30 June 2000

Future for commercial coppicing in electricity

Does commercial coppicing

have a future in the UK? The

National Coppice Open Day

held near Retford, Notts on

Jun 6 may have answered

the question. Andy Moore

reports

GROWING short rotation coppice as a renewable fuel for generating electricity can provide an attractive means of diversification for UK producers, insists MAFF.

And to drive this message home, the National Coppice Open Day saw MAFF promote a £30m energy crops grant package, which is to be made available to UK producers over the next seven years.

Notts-based Coppice Resources Ltd (CRL), used the open day – held near Retford – to demonstrate coppice cultivation, planting, spraying and harvesting machinery.

A holding company associated with coppice agronomy and machinery engineering, CRL produces short rotation coppice for ARBRE Energy – a power generation company based at Eggborough, Yorks.

Over the past five years, CRL has gradually increased its coppice growing area to 1100ha (2717 acres) over 55 sites including 500ha (1235acres) which was taken on this year.

Throughout the sites, coppice has been planted into minimally-tilled ground using four tractor mounted Step Planter machines built by Swedish-manufacturer Salix Maskiner.

The machines have two main parts – opener discs and a planting unit. At the front of the planter, the series of opener discs create four 20cm deep rows – two spaced at 75cm intervals each side of the machine.

The second part of the planter consists of four pto powered plunger units which are manually fed with coppice rods up to 3m long. The coppice rods are taken from bundles stored on the back of the machine.

Each plunger unit is equipped with contra-rotating belts which pull the coppice rods into a twin knife cutting unit where they are cut to lengths of between 15cm to 20cm. The cuttings are then injected vertically into the pre-formed rows at 43cm intervals.

Planting rate is in the 15,000 to 20,000/ha range.

CRL claims the machines are each capable of planting 8ha/day (20acre) – with 20,000 cuttings costing about £1200.

The National Coppice Open Day also provided a public viewing for a tractor mounted inter-row sprayer built by south Yorks-based DiFuria Contractors for the ARBRE project.

Based on a front press head stock and frame, the sprayer has been designed to apply sprays such as Gramoxone or Roundup to kill off young and mature weeds in-between four coppice rows.

Powered by a 12v motor driven pump, the sprayer distributes chemical from a 500lt tank to nine Flat Fan nozzles positioned along the width of the boom. Nozzles are contained within curtains to prevent spray drift from contacting planted coppice rows.

For spraying different weed heights, individual nozzle heights can be set, while two jockey wheels can be used to adjust overall boom height. Typical spray volumes of 200lt/ha allow workrates of up to 20ha/day (50acres), says DiFuria Contractors.

On the coppice harvesting side, the open day enabled visitors to witness a two-row tractor mounted machine built and developed for the ARBRE project by CRL in association with its daughter company &#42 Mell & Son.

Adapted from a JF FC800 side mount forager, the coppice harvester has been used to harvest 32ha (80acres) over four commercial sites since it was built last year.

"Designing and building the machine was very much a trial and error approach," says Chris Mell of &#42 Mell & Son. "We looked at harvesters working in Denmark and Sweden but found they were unsuitable for harvesting coppice grown in UK conditions. Our challenge was to build a machine robust enough to harvest thick stemmy coppice."

Conversion work firstly involved removing the foragers pick-up header and adapting the rest of the machine to fit on a front or rear three point linkage.

For the cutting head, &#42 Mell & Son and CRL engineered a hydraulically powered feed rotor, designed to fold coppice over two serrated disc blades which cut coppice 7cm to 10cm above the ground.

After the cutting blades, coppice is fed into the modified JF chopping cylinder by a second hydraulically powered floating feed roller.

Initial results of the harvester are said to have been successful, according to Mr Mell. "We tested the machine in a light willow crop last October and December and found it had a higher appetite than expected," he claims "We started by throwing in pieces of willow manually – but eventually after numerous modifications – the chopping cylinder was capable of higher throughputs."

In operation, the harvester works with a 190hp Valmet 8750 tractor in reverse drive mode, with its discharge head delivering chopped material through a pipe into a 10t trailer behind the outfit.n

COPPICING COSTS (£/ha)


Rabbit fencing £125

Cultivation/spraying £120

Cuttings 15,000/ha (6p each)

Planting £160

All sprays £190

Cutback (year 1) £50

Yield (year 1) 9t-10t/ha

Return £35-40/ovt*

Total £1545

*Oven dry tonnes

Coppice Resources Ltd employs four 4-row Step Planter machines built by Swedish-manufacturer Salix Maskiner – planting rates are 15,000 to 20,000 cuttings/ha.