handbook for energy producers_www version[1]

8/12/2019 Handbook for Energy Producers_www Version[1]

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Energy from field energy crops a handbook for energy producers


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Copyright Jyvskyl Innovation Oy & MTT Agrifood Research Finland , 2009

PUBLISHER Jyvskyl Innovation Oy, P.O. Box 27, FI - 40101 JYVSKYL, Finland Tel. +358 14 4451 100, fax +358 14 4451 199

Layout: Katja Maunonen, Jyvskyl Innovation Oy Photos on cover page: Timo Ltjnen, MTT, Lorenzo Corbella, ETA & Michael Finell, SLU

www.encrop.net

The sole responsibility for the content of this publication lies with the authors. It does not represent the opinion of the EuropeanCommunities. The European Commission is not responsible for any use that may be made of the information contained therein.


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Contents Preface .....................................................................................................................................................4

List of concepts and abbreviations .........................................................................................................5

1. Introduction ........................................................................................................................................6 What is biomass? ...................................................................................................................................................

Food vs.fuel ............................................................................................................................................................Energy crops - current situation in Europe ........................................................................................................8Energy crops - potential in the near future in Europe ....................................................................................10Energy crop fuel characteristics ..........................................................................................................................1 Top incentive schemes .........................................................................................................................................1

2. Reed Canary Grass in Finland .......................................................................................................... 14Current production and potential in the near future .........................................................................................14 Technologies in cultivation and harvesting .........................................................................................................14Field transport and intermediate storage ............................................................................................................17Long distance transport and logistics ..................................................................................................................1Energy production technologies ...........................................................................................................................1Energy and greenhouse gas balances ...................................................................................................................2Markets and economics of production ...............................................................................................................20Good case example .................................................................................................................................................

3. Willow and hemp in Sweden ............................................................................................................. 24 Willow .....................................................................................................................................................................Current production and potential in the near future .........................................................................................24 Technologies in cultivation and harvesting .........................................................................................................24Logistics .................................................................................................................................................................Energy production technologies ...........................................................................................................................2National laws and incentives programmes ..........................................................................................................26Good case example .................................................................................................................................................Hemp .....................................................................................................................................................................

Current production and potential in the near future .........................................................................................29 Technologies in cultivation and harvesting .........................................................................................................29Logistics .................................................................................................................................................................Energy production technologies ...........................................................................................................................3National laws and incentives programmes ..........................................................................................................32Good case example .................................................................................................................................................

4. Poplar in Spain and Italy ................................................................................................................... 34Current production and potential in the near future ..........................................................................................34 Technologies for cultivation and harvesting .......................................................................................................35Logistics .................................................................................................................................................................Storage ...................................................................................................................................................................

Energy production technologies ...........................................................................................................................3Energy and greenhouse gas balances ...................................................................................................................3Markets and economics of production ...............................................................................................................40National laws and incentive programmes ...........................................................................................................41Good case examples ...............................................................................................................................................

5. Biogas from crops in Austria and Germany ......................................................................................47Current production and potential in the near future .........................................................................................47Sustainable energy crops cultivation ....................................................................................................................4Harvesting and logistics of biogas energy crops ...............................................................................................50Energy production technologies ...........................................................................................................................5Energy and greenhouse gas balances ...................................................................................................................5Markets and economics of production ...............................................................................................................52National laws and incentives programmes ..........................................................................................................53Good case examples ...............................................................................................................................................

6. Conclusions ....................................................................................................................................... 59


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Preface

This handbook contains practical information on the utilisation of eld energy crops for heat andpower. The crops discussed are reed canary grass (RCG), willow, hemp and poplar. Productbiogas from energy crops is also introduced. The handbook details cultivation and harvestcrops, logistics, energy production technologies, rationality and economics of production. important issues, including support and incentive mechanisms, are also discussed. These cropchosen because they are the energy crops with the greatest potential in the project countrieland, Sweden, Italy, Spain, Germany and Austria. Miscanthus and cereal straw, for example,discussed in the handbook because their use is already well reported elsewhere.

