SRA Annual Report 2020-21: Wetland biomass feasibility study

“Greater resilience to climate and economic change”

One of the aims of Somerset’s 20 Year Flood Action Plan is to facilitate “better management of the most vulnerable and challenging parts of the Somerset Levels, with the consent of owners and occupiers, with the intent of helping them to remain profitable and build greater resilience to climate and economic change.” This ambition has fed into many different parts of the SRA’s work, particularly into studies of possibilities for Wetland Biomass and into Adapting the Levels.

Wetland biomass

Background

‘Biomass’ means natural material that can be used as fuel. In the specific context of the Somerset Levels & Moors and Somerset’s 20 Year Flood Action Plan, it means wetland products such as reeds and rushes harvested from hard-to-farm areas of high environmental value. Early versions of the Flood Action Plan envisaged the creation of an ‘Ecological Enterprise Zone’ and called for the increased use of wetland biomass to be explored, for two main reasons. Firstly, to create an economic incentive for wetlands to remain wet, as a buffer against flooding. Secondly, to preserve and possibly enhance and expand environments for wildlife.

In 2015-2016, the SRA and RSPB funded an initial study into the possibilities of establishing a wetland biomass-to-bioenergy scheme on the Somerset Levels, based primarily in the Brue catchment, but also potentially around West Sedgemoor, Aller Moor and King’s Sedgemoor.

The resulting documents outlined ideas for “creating a new limited company to purchase and run a medium sized anaerobic digester (AD) and by using the heat and power generated to run a separate plant operated by a local community group producing fuel briquettes.” Estimated cost of building plant and digester: nearly £2 million. The RSPB described “conservation biomass to bioenergy” as “a great new initiative that can provide a direct link, and foster a personal connection, between communities and their local wildlife, sites and the landscape, and also highlights how that landscape is benefiting them”.

In March 2019, to see whether using local wetland biomass as fuel could be a realistic commercial proposition, the SRA Board agreed to fund a real-life case study. This centred on the possible installation of a boiler using wetland biomass in Somerset County Council’s highways depot at Dunball north of Bridgwater, which is run by Milestone (known before April 2021 as Skanska).

Activities in 2020-21

A feasibility study was completed by Skanska in December 2020. Skanska assessed the need for heating Dunball Depot’s two buildings and found that it would be “possible to provide a biomass system which connects and meets the full seasonal load of both buildings”.

Using wetland biomass for heating instead of natural gas would not be free of greenhouse gas impacts. Skanska noted that carbon dioxide emissions would be generated during the fuel’s production, for example in powering machinery and during transportation, while actually burning the fuel would create CO2 and other emissions with greenhouse potential such as nitrous oxides.

However, as biomass fixes CO2 from the atmosphere during its growth, on balance Skanska estimated that its use “would reduce annual greenhouse gas emissions from the Dunball facility by between 25 and 30 tonnes of CO2 equivalent per year. Further to this the use of wetland biomass supports an important carbon sequestration habitat which could lead to much wider benefits.”

But numerous challenges would need to be overcome. Wetland biomass meant to be used as fuel would need to be harvested, transported, processed, stored and burned as drily and densely – and as easily and cheaply – as possible. Skanska’s study shows how a quest for maximum dryness and minimum bulk would affect all aspects of wetland biomass fuel production and consumption. Subjects covered include the kinds of machinery that could best be used for harvesting and pelleting, the practicalities of fuel delivery, and the problems that can be caused by higher ash levels from biomass.

Skanska made six recommendations for further SRA-funded tests and investigations, but SRA Technical Group members agreed that any further moves at Dunball should be decided upon independently of the SRA by Skanska and Somerset County Council. As for wetlands and biomass, all of the studies funded by the SRA since 2015 are now available Somerset Biomass Options Project 2016 DRAFT Business Plan for SRAon the SRA website (see the links at the bottom of this page). They contain a large amount of information and expert analysis, which will be useful to individuals, groups or organisations who are thinking about developing wetland biomass projects, or to anyone who is interested in learning more about the complexities of seeking to reduce carbon emissions.

The studies’ sharp focus on new ecological and economic possibilities in wet low-lying areas of Somerset is also relevant to Defra’s newly-published England Peat Action Plan. Defra is keen to invest in new schemes “that reward farmers and land managers for producing public goods” such as natural flood management and drought resilience. The studies commissioned by the SRA are expected to help in the development of proposals as the Peat Action Plan progresses.