Sweet Heat
Warmth from the woodland in Kent
John Atkins set out to create a supply of woodchip from local trees for energy generation in commercial biomass boilers. Based at Amery Court in the village of Blean near Canterbury in Kent, his company (CE Murch Ltd) is working to this goal by integrating resources, skills and experience from farming and forestry. John Atkins, long-time farmer and now forester too, has already designed and developed neat, integrated systems for production and processing of woodchip and its use as biomass to generate combined heat and power (CHP).

He harvests his own timber and produces quality woodchip biomass for burning in two commercial biomass boilers, currently heating five houses and a one-hectare greenhouse complex producing premium, out of season (early maturing) soft fruit (raspberries) within a ‘District Heating Scheme’. John is now looking farther afield to extend his on-site ‘District Heating Centre’ at Amery Court into a much larger ‘District System’ to supply hot water to at least another 50 houses in the village. In addition CE Murch sells quality woodchip of guaranteed size and moisture content to companies with commercial biomass boilers.

Wood biomass supply CE Murch is in the right place for a ready steady supply of wood. It is surrounded by Canterbury’s ancient Blean Woods, covering over 1000 hectares and rich in renewable (Sweet) chestnut coppice. This was once in high demand for fencing and other traditional uses but is now ‘going begging’ for use in the fast growing woodchip biomass industry. John is clearly a resourceful man and unlikely to leave anything to chance. Not wanting to get ‘stuffed’ on supply in the future, he purchased 100 hectares of woodland ten miles away at Charing, primarily renewable chestnut coppice and larch with a small amount
of Douglas fir. “I wanted to harvest my own wood,” says John, “not by sending in ‘two men and a chainsaw’ but by using a small mechanised and well integrated system.”

Anyway, as John points out, remaining guys in the area with experience of harvesting Sweet chestnut coppice are, like its use for fencing, well past their sell-by date. Moreover the ‘chestnut auction’ disappeared 15 years ago and the government currently pays grants for the woods to be coppiced. Chestnut for coppicing is usually planted at 3.5m spacing to give 800 to 1000 trees per hectare, and is traditionally coppiced every 15-20 years to yield around 50 wet tonnes per hectare.

“We wanted to mechanise but not with great big machines,” says John, “because most Sweet chestnut coppice has strong conservation aspects and angles. We needed a system that could cut and harvest with low level intrusion in what are relatively small areas,” he says. “Coppicing doesn’t require harvesting the whole plantation at the same time, but rotational cutting in chunks for good conservation. By cutting selected blocks we aim to simultaneously satisfy the needs of different tiers of wildlife. Thus wildlife that likes newly cut areas and that which prefers semi-mature and mature Sweet chestnut coppice is all catered for.”

Harvesting and processing The solution is a highly integrated small-size and low-weight mechanised system giving correspondingly low-level intrusion and impact. It comprises a Valtra T180 180hp tractor, Botex 580TL crane and a Naarva Grip harvester handling trees up to about 9 inches. A Botex 11000 Euro harvesting trailer was purchased to bring timber out of the woodland and a Junkkari HJ 500C 18-inch disc chipper to produce woodchip biomass.

The crane feeds the chipper which runs off the tractor. All equipment is supplied by Jas P Wilson of Dalbeattie in Scotland. The system is currently up and running in Longbeech Wood, John’s own woodland resource at Charing, currently down to chestnut coppice and larch but with a name indicating a previous life as native hardwood timber. On the day of our visit in July 2009 they were thinning out the larch, cutting out every seventh row allowing thinning of the three rows on either side. Longbeech Wood is about 10 miles from Blean, about the maximum distance practical and economic to bring back harvested wood for chipping, says John Atkins.

He purposely went for a disc chipper to obtain the right dimension of woodchip for use in his two Talbott biomass boilers (100kW and 300kW). The disc chipper, says John, produces the right size distribution of chip with less dust and stringy material, ideal for his commercially
automated heating systems. If chip size is too big it just ‘jams up’ the machinery – too small and it gets ‘blown away’ up the chimney. The other key requirement factored into John’s system is moisture content of the woodchip burnt, and to this end he converted a graindrying facility into a continuous drying floor for woodchip. He accepts there are boilers which function perfectly well on ‘wet’ wood containing some 45-50% moisture but insists it is much more efficient to reduce the water level further before burning.

This was traditionally achieved by cutting the wood in spring and leaving it for 6 months before chipping to obtain woodchip with about 35% moisture. That said, there is some disadvantage because drier wood is more aggressive towards the chipper. The other option was to chip the cut the wood immediately with its 45-50% water, the ‘softer’ wetter wood being easier on the chipper, but this is completely outweighed by the sheer inefficiency of having to drive off the extra water before the woodchip burns. The wetter the wood, the less its true heat-value on a volume for volume basis. The continuous drying floor takes the woodchip down to 20-25% moisture using ‘waste’ heat from the boiler that would otherwise
be lost, thereby providing the two on-site boilers and the company’s customers with optimally dry woodchip that provides a more efficient burn with less smoke.

“If we are going to persuade people to install industrial woodchip boilers in built-up areas then we don’t want a lot of smoke,” says John Atkins, adding how this is not a consideration for biomass power stations with their ‘smoke scrubbers’ and other paraphernalia.

