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AD Network Research Colloquium
Harvesting our roadsides for Low input High Diversity (LIHD) biomass
Dr Nick Cheffins
M.D Peakhill Asociates Ltd
LINCOLNSHIRE ROAD VERGE BIOMASS PROJECT
Project background• In Lincolnshire there are approximately 8,750 km (5,500 miles) of
highway of which 6,173 km are termed ‘rural’ and largely bounded by grass verges
Typical Lincolnshire ‘Drove’ verges
Project drivers
Economic• Local authority budget reviews to reduce the
management of the highways ‘soft landscape’ especially road verge will reduce the current flail and leave programme to one per annum on junctions and none elsewhere
• Could LIHD biomass work as a feedstock for s Anaerobic Digestion?
• Could its uptake reduce the land use for energy rather than food crops.
• Lincolnshire has one of the highest densities of farm based AD operators in the UK
Environmental & policy• Work by Lincolnshire Wildlife Trust and study
sites across Europe (PROGRASS / COMBINE)have confirmed the biodiversity gains from actively harvesting LIHD biomass
• Initiatives such as the National Pollinator Strategy are producing a supportive environment for LIHD Biomass related projects
• Improve the public perception of AD as bringing wider environmental benefits
Harvesting possibilities – preliminary demonstration August 2015
French Noremat engineered, tractor mounted 1.6m head front fixed & tractor with side mounted extendible arm 1.1m head cut and collect systems with detachable trailers
The 2016 Lincolnshire verge harvesting project – May 2016• Consortium project led by
Peakhill Associates Ltd
• Partnership• Lincolnshire County Council
• Lincolnshire Wildlife Trust
• Leeds University
• Gramagen Ltd (London Business School spin out)
• Scrivelsby Biomass Ltd
The 2016 Lincolnshire verge harvesting project – May 2016• Self propelled harvester on trial • Harvester unloading
Storage and use of verge biomass samples
• Samples from each harvest site stored in high density bales – May 23rd 2016 – 9 sample sites
Approximately 30 tonnes stored until bales opened 9th February 2017. Bales fed over one week -constituted approx. 20% of feedstock
Harvesting results
Region Site Harvest
Mowing
Strip No. Fwt/km Harvest Fwt/km Comments on August samples- NC
Wolds S1 H1 1 1.547 H2 0.9 Grass dminated verge for first breedWolds S1 H1 2 3.079 H2 1.2 Wider spectrum of plants in second breed
Wolds S2 H1 1 1.505 H2 0.8 Fine grass dominated
Wolds S6 H1 1 1.186 H2 0.7Plot located on the only regularly salted road included in
the trial - Thinnest and shortest (possible salt effect?)Fens S9 H1 1 1.604 H2 X 1.5 m breed mowed by third party prior to second visit
Fens S9 H1 2 2.205 H2 X 1.5 m breed mowed by third party prior to second visitFens S10 H1 1 1.071 H2 X 1.5 m breed mowed by third party prior to second visitFens S10 H1 2 1.942 H2 X 1.5 m breed mowed by third party prior to second visit
Fens S11 H1 1 3.09 H2 1.2 Coarse vigorous regrowthAverage 1.67 0.9 Average total fwt over two cuts = 2.57 t fwt/kmSTDEVA 0.73 0.2 Equivalent yield / ha = 23.4 t fwt/ha
Harvest Fresh Weight (Fwt) data and summary comments / calculations
May 20-23 2016 August 2-3 2016
Harvest dates
Soluble Contaminant analyses
• PTE levels analysed for all nine sample sites by University of Leeds produced values below the threshold requirements within the EA’s PAS 100 / 110 across all the samples
• One exception for one element (Hg) on one of the nine H1 samples was retested by a UKAS accredited lab and also returned a value within the above standards
• PAH levels came within the PAS standards for all 16 PAH compound assessed individually and as a total PAH presence for all the sites
Physical contaminant analysis
127369
33982
261635
3371713
278821292917450164213121100178119010118
0 200 400 600 800 1000 1200 1400 1600 1800
123456789
10111213141516171819202122232425262728293031323334353637
Number of items
Sep
arat
ed
was
te c
ate
gori
es
Incidence of retrieved litter by category
4=metal drinks cans, 6=paper and cardboard & 8=plastic food packaging
Approximately 50 – 70% of collected litter is found within 50m of a
junction
Scrivelsby Biomass Ltd
0
100
200
300
400
500
600
BM
Pth
(m
l CH
4 /g
VS)
The theoretical biomethane potential of Lincolnshire roadside grass samples; highlighted as green bars and current feedstocks used in AD; highlighted as black bars.
