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EURIS Europeans Using Roundwood Innovatively & Sustainably Wood Energy Extracting Energy from Small Diameter Wood EURIS Module 12 Tuomo Pesola 1, Janne Alahuhta 1, Raffaele Spinelli 2, Anabela Rodrigues 3, Jos Vicente Ferreira 3 & Tom Kent 4 1 Oulu Polytechnic, School of Renewable Natural Resources Finland; 2 CNR Ivalsa Italy; 3 Viseu Polytechnic Institute; 4 Waterford Institute of Technology Slide 2 Overview of International policies supporting wood energy Basic understanding of wood as a fuel Basic understanding of possibilities and significance of forest wood energy utilisation Knowing the most essential harvesting methods and appliances used in wood energy production Knowing the combustion process of wood and burning characteristics Knowing the basic solutions of heating systems EURIS Europeans Using Roundwood Innovatively & Sustainably Lecture Objectives Slide 3 EURIS Europeans Using Roundwood Innovatively & Sustainably International Pledge to achieve stabilisation of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system Earth Summit, Rio de Janeiro, 1992 Kyoto Agreement, 1997 Legally binding targets 5% reduction in GHG on 1990 levels for Annex 1 countries 8% reduction for EU Means include: Protecting natural carbon sinks (forests) Developing renewable energy (wood fuel) International Policy on Climate Change Source: International Energy Agency, World Energy Outlook, 2000 Slide 4 White Paper on Renewable Energies COM(97)599 Objective to double RE from 6% to 12% in EU by 2010 Specific targets for 2010 include: Other policies supporting RE and wood fuel are: Green Paper on Security of Energy Supply COM (2002) 321 Directive 2001/77/EC on promotion of electricity from RE Directive 2003/30/EC on the promotion of biofuels Energie Intellegente - Europe (2003-06) Support Programme EURIS Europeans Using Roundwood Innovatively & Sustainably European Policy on Renewable Energy Slide 5 EURIS Europeans Using Roundwood Innovatively & Sustainably Current Position of Wood fuel in Europe 6% of EU energy came from RE in 1998 Biomass made up 63% of EU RE supply Only 9% of EU electricity was produced from biomass Biomass accounted for 97% of RE heat production Source: Eurostat, 2001 Slide 6 EURIS Europeans Using Roundwood Innovatively & Sustainably Future Potential of Wood fuel in Europe Share of Primary Energy Produced from Wood in 1998 Source: Eurostat, 2001 0 10 20 30 40 50 60 70 80 90 EU15FINIRLINLPSKUK % Total Energy Requirement % Renewables 4% in 1998 8% in 2020 20% in 2020 13% in 2020 Slide 7 EURIS Europeans Using Roundwood Innovatively & Sustainably Wood energy satisfies Europes needs for: limiting greenhouse gas emissions, clean, environmentally benign fuel, sustainable, renewable, indigenous energy, alternative land uses & rural enterprises, sound silviculture for sustainable forest management. Benefits of Wood fuel Slide 8 Wood Calorific value (C.V.) = 18 - 21GJ/t Power output = 5 - 5.8MWh/t (oil = c. 40GJ/t, c. 11MWh/t) Moisture Content Fresh wood contains c. 50% water Vaporising water uses energy C.V. increases as m.c. decreases Calorific Value Little variation between species Energy density (GJ/m 3 ) varies with basic density of species EURIS Europeans Using Roundwood Innovatively & Sustainably Wood fuel Moisture Content & Calorific Value Heating value Moisture (%) Source: Wood fuels information pack 2002 SpeciesWoodBarkFoliage Fraxinus spp.19.9619.3021.43 Quercus spp.20.0019.3521.21 Pinus sylvestris19.3119.5320.23 Picea abies19.0518.8019.77 Calorific Values of Tree Components MJ/kg Source: Wood fuels Basic Information Pack, 2000 Slide 9 EURIS Europeans Using Roundwood Innovatively & Sustainably Measurement units for energy content Wood Calorific Value = 18-21GJ/t (dry matter or odt - oven dry tonne) 1 odt = 1 / [basic density (kg/m 3 ) / 1000] m 3 solid volume Quantification of Wood fuel Measurement units for wood fuel production, supply, transport and storage Roundwood 1m 3 solid volume= Firewood 1.49m 3 stacked volume = Chips 2.5m 3 bulk volume Source: Wood Fuel Basic Information Pack, 2000 Slide 10 Forest management Unmerchantable timber species / sizes First thinning / small dimensions Branch and tree top material from harvesting Wood industry residues Primary processing: wet sawdust, bark & chips Joineries: dry sawdust, shavings and offcuts Pulp & paper: bark & black liquor Energy crops Willow coppice, poplar, eucalyptus Fast growth short rotation Harvested as chips or whole tree lengths EURIS Europeans Using Roundwood Innovatively & Sustainably Sources of Wood fuel Slide 11 Firewood Bulk density 350 - 400 kg/m 3 50% Moisture content green, 25% dry Calorific value 4.5 - 5.5 GJ/m3 Wood chip Bulk density 300 kg/m3 45-60% m.c. green, 10-30% dry Calorific value 2 - 3 GJ/m3 Densified wood (pellets & briquettes) Bulk density 600 - 700 kg/m3 10% moisture content Calorific value c.17GJ/t EURIS Europeans Using Roundwood Innovatively & Sustainably Types of Wood fuel Slide 12 EURIS Europeans Using Roundwood Innovatively & Sustainably What? Pre-commercial thinning Unmerchantable timber species / sizes Branches and tree tops from felling Why? Renewable & sustainable energy harnessed & used locally facilitates good forest management practice rural development & maintenance of jobs local industries developing indigenous resources local & community energy suppliers decoupling economic development from environmental degradation EURIS Wood Fuel Resource Slide 13 Harvesting - Thinning (or final felling) / delimbing / (bucking) / bunching / haulage Drying Transportation - from roadside to primary user Processing of energy wood - into firewood - into chips EURIS Europeans Using Roundwood Innovatively & Sustainably Energy Wood Chain Slide 14 EURIS Europeans Using Roundwood Innovatively & Sustainably Choosing Harvesting Sites Site conditions - Nutrient balance / tree species / bearing capacity / undergrowth / stoniness Access Economic conditions Availability of machines and labour force Always envisage whole-chain approach! Slide 15 Harvesting Systems for Energy Wood EURIS Europeans Using Roundwood Innovatively & Sustainably Non-associated harvesting Energy wood (pruning, thinning) Simple organization Economic limits Harvesting yield depends on the stage of thinning (first / second), degree of thinning and tree species Unutilized possibilities Slide 16 Energy wood (felling residues) + traditional assortments Economic integration, optimization feasible, organization complex Availability of energy wood and / or traditional assortments has to be adequate 1. Non-integrated Two independent operations 2. Integrated Two interdependent operations EURIS Europeans Using Roundwood Innovatively & Sustainably Associated harvesting SprucePineBirch VTT Energy Slide 17 Approximately one half of fresh, just felled tree is water Need of drying depends on utilization purpose of firewood Drying process varies depending on climate, time of year, tree species, part of stem in question and storage phase Wood can be piled up in stacks (over summer) for drying to take place EURIS Europeans Using Roundwood Innovatively & Sustainably Drying of Wood Slide 18 Transport vehicles - Farm tractor and trailer - Truck - Container truck - Truck and trailer train - Semitrailer Transportation is planned integrationally to the whole energy wood chain in order to minimize expenses Transport EURIS Europeans Using Roundwood Innovatively & Sustainably VTT Energy Vehicle mobility, speed and load capacity depend on transport distance and road quality Energy wood can also be baled in the forest and transported to primary user in bundles Slide 19 Wood Chips EURIS Europeans Using Roundwood Innovatively & Sustainably Fluidized wood Simple process Can utilize small wood Special tools - Chippers (disc / drum / auger) - Crushers & hammers - Chipper Configuration Tractor-powered / independent engine / self-propelled / truck- mounted / chipper on site Slide 20 EURIS Europeans Using Roundwood Innovatively & Sustainably Thinning / delimbing / bucking / bunching Baling of energy wood Haulage of energy wood Chipping and haulage Haulage of bundles and energy wood Chipping in temporary storage Transportation of bundles and energy wood from forest to primary user Chipping or crushing at the primary user Small scale plants Large scale plants Transportation of wood chips from forest to primary user Wood chip chain Needs of primary user define choice of working mode in wood chip chain - Different needs for farm boiler and heat power plant Drying (if necessary) Drying Slide 21 Firewood Production EURIS Europeans Using Roundwood Innovatively & Sustainably Traditional > well known Wide and active market International trade Harvesting in the terrain - Chainsaw / tractor + trailer / mules or horses Processing at the yard - Sorting / crosscutting / splitting Slide 22 Firewood processing techniques All techniques receive power from P.T.O. or electricity 1. Crosscutting with saws (disc / (band) / chain) 2. Splitting Mechanical / hydraulic Wedge run (horizontal / vertical / multi-directional) Screw type 3. Firewood processors Combined crosscutting, splitting and loading Different levels of sophistication EURIS Europeans Using Roundwood Innovatively & Sustainably Slide 23 Combustion Combustion steps (dependent on temperature): 1) Drying; 2) Heating, gasification and combustion of gasified substances; 3) Combustion of solid carbon (end-combustion) 3 parameters affect good combustion result: a) Time; b) Temperature; c) Turbulence VTT Energy Slide 24 EURIS Europeans Using