Water washing best for preparing energy crops

A new study from the Energy Technologies Institute has looked at how second generation crops will help the UK meet its energy needs by 2050.

The research has found that water washing is the most effective technology to prepare crops for energy use.

Titled ‘Understanding variability in biomass feedstocks and the opportunities for pre-preprocessing’, the report looks at the long-term potential of increasing domestically grown biomass by using second generation crops, while also reviewing ‘the impact of pre-processing technologies on UK bioenergy value chains’.

The study notes that for bioenergy to sustainably deliver 10% of UK energy demand in the 2050s, a mix of domestically grown biomass, residual waste streams and imported biomass will be required. Expanding UK biomass production will depend on the country using existing forestry more effectively, alongside expanding production of second generation energy crops.


A nascent market

Although observing that second generation crops are used for power and heat already, the report argues that the market is nascent.

For this reason, the report says that changes will be needed. To successfully integrate feedstocks such as miscanthus and short rotation coppice willow, end-users must be able to accept greater physical and chemical feedstock variability, or feedstock production techniques and pre-processing must be used to make feedstocks more homogenous.


Assessing pre-processing

The report concludes that densifying biomass is ‘unlikely to pay off in reduced transport costs because of the relatively short distances travelled’, but improving the chemical characteristics of feedstocks could.

Apparently, this is particularly the case if the pre-processing brings feedstocks into the range required to retain boiler performance or lifetime guarantees.

ETI’s project partners, led by E4tech, assessed a range of pre-processing technologies in the study, including forced drying, torrefaction, steam explosion and water washing.

It was concluded that water washing was the most effective at improving biomass characteristics. The process removes surface contamination and encourages problematic compounds to leech from the biomass.


£200 billion

“Failure to develop the role of bioenergy beyond today’s level would cost an additional £200bn to meet UK climate targets,” said Geraint Evans, ETI’s bioenergy programme manager.

“However, our research has identified some of the technical and market barriers that the UK must overcome to meet these critical targets. One solution could be to develop new markets for second generation crops by blending them with other sources of biomass. This could help to scope out alternative end uses for second generation crops and support the investment decisions of farmers, who need a reliable market to sell in to before they commit to planting.”

The full ETI study is available here.



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