Scientific collaboration is deeply rooted within Lenzing’s R&D. As a pioneer of sustainability Lenzing is actively seeking partners to speed up the developments and to make the necessary impact timely. The collaborations range from large research centers to small individual projects and also include important networking with the scientific community.
For more information, please see the “Stakeholder engagement” chapter.
Alternative sources of raw materials for fiber production
Any plant-based material can potentially serve as a source of cellulose and hence as dissolving pulp for fiber production. Lenzing has undertaken extensive research into many different alternative non-wood cellulose sources. In its research, Lenzing identifies promising new cellulose sources and carefully considers their availability, technical feasibility, and economic scalability as well as the overall ecological impact with respect to Lenzing’s climate target and circularity approach.
Studies have been conducted on sources such as annual plants like hemp, straw, and bamboo. In general, annual plants have a higher growth rate per hectare than trees. Additionally, certain species have a higher cellulose content. Some of them are already available in large quantities, especially in the form of agricultural waste. This allows an attractive cellulose yield per hectare to be achieved; however, the feasibility of any alternative raw material needs to be assessed on a case-by-case basis.
Based on current data, large-scale and sustainable production of cellulose is still best conducted using wood from well-managed forests instead of the above mentioned alternatives.
At the moment the most promising alternative raw materials to wood are residuals from textile production and used clothing. This is where Lenzing developed the first industrially implemented solution: REFIBRA™ Technology, which uses up to 30 percent of textile waste as feedstock and represents an important step towards achieving a circular economy. In order to progress faster and deliver relevant volumes to the market, Södra and Lenzing teamed up in textile recycling in 2021. They are now jointly developing their respective processes with the goal of implementing a recycling plant with a capacity of 25,000 tonnes in 2025. For more information, please see the “Circularity & resources” chapter.
At the same time, as an innovation company it is Lenzing’s aspiration to find new solutions, looking beyond the horizon. After the successful first limited edition fibers with alternative pulp sources in 2021 (pulp derived from orange residues by Orange Fiber), another limited edition followed in 2022. This time a part of the wood pulp was replaced by hemp pulp and the produced fibers are the basis for the world´s first biodegradable stretch denim fabric, made by Candiani Denim. Within the framework of the INGRAIN innovation alliance the first development project was started together with RWTH Aachen and other partners. Furthermore, Lenzing is in exchange with manufactures of pulp form alternative cellulose sources (like straw) and evaluating the suitability of these pulps.
The development of further new sources of non-wood-based cellulose in the future will require targeted research into the ecological and economic aspects of industrial production as well as increased cooperation. A number of challenges need to be addressed and are described in more detail below.
Alternatives such as bamboo, straw, and various annual plants do not yet meet Lenzing’s needs in terms of availability in the required quality and quantity. Many sources from annual plants are only available in the harvesting season and are difficult to store for year-round use. Annual plants are thus especially suitable for seasonal production campaigns. Despite specific benefits and high annual growth per hectare, the material is very bulky and more costly to transport. This favors obtaining the raw materials locally and keeping production capacities small.
The conversion of forest to agricultural land for annual plants is a worldwide phenomenon that increases pressure on all kinds of forests. Its drawbacks can be seen with palm oil production, for example. As well-managed forests store much more carbon per hectare than annual crops, this trend adversely affects the carbon balance of the entire value chain. The carbon balance must therefore be thoroughly calculated while including all co-products from annual plants.
Another important factor in the performance of annual plants is the management of the agricultural areas. Highly productive sites need far more fertilizers and pesticides than forests, causing other environmental issues. For example, the overall environmental profile of large-scale bamboo plantations is known to be unsatisfactory.
When considering processing, important factors that affect the environmental impact include energy consumption and the use of process chemicals in pulp production. They depend heavily on the actual process and vary significantly from one annual plant to the next. For instance, dissolving pulp can be made with cotton linters, as practiced by the viscose industry in some regions. However, the pulping process uses substantial amounts of chemicals and energy. If cotton linter pulp facilities are not state-of-the-art, resource use, emissions, and waste could be higher for cotton linter pulp.
Apart from not causing additional environmental issues, fibers produced with alternative feedstock must meet the same quality criteria as derived raw material wood fibers. The biorefinery process for derived raw material wood fibers is closely aligned with the raw material. This keeps quality and efficiency high and yields bioenergy as a co-product. With non-wood feedstocks, less bioenergy may be generated as a co-product, requiring additional energy sources for processing the feedstock into dissolving pulp, resulting in a potentially negative environmental impact.
Annual plants contain more mineral components and organic substances that have to be removed to produce high-quality dissolving pulp. This purification typically requires the use of aggressive chemicals and causes waste issues. It is a big challenge to develop new technologies, which help to reduce impact on the environment for these materials while maintaining product quality. By contrast, in woody plants like trees, these components are concentrated in the bark, which can be easily removed in the first stage of the process.
Paper industry experience of these sources is of limited use since dissolving pulp has to meet very different quality and purity requirements. While modern breeding and harvesting concepts have been developed, a new biorefinery process for annual plants still has to be adapted to the special requirements, not to mention circulation management for process chemicals and treatment of impurities originating from the plants. So far, no established industrial process meets these prerequisites.
For more information, please see the “Wood & pulp” focus paper.