0
50
100
150
200
250
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
BM
Pex m
l C
H4/ g
VS
Days
S2/H1.1 Maize
The experimental biomethane potential of Lincolnshire roadside grass sample S2/H1.1 and maize sample.
0
50
100
150
200
250
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
BM
Pex m
l C
H4/ g V
S
Days
Co-Digestion Control Co-Digestion 10% VG Co-Digestion 30% VG
The experimental biomethane potential of co-digestion experiments. VG= verge grass.
Conclusions• The verge harvester as tested produced a good quality cut that
ensiled satisfactorily.
• The gas out put at Scrivelsby increased when the verge biomass was added as 30% of the feedstock input for one week.
• The laboratory performance of the biomass did not decline after ensiling (Limited sampling)
• The verge harvester design of the Herder was problematic for UK economics – the fixed body reduced productivity
• Optimising productivity requires the harvester to be kept in operation with detachable trailer system
• The likely radius of operation would be within 10km of an ADO
Biomass valuation – trend interaction
March April May June July Aug Sept Oct Nov
Monetary value / t feedstock to AD plant operator function of dry matter digestibility and content
Digestiblity = bio-methane yield / unit dry matter
Dry matter yield t / km
Next stage in Lincolnshire - 2018
• Machine capable of maximum forward working speed in excess of 6.0 km/hour
• Evaluate potential to incorporate frame steering to assist manoeuvrability
• Carrying Capacity of up to 10 t biomass (Likely volume – 20 m3)
• Evaluate potential for side extension system to maximise carrying capacity whilst minimising overall vehicle length
• Guidance on overall width, length and height dimensions to be provided by Local Highways Agency
• Emptying and possible compaction systems to be proposed
• Unit to be capable of road travelling speed of up to 68 k/hr
• Cyclone style suction linked to arm capable of reaching 3 m to the side of its mounting
• Wrap around configuration preferred
• Diver view of harvester head overriding consideration
• Height of arm lift to be controllable to prevent contact with overhead electricity cabling
• Flail mowing and rotary cutting systems to be proposed
• Cutting head minimum width 1.1m
• Evaluate implications for a collecting head of up to 2.0m width
• Interchangeable cutting head to be proposed
• Proposals could consider a fixed body or demountable trailer system
• Requirements for highways signage and speed indicator systems to be specified by Local Highways Agency (needed)
20
Herder Kontannier 1.1m flail head cut and collect – 280,000 euro
Noremat harvester 1.1m flail head cut and lift with hook lift trailer – 230,000 euro
The Mulag SB 500 (Unimog mounted)
• So how much LIHD biomass is out there?
Asset Length - km
Accessible length - km
Harvestable area – ha 1
Potential biomass yield – t FWT at 24 t / ha
A road 69 38a 141 336
B road 62 43b 161 384
Unclassified 508 355b 1331 3,192
Km of drains 431 345c 2072 4,968
Total 1,070 781 370 8,880
a = Assumes 50% of the length of A roads is accessible – taking account
of the urban area of Boston and hard road verges etc.
b = Assumes 70% accessible of the length of B and unclassified roads is
accessible as above
c = Assumes 80% accessibility to dyke banks and berms with 20% lost
around bridges etc
1 = Assumes 70% of the accessible verges will also allow access to a
second 1.1 m wide strip giving a total cut of 2.2m. This also assumes that
both sides of the accessible road length provides an equal length and
area of verge.
2 = Assume the greater width of dyke bank and berms allows all the
accessible lengths to be cut to a width of 3.3m This also assumes that
both sides of the accessible road length provides an equal amount of
verge.
Linear assets and biomass yield estimates in the 10 km radius circle surrounding Hubbert’s Bridge
What could be out there
• The Linear Infrastructure Network – LINet , representing national, regional and local owner/mangers of soft landscape linear infrastructure in public and private ownership
• LINet has estimated that, across the UK there is a soft landscape of: • 400,000km of road verges + 31,000 km of Network Rail and
energy networks is equivalent to the land area of Essex!
• https://www.tcpa.org.uk/pages/category/green-infrastructure-partnership
Implication for future management for biodiversity
Linear mosaic cutting and regrowth windows