Next time you walk through a park, notice the grass. Is it nicely mowed, or does it look messy? How would you like it to look? Usually, a nicely mowed lawn in a park or garden is aesthetically pleasant, but in nature, a nicely mowed and ordered lawn looks strange. Human beings are sharp recognizers of patterns, being picky about how things should be. The tendency to homogeneity and recognizable patterns also applies to the shift towards circular systems and bio-based materials. However, this paradigm shift has proven to be a difficult task. In many cases, the challenge comes from the consumer’s view on how a certain product should look like. In nature, we expect things to be as they naturally are. So, what should we expect from something produced from nature? What should we expect from the products of a biorefinery?
A biorefinery is an industrial facility where biomass is refined and valorized. Biorefineries as a concept have been around for several hundred years. Some examples include dry distillation to produce tar for e.g. ship making, collection and purification of pitch for resins and turpentine, e.g. for medicinal use, and the recovery of potash from minerals in wood ash for cement, fertilizer, and glass. Pulp and paper mills were the first industrialized biorefineries. In addition to pulp and paper, they nowadays also produce i.e. turpentine, tall oil, and energy. While energy is an indispensable product, it is of low value compared to cellulose, chemicals, and other materials being produced by modern biorefineries. The main reason why energy is produced in biorefineries is because some materials are just easier to burn than to valorize. These materials are called “side-streams”.
Side-streams are usually heterogeneous. They are materials that resist our attempts to create order. They may sometimes seem homogeneous to the eye, but when applied in products, their disorderly nature emerges. In pulp and paper mills, the main side-streams are mono- and oligosaccharides from degraded carbohydrates, and lignin. Sugars have been of interest both in nutrition and fermentation since the start of the 20th century, but lignin could not be cracked. Until today, biorefineries struggle to solve the lignin problem. At this point, Boreal Bioproducts steps in, focusing on valorizing all materials and aiming to mainstream the side-streams.
The side-streams, such as lignin but also hemicellulose and other sugars, can be crucial for the commercial feasibility of the mainstream production. The mathematics are simple: something goes into the factory, there is a certain cost associated with the refinery, and the profit is the costs subtracted from the sales revenue. Incinerating the side-stream is cheap, so there would be a very small additional processing cost for the side-stream materials that are used to generate energy. However, if they are valorized, the extra processing brings extra costs. The process costs for each stream need to match its anticipated revenue. However, all materials experience the same costs during the initial separation stages. Thus, if the side-streams are incinerated for low-value energy, the mainstream has to take on most of that cost itself.
The techno-economic challenge is to find ways to valorize the side-streams into something that is useful enough to cover the refining costs. If achieved, the refinery would have new revenue streams and would loosen up margins of the mainstream material. Below is a visualization of this concept.
The image above is a simplification, but it shows two important things:
As the plant needs more equipment to perform the valorization, the facility costs increase. In the chemical biomass processing field, side-stream valorization is accompanied by risk. There are few products from valorized side-streams that are profitable. This means that the expected return from the valorization capacity is to some extent speculatory. Simply put, the investment risk is larger for a biorefinery with high side-stream valorization capacity. This risk can be reduced by proving the value of side-streams. Within the LUCRA project lignin removal is a central pre-processing step, resulting in lignin being one of the main “side-streams” of the succinic acid production. Therefore, let’s have a deeper look at lignin.
Lignin is a polyphenolic compound, that is often obtained as a brown powder. Traditionally, lignin is incinerated for energy. However, more and more companies are investing in lignin purification facilities and are finding new applications for it. Purified lignin has been commercialized as component in adhesives and some thermoplastic resins, but its use is still very limited. There are several reasons for this. Lignin is a rigid polymer that does not mix properly in most systems. Its structure is not hydrophobic, but it also does not dissolve in water, which makes it difficult to incorporate in water-based products. Its strong brown color is an additional issue for many applications. Nevertheless, there are several good reasons to valorize lignin, from an economic, environmental and political perspective. Replacing imported fossil-based materials with locally produced materials increases self-sufficiency and local value-addition. Lignin is naturally produced from atmospheric carbon and is also biodegradable. However, lignin resists our attempts of creating patterns and order. To apply it in our world, we need to play by its rules.
The risk of investing in side-stream valorization can be lowered by demonstrating that the materials can be profitably applied. The first obstacle to apply lignin is its solubility: lignin does not dissolve or disperse in neutral water. It does dissolve in alkaline conditions, but alkalinity is a problem in most applications. To tackle this, Boreal Bioproducts started developing a method that helps prevent lignin from separating from the water phase in near-neutral solutions. This development project resulted in the SOLV™ method.
Having achieved the development of a ‘more easily applicable lignin’, the next challenge became the area of application. Because lignin has both hydrophilic and hydrophobic structures the SOLV™ lignin becomes surface active, meaning it can bridge hydrophilic and hydrophobic surfaces. Surface-activity is useful for various applications, for example antifog products. Fogging occurs when moisture from the air condenses into droplets on transparent surfaces. These droplets are round and therefore refract light in different directions. To see clearly through a transparent surface, the light that passes should remain undistorted. There are two ways of reducing fogging: reducing condensation by making the surface hydrophobic or making the droplets less round. The latter solution can be achieved by making the surface hydrophilic, as the water then spreads into a thin even film, that does not distort light. This is what happens to the surface activity, when applying SOLV™ lignin onto glass or plastic lenses. A simplified mechanism is shown in the figure below.
After fine-tuning and field tests – first with hobbyists, then with high-level athletes – LigNoFog® was launched, being the very first consumer product where lignin is the main ingredient. The feedback on its properties has been tremendous, even though the solution’s dark color surprised people when using it the first time. The color is of course not visible when the solution is applied, but people simply expect antifog solutions to be colorless. Nevertheless, after seeing how well it works, users accepted that a natural product has a natural look. Users were not only impressed with LigNoFog’s properties, but also that they did not experience eye irritation when using it.
This case demonstrates how the applicability of lignin can fundamentally be turned upside down by solving its main obstacles. Besides LigNoFog®, there are several other water-based products where the SOLV™ lignin could be an excellent ingredient. In the near future, people will hopefully be able to accept that we have to play by lignin’s rules. Lignin does an excellent job, give it a chance!
Dr. Alexander Henn
Boreal Bioproducts
alexander.henn@borealbioproducts.com
The project is supported by the Circular Bio-based Europe Joint Undertaking and its members.
Funded by the European Union. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or CBE JU. Neither the European Union nor the CBE JU can be held responsible for them.
This work was also co-funded by UK Research and Innovation (UKRI) under the UK government’s Horizon Europe funding guarantee grant number 10082169.
