So far, wood has been the main raw material for paper production – a resource that is only slowly growing. The North American silphie plant could offer an alternative; the first papers from this fast-growing sunflower are already available. Scientists have now investigated in more detail what the life cycle assessment of such Silphie papers looks like. The result: In almost all aspects, Silphie is better off than the classic pulp made from wood.
The demand for paper and cardboard packaging is increasing. One of the reasons for this is that paper products are increasingly replacing conventional plastic packaging, for example in online retail. However, paper production is also not without its problems: it requires a lot of energy, some environmentally harmful chemicals are used and the raw material wood only grows back slowly. If the cellulose for the paper is obtained from trees felled especially for this purpose, paper production therefore contributes to the destruction of forests.
Energy plant as a fiber supplier
Scientists around the world are therefore looking for ways to make the manufacture of paper and cardboard more environmentally friendly and sustainable. In addition to the recycling of waste paper, another alternative is the use of faster-growing plants as a supplier for the paper fibers. A candidate for this is the streaky Silphie (Silphium perfoliatum). Native to North America, this sunflower grows up to three meters tall and grows well even in dry locations. In addition, these yellow-flowering perennial plants require little fertilizer and no pesticides from the second year of growth. Because the Silphie is rapidly growing in biomass, it is considered a promising energy plant for biogas production.
But also in paper production, the streaky Silphie has advantages: It only needs a year to grow back and provides plenty of fibers from which paper can be made. So far, however, this has only worked if a certain proportion of cellulose from wood fibers is added. Researchers at Fraunhofer UMSICHT have now investigated whether paper products made from silicon are more environmentally friendly than normal paper made from cellulose. To do this, they compared the eco-balance for Silphie papers from the manufacturer OutNature with that of conventional packaging paper made from fresh fibers. In doing so, they took into account the cultivation, the material and energetic utilization of the Silphie fibers including the disposal.
Positive balance with small drawbacks
The result: The Silphie paper can score points over cellulose cardboard in a number of areas. The processing of the silphie leads to less eutrophication of the waters and fewer minerals and metal raw materials are required in paper production. According to the life cycle assessment, Silphie fiber production has a lower overall environmental impact than pulp production. Compared to cellulose, Silphie fibers also have a lower impact on the climate. Because of the rapid growth, the Silphie contributes to the binding of CO2 and enables a more sustainable supply of raw materials. However, wood does better if you look at the effect on the soil: forest does not need fertilizer and does not leach out the soil.
Positive for the Silphie, on the other hand: Similar to normal paper, paper and cardboard based on Silphie fibers can also be recycled and made into new paper. “The generation of biogas from Silphie and its conversion into electricity also has a positive effect on the overall balance,” explains Daniel Maga from Fraunhofer UMSICHT. Part of the plant material can thus be used to generate the energy that fiber processing requires. For this, the Silphie fibers are fermented and the resulting gas can be burned. One shortcoming, however, are the machines that have been used for testing Silphie paper production up to now, as the team found: Because the test systems are at the technical level of the 1960s, they are not very energy-efficient.
All in all, the researchers in papermaking from Silphie give it a very good report. “The results of the life cycle assessment study are very promising. With Silphie fibers, we have succeeded in generating a regional and renewable raw material with a transparent supply chain, which as a cellulose substitute also makes sense from an ecological point of view, ”explains OutNature Managing Director Thomas Tappertzhofen. “Only the papermaking process currently causes the largest amount of greenhouse gas emissions.” There is a need for improvement here.
Source: Fraunhofer Institute for Environmental, Safety and Energy Technology UMSICHT