What’s next for state-of-the-art bioproduct mill?

Pulp mills have not had the best of reputations over the years. Looking back to my childhood in the 1970s, some of that infamy is merited, but we can all be proud of the industry today and the improvement of environmental performance alongside raw material and energy efficiency.

Modern chemical pulp mills have low heat consumption of below 9 GJ per air dry tonne (ADT) and low electricity consumption of about 500 kWh/ADT. Mills can operate without any fossil fuels, and the recovery boiler is sufficient for the mill’s electricity and steam consumption, while even providing renewable electricity for outside use. With advanced automation, the mill can operate optimally and, with regular maintenance and upgrades, enjoy a long and profitable life.

I see the next challenge as water scarcity, which climate change is making more severe. In recent years, we have seen some mills even having to curtail their production due to a lack of water. But rest assured – we have the tools to tackle this challenge as well. We need to design mills to use as little fresh water as possible and further improve their reuse of washing water and evaporation condensates.

Improving energy efficiency has also made it possible for chemical pulp mills to start producing even more bioproducts.

Environmental performance, combined with economic benefits, has been the driver for closing the mill’s chemical circles and sidestream utilization. For example, using the mill’s own odorous gases for onsite sulfuric acid production has multiple economic and environmental benefits, improving the sodium–sulfur balance, reducing the need for makeup sodium hydroxide, and eliminating the need to buy sulfuric acid from outside suppliers. It also indirectly reduces CO2 emissions.

Many mills have eliminated fossil fuels in lime kilns through either wood power firing or biomass gasification. Improving energy efficiency has also made it possible for chemical pulp mills to start producing even more bioproducts. For example, part of the lignin in black liquor can be extracted and used to produce high-value end products, with all the required steam and electrical power still produced from black liquor.

When I visit pulp mills around the world, I often hear about the challenge of attracting new employees. Telling the proud story of the environmental performance of modern mills and the opportunities of new bioproducts and digitalization could also help us in this aspect.