A real Christmas tree is the centrepiece of many households' festive decorations but apart from filling the room with a woody fragrance, pine needles have a key role to play in addressing challenges relating to energy.

Cellulosic pine needles (CPNs) are the largest source of renewable biomass produced worldwide. They can also be used in a range of bioproducts, especially for agri-food energy sectors.

However, a review by researchers at Scotland's Rural College (SRUC), in partnership with scientists at Sri Sai University and Sher-e- Kashmir University of Agricultural Sciences and Technology of Jammu in India, found CPN waste is currently underutilised.

They said to maximise the environmental benefits of pine needles, it was necessary to scale up the range of processes for creating value-added products.

This includes gasification to turn CPNs into bioenergy; pyrolysis – the use of extreme heat – to create various carbon-based water purification materials; and saccharification combined with fermentation to produce bioethanol yields. In addition, nano cellulose extracted from CPNs can be used as packing materials.

Vijai Kumar Gupta, Senior Challenge Research Fellow at SRUC, said: "Cellulosic pine needles are substantially better than coal in terms of the economic benefits of bio-energy generation at different CO₂ emission reductions.

"CPN wastes are underutilised, but they have remarkable potential to act as feedstock for generating bio-based products and bioenergy."

Co-author Professor Vijay Thakur added: "To maximise the environmental benefits, it is critical to utilise the full valorisation potential of CPNs, developing various biobased product types for sustainable biorefineries and the circular economy concepts."

The review was published by Bioresource Technology.