STOCKHOLM: Stockholm City's pledge to be fossil-fuel-free by 2040 hit a setback last year when carbon dioxide emissions actually increased throughout 2018, Swedish Television (SVT) reported on Monday.

The Scandinavian country has an international reputation for energy reform and is a global leader in waste-to-energy solutions.

For this reason, fossil fuel use has been in steady decline since the 1980s.

Electricity and district heating plants, however, still use some coal and oil. Burning plastic waste for energy can likewise contribute to carbon dioxide emissions.

Last year, electricity and district heating plants in Stockholm County used more fossil fuels than usual, resulting in a carbon-emission increase of nine percent.

"We had expected an increase, but we did not know that it would be such a big increase," Fredrik Hannerz, of the Swedish Environmental Protection Agency, told SVT.

Ulf Wikstrom, head of Sustainability at Stockholm Exergi, explained to SVT. "We had to use more oil and coal than we had planned because it was difficult to obtain biofuels from the Baltics and there was no alternative," he said, adding "We are putting our eggs in more baskets now so that we can ensure that we always have biofuel, in case this should happen again."

More than half of Sweden's energy comes from renewable sources, according to the Swedish Institute, earning the country a reputation as an environmental pioneer.

Increasing carbon emissions in Stockholm, however, show that further action is needed if Sweden is to tackle climate change. The Swedish Environmental Protection Agency remains hopeful that this can be done.

"I'm hopeful, especially when it comes to coal use here in Stockholm. We should be able to fix that. Waste incineration is perhaps a bigger challenge," Hannerz told SVT.