Harvesting Energy Wood to Warmth: Opportunities and practicalities 22 nd February 2013 Matthew...

Harvesting EnergyWood to Warmth: Opportunities and

practicalities22nd February 2013

Matthew WoodcockPartnerships & Expertise Manager South East England

Forestry Commission

Wood to Warmth:

Opportunities

3 Harvesting Energy - Wood to Warmth: Opportunities and practicalities 22 February 2013

South east England Woodland - Background

Undermanaged mixed (conifer/broadleaf)

woodland planted in the 1950’s

Typical broadleaved woodland of south east England – overstood coppice last cut > 40 years agoAlso ancient woodland with high ecological value – declining through under-management


Future vision for SE woods

Active management of coppice with standards woodland

Impacts of management


Potential for sustainable production?

Traditional broadleaved trees like beech and oak

can grow at 4m3 per ha per year

Conifers like Scots pine can grow at > 8m3 per ha per year

Traditional coppice species like sweet

chestnut and ash can grow at > 6m3 per ha

per year


Potential from New Forest LA District

Private Woods

ha Est YC m3 per ha per yr

Yield from 75%

Sawlogs Woodfuel

Slabwood MWh/yr

Conifer 896 8 7,168 5,376 3,226 2,150 1,613 3,871

Broadleaved 5,483 4 21,932 16,449 1,645 14,804 822 37,010

Mixed (*3) 1,259 6 7,554 5,666 3,399 2,266 1,700 4,986

Coppice (*8) 2 2 4 3 0 3 0 5

Coppice with standards (*8)

290 2 580 43544 392 22 705

Windblow (*4) 0 4 0 0 0 0 0 0

Felled (*4) 15 4 60 45 5 41 2 73

Open space 945 0 0 0 0 0 0

TOTAL 8,890 37,298 27,974 8,318 19,655 4,159 46,649

FC Woods ha Est YC m3 per ha per yr

All managed Sawlogs Woodfuel Slabwood MWh/yr

Conifer 4,314 10 43,140 43,140 25,884 17,256 12,942 31,061

Broadleaved 5,613 4 22,452 22,452 2,245 20,207 1,123 50,517

Mixed 2,151 6 12,906 12,906 7,744 5,162 3,872 11,357

Coppice 0 6 0 0 0 0 0 0

Coppice with standards

0 6 0 00 0 0 0

Windblow 0 4 0 0 0 0 0 0

Felled 334 4 1,336 1,336 134 1,202 67 2,164

Open space 1,154 0 0 0 0 0 0

TOTAL (*2) 13,566 79,834 79,834 36,006 43,828 18,003 95,099


Assumptions

*1 Based on latest IFOS dataset which having utilised much more sophisticated systems than NIWT1 reveals that the total area of woodland in SE&L is 323,152 ha (NIWT1 was 270,079). Breakdown into Forest Types is based on proportions identified in NIWT1 as IFOS data isn’t broken down to that detail yet.

*2 Area of FC woodland will have been reduced by sales during this period so area of non FC woods could be slightly greater.

*3 Assume 60% broadleaves by area and 40% conifer by area – on basis that most mixed crops will be > 40 years old and well into their thinning regime to establish a final crop of broadleaves

*4 Assume windblown and felled areas will be restocked with broadleaves

*5 Estimate that 25% of all woods will not be actively harvested due to owners preference or site difficulties

*6 Estimate that 60% of conifer and mixed crops, and 10% of broadleaf growing resource could be used as sawlogs

*7 Estimate that there is a 50% conversion rate of saw logs into sawn timber, hence 50% of the sawlog volume will be slabwood or sawdust and hence potential woodfuel

*8 Traditionally many of the broadleaved woods in SEE would have been managed as coppice, or as coppice with standards, whereby the stems were felled every 7 (hazel) to 15 (sweet chestnut) years and then allowed to regrow from the cut stump. Having the well established root stock effectively supporting regrowth the growth rates of coppiced woods are significantly higher in their early years than would be possible from newly planted trees. Our ancestors found that this was the most effective way to produce the fuel and building material they needed. I have used an estimated growth rate of 6 m3 per ha per year to balance between hazel where the volumetric growth rates appear to be lower (no-one to my knowledge has done any research on this as hazel has traditionally been used for the hurdle and thatching market) and where we break the estimate down to counties I have dropped the estimated growth rate for Hampshire coppice to 2 m3 per ha per year as a good proportion of Hampshire coppice is hazel). At the other end of the spectrum sweet chestnut on a 15 year rotation will deliver 8 m3 per ha per year BUT if the rotation is extended to 20-25 years this increases to up to 12 m3 per ha per year.

However, we should also remember that sweet chestnut coppice can be converted into a whole range of products - spile fencing, cleft fencing, even faggots for flood defence but having a use for the lower quality elements and offcuts is essential to make the whole business work. This principle of increased average growth rates by extending coppice rotations to 20-25 years is likely to hold true for all major broadleaved coppice species such as ash and hornbeam. Overall traditional coppice management appears to offer considerable opportunites for woodfuel production - just as our ancestors found!

