By Dr Edmund Fleck, President, ESWET
Energy systems of the future and the Circular Economy are being developed separately. If Europe acts smartly, Waste-to-Energy can connect the two.
What to do with our waste?
The best solution would be to not generate waste in the first place. Thus a zero-waste-society would be the ultimate aim to achieve. But as mankind is not perfect, human beings are not perfect, reality is not perfect, a zero-waste-society will not materialise anytime soon.
The next best option is to apply the EU Waste Hierarchy: Reduce, Reuse, Recycle, Recover and, as a last resort, Dispose. Once waste is generated, sorting it to encourage reuse and recycling should be the preferred choices. Nevertheless, not everything can be recycled. Residual municipal waste, the waste stream focussed on in this article, contains a mix of many materials that can only be recycled by creating a low-grade recyclate, e.g. paper which ended up being soaked by liquid or greasy substances.
A solution is needed to recover the energy and materials from residual municipal waste. This can be done with different technologies, but the best overall environmental benefits are yielded by a plant that can co-process all types of residual municipal waste and re-insert its energy and materials back into the circular economy; Waste-to-Energy (WtE) plants.
This technology has enabled many European countries to have among the highest recycling rates in the world and at the same time to minimise the amount of waste ending up in landfills.
Which technology is the most suited for residual municipal waste?
There are several candidate technologies to handle residual municipal waste. On the one hand, Waste-to-Energy (grate incineration with energy recovery and flue gas cleaning), the technology supplied by ESWET Members, has been used for decades worldwide.
Waste-to-Energy plants have the lowest emissions of all European combustion industries.
On the other hand, many emerging processes, which promise superior performance and results, fail to break ground on the market due to yet unresolved core technical issues.
Residual municipal waste is a complex resource, challenging any treatment because of its heterogeneity. This same characteristic makes energy recovery processes such as gasification and pyrolysis, which thrive on “pure” fuels or waste streams, struggle to process mixed waste, whose nature is constantly fluctuating, on an industrial scale.
The most energy-efficient treatment of residual waste must minimise the amount of energy needed to make the waste usable as a fuel, and valorise all combustible fractions. Any avoidance of sorting or pre-treatment of the residual waste is saved energy. Additionally, fractions of residual waste that do not undergo thermal treatment will likely head for landfill, "burying" that energy.
WtE plants combine a maximum energy production from waste, while minimising pre-treatment energy losses. On top of that, the process can be arranged locally, reducing fossil-fuelled transportation.
Increasing the energy efficiency
Around 85% of the energy contained in waste can be recovered by Waste-to-Energy plants’ boilers. About half of this energy is considered renewable as it comes from the biogenic part of waste. If it is converted into electricity, waste will act as a dispatchable source which can feed the European grids with much-needed reliable and balancing electricity.
However, grid access is becoming increasingly challenging, but waste incineration is better performed in a steady and continuous manner. Hence, electricity production should be complemented by heat supply wherever possible, also in order to increase the overall energy efficiency of the process.
This is where District Energy from Waste kicks in. Waste-to-Energy plants operating as CHP (cogeneration of combined heat and power) maximise the energy output from waste and help powering the circular economy we all crave for. Supplying a city’s heating and/or cooling networks with indigenous energy – its own waste – helps securing Europe’s energy supplies. It also contributes to reducing Greenhouse Gas Emissions (avoided landfilling and its associated methane emissions) and increases the reliance on renewable energy. ESWET, along with partner associations, advocates for the continued development of District Energy from Waste1.
Closing the loop of the circular economy
Along with the energy-producing benefits that Waste-to-Energy entails, those plants also sort material and make them available for various uses in the circular economy.
Valuable materials that would have swelled landfill volumes if they had not been treated in Waste-to-Energy plants – metals and minerals – are routinely recovered from Waste-to-Energy plants’ residues. For instance, 116,176 tonnes of ferrous metals were recycled from Dutch Waste-to-Energy plants in 20132.
Similarly, in European countries that have minimised landfilling it is estimated that 40% of the aluminium recycled from Municipal Waste comes from Waste-to-Energy plants. And in some fore-running plants, it has been possible to recover a few kilos of gold per year from waste3 thanks to advanced sorting.
Integrating the circular economy for materials in a sustainable energy system
At the moment, Europe is pondering its energy future while simultaneously – but separately - yearning for a circular economy.
A clear example of this compartmentalised thinking is the current approach to Waste-to-Energy. On the one hand, it is not seen as a significant energy source, despite already fulfilling 1.3% of total European energy needs, equivalent to 19% of the EU gas imports from Russia4, and heating entire city blocks. On the other hand, it is shunned from the circular economy, despite producing valuable energy and materials from polluted or unwanted resources that would otherwise have been landfilled.
Realising that energy and circular economy are intertwined should guide decision-makers to increase synergies and coordinate support while making Europe more competitive and sustainable. Such goals cannot be fully accomplished without policies that minimise landfilling while developing the necessary Waste-to-Energy infrastructure in each EU Member State. ESWET is ready to answer that call.
1 http://www.eswet.eu/tl_files/eswet/1. Welcome/Warmth from Waste2014.pdf