Years after many other urban hubs started collecting organic waste and turning it into biogas and fertiliser, Copenhagen has finally begun to follow suit. As part of its strategy to be the first carbon-neutral city by 2025, Copenhagen will use its residents’ organic kitchen waste to fuel shiny new carbon-neutral busses.
Copenhageners appear willing and ready to accept changes – even inconvenient ones – in order to become more sustainable. One survey commission by Copenhagen Municipality shows that 78 percent are willing to support initiatives to make Copenhagen more green.
That level of commitment to sustainability is a boon for Morten Kabell, Mayor for Technical and Environmental Affairs, who this summer equipped the first 85,000 Copenhagen households with organic waste bins – all 280,000 apartments should have an organic waste bin within the next four months.
“This is a testament to the fact that Copenhageners value recycling, the environment and the climate,” Kabell said.
The small green tubs arrive with a starter pack of 100 bags that can be deposited into larger bio-bins located in the courtyards of apartment blocks. Stand-alone houses and villas have the option to refuse the inconvenience of an additional bin cluttering their yard and kitchen.
The measure was agreed upon two years ago and is designed to help meet the city’s ambition to recycle and reuse 45 percent of all municipal waste by 2018. According to Kabell, the initiative will also save the city around 77 million kroner a year.
Around 40 percent of household waste is organic and compostable, so sorting it will reduce pressure on the city’s waste disposal system.
Quality or Quantity of Waste?
While recycling seems intuitively good, critics argue that forcing residents to sort waste might actually result in a lower participation rate and less bio-waste for recycling.
The alternative is a “single stream” system that would allow residents to toss paper, metals and plastic recyclables into one container, to be sorted later at a processing plant. DONG energy’s REnescience firm bid on a contract to build and operate such a plant in Copenhagen, which would have used state-of-the-art enzyme-based technology to process the waste into products that can be sold onward, such as biogas.
A single-stream approach has proven cost-effective in similarly-sized cities around the world. Among its benefits is allowing cities to streamline their fleet of collection vehicles. Copenhagen currently has a number of different collection vehicles, and has added a new vehicle dedicated to collecting biowaste. Using a single vehicle allows for more frequent pick-ups, as well as greater flexibility when containers are unexpectedly overwhelmed, since municipalities only need one standardised truck to collect waste.
DONG’s single-stream plant was never built, however, because City Hall voted instead to exclusively support increased source separation and the introduction of the bio-bin, which joins the paper, cardboard, glass, plastic, metal and electronics containers.
Kabell decided against the single-stream option after weighing the willingness of Copenhagen residents to sort their waste alongside questions concerning the quality and reliability of the REnescience product. An analysis by the municipality showed levels of mercury and plastic in their bio-liquid and would-be fertilizer that exceed safety levels set by the Environment Ministry. This would render the waste byproduct unusable in agriculture and therefore not conducive to the goal of reaching 45 percent recovery rates of waste under the current rules.
A Bridge Too Far?
The city’s biogas programme has run into trouble, however. Under the original plan, the wastewater utility Biofos was to have been equipped with a biogas facility to treat the organic waste. But they need 50,000 tons of organic waste a year for the enterprise to be profitable, and when waste-to-energy plant Vestforbrænding decided not to cooperate with the programme earlier this year, only 30,000 tons of waste could be guaranteed, leading Biofos to pull out.
As a result, the organic matter will have to be treated and converted into biogas by Hashøj Biogas in West Zealand. This facility will not be able to treat all the organic waste, however, and the remainder will have to be transported all the way to South Jutland.
“We chose to follow suit with Vestforbrænding when we saw that they put the project on hold,” Biofos’ director John Buur Christiansen recently told Ingeniøren, adding that they might decide to rejoin the programme if it looked like there was enough organic waste being collected to make the project viable.
“I’ve definitely not given up the idea of a biogas plant in Copenhagen or in one of the surrounding municipalities,” admits Kabell.
“Copenhagen once led the charge toward a goal in which several municipalities from around the country joined forces to establish facilities capable of recycling plastic. And I’m quite sure that we can find a group of cities similarly interested in partnering up to deliver organic waste to a new plant.” M