This article looks into waste incineration from the point of view of sustainability. How sustainable is this process and what does the future hold?
Waste incineration is a process that is also sometimes called energy recovery, energy from waste or waste to energy. The choice of language very much depends on which side of the debate you are on. For the purpose of this short article, these will all be grouped under the banner energy from waste (EfW).
This article was inspired by the recent and very interesting Eunomia Residual Waste Infrastructure Review. I would definitely recommend reading the BBC article linked below as well as tracking down the original paper. The impact of EfW on recycling is an important consideration and we will dig into this shortly.
How sustainable is EfW?
Like anything, when concluding how sustainable a process is, the question to ask is, “compared to what?” The other main options can all be found in the waste hierarchy.
Prevention is the most preferred option. Waste that doesn’t get produced doesn’t have to be contained, transported and dealt with by any means. This is the most sustainable option and more focus needs to be placed on this by businesses, governments and citizens.
Re-use is the next most preferable option. Re-using the same item multiple times for the same purpose or again for a different purpose is a great way to use resources sustainably.
Recycling is the sustainable process that people are probably most acquainted with. For those not entirely familiar with the totality of the sustainability agenda, it can sometimes be confused with the entirety of the sustainability equation. Recycling is very important, it reduces the demand for new oil to be drilled, new forests to be cleared and new glass to be melted. It is a very important process. Without recycling on a large scale, the sustainability of developed economies doesn’t look so great.
Most EfW sites sort the waste they receive. This allows for the removal of large appliances and items that have made their way into this waste stream such as refrigerators and car tyres. Small items such as aerosol cans and any other metals can be removed with a magnet.
The next step in the recovery process is the burning of the residual waste to recover energy from these items. Many of these energy recovery plants, particularly the newer ones are state of the art facilities utilising the best available technology to incinerate and recover energy from the waste.
Some of the benefits of EfW include a significant reduction in the size of the material sent for final landfilling. We will see more on this shortly. This would be an important consideration in land constrained countries.
Another benefit of EfW is that it allows for energy to be recovered as heat, electricity or combined heat and power. This is a significant benefit and is why EfW is preferred to landfilling. However, previously a significant advantage of EfW was that it displaced fossil fuels, principally coal from the energy generation process and so displaced large amounts of CO2.
But as the link below shows, as energy grids are rapidly decarbonised, it is only fair that this benefit is called into question.
In the UK for instance, the carbon intensity of electricity has fallen 23% since 2015. It remains to be seen whether this trend will continue into the future, but even at present rates, the CO2 benefits of EfW look to be increasingly questionable.
EfW is not without its disadvantages. It must be said that much of the value of recyclable materials, which have not been removed before burning is lost in this process. This is wasteful and leads to the squandering of resources at a time when we should be conserving resources.
EfW can also be criticised on the grounds that the pollution from the chimneys can be quite nasty, especially if items such as batteries have not been removed before incineration. Furthermore, the EfW plants also leave behind ash, which contains toxic components and is a hazardous material. After testing by the US EPA, the ash was found to contain high levels of cadmium, lead, furans and dioxins.
Overall, as we can see, there are strong arguments for and against EfW as a waste management process. But the sustainability of EfW must be viewed against other options.
Disposal is the final stage in the waste hierarchy.
Even EfW plants, which allow their clients to proclaim to be zero to landfill, still have to dispose of the ash from the furnaces. When all is complete on the energy recovery side, residual ash and un-burnable residues representing 10-20% of the original volume are left to be disposed of at a landfill. The claim that EfW plants are zero to landfill is therefore false. It is interesting that such an inaccurate claim could have persisted for so long.
Landfilling can also be used directly with no sorting or energy recovery. This leaves the potential for hazardous materials as well as recoverable materials to be lost in a sea of rubbish.
Landfills also consume land that could be used for other purposes, produce methane, only a small percentage of which can be collected and in old style pits leads to the contamination of groundwater. Overall, landfilling is a nasty process, which if the waste hierarchy was properly implemented would be significantly reduced.
What the future holds
The future for sustainability looks bright, however, the future of EfW does not look so bright.
Since 2009 the UK’s incineration capacity has more than doubled from 6.3 million tonnes to 13.5 million tonnes. However, the quantity of residual waste suitable for treatment has fallen from 29.9 million tpa to 26 million tpa. If more capacity was to come on line, and this is expected to be the case and the amount of waste available falls further, gate fees for this process would come under significant pressure.
The impact of incineration capacity on recycling is also an interesting phenomenon. To a very great extent the growth in incineration capacity and recycling rates are linked. As the Eunomia paper shows, each new facility constrains the maximum level of recycling that can be achieved. EfW plants feed heavily on the high energy value of plastics and papers, which with the right collection, should have been recycled.
As already mentioned, as energy grids become cleaner incineration begins to look like an increasingly dirty option. This will no doubt see it come under some pressure. That being said, in a future electricity grid dominated by renewables and energy storage, the ability of EfW plants to provide a support function at peak demand would be welcomed.
What does the future hold for EfW? As we looked into at the beginning, determining the sustainability of EfW very much depends on how it compares to other methods. It is more preferable to landfilling and the process will no doubt continue, but will come under some price pressure as capacity expands and available material contracts.
We can only hope that more focus is placed on prevention, re-use and recycling so that EfW when needed is only needed sparingly.
What you need to know
This article looked into waste incineration from the point of view of sustainability. We assessed how sustainable this process is and what the future holds for EfW.
What then is the answer to the question, to burn or not to burn? The answer has to be no, not if it can be avoided as it can be avoided. The primary goal must be prevention, then re-use, then recycling. The waste hierarchy should be applied flexibly between these three options depending on local conditions. But EfW is most certainly a quantum leap from these three options.
What the future holds for EfW is hard to calculate as it depends on a number of factors. It will no doubt continue, but the trend towards increasing capacity and decreasing supply will put pressure on prices.
Responsibility for waste needs to shift up the lifecycle of products, but this does not occur in a vacuum.
Ultimately people, who are both voters in elections and purchasers of products, need to start demanding smarter regulations from their politicians and investing in companies who are committed to implementing the waste hierarchy.
The fall back option is more landfills and more EfW plants. A better world is possible, but it requires active and engaged citizens. It requires people to reduce the production of waste wherever they can, to re-use what they can and recycle everything they can.
Businesses and politicians react to the demands that they see within a population. Don’t sit on the sidelines, play a role in creating a more sustainable future.
Thank you for reading,
By Barnaby Nash
Please share your thoughts in the comments section below. It’s great to hear about other people’s experiences in taking sustainability forward.