Tim Jones, senior environmental consultant, CH2M outlines how it has helped Highways England trial biomass harvesting on its estate.
A key debate in our current time is how to create a more resilient natural environment that supports our society in the context of climate change. Management of the land owned by Highways England beyond the edge of carriageway can contribute to this goal.
A-one+, a joint venture between CH2M, Colas and Costain, is the managing agent contractor for a section of Highways England’s network known as Area 12, which covers 354km of motorways and 349km of trunk roads in Yorkshire and Lincolnshire. It is trialling use the 1,778 hectares of soft estate in Area 12 as a biomass resource converting low grade timber into wood chip to provide sustainable, low carbon fuel for heat production. These woodland assets have been historically undermanaged and their economic potential untapped.
Innovative approach
A-one+ is leading the way in developing a financially and environmentally sustainable model for the management of the Highways England soft estate, in which innovative harvesting, extraction and haulage methods in the highway environment are being implemented. Prior to this trial, no biomass had been extracted from Highways England woodlands to produce renewable energy and this source will create an as yet untapped income stream and offers the environmental benefits of effective woodland management. The trial also provides data that can be used to value the wooded estate as an asset, previously deemed an intangible figure and provides a meaningful biomass dataset that can be extrapolated on a national scale.
Environmental benefits
There are considerable environmental benefits to the biomass harvesting approach. Managing the land in this way increases the potential for renewable energy, in which the woodland resource generates wood fuel as a substitute for high carbon footprint materials. Managing the woodland also enhances the potential for plants growing on the woodland floor, diversifies species composition, removes old trees and produces a more open and attractive woodland. It also contributes to enhancing carbon storage, and opening up watercourses which improves its ecological condition and bank stability. Biomass combustion also produces less ash than coal and reduces ash disposal costs and landfill space requirements.
No landscape contractor had previously approached Highways England with a view to extracting this material from site, due to the low volumes produced in isolated areas and a perceived difficulty in extracting biomass from the motorway environment. As a result, arisings from woodland activities have traditionally been felled and left in situ.
As part of the trial, Forestry Commission felling licences were granted for each of the selected sites and ecological walkovers were undertaken at each location to identify site constraints and appropriate methods of working and on-site supervision requirements.
A study was then undertaken to review the scope of possible works and estimate potential biomass harvest. Over 150 plots larger than 1ha were identified in Area 12, predicted to generate 4,349 tonnes of biomass on the basis of a 35% thin (with an assumption of 170m2 generating 1 tonne of biomass). On completion of the study, four of the woodland plots were selected following detailed analysis of individual plot characteristics – size, age of tree stock, thinning potential and access.
Early contractor involvement with supply chain partners proved invaluable providing recommendations on the plant requirements, production and productivity rates, yield for each plot and identifying end users. This information was then used to enable A-one+ to have a meaningful discussion with Highways England, satisfy their procurement process and ultimately fund the project.
Implementation
Tree felling commenced in January 2015 on the selected plots and felled timber was extracted to the verge where it was separated into firewood and timber for chipping. Biomass is a growing market for all wood products, driven by government subsidies. A-one+ has demonstrated that biomass harvesting is a sustainable model that can be implemented nationally. The local small-to-medium scale biomass heat market (firewood, woodchip and pellets) is one which will grow in significance and provide an important market for the timber coming out of England’s undermanaged woodland resource. The economics of thinning and harvesting are becoming much more attractive for owners and viable for contractors. This trial has also contributed to the Humberhead Levels Nature Improvement Area project which is an example of working in partnership with adjacent landowners and leads to larger biomass yields.
Best value and overall cost benefit
Ultimately, there needs to be an incentive for timber to be extracted as biomass. During the trial, 1,424 tonnes of biomass has been generated with a value of approximately £42,000. The success of the trial was echoed by the Area 12 horticultural manager, who said: ‘the biomass trial was successfully completed to time and budget through innovative construction techniques and collaborative working, highlighted by the project being shortlisted for project of the year at the Constructing Excellence Yorkshire and Humber Awards 2015.’
