Energy Recovery: Europe's Favourite Way of Dealing with Waste Plastic

EUPHEMISM [noun] eu· phe· mism | \ ?yü-f?-?mi-z?m- the substitution of an agreeable or inoffensive expression for one that may suggest something unpleasant.

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Energy recovery is the favourite guilty-phrase of the plastics world that never fails to bring a sad smile to my face.

- while we’re at it, let’s rename landfilling into a “raw material storage for future generations” and coal power plants into “prehistoric sunshine repurposing facilities”...

On a slightly more serious note - how does ?????? ???σ???? actually work? and just how bad (or good) is it for our circularity ambitions?

…aaand yes, I’ll keep highlighting it throughout the text, just because I’m such a “fan” of the phrase ??

First off, we need to make sure that one thing is clear and understood:

energy recovery = incineration

i.e. burning things, in this case plastic waste. Or more specifically, plastic-containing waste - it’s an important distinction, as we’ll see in a moment.

Waste-to-Energy (...and to Some Other Stuff)

In order to understand the implications of burning our trash, let’s take a walk through a typical ???????????? ???????????????? plant:

1?? First, municipal waste arrives in trucks. By definition, it’s the NON-recyclABLE waste, otherwise it would be sent for recycling ??

This is literally everything people throw out and don’t sort, from greasy plastic packaging, to old polyester pants, to garden furniture - so we need to make it more homogenous.?

You know, for a steadier burn…?

So a pair of big-ass claws go through the waste pit, mixing it like a bowl of salad.

2? Now we burn stuff! ?? Combustion happens in a furnace at around 1100 degrees Celsius, which is enough to turn everything into gas and ash, destroying all organic matter in the process.

The resulting ash consists of heavy bits (bottom ash) which stay in the furnace, and light particles (fly ash) which join the outgoing gas.

3? The gas, which is obviously really hot, is sent through a generator, turning heat into electricity ? that is sold into the grid. Yay! Sometimes the heat is also used directly in other industrial processes or for district heating.

4? Finally, the gas goes through a bunch of filters, removing most of the really dangerous stuff like nitrogen and sulphur oxides (NOx and SOx), as well as mercury and other heavy metals ???

5? The scrubbed exhaust is released from a chimney, by which point it mostly contains CO? and water.

Time to take stock:

The Good, the Meh, and the Ugly

If the waste-incineration furnace is designed well, and the filters are thorough enough (which by EU regulations they must be!) there are pretty much 3 outputs of the process:

1. Electricity - around 500-700 kWh per ton of initial waste, or about 5x less than coal, which is the least energy-dense fuel used today.
2. Ash - the bottom ash, i.e. the residue in the furnace, is basically a mix of minerals. It represents ~20% of the initial waste mass and is usually sent to landfills due to being quite inert but not too useful either.
3. Carbon dioxide - the filtered gas that’s left over after electricity generation is mostly "greenhouse goodies", around 0.7-1.7 tonnes of CO? per tonne of waste.?

Let’s crunch the numbers: the above data implies that a typical energy recovery plant emissions profile is in the range of 1.4-2.4 t CO? per MWh.?

Compare that with coal (1.0 t CO? per MWh), the dirtiest major electricity source, and then also with the EU-average carbon intensity of power generation of 0.3 t CO? per MWh!

Not too pretty.

Well is it at least cheap?! After all, we’re literally burning garbage - people should be ready to pay to get rid of it, so it must be the cheapest fuel imaginable…

…until we take into account the capital costs.

While it’s true that most of the energy recovery revenue are indeed payments from garbage collectors (so-called tipping fees) -

it costs an eye-watering €100 million to build even a small-ish waste incineration plant - big ones can cost up to €1 billion.

This makes it much more expensive per tonne of waste treatment than even the most advanced sanitary landfills (see the previous essay in this mini-series).

Hmmm…

The Clever(er) Way of Exporting Waste

Wait, are we getting this right? Waste incineration is: a). super expensive per ton of waste and b). produces electricity that’s 2x more carbon-intensive than coal ??

Then why on ?? is it the most popular way of handling plastic waste in the EU right now?!

Wouldn’t it make more sense to invest into collection, sorting, and recycling infrastructure, while simultaneously adding more low-carbon power generation like solar and wind?

Yes. Yes, it would.

And that’s, hopefully, the main reason why the share of plastic waste sent for e?n?e?r?g?y? ?r?e?c?o?v?e?r?y? at least hasn’t been growing in Europe in the past several years.

Truth be told, the longer you stare at incineration as the means of tackling plastic (and any other) waste, the more it feels like a little trick:

Energy recovery is basically swapping landfills for emissions - and CO2 doesn’t accumulate inside country borders…

It’s almost like disposing of your waste around the world - without having to export it!

Stop Setting Things on Fire

At this point it’s just plain hard for me to go looking for the upsides of e??n??e??r??g??y?? ??r??e??c??o??v??e??r??y?? that would tilt the scale in any significant way, so let’s sum up:

• It generates electricity with some of the worst emissions profiles imaginable, at pretty much the highest price point,
• It converts a potential treasure trove of raw materials into the lowest possible value - inert, mixed ash,
• And decreases motivation to step up our reduce-reuse-recycle efforts (it’s just? so tempting to use the good-ol’ furnace to instantly get rid of all your plastic!)

As a civilization, we’ve achieved mind-blowing feats with tiny silicon chips and precisely engineered proteins, but still can’t seem to get rid of our ancient pyromania -

- yet "let's burn it" is almost never a good answer to anything.

There are both more ??boring and more ?elegant ways of solving the plastic crisis, from product design and legislation, to bioplastics and advanced molecular recycling.?

…and that’s exactly what we’ll be exploring in the following essays of the #plastics #circularity series. Stay tuned!

Selected Sources and Further Reading

The Decision Maker's Guide t?o? ?t?h?e? ?G?a?l?a?x?y? to Solid Waste Management Technologies by the World Bank is one of the best compendia covering landfilling, composting, and incineration: https://openknowledge.worldbank.org/handle/10986/31694

Directive 2010/75/EU of the European Parliament on Industrial Emissions is the current regulating document for waste incineration facilities in the Union - as you might expect, a breezy read: https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX%3A02010L0075-20110106

Chapter 3: Incineration Processes and Environmental Releases from Waste Incineration & Public Health by the National Research Council (US) offers a detailed overview of the technology base: https://www.ncbi.nlm.nih.gov/books/NBK233627/