Understanding Variability in Biomass Feedstocks and the Opportunities for Pre-Processing

Published: 23 March 2018

The race to decarbonise the UK’s energy system will not produce one overriding technology ‘winner’, but rather a mix of different low-carbon innovations that come together to form one powerful whole system – a jigsaw made up of lots of different parts – including bioenergy.

Up to 10% of the energy jigsaw could be made up of bioenergy by 2050 by upscaling and sustainably delivering a mixture of UK-grown biomass, residual waste and imported biomass.

The Whole Systems Analysis (WSA) team at the Energy Systems Catapult has been commissioned by the Energy Technologies Institute (ETI) to produce an Insight Report that presents the findings of two key studies from the ETI’s bioenergy programme, exploring the role of biomass feedstocks as part of the whole energy mix.

These studies gathered data on the chemical characteristics of UK-grown energy crops and carried out a techno-economic assessment of biomass pre-processing technologies, to assess the cost-benefit ratio of pre-processing biomass (to improve its physical and/or chemical properties), in the context of the whole supply chain.

Headline observations

  • To meet the projected energy demand in 2050, UK biomass production will need to expand, meaning we will in turn have to make more effective use of new and existing forestry, and second-generation energy crops.
  • Emerging second generation feedstocks have an important role to play, however the physical and chemical characteristics are different to commonly used wood chips and pellets – if not managed properly, mis-handling can lead to issues with boilers and other conversion technologies, causing costly and needless problems.
  • To successfully integrate new feedstocks, end users must be able to cope with greater physical and chemical variability, or pre-processing techniques must be established to make the feedstocks more readily accessible. This includes water washing, which can improve biomass characteristics by removing surface contamination and encourage leaching of problematic species from the biomass.
  • Biomass characteristics vary between species, times of harvest – even between different parts of the same plant. Many of these factors can be controlled by the grower, including how harvested feedstocks are stored to minimise degradation, however no one type of storage offers a golden solution across all feedstock types.
  • Pre-processing technologies can be used to alter the physical and/or chemical properties of biomass, but the additional costs and emissions associated with this need to be balanced against any savings further down the supply chain. In the UK, processing costs are likely to outweigh transport cost and emissions benefits, but altering the chemical characteristics may be worthwhile, especially if this makes the product more readily accessible for existing boilers.

What’s next?

The projects highlighted the potential value of water washing biomass to remove contamination. Successfully demonstrating this technology at a commercial scale will be a valuable step in unlocking the potential of a range of different biomass feedstocks.