The handbook is mainly targeted at authorities, project developers, investors, plant operatotential bioenergy users, the applied research community and representatives of companies inin the crop-to-energy production chain. This handbook was produced as a result of a projecpromoted the production and utilisation of energy crops in Europe (ENCROP - Promoting

production and utilisation of energy crops at European level, EIE/07/073). In addition, ve natio -nal handbooks were produced during the project, which give more precise information on secrops than this compilation. Those books are available at www.encrop.net.

The ENCROP project was funded Intelligent Energy for Europe programme of the EuroCommission., the Ministry of Employment and the Economy (Finland), Vapo Ltd., the SwEnergy Agency, Kempestiftelserna (Sweden) and the Swedish University of Agricultural S The following organisations contributed to Encrop practical information in Spain: Ciemat, Sare, Valoriza Energa, and ADABE (National Association for Biomass). We would like to acknge all co-operation and support.

The text for this handbook was produced by Peter Rechberger (European Biomass Associ AEBIOM), Timo Ltjnen & Katri Pahkala (Agrifood Research Finland, MTT), Petri VesMatti Hiltunen (Novox Ltd., Finland), Shaojun Xiong & Michael Finell (University of AgrSciences, SLU-BTK, Sweden), Lorenzo Corbella & Maurizio Cocchi (Energia, Trasporti, Agsrl, ETA, Italy), Margarita Salve Diaz Miquel (ESCAN, S.A., Spain), Wolfgang Gabauer (Ufr Bodenkultur Wien, BOKU, Austria), Dominik Drrie (German Society for Sustainable and Bioenergy Utilization, GERBIO, Germany) and Tytti Laitinen (Jyvskyl Innovation LFinland). The editing work was done by Timo Ltjnen.

We wish to acknowledge the contributions of all writers and funding agencies for their co-tion.

15.06.2009

Timo Ltjnen Tytti Laitinenproject manager project coordinatorMTT Agrifood Research Finland Jyvskyl Innovation Ltd., Finland


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List of concepts and abbreviations

Bioenergy = Energy from biomass (does not include e.g. wind, solar or hydroelectric power).

Bioenergy crops = The crops cultivated in the eld for bioenergy purposes.

Biofuel = Solid, liquid or gaseous fuel produced from biomass. For example, wood chips, ethanoland biogas.Biomass = The biodegradable fraction of products, waste and residues of biological origin fromagriculture (including vegetable and animal matter), forestry and related industries, including

sheries and aquaculture, as well as the biodegradable fraction of industrial and municipal waste.

CHP-plant = Combined heat and power plant.

dm = dry mass, oven-dried biomass

1 EJ = 103 PJ= 106 TJ = 109 GJ = 1012 MJ = 1018 J = 277.78 TWh

Feed-in tariff = Extra payment (/kWh) for renewable energy producers (usually for electricityproducers), which is paid over and above the normal market prices.

Fouling = Condensation of gaseous emission into particles and deposition on cold surfaces inboiler or steam tubes.

1 J = 1 Ws

GHG = greenhouse gases

GW = 109 W

Miscanthus = A perennial bioenergy crop (Miscanthus giganteus).

MW = 106 W

MWel = Electrical power in megawatts

MW th = Thermal (heating) power in megawatts

RCG = reed canary grass

Slagging = For example, production of the hard formations when fuel ash is smelted in a boiler.

SRF = Short rotation forestry (for example, willow, poplar)

toe = tonne of oil equivalent = 42 GJ = 11.6 MWh TW = 1012 W


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directive. 20 % of the nal energy consumptionhas to be provided using renewable sources by2020. This is an ambitious target consideringthe current 8.5 % share. According to theresults of a study done by the EuropeanEnvironmental Agency, the potential from

agriculture is still largely underexploited andthis sector is expected to have the highestgrowth rates in the coming years.

