Energy from waste is a contentious subject in the resources sector. Here, experts on different sides of the debate give an overview of the arguments for and against.
On the face of it, the energy from waste (EfW) sector solves an important problem: what to do with Britain’s residual waste – the non-hazardous material we produce every year that cannot be reused or recycled. However, with the industry burning millions of tonnes of valuable resources every year, is this really the right solution?
According to figures from waste consultancy Tolvik’s annual snapshot of the sector, more than half (15Mt) of the UK’s annual residual waste is sent to domestic EfW facilities for energy recovery, while the remainder is buried in landfill (9.49Mt) or exported overseas (1.81Mt).
By far the most common form of EfW is incineration, where burning waste powers turbines that generate electricity and can export heat. Approximately 3.2% of net UK power generation was provided by EfW in 2022 (source: Tolvik), although heat exploitation has been low in the UK historically.
EfW offered councils a simple and proven technology that has since prevented millions of tonnes of waste from going to landfill.
Adam Read, chief sustainability and external affairs officer at Suez Recycling and Recovery UK – one of the three principal EfW providers – says the volume of residual waste sent for energy recovery in Britain grew sharply after the introduction of the Landfill Tax in the mid-1990s. This imposed costs on local authorities and businesses for sending waste to be buried in the ground.
“Put simply, EfW offered councils a simple and proven technology that has since prevented millions of tonnes of waste from going to landfill,” Read says.
Landfills have the potential to cause a wide range of ecological problems – such as groundwater and soil contamination, bad odours and vermin – and significant climate emissions in the form of methane, a particularly potent form of greenhouse gas, around 28 times more harmful than carbon dioxide (CO2).
Greenhouse gases
While energy recovery has undoubtedly reduced the volume of methane emissions from landfill, this has come with a price tag in terms of direct CO2 emissions. Most studies show that, for every tonne of waste incinerated through EfW, one tonne of CO2 is released into the atmosphere, with a 50:50 split between biogenic and fossil carbon emissions (for reference, one tonne of CO2 is roughly equivalent to driving 6,000km in a diesel car).
In its annual report on the EfW sector, Tolvik emphasised that these carbon emissions are partially offset by the benefit of the plant in terms of heat and power and that net carbon emissions are closer to 0.3 tonnes of CO2 equivalent per tonne of waste burned across the UK’s capacity (excluding any benefits from avoiding landfill).
Figures put forward by the UK Without Incineration Network (UKWin) – a group that campaigns for the rapid phase-out of waste incineration across the UK – suggest that EfW plants create more greenhouse gases over their lifespan than would arise from sending the equivalent waste to landfill, although this is not a conclusion supported by the wider scientific consensus.
All sides of the conversation seem to agree that overreliance on energy recovery can result in far too many valuable resources being burned. Indeed, EfW as a waste solution is considered Level 4 on the waste hierarchy – far too low for many people, representing a huge “leakage” from the circular economy. Indeed, according to a Defra study from 2017, cited by UKWin, around 53% of residual household waste could be considered “readily recyclable”.
For Shlomo Dowen, UKWin’s national coordinator, the resources and waste industry should be investing more time and money in boosting recycling rates to create a circular economy, instead of continuing to build EfW capacity.
“We see no role whatsoever for municipal waste incineration as part of the circular economy and no role for incineration within the context of net zero,” he says.
Recycling rates
Dowen and UKWin advocate for a much higher recycling target of 75% (the current target for England is 65% by 2035; Wales exceeded a 65% recycling rate last year), to reduce the amount of recyclable material that ends up in residual waste. While such ambitions are laudable, says Read, they are very hard to achieve in practice.
“I would always advocate for removing as much useful material from the waste stream as possible before incineration. The plain fact is that, for a variety of reasons, we have struggled, as a society, to bring our recycling rates above 40-50%.
“Even if you did achieve a recycling rate of 75%, which would require a sharp increase in performance throughout every stage of the recycling chain – from consumer action through to collection, recycling and then secondary processing – you have still got that 25% of residual waste that needs to go somewhere.”
While it’s hard to imagine the UK will eliminate its residual waste stream completely in the near future, most experts agree that the question boils down to exactly how much EfW capacity we need.
As of this year, 14 EfW plants are under construction in the UK, while three facilities have been mothballed (source: Tolvik).
I would always advocate for removing as much useful material from the waste stream as possible before incineration.
Total permit capacity was 23.24Mt per annum (pa) in 2022, an increase of 7.2% from the previous year. Figures show that capacity levels have increased slowly but steadily, and that operational capacity – a metric that more closely reflects EfW facilities in use – is expected to be around 20.7Mtpa by 2027.
However, in February, the government published legislation confirming that residual waste volumes will need to be halved by 2042, a target based on 2019 numbers. It stands to reason that as volumes of residual waste start to drop in line with legislation – including moves such as extended producer responsibility and deposit return schemes – there is a real risk that EfW plants will become “stranded assets”; all fired up with no waste to burn.
“It is no surprise that the Committee on Climate Change wants a moratorium on new waste incineration capacity as part of its call for a step change away from incineration and towards a circular economy,” says Dowen.
“The amount of feedstock that will be available for incineration is lower than the incineration capacity that is currently operational and under construction, so the level of incineration capacity will soon need to be going down, rather than continuing to climb.”