*9 Assumes wood is seasoned to 30% moisture content (as a proportion of overall weight), broadleaves deliver 2,500kWhrs per m3, conifers 1,800kWh per m3 and mixed crops 2,200kWh's per m3. Again figures are conservative as oak and beech will manage 2,800 and 2,700kWh per m3 respectively but poplar and willow will deliver about 1,800kWh's per m3


Value of wood as a heat source?

• As we all appreciate unseasoned wood comprises around 50% water, and water doesn’t burn well!

• When seasoned to 30% wood can deliver about 3,500kWhs per tonne

But different species vary in density:

• Broadleaved wood approx. 2,500 kWhs per m3

• Conifer around 1,800 kWhs per m3


Compared to heating oil:

• Heating oil at 60 pence per litre• Provides 10kWhrs per litre • Cost = 6 pence per kWhr

• Seasoned broadleaf wood (30% MC)• Provides 2,500 kWhrs per m3

• The cost of heating oil to deliver the same heat = > £150 per m3

• The 28,000m3 from the New Forest could deliver 46,000MWh’s of heat

• Heating oil to deliver the same would cost > £2,500,000


Energy value of conifers


Energy value of broadleaves


Existing markets: timber and wood

Verdo

Slough

Bedmax


Medium scale CHP

BAA – Heathrow T2


Small scale CCHP

Waitrose


Domestic markets


Hoathly Hill community


Hoathly Hill - Woodheat production


Hoathly Hill – woodheat distribution

Energy centre

Heat distribution

network (underground

hot water pipe)


Hoathly Hill – woodheat management

Woodheat distribution

pipe

Woodheat control centre


Farm diversification


Difficult land


Heathland maintenance – New Forest


Biomass Baler


Future vision - Mureck SE Austria

Two 1 MW Woodfuelled boilers have been running since 2001

Biogas production from slurry


Mureck - continued

Biodiesel

Solar voltaic


FC Support:

Technical information and advice

www.woodheatsolutions.eu

www.biomassenergycentre.org.uk


FC Support:

English Woodland Grant Scheme: Woodland Management Plans


English Woodland Grant Scheme:Woodfuel Woodland Improvement Grant

FC Support:


FC Support:

Supporting access to other elements of the RDPE: - Leader; - Farming & Forestry Improvement Scheme; - Rural Economy Grants; and - Support for training and apprenticeships.

Wood to Warmth:

Practicalities

Boiler sizing


FC Bucks Horn Oak

• Average heat demand over design day = 15kW• Total energy demand over design day = 370kWh• Annual energy demand = 14,000kWh• Allowing 88% efficiency for boiler would require about 16,000kWh of

energy from the wood pellet fuel = approx 3.5 tonnes per year


The woodpellet heat system


Woodpellet delivery


Accumulator tanks are crucial

• Woodfuelled boilers tend to work most efficiently when they are working at a high proportion of their maximum capacity; and• An accumulator tank is purely a large, highly insulated, hot water tank which stores heat – very like a rechargeable battery.• For example:

‘Large’ accumulator

working with a 250kW boiler to

heat a large country house

Accumulator (left rear) linked to a 100kW boiler (right centre) to provide

heat for a community building

Domestic accumulator drawing heat from a wood burning stove and solar thermal array, with electric emersion coils for frost protection when owner is away in winter

Fuel bunkerage


Sizing

• Heat load: Woodchips need lots of space as loose woodchips may contain as little as 500kWh’s per loose cubic meter.

• Buffer required between deliveries: for instance in winter how long do you need to ‘run’ between fuel deliveries.

• Method of delivery: Delivery of a full load of woodchips will be cheaper than part loads and tipper lorry/trailers are cheaper than blower systems.

• Avoid ‘just in time’ constraints: The bunker should be large enough to hold at least 1.5 times as much volume as the largest delivery vehicle.


Usable capacity

Access doors for tipping woodchips into bunker are sited

in the centre of the bunker

Allows the delivery to drop into the centre of the bunker, keeping the

unused space to the minimum


Access

• Ensure that the delivery vehicles you are likely to use can access the bunker easily.

Example: Surrey University Sports Centre: Access is well designed and ‘marked’ to discourage inadvertent parking, thus allowing easy delivery of woodchips from a local estate using existing farm equipment


Location

• Boiler location: the bunker needs to be adjacent to the boiler BUT as it is easier to transport heat through a hot water pipe than woodchips the mode of supply may have a greater influence on the location of the boiler than the property being heated!

• Landform: Fully sunken woodchip bunkers offer great flexibility but are expensive to construct and maintain (also vulnerable to flooding). Semi-sunken systems taking advantage of sloping ground, or even man made landform, can be more cost effective. Hence if you have landform – use it!

• Delivery method: The more flexible the system the greater the choice of woodfuel supplier, hence if a bunker can be accessed easily by a tipping articulated lorry then it can also be accessed by tractor trailer etc. However, the capacity of the store needs to be at least 1.5 times the capacity of the biggest delivery vehicle (as delivering part loads from tipping systems doesn’t work well!

Woodfuel quality


Woodchip quality

•Moisture content

•Chip size & distribution


Thank youwww.woodheatsolutions.eu

Harvesting Energy Wood to Warmth: Opportunities and practicalities 22 nd February 2013 Matthew...

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