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Perhaps unsurprisingly, the country has one of the cleanest records in the world when it comes to this particular metric. The UK and France, by comparison, send a respective 28% and 22% of their collected refuse to landfill sites, where it releases methane and pollutes groundwater as it breaks down.
However, Sweden doesn’t strictly recycle the remaining 99% of its rubbish. It incinerates about half of it to generate heat and power across its 34 waste-to-energy (WtE) plants.
Once the combustion process is complete, all that remains is ash, flue gas and heat – which is made into steam that drives a turbine to create electricity. The energy efficiency of modern incinerators varies widely, with most estimates falling somewhere between 15% and 30%. These figures improve drastically when the residual heat in exhaust steam is captured and distributed to households via district heating networks. More than one million Swedish homes are kept warm thanks to the country’s comprehensive rubbish incineration and heat recovery schemes.
In an era when public concern about pollution – especially the plastic variety – has reached an all-time high, incinerators appear to provide a practical alternative to landfill disposal. But critics point out that the facilities are no panacea when it comes to the separate, albeit related, fight against climate change. The level of carbon dioxide emitted through the combustion of one tonne of waste depends on what the waste is made up of. If plastics (themselves made from fossil fuels) dominate, then the CO2 emissions from incinerators can be higher than from traditional gas-fired power stations.
Some environmental groups are also concerned that excessive use of WtE plants could hamper recycling and circular economy efforts. Sweden and Denmark both invested in incinerators in response to landfilling bans in the early 2000s. At the time, sceptics were concerned that building too many incinerators would incentivise the combustion of recyclable materials. This led countries that had made significant incinerator investments – including Germany and the Netherlands – to import waste from abroad while upping their domestic recycling efforts.
Burning recyclables
“Many reports acknowledge the high percentage of recyclables in the residual waste that is used as a feedstock for incinerators,” said Janek Vähk of the NGO Zero Waste Europe. “Countries burning more than half their waste risk contradicting the EU’s new recycling target, which states that 65% of waste must be recycled by 2035. Those countries have to scale down incineration.”
However, proponents of waste incineration state that WtE plants can still provide a necessary service to society by treating refuse that cannot be recycled. If all recyclable materials are sorted and separated, incinerators could still be fed by sanitary waste, waste polluted with substances of concern or waste that is degraded after several rounds of recycling. Calculations from the Confederation of European Waste-to-Energy Plants (CEWEP) show that there will still be 140m tonnes of residual waste that will need treatment in 2035. According to CEWEP, the current WtE capacity in Europe is 90m tonnes, meaning that there may be a case for incineration after all.
“The waste input into WtE plants is determined by consumer behaviour and local waste management systems,” said Dr Ella Stengler, the managing director of CEWEP. “Proper waste separation at source and efficient collection are the best way to ensure that all the waste that can be recycled from the technical, environmental and economical perspective is recycled and that only waste that does not fit these criteria is delivered to the WtE plants.”
Search for sustainability
In the long term, WtE plants will still have to reckon with the inevitable CO2 emissions that come from combustion, as well as other air pollutants linked to the process of burning waste. Carbon-capture technologies could offer some help in this area. A small handful of WtE facilities have figured out how to capture carbon and offer it to other industries. One plant in the Netherlands started supplying CO2 to greenhouses last year, for instance.
Incineration isn’t the only way to produce energy from waste. It’s just the most common method in use today. There’s some evidence that pyrolysis and gasification could treat waste more sustainably – but the byproducts of these processes would also be combusted to create energy. Organic wastes can also be broken down inside an anaerobic digester to create fertilisers and biogas.
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