Lignin 101
of all the biogenic carbon found on land is contained in lignin, which makes it the most abundant aromatic biopolymer in the world.
What is lignin?
Lignin is a natural polymer that contains over 60% carbon and displays high aromaticity. It can be found in most terrestrial plants as well as in algae. In fact, 30% of all the biogenic carbon found on land is contained in lignin, which makes it one of the most abundant biopolymers in the world.
The main source of lignin nowadays is wood, however novel extraction methods allow the sourcing of lignin from other streams, in particular agricultural residues. Lignin typically makes up 18 to 32% of wood biomass, depending on the species.
The function of lignin in nature is to hold together the plant cell walls and to facilitate the transport of water and nutrients. From an evolutionary perspective, it is lignin that allowed plants to grow strong and vertical up to the tallest of trees.
For all these reasons, lignin possesses intrinsic properties that could be of interest in specific applications, if they were to be retained in the produced materials:
- UV-stabilization
- Relative hydrophobicity
- Antioxidative properties
- Antibacterial properties
- Flame resistance
- Intermediate biodegradability (much more degradable than fossil-based plastics, but more durable than most biopolymers)
Other properties of lignin, in particular its disordered nature and poor solubility in many media, make it difficult to use in practice. Thanks to our patented technology, we overcome some of these hurdles and pave the way for lignin to become a commodity product to be used in a multitude of applications.
Where would we get lignin from?
Focusing on wood biomass, lignin is nowadays mainly a residue of Pulp & Paper production with a high energy value. As a result, it is mainly burnt on site to generate additional heat for the pulping process. However, not all lignin can be used to that end and the excess is largely under-utilized, for example as a low-value filler. In fact, it is estimated that pulp mills could extract up to 25% of the lignin present in black liquor without disrupting the chemical balance of the pulping process. Doing so would not only reduce the CO2 emissions of the mill by 9 000 tons every year, but it would lead to large quantities of lignin being available for applications with higher added value. We are talking about a potential yearly volume of over a million tons in Sweden alone, and up to 8 million tons in Europe! Not to mention that, besides wood, many agricultural activities also produce residues with high lignin contents. This potential is about to be unlocked, as Södra announced that they will build the world’s largest Kraft lignin production facility by 2027, in southern Sweden. And others will follow.
Does this really help with the environment?
Absolutely!
If the lignin would stay in the black liquor and get combusted for excess energy, the biogenic carbon that it contains would immediately be released back to the atmosphere. Instead, by extracting the lignin and incorporating it in materials, the carbon will be stored in the materials during their whole lifetime. They might even get recycled and reused, before eventually being incinerated and finally going back to the carbon cycle. This principle leads to lignin-based materials with an outstandingly low environmental impact, boasting negative CO2 emissions and thus mitigating global warming.
Regarding our forests, it is important to realize that, in Sweden, there is more forest today than there ever was in recent history. The forest area increased by 25% in the last 25 years and has doubled since the 1920s. The forest industry is thus contributing to reforestation, rather than deforestation, and the valorization of lignin will allow us to make as much as possible of every tree that is cut. This highlights another great competitive advantage of lignin over other biopolymers: the fact that it is obtained from residues of other industries and does not require additional land or resource use. On the contrary, many other bio-based materials rely on crop cultures that inevitably occupy the land and raise prioritization questions, in particular when food becomes an ever increasing challenge in the coming decades.
The lignin is there, lots of it. It just needs to be extracted and transformed. It is up to us to accelerate the development of this sector by showing that there are great opportunities to valorize this resource and lower the environmental impact of many industrial areas.
Opportunity
A prime example of industrial sectors that would greatly benefit from the development of biobased raw materials with a low environmental impact is of course the plastics industry. As opposed to fossil-based plastics, both virgin and recycled, using biomass as a raw material for plastics does not bring additional atoms to the carbon cycle, which paves the way towards carbon neutrality for the industry. With that said, despite increasing efforts through regulations, policies and outreach, the share of biobased plastics in the global production remains very low. In 2022, 400 Mt of plastics were produced worldwide, of which 99% less than 1.5% were biobased.
The lignin-based materials developed by LigniCore are advancing innovation in biobased plastics, but also biocomposites, coatings, elastomers and so on. Our highly energy-efficient and benign processes convert lignin into functional materials capable of replacing their fossil-based equivalents with a much lower environmental impact. Our materials are destined to help a wide variety of market segments transition towards carbon neutrality, including construction, road infrastructure, automotive, indoor commodities, packaging, performance composites and other advanced materials.
The purpose of LigniCore is to develop products and know-how to connect two key aspects of the green transition:
- The forest and agricultural industries that potentially have access to enormous amounts of lignin and look for applications and incentives to isolate and valorize it.
- Industrial actors facing new regulations and an increasing demand for biobased alternatives, but struggling to move away from the fossil comfort zone.
