Optical Waste Sorting by Bag Colour (Haraldrud & Klemetsrud)
Since 2009, Oslo residents have sorted food waste into green bags and plastic packaging into purple bags (blue before 2021), tossing all bag types into one bin picked up by ordinary trucks. Optical scanners at Haraldrud (2009) and Klemetsrud (2012) then sort the bags by colour: food goes to biogas, plastic to recycling, residual waste to district heating. Combined capacity: 150,000 tonnes a year.
📊 Impact
Oslo's own climate agency reports the technology works but participation lags it: in the most recent published data (2023, released March 2025), only about a third of plastic packaging (16.3 kg per resident that year) was sorted into the correct purple bag, and roughly half of all food waste still ends up in ordinary residual-waste bags rather than the green ones the optical scanners are built to catch.
🎓 Lesson
The optical readers do their job — bags that reach the plant get sorted correctly. The bottleneck is upstream, at the kitchen counter: a 2021 national bag-colour standard and repeated information campaigns still leave most residents putting plastic in the wrong bag. Worth noting: this is a distinct system from the Klemetsrud waste-to-energy plant next door now being fitted with carbon capture (see oslo-klemetsrud-carbon-capture) — one recovers materials from bags, the other burns what's left and is trying to catch the CO2.
📖 Terms in this entry: Pay-as-you-throw (PAYT) · Pneumatic waste collection · Adaptive traffic signals
Sources
This overview was generated with AI from the public sources listed above and checked against them before publication. It has not had a complete human fact-check — treat it as a starting point and follow the sources.
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📎 Cite this project
1001 Smart Cities (2026). “Optical Waste Sorting by Bag Colour (Haraldrud & Klemetsrud)” — Oslo, Norway. The Smart City Atlas. https://1001smartcities.org/projects/oslo-optical-waste-sorting/ (last verified 2026-08-04). Data: CC BY 4.0.
The underlying data is free to reuse with attribution — see the open data page.