% (including metals recovered from EfW bottom ash), and the GHG impact of landfilling this material can be greater, depending on the quantity of uncaptured methane-rich landfill gas emitted.

Consideration needs to be given to the potential carbon impact of sorting residual waste for further recycling, given the high power demands of material recovery facilities, and whether this demand can be met through renewables and other forms of low-carbon electricity. Also to be considered are emissions from logistics between waste transfer stations, intermediary recycling facilities and material end-users, where these still rely on petrol- and diesel-powered vehicles.

A more commercially centred aspect relates to another factor highlighted in the BBC report, that of potential “EfW lock-in”. Many UK local authorities have contractual arrangements with operators that may result in financial penalties or other implications if there is a reduction in supplied feedstock.

EfW is clearly needed in the UK to deal with non-recyclable waste and the BBC report is likely to fuel efforts to incentivise the sector to reduce its carbon emissions. Under the previous Westminster government, Defra consulted on an expansion of the UK Emissions Trading Scheme (ETS) to include GHG emissions from waste incineration (which would include EfW facilities). Although the outcomes of the consultation are yet to be published, this would seem to be the most likely option that would be chosen on the basis that it is the most evolved policy-wise.

I have previously reported on the potential costs to the industry of the ETS expansion, the majority of which relate to the purchasing of carbon allowances to cover CO2 emissions. Sector decarbonisation for EfW is an essential process to limit cost impact to both operators and their customers, but it will be challenging to achieve without proper feasibility planning and an understanding of impacts on feedstock, etc. Upstream strategies such as improving recycling rates and a move away from plastic packaging will be effective methods of reducing waste-derived carbon emissions in the long run, but the industry needs to avail itself of other technical solutions for decarbonisation in the immediate future to deliver more short-term results. The potential options include the following:

Direct carbon capture, utilisation and/or storage: This option will have the largest impact on directly reducing emitted carbon. As the preferred methodology in the ETS expansion proposals is to monitor CO2 from stack emissions, direct capture would seem to be one of the best-suited techniques for insulating against cost impacts. However, carbon capture technology is still a relatively new concept and its application to the UK EfW sector is still very much in its infancy. Currently, only one pilot-scale carbon capture system has been installed and at the time of writing, it has been operational for less than six months with no performance data available in the public domain as yet, but the operator (enfinium) has consulted on the installation of additional full-scale plants within the UK. Although direct carbon capture has been utilised at other types of power generation facilities, there are some unique challenges posed by applying it to the combustion of waste, including amine solvent degradation caused by sulphur oxides and particulates in the flue gases. It remains to be seen whether direct CO2 capture can feasibly reduce emissions (and therefore ETS-related costs) in a way that justifies the additional capital and operational expenditure associated with its implementation.

Plastics removal: The proposed expansion of the UK ETS to waste incineration will only require the monitoring and accounting of “fossil” CO2, i.e., CO2 produced from the combustion of fossil-fuel-derived hydrocarbons (as opposed to ‘biogenic’ CO2 from biodegradable sources, such as food and garden waste). The source of most fossil CO2 in residual waste comes from plastics, which in England constitute approximately 16% of the overall composition of residual municipal waste.

An alternative approach to direct carbon capture that would have the same impact on emissions would be to remove as much of this plastic as possible. This could be achieved by investing in additional pre-segregation of plastics by local authorities and businesses, as well as using front-end material recovery facilities to remove plastics from EfW feedstocks. Challenges in the former approach centre around additional budgetary requirements for councils, as well as promoting householder buy-in to using the additional segregation facilities. Plastics recovery may impact EfW plant performance as feedstock calorific values will be reduced, thereby requiring a greater material throughput to achieve the same electrical output. Both approaches to reducing the volume of plastics in EfW feedstocks may have contractual ramifications for feedstock suppliers if they obligate minimum tonnage requirements or if the feedstock moves outside of agreed calorific parameters. Further studies are required to ascertain where the optimal trade-off point exists between the operational and contractual costs associated with reducing feedstock plastics and the additional costs of complying with the UK ETS.

Waste heat capture and use: To keep the carbon accounting process as straightforward as possible, the monitoring proposals under the ETS expansion focus on actual emissions from EfW plants and would therefore not be impacted by the reuse of surplus heat. However, there are some scenarios in which waste heat capture and redistribution may still prove beneficial to the operator. For example, if EfW heat can be utilised in a secondary industrial process that is within the scope of the ETS in such a way that it replaces some or all of the existing fuel combustion to fulfil heat demands, then this would reduce the amount of carbon allowance required to cover that secondary activity.

If the activity is controlled by a third party, the operator could offer commercial terms to that party that would result in an overall saving on the latter’s combined energy and carbon allowances costs, while generating revenue for the EfW operator. This helps them to recover their own costs associated with their emissions under the ETS, thereby providing a mutual benefit. Of course, any benefits need to be weighed against heat network implementation costs but in other industries, use of waste heat is frequently one of the more cost-effective methods of decarbonisation.

The proposed implementation date for the expansion of the UK ETS to the waste sector is 1 January 2028, and if the recent media attention around EfW sector emissions is anything to go by, it is more likely than ever that this will be introduced in some form. A number of leading sector stakeholders have recently voiced support for tackling EfW emissions, including the Chartered Institution of Wastes Management (CIWM), which has called for the quick implementation of the ETS in the waste sector. The National Infrastructure Commission has recommended to the UK government that new long-term EfW contracts should be banned for facilities that do not include plans for carbon capture. While EfW retains an important role in the management of the UK’s waste, it seems that the time is fast approaching for the industry as a whole to take action.