Unfortunately, we are living with the legacy of an ineffectual waste system from the last century.
That said, it’s good to remember to plan for the unexpected: the recent requirement for POPs waste to be incinerated meant that other material was kicked out of the EfW waste stream because there wasn’t room for it.
Read confirms that Suez has no plans to expand its EfW portfolio. However, he points out that it will take time for the impact of legislation to show up in recycling rates and that EfW is a key tool in dealing with residual waste in the interim.
“Unfortunately, we are living with the legacy of an ineffectual waste system from the last century. In my view, we are going to need EfW for the next generation, around 30 years or so, while we transition to more sustainable systems,” he says.
Solution or problem
Dowen takes issue with the idea of EfW being a “transition technology”, arguing that the incineration industry is acting as a drag on the speed of this transition – and this is the nub of the debate: identifying the point at which EfW tips over from being a useful solution to becoming part of the problem.
“Many councils are signed up to long-term waste contracts that involve incineration,” says Dowen. “These contracts usually ensure that the council takes on the primary risk of the incinerator not getting enough waste to burn, so councils are, in effect, penalised for not sending enough waste for incineration.”
Read certainly acknowledges that some local authority contracts are no longer fit for purpose. “Some of them date from the time when government was rapidly trying to get out of landfill,” he says. “At the time, councils were faced with either very expensive EfW contracts or very long ones. For financial reasons, they took the latter option. We’d definitely do things differently today.”
At the time, councils were faced with either very expensive EfW contracts or very long ones.
Paul James, who used to lead CIWM’s EfW Special Interest Group and is now technical director at SLR consulting, broadly agrees. However, he rejects the idea that a few short-sighted planning decisions made a quarter of a century ago should be used as a pretext to “delegitimise an entire technology solution”. James also points out that “it is about applying the right solutions to the right waste streams, and doing our best to plan the right capacity”.
“With current data showing close to 10Mt of waste per year being landfilled in the UK alone, and nearly 2Mt being exported, there is plenty of scope for improvement,” he adds.
There is little solid data on just how many local authority contracts fall into this problematic category, how long they have to run before they can be renegotiated, or precisely what impact they have had on local and national recycling rates.
UKWin has put forward figures that seem to show a correlation between falling or static recycling rates in some areas and a comparable increase in incineration rates. However, establishing a causal link is not straightforward and, as Read points out, after the Landfill Tax was introduced in the 1990s, recycling rates boomed from about 5% to 40%, in parallel with a sharp rise in EfW volumes.
The example of our European neighbours – including Denmark, Germany and the Netherlands – appears to illustrate that there is no inherent tension between comparably high levels of energy recovery from residual waste (including by incineration) and high rates of recycling. However, the European Commission stated in 2017 that “some individual member states are excessively reliant on incineration of municipal waste” and that this was “inconsistent with more ambitious recycling targets”.
Over the next 10 years, assuming policy requiring separate food-waste collection is implemented, the UK will probably see an expansion in the use of technologies – such as anaerobic digestion (AD) – that, in some cases, can supply biomethane to displace North Sea fossil-fuel gas. This will also reduce the proportion of food waste in the residual waste sent for energy recovery and landfill.
Suez is confident enough in the growth of this market to have planned to build four such facilities, says Read, although the company will wait until market conditions are right before developing them.
“We’ll wait until we see kerbside collections of food waste increasing,” he adds. “Also, we need to develop the onward markets enough to make sure there are customers for the digestate – something in which I hope government will take a greater role.”
Another development that could shift the needle of the debate is carbon capture. James, who has been involved in the development of this technology, is enthusiastic about its potential.
“The market has completely changed in the past 3-4 years, and the addition of carbon capture to residual EfW really is a game-changer,” he says. “As well as capturing all of the fossil-based carbon emissions emitted by an EfW plant, you are removing the biogenic component. This means you are capturing “negative” emissions, which could potentially be traded with other sectors, such as transport, that are harder to abate.”
Planning and nuisance
Of course, the elephant in the room when it comes to EfW is the fact that plants (including AD facilities) are unpopular with residents because of the traffic, bad smells, and a perception that they make the air less healthy.
While it’s true that any major infrastructure project will face local objections, Read is confident enough in the design of new facilities to state that he would be content to have one built near his home, provided it made logical sense from a planning perspective.
“If we are to avoid landfill, at least in the short term, we need EfW,” he says. “The key is for these plants to be flexible enough to change as waste flows evolve. For example, as residual waste starts to fall, we might see some of our stock turning into chemical recycling plants.”
If we are to avoid landfill, at least in the short term, we need EfW.
Drawing definite conclusions on EfW is beyond the scope of this article. However, the argument could be framed as between “idealists” on the one hand, who believe EfW can and should be phased out sooner rather than later (if only recycling rates can be improved), and “pragmatists”, who see – for practical reasons – the UK relying on the technology for some time yet.
The issue remains whether this technology is helping or hampering the transition towards a low-carbon circular economy, and exactly how much EfW capacity we will need in the future.
However, unless there is a radical change in direction from government (bearing in mind a General Election is on the way), we can be fairly certain that EfW will continue to be part of the waste and resources jigsaw puzzle for the foreseeable future. Exactly what that future looks like is still up for grabs.
