A new study from the Technical University of Denmark (DTU) indicates that Denmark’s carbon dioxide emissions are double the previous calculation and have probably been so for years.

Accordingly, Denmark is exceeding its carbon dioxide goals under the Kyoto Protocol.

Widespread municipal rubbish incineration – the same waste-to-energy system that has been touted internationally as a model for clean energy resourcefulness – is the main culprit.

The incineration itself is not necessarily the problem. It is just that there is too much plastic in our trash, say experts.

The new findings come from a current study on the composition of the nation’s household rubbish, by DTU associate professor Thomas Astrup. He found that the actual amount of ‘fossil content’ – plastics, in other words – in rubbish that is being incinerated is twice what authorities were estimating.

Although the study’s final results will not be ready until summer, the preliminary data was strong enough to convince the National Environmental Research Institute (DMU) to begin revising its annual report to the United Nations Framework Convention on Climate Change (UNFCCC), which monitors whether countries are meeting their Kyoto Protocol commitments.

Based on the new carbon dioxide calculations from the DTU, Denmark is not.

“Our preliminary research shows that our emissions are in the range of 32.5 kilograms of carbon dioxide per gigajoule – which is twice as much as the 17.6 kilograms of carbon dioxide per gigajoule we used to think we were putting out from incinerators,” Astrup told science website videnskab.dk.

Some 700,000 tons more carbon dioxide escape into the atmosphere every year than previously thought, according to his computer models.

Denmark burns approximately half of all its household rubbish at incinerator plants that convert rubbish into energy for residential electricity and heat. Widespread municipal rubbish incineration means that just five percent of Danish rubbish gets buried in landfills. But it also means that we emit extra carbon dioxide.

“Carbon dioxide emissions were probably higher in previous years also. We just didn’t know,” Astrup told The Copenhagen Post.

According to a DMU report from 2010 – before the new data – the average Dane is responsible for releasing two and a half times more carbon dioxide into the atmosphere than the average world citizen. That number could be much higher when new calculations are taken into account.

Double the plastic in household rubbish means double the carbon dioxide emissions, when that rubbish gets incinerated.

“In Denmark we often sort less and incinerate more than other countries,” Astrup said. “But it makes sense, because we have a very developed district heating system that is very efficient at turning it into energy. This makes Denmark somewhat different from most other countries.”

There is a misconception that state-of-the-art incineration plants reduce carbon dioxide emissions. But that is not the case. They filter out dioxins and other poisons that might otherwise escape into the air, and if they are highly efficient, as in Denmark, they provide more energy from less rubbish.

The key to reducing carbon dioxide emissions from the rubbish that is burned is making sure that there is less fossil content in it.

“The carbon dioxide coming from waste incinerators depends upon the waste composition and not the technology or efficiency of the plant,” said Astrup.

Separating and recycling more plastics from household rubbish would seem to be the answer, but Astrup warns that is not necessarily the ‘greenest’ solution:
“Burning the plastic in highly efficient Danish incinerators generates energy that we then do not need to produce at power plants using coal and gas. This saves carbon dioxide emissions elsewhere.”

“If the plastic can be sorted out in clean fractions and recycled properly to make new plastic, then it’s a good idea. But if it’s not clean, it can only be recycled into secondary materials, which saves less new plastic and less carbon dioxide emissions. Then it is better to incinerate the plastic in Denmark at high efficiency,” he added.