Roundwood Innovatively & Sustainably VTT Energy Several characteristics affect combustion process: moisture, chemical composition, density, ash composition, particle size distribution, tree species Burning reaction: C + O 2 CO 2 + 32,8 KJ/kg Carbon 2H 2 + O 2 2H 2 O + 142,2 MJ/kg Hydrogen Slide 25 Boilers 1. Over-combustion (only firewood) Fuel is fed and combusted all at once + natural air through controllable fire door Controlling of efficiency is poor EURIS Europeans Using Roundwood Innovatively & Sustainably Small Scale Burning Appliances Over-combustion (VTT Energy)Under-combustion (VTT Energy) Slide 26 2. Under-combustion (both firewood and wood chips) Fuel gasifies and combustion takes place in lower part of wood material Formed gases and flames are led to gas combustion chamber for final burning Air through controllable fire door under the fireplace or with fans situated outside the boiler Controlling of efficiency is good 3. Reverse-combustion Basically improved under-combustion fireplace Combustion of gases in gas combustion chamber is controlled better than in under-combustion High temperature EURIS Europeans Using Roundwood Innovatively & Sustainably Slide 27 Feeding and burning appliances Use mainly wood chips Burner is connected to boiler, inside of which heat recovering takes place 1. Type 1 Needed amount of chips, which is equivalent to heat consumption, is fed to the combustion unit Combustion on grate (temperature >1000C) with automatically controlled air suppliers 2. Type 2 Combustion begins from very isolated space, where fuel is fed constantly Suitable also for humid wood chips, sawdust and firewood Hot water Burner Fuel storage of stocker Ashes EURIS Europeans Using Roundwood Innovatively & Sustainably (VTT Energy) Stockers Slide 28 EURIS Europeans Using Roundwood Innovatively & Sustainably Fire places Use fire wood 1. Open fire place Large loss of heat due to too much air For atmospheric purposes 2. Storage fire place Amount of air is controlled with fire doors Gases cycle in structures reserving heat For atmospheric and heating purposes Baking ovens Combine baking facilities and reserving fire place Storage fire place Slide 29 EURIS Europeans Using Roundwood Innovatively & Sustainably The principle of heating system (Wood fuels basic information pack 2002/VedTek 1996) Heating System Heating system has a boiler, pipe system, pump, valves, expansion tank, accumulator tank and radiator system in the house Accumulator tank is beneficial, but not compulsory, if combustion is controlled well - When fire wood (or large size wood chips) are combusted accumulator tank is required Cold water returning to the boiler must be at least +70C Slide 30 EURIS Europeans Using Roundwood Innovatively & Sustainably Principles in Dimensioning the Heating System Depend on heating purposes - farm boiler / heating plant The following information of buildings influence on dimensioning: - Surface areas and volumes - Operating time (unless used 24h/day) - Operating times of air conditioning - Special operating times and needs of warm water - Current heating systems and possible additional heating systems and condition of heating devises Dimensioning can be done based on previous consumption figures (during past couple of years) or calculations. Slide 31 EURIS Europeans Using Roundwood Innovatively & Sustainably Large Scale Boilers Grate boilers - Solid inclined grate / moving grate / plate grates Fluidized beds - Velocity - Conventional fluidized bed / circulating fluidized bed / multi-bed combustion Cleaning of exhaust gases - Mechanical collector / scrubber / electrostatic precipitator / suppression filters Cleaning of SO x and NO x Wood energy information pack 2002 Slide 32 EURIS Europeans Using Roundwood Innovatively & Sustainably CHP Combined Heat and Power Plant Plant producing both heat and electricity simultaneously Efficiency of CHP is much better than that of separate condensing and heat plants. The same amount of energy is produced in two ways: - CHP: with 100 fuel units efficiency is 85 % - Separate condensing and heat plants: with 152 fuel units efficiency is 56 % Number of CHPs is increasing and the size of profitable CHPs is decreasing due to improved technology Principle of CHP (wood fuels basic information pack 2002) Slide 33 EURIS Europeans Using Roundwood Innovatively & Sustainably Conclusion Production of wood energy combines silviculture, wood production, energy production and environmental aspects Conforms to sustainable development (ecological, economical and social) Supports local employment Covers wood energy chain from domestic use to industrial energy production Development of technology promotes increase of wood energy utilisation Large differences between countries in utilisation possibilities and ways