A new study has shown for the first time that waste cardboard can be used as an effective source of biomass fuel for large scale power generation.
Engineers from the University of Nottingham have provided the first comprehensive characterisation of cardboard as a potential fuel source and created a new method to assess the composition of the material providing a practical tool for fuel assessment for cardboards. The study has been published in the journal Biomass and Bioenergy.
This research demonstrates that cardboard shows differences in physical and chemical properties, including lower carbon content, reduced heating value, and a high prevalence of calcium carbonate fillers, particularly in printed grades. The researchers have also developed a new technique to analyse the calcium carbonate content of cardboard. Calcium carbonate is added to cardboard to improve its optical properties and stiffness, but forms ash during combustion which can reduce a boilers performance.. The novel thermogravimetric method was developed to measure calcium carbonate content, offering a practical tool for fuel assessment for cardboards.
Picture below shows L to R: Blocks of biomass chars prepared for char morphology analysis using image analysis and milled cardboard.
Biomass is the second largest contributor of renewable energy to the UK, providing 31.1 terawatt-hours of electricity generation in 2022. Currently, around 8.3 million tonnes of biomass is used annually for pulverised fuel (PF) combustion in the UK, which accounts for 21% of the global wood pellet market.
This is dominated by wood pellets and wood chips, followed by recycled and waste wood, with other types of biomasses making up only around 1% of the total. The majority of the UK wood pellet demand is also met by imports, with the United States and Canada being the major suppliers. There is need to identify more domestic sources of biomass for bioenergy to enhance UK energy security.
With an estimated 5.4 million tons of paper and cardboard packaging wastes generated in the UK in 2021, cardboard represents a potential domestic biomass resource available in large quantities for various applications. There is a practical limit on the number of times that cardboard can be recycled (usually between five and seven times) due to the shortening of fibre length and decrease of quality as the material is recycled, after which it is composted or burnt with other materials as refuse derived fuels in energy from waste plants.
Using our industry standard facilities at the University we have been able to show that cardboard is a viable option for use in large scale energy production. With new methodology for analysing the exact composition of the different types of cardboard we can provide a tool that shows how effective it will be. The use of cardboard could provide a secure and stable pipeline for biomass fuel that will help energy industry reach its sustainability goals.
