The world's first experiment to capture carbon dioxide from the fumes of burning rubbish is nearing completion in Oslo.
The trial at the Norwegian capital's main waste incinerator began in January in a groundbreaking bid to develop technology to enlist the world's trash in slowing global warming.
The test at the Klemetsrud incinerator, which burns household and industrial waste, is a step beyond most efforts to capture and bury greenhouse gases at coal-fired power plants or factories using fossil fuels.
So far, high costs have plagued technology for carbon capture and storage. Last December, almost 200 nations agreed a deal in Paris to fight climate change in a new spur for technologies to reduce greenhouse gas emissions.
Johnny Stuen, technical director of the Klemetsrud waste-to-energy incinerator, said the plant already generates heat to warm buildings in the city. "When it comes here what we want to do is to burn the rest that is not usable for material recovering because it's too dirty or too mixed or whatever," Stuen told Reuters. "We want to recover the energy in it because that's still available. So that's when it comes here and we take care of it and burn it up and then we use the energy to district heating and producing electricity."
The Klemetsrud incinerator emits more than 300,000 tonnes of carbon dioxide a year, or 0.6 percent of Norway's man-made emissions. It also burns imported rubbish from Britain.
Carbon dioxide is the main gas blamed for stoking rising temperatures and more droughts, floods and rising seas.
The test plant, in five containers feeding exhaust gases through a series of pipes and filters, will capture carbon dioxide at a rate equivalent to 2,000 tonnes a year until the end of April.
"On average we're capturing about two, two-and-a-half tonnes, a day. That's our average, more or less, that's because of the restrictions of the unit itself," said Espen Jorgensen, site manager of the test unit for Aker Solutions, which is running the trial.
The project is being funded by Gassnova, Norway's state enterprise for developing carbon capture and storage.
Oscar Graff, head of CCS at Aker Solutions, said he expects the experiment to capture up to 90 per cent of the CO2 emitted by the plant. "Up until now we have about 700 operating hours here at Klemetsrud and we have captured about 80 tonnes of CO2, and what is nice from this flue gas from Klemetsrud is the high content of the CO2, it's about 12 percent, volume percent, of CO2," said Graff. "It's fairly easy to capture. So up until now we have no problem with the process, it works very steady and so far all the test results look very promising."
If it works, a full-scale carbon capture plant could be built by 2020, officials said. Carbon dioxide could then be shipped to the North Sea for injection and permanent storage in geological structures below the sea bed or injected into oil and gasfields to help boost pressure and raise production.
"So 300,000 tonnes comes here every year and we can capture 300,000 tonnes CO2 from those 300,000 tonnes of waste. So it's approximately one ton of CO2 per ton of waste that can be captured," said Stuen.
Officials declined to discuss costs but said the price of emitting carbon dioxide in the European Union emissions trading market would have to be far above a current 6 euros ($6.50) per ton for the technology to be feasible at scale.
About 60 percent of the rubbish burnt at Klemetsrud is of biological origin - from waste wood to food. That means that capturing emissions would be a step to extract carbon from a natural cycle in so-called "negative emissions".
"If we succeed in this, this will be negative emissions because the mix of carbon in the waste is approximately 50 to 60 percent biological and 40 to 50 percent fossil, so the biological part of it will be carbon negative, or negative emissions," said Stuen.
A 2015 report by the Australia-based Global Carbon Capture and Storage Institute said there are just 15 big CCS projects in operation worldwide, including a coal-fired power plant run by Canada's Saskatchewan Power[SSPOW.UL].
If the experiment is successful, Aker Solutions hopes to use the technology at waste-to-energy sites around the world, of which there are around 450 plants in Europe and about 700 globally.