The production of Multicopy paper is about to contribute to the biofuel production in Sweden. The energy company Gasum and Stora Enso will together turn waste into renewable green energy.
Wastewater can be a challenge for mills. Vast volumes of process water containing organic residues need to be treated. At the Stora Enso’s Nymölla Mill, the water treatment facility is the size of ten football fields, and each holding basin is seven metres deep.
“We’ve been looking into biogas for many years,” confirms Michael Lindemann, Mill Director at Nymölla. “When we initially determined biogas could be made from our process water, we wanted to use it to power the mill.”
Looping the mill’s process water through the biogas reactors breaks down the organic content to produce methane. This process reduces the organic content up to 60 per cent after just five hours in the reactors, leaving far less to be treated in the wastewater facility.
“The key here is that today we can liquify the biogas,” says Erik Woode, Director, Biogas Business Development at Gasum. “Historically it was quite expensive to do that, but technology has advanced to the point where we can do it economically.”
Liquified biogas (LBG) is comparable in energy-density to diesel fuel, making it ideal for the heavy transportation sector, a major source of carbon emissions. LBG emissions are 90 per cent less than diesel, and LBG produces far fewer particulates, further minimising impact on air quality.
Replacing liquid natural gas (LNG) with LBG is the immediate goal. “LBG is what we call a drop-in fuel,” explains Woode. “It is 1-to-1 with LNG, and we are hurrying now to fill our stations with LBG because that is what our customers want.”
The LBG from Nymölla will improve the overall balance of renewable energy in Sweden considerably, accounting for a 5 per cent increase in biogas production.
Final assembly of the LBG plant should be completed during springtime this year. The mill will start pumping water shortly thereafter, followed by a ramp up period as Gasum tunes operations for full capacity.
Stora Enso is a leading global provider of renewable solutions in packaging, biomaterials, wooden construction and paper.