Combined Heat and Power (CHP)
Customers are provided with quality woodchip of guaranteed size and moisture content in the firm belief that combined heat and power (CHP) generation on relatively small individual scales, close to sources of biomass, is the way forward. Transporting biomass is expensive and CHP is most efficient when the useful heat produced can be used on site or very close to it. Moreover, small-scale systems in which a smaller proportion of heat (to electricity) is produced (cf largescale plants), and set up with ‘onsite’ and ‘District Heating’ opportunities,
have the capacity to fully utilise the heat energy produced. For instance, a small-scale steam generating plant will typically produce 35% of its energy as electric power and 55% as heat with the remaining 10% going to waste.

However, in large-scale plants the proportion of ‘hot water’ produced is twice that of electricity, and such quantity is difficult to find full use for. Moreover 5% of the electricity
is lost during transmission, which means overall only 30% energy is retrieved from the 100% of biomass energy put in. This company went for a ‘Local CHP’ system providing 20% as electricity and 70% directly as hot water, currently heating five houses and one hectare of greenhouse. John concedes it is less efficient (at the point of energy production) than a steam generating system, but steam generation is not an option here.

‘High pressure’ equipment cannot be used in the farm environment for safety reasons, requiring the fulltime presence of a fully qualified heating engineer. Feed-in tariffs John Atkins is looking ahead with eyes firmly focused on increasing his CHP generation system and expanding the ‘District Heating Centre’ with up to 70 houses in the neighbouring village being given the opportunity for ‘green’ hot water. 40% of the energy supplied to homes is typically consumed as heat. Try as they might, entrepreneurs like John Atkins are unlikely to achieve this alone but require the government to convert its recently self-proclaimed ‘green’ credentials into ‘hard green currency’ with subsidies at the consumer end to filter down through the industry. The government has already promised to bring in one such subsidy as a ‘Feed-in Tariff’ for electricity- generation from biomass by 2010, although they haven’t stated
how much. John Atkins has always maintained that an additional and separate Feed-in Tariff for the heat energy element of CHP is required, and although government has ‘promised’ this by 2011 they are yet to put a figure on the amount.

A ‘District Heating System’ requires insulated pipework to be laid at a minimum cost of £100/metre and, although it will have a lifespan of 30 years, the numbers will not add up without a subsidy for heat as well as electricity. Basically the householder will pay the generator for his/her ‘green’ hot water at a price that undercuts current prices paid for fossil
fuel generated heat. The ‘Feed-in Tariff’ is inserted with government ‘picking up the tab’ most logically through ‘loading’ the big fossil fuel generators.

Trickle down treats for homes and industry
A Feed-in Tariff for heat is the key to unlocking the promised ‘treasure’ of ‘green’ hot water from biomass burning, claims John. Once the ‘Feed-in Tariff’ for heat is fed in at the consumer end, CHP generation becomes a practical proposition. Immediate benefits for consumers start to trickle down into homegrown industries, by promoting conservation, sustainable management and use of wood resources, with new planting and unmanaged woodland brought back into production.

There will be energy savings, jobs in CHP generation and the creation of new manufacturing
industry with hundreds of thousands of new ‘green’ jobs to make boilers and pipework, as envisaged by the government in recent statements on Britain’s ‘Green Future’. John Atkins believes one of the biggest benefits will be the ‘connections’ created between people and their power supplies. Once local communities can ‘see’ their energy supply as a real and tangible entity, rather than something virtual coming out of a switch, they will appreciate
its importance, become more involved and be prepared to fight for it.

Fast forward future
The CE Murch operation is leaving nothing to chance through exploring all avenues for the business. Now with its own wood biomass supply the company is producing high quality woodchip of appropriate dimension and moisture content for burning on site, or for sale to customers with biomass boilers. In his latest venture John Atkins is using the continuous on-floor drying facility to take woodchip down to 10% moisture for manufacture of chestnut ‘briquettes’. “These ‘briquettes’, which have 2.5 times the density of wood, are absolutely perfect for burning in woodfuel stoves,” says John.

Observers from more northerly and nominally colder climes in the United Kingdom may wonder why all this activity is taking place in the supposedly ‘balmy’ conditions of southern England. But as any ‘Man of Kent’ (east of the River Medway) or ‘Kentish Man’ (west of the River Medway) will tell you, by jutting out into the English Channel Kent experiences some pretty cold weather with higher than average snowfalls. Indeed, last year, in the run-up to Christmas, one retail outlet in Canterbury was installing five domestic woodburning stoves a day, and by February 2009 the area was experiencing a shortage of suitable woodfuel. “People were being sold green (wet) chestnut for burning in their stoves, which is totally unsuitable because of its low efficiency,” says John.

That apart, John’s main aim remains expansion of the ‘District Heating Centre’ which fits in with his CHP green energy generation views – that is, to start small and then add on units, so that the heat element of CHP is utilised – rather than ‘going large’ straightaway and generating a lot of heat that ends up being wasted. Entrepreneurs like John are clearly thinking fast-forward, but require the government to ‘put its money where its mouth is’ before the dreams become a wide reaching reality. As John points out, the potential benefits should be viewed as ‘free home-grown energy’, ‘free’ that is from a ‘national accounting’ standpoint, because the government will not be paying the Saudis for petroleum oil.

John Atkins: info@bleanwood.co.uk
ja@amerycourt.co.uk
Tel: 07870 250000
www.bleanwood.co.uk
Terry Mabbett