New opportunities for managing residual streams

Essentially, all methods of production give rise to residual streams in some form. It may involve materials, energy or chemicals being wasted during the manufacturing process, but may also have to do with residual streams from raw material extraction or end-of-life products. A growing number of industries and companies have started to investigate how they can reduce and find value in their residual streams.

Find streams not being used

At RISE we develop technologies for gaining the highest possible value from residual streams. An area in which we are running several projects is tyres and rubber. Around 1.5 billion tyres are produced each year. Tyres that end up in landfills instead of being recycled are a global problem. Recycling materials from tyres has many benefits: waste is reduced, worn tyres are reused and fossil fuel consumption is reduced.

– “It all has to do with finding the streams that are not being used,” says Jonas Persson, Development Engineer at RISE. “A tyre is made up of several different materials. We separate the materials by means of a pyrolysis process. We place the rubber in an anaerobic container and heat it up to 550 degrees. Some of the material is then converted into oil, with metal and carbon black remaining solid in the reactor. All these materials have the potential to become building blocks in new products.”

Transition requires financial instruments

In the past, recycling often involved burning residual streams in order to generate heat. Swedish companies have invested heavily in energy recovery, which is certainly better than landfills, but there are more effective solutions for generating heat.

– “To put an end to this form of energy recovery, a driving force must exist,” says Persson. “In order for industry to transition to more efficient, eco-friendly recycling, financial instruments are required.”

At present, more electronics than ever before are being recycled. Everything from solar cells to products with plastics and metals such as PCBs. By using a pyrolysis process, the different materials can be separated.

– “Many products are very compact and difficult to disassemble,” says Persson. “By means of pyrolysis, the plastic in a PCB can be converted into a type of oil before the metals are melted for recycling.”

Bio-based also creates residual streams

There is growing discussion within industry about a bio-based economy with the goal of replacing fossil fuel materials or products. However, increased circularity and residual stream management must also be ensured in a bio-based circular economy.

– “If we want to build more wooden houses instead of using concrete and iron, if we want fibre-based packaging instead of plastic, and if we want wood-based textiles to replace fossil textile materials, there will be an increase in bio-based residual streams linked to this substitution,” says Johanna Mossberg, Acting Head of the Biorefinery and Energy department at RISE. “The progress being made towards replacing fossil materials with, for example, renewables from the forest is paramount, but we also need to have a plan for managing residual streams from production.”

Already today we are seeing voluminous residual streams from forestry, primarily bark, woodchips, branches and treetops.

– “Right now we are only handling a very small proportion of these residual streams effectively. Tremendous untapped potential exists here,” says Mossberg.

Residual streams have different natures and require different technologies

At RISE, we work with several different technologies and system solutions to convert bio-based residual streams into more high-quality products.

– “Our ability to examine multiple technologies simultaneously is one of our strengths at RISE,” says Mossberg. “Residual streams have different natures and emerge with various volumes. There is no single technology suitable for all raw materials, and the end product and value chain of interest also play a certain role. There is a big difference between upgrading fibre dregs, pine oil and bark.”

Collaboration spurs development

In a growing bioeconomy, bio-based residual streams will increase. In Sweden, large volumes originate from forestry and agriculture, and much can be accomplished here. However, it is sometimes challenging since the products and value chains created when using the residual streams are outside the core expertise of the companies. For instance, if pulp mills or sawmills were to suddenly start producing fuel components or chemicals. Completely new and cross-industry value chains often need to be created.

– “If we are going to have a chance, we must ensure that we optimally utilise all residual streams,” asserts Mossberg. “We can really see things happening when numerous operators from different sectors interconnect across the value chain. SunPine is a good example of this. Their raw material is a residual product from paper and pulp production, and the end product in the value chain is a renewable diesel. SunPine is owned by Preem, Sveaskog, Södra and Lawter.”

Successful collaborations involve operators from different parts of the value chain. In this, RISE serves as an important catalyst with both knowledge and networks, and is able to play a part in developing technologies and identifying cross-industry value collaborations.

– “Tree to Textile is another successful collaboration between several different operators across the value chain. HM Group, Inter IKEA Group, Stora Enso and innovator Lars Stigsson are all involved. Tree to Textile develops and industrialises a new cellulose fibre technology that produces textile fibre with high durability and performance at a low cost. The development has been facilitated by RISE’s test and demo infrastructure, and the technology has been pilot tested and is now ready to be scaled up,” says Johanna Mossberg.