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The what, how and why of using biomass
Geoff Hogan
Biomass Energy Centre
So what is theBiomass Energy Centre?
Biomass Task Force
• Launched October 2004• Led by Sir Ben Gill• Report published October 2005• 42 recommendations designed
to ‘..shift barriers which stand in the way of the greater use of the biomass resource..’
• “current lack of knowledge and awareness of biomass energy”
Biomass Energy Centre• Launched April 2006 in the Government’s response to
the Biomass Task Force
• ‘Owned and managed by the FC’
• ‘Dedicated website and helpline’
• Answer enquiries from the general public, local authorities, architects, developers, services engineers, biomass industry, central government, etc.
• ‘A single point of contact on biomass’ (not fount of all knowledge!)
• Work with wide range of specialist contacts
• ‘Actively engaging with regional and national information providers’
www.biomassenergycentre.org.uk
• Website live since September 2006
• Over 700,000 page hits recorded
• More than 2,600 enquires answered
• 9 information sheets of our own
• Wide range of electronic and printed
documentation
What?
Potential biomass fuels• Virgin wood
– woodland residues: thinnings and trimmings; firewood– arboricultural arisings– woodprocessing co-products– pellets and briquettes
• Agricultural residues– straw– slurry, FYM– poultry litter
• Energy Crops– SRC, SRF– Miscanthus– oil crops, wheat, sugar beet, sugar cane
• Food waste• Industrial wastes and co-products
– untreated waste wood: old pallets, offcuts– treated waste wood– paper pulp– textiles– sewage sludge
How?
Choices, choices
Burning logs 1
• Simple, ad hoc• No special equipment• Stoves, ranges• With or without back boiler• Moderate efficiency (open
fire very low efficiency)• Continuous manual
feeding
Burning logs 2
• Log boilers• High efficiency• Sophisticated• Periodic manual filling• Buffer tank essential• Self supply• Relatively low capital cost; cheap
fuel
Burning pellets
• Pellet boilers and stoves• Very high efficiency• Very sophisticated• Built in hopper: manual filling• Bulk hopper: ~ annual filling• Range of sizes• Commodity fuel; more expensive
Burning wood chips
• Automated• Suitable chipper required
or contract chipper• Dry fuel store required• Not for small applications• Low bulk density fuel• High capital cost; cheap
fuel
CHP
• >2 MWe steam turbine: mature
• 200 - 2,000 kWe ORC: semi-mature
• <1,000 kWe range of technologies:– gasification + ICE– Stirling engine (+
combustion/gasification)– microturbine– reciprocating steam
Why?
Carbon emissionsFuels for heating and power
Fuel Netcalorific
value
Carboncontent
Direct carbonemission from
combustion
Direct CO2
emission fromcombustion
Approx. life cycleCO2 emissions
(includingproduction) ‡
Annual total CO2
emissions to heat atypical house
(20,000 kWh/yr)
Annual total CO2 savings toheat a typical house
(20,000 kWh/yr)
MJ/kg % kg/GJ kg/MWh kg/GJ kg/MWh kg/GJ kg/MWh kg kg comparedwith oil
kg comparedwith gas
Hard coal 29 75 26 94 95 345 134 484 9,680 -2,680 -4,280
Oil 42 85 20 72 73 264 97 350 7,000 0 -1,600
Natural gas 52 73 14 51 51 185 75 270 5,400 1,600 0
LPG 49.7 82 17 60 60 217 90 323 6,460 540 -1,060
Electricity(UK grid)
- - 35 125 128 460† 150 540 10,800 -3,800 -5,400
Electricity(Large scale woodchip combustion)
- - 160 576 584 2,100 16 58 1,160 5,840 4,240
Electricity(Large scale woodchip gasification)
- - 80 286 292 1,050 7 25 500 6,500 4,900
Wood chips(Oven dry)
19 50 26 94 95 345 1.2 - 1.7 4.2 - 6.2 84 - 124 6,916 - 6,876 5,316 - 5,276
Wood pellets(starting from drywood waste)
19 50 26 94 95 345 5.6 20 400 6,600 6,000
Grasses/straw(Oven dry)
18 45 25 90 92 330 1.5 - 4.1 5.4 - 14.8 108 - 296 6,892 - 6,704 5,292 - 5,104
Biogas (60% CH4
40% CO2)20 45 23 81 83 297
† www.electricity-guide.org.uk/fuel-mix.html‡ Life cycle analysis data from: “Carbon and energy balances for a range of biofuels options” Elsayed, MA, Matthews, R, Mortimer, ND. Study for DTIURN 03/836and: "Comparison of energy systems using life cycle assessment" A special report for the World Energy Council July 2004
Fuel costs
How much land is needed?Biomass heating of buildings of different sizes
Building Annual energydemand
Systemsize
Wood chipsrequired1
@ 30% MC
Volume of woodchips required2
@ 30% MC
Wood pelletsrequired3
Volume ofWood pelletsrequired4
Land arearequired:
forest residues5
Landrequired:
SRC6
Land arearequired:
miscanthus7
KWh kW tonnes m3 tonnes m3 ha ha ha
Domestic house 20,000 20 5.7 23 4.2 6.3 2 0.5 0.3
Small industrial unit 140,000 100 40 160 29 44 14 3 2.3
Large farm withoutbuildings
400,000 150 114 460 83 125 40 9 6.5
Hotel 660,000 250 190 760 138 205 66 15 11
Municipal complex 360,000 300 100 400 75 115 36 8 6
District heatingscheme
600,000 500 170 700 125 190 60 13 10
Municipal buildings 1,000,000 700 290 1150 210 315 100 22 16
Greenhouse 4,200,000 1,200 1200 4800 875 1,300 420 93 70
CHP/Power station 16,000,000 2,000 4,570 18,000 3,300 4,950 1600 355 260
1 3.5 MWh/tonne (12.6 GJ/t) mixed hard & soft wood
2 250 kg/m3 = 0.9 MWh/m3 (3.2 GJ/m3)
3 4.8 MWh/tonne (17 GJ/tonne)
4 670 kg/m3 = 3.2 MWh/m3 (11.4 GJ/m3)
5 2 odt/ha = 2.9 tonnes @ 30% MC
6 9 odt/ha = 12.9 tonne/ha.a @ 30% MC
7 13 odt/ha = 17.3 tonne/ha.a @ 25% MC