Food vs. fuel

This debate is largely driven by rising grain prices, which were blamed on increased production of

rst generation liquid biofuels such as biodieseland bioethanol. While any use of arable landcan in uence prices for agricultural products,many factors, both structural and cyclical,can have a substantial impact on food prices,including:

Weather conditions Oil price

Growing demand from emergingeconomies

Low investment in agricultural research Export/import policy Speculative investment Competition for arable land (urbanisation,

forestation)

It is important to note that after the relativelyhigh grain prices at the end of 2007, wheatprices fell to very low levels in early 2008, as formany other commodities, including metals, oil,cement, etc.

Global grain consumption increased by over 300million tonnes during the last 10 years. Almostthree quarters of the additional demand wasfor food, industry and especially animal feed.Biofuels from protein-rich feedstock produce valuable animal feed as a by-product therebylowering the environmental impact of increasedmeat production. In Europe about 5 milliontonnes of grain were used for the productionof bioethanol in 2008 while uctuations ingrain harvest attributable to the weather caneasily reach 50 million tonnes. Currently lessthan 3 % of cropland in Europe is used forenergy production.

Maize is an important fodder and food crop. On the other hand it can be used as a raw material for bioethanol and biogas production. (Photo: Timo Ltjnen, MTT)


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The European agricultural policy has alsocontributed greatly to the current situationas has subsidised production, resulting insurpluses sold cheaply to developing countries,thus hindering development of their domesticagricultural sector. Developing countries shouldbe supported to become less dependent onfood produced by Europe and the USA. Takingthis into account, Europe could use even morearable land for energy generation withoutjeopardising the security of food supply orincreasing commodity prices. Furthermore,sub-optimal and set-aside land could contributeto bioenergy production.

In summary, the food vs. fuel debate is largelybased on assumptions and does not always takeinto account all the facts. One cannot judgethe impact of biofuels on global nutrition andprices without looking at the whole agriculturalproduction system of which biofuels representa component.

Energy crops - current

situation in EuropeHigh yielding energy crops are already usedfrequently in well-tested systems such as

agricultural biogas production (maize together with manure). The biogas is normally used forCHP plants (generating from a few hundred kWup to 40 MW; 20 MW el and 20 MW th ), which areespecially popular in Germany, Austria, Italyand Denmark. The use of upgraded biogasas a transportation biofuel is a relatively newdevelopment, but might drive the increased useof maize and other energy crops in the future.For 2006, AEBIOM estimated that around600,000 ha of arable land were used to produceenergy crops for biogas production plants.

In Europe, solid biomass energy crops coveredabout 50,000 60,000 ha of land in 2007.It is a rather small area compared with thatused for traditional energy crops grown fortransportation biofuels, which cover about 2.5million ha (mostly cereals and rape). The largestareas of energy crops are found in the UK(mainly miscanthus and willow), Sweden (willowreed canary grass), Finland (reed canary grass),Germany (miscanthus, willow, etc.), Spain andItaly (miscanthus, poplar). Statistics of energycrop plantations for solid biofuels are almost

inexistent in many European countries.

Routes of agricultural crops to bioenergy.

Traditional crops

Byproducts

Dedicated crops

cerealssugar-beet

oil cropsmaze silagegrass

manurestraw

miscanthus

reed canary grassshort rotation coppice

Transportation biofuels

Heat/Electricity

biogas


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Energy crops in selected European countries in 2008. Data refer to hectares of cultivated land. Note thmissing from important energy crop producers like Great Britain, Denmark and Germany.(Source: AEBIOM 2009)

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

20000

H e m p R C

G W i

l l o w P o

p l a r

M a i z e

M i s c a n

t h u s

R a p e

S u n f l o

w e r

h a

Sweden

Finland

Italy

Austria

Spain

The situation of Germany shows that energy crops for rst generation biofuels utilize the largest part oagricultural land for energy production. Maize, sugar beet and other crops for biogas production were pon 500.000 ha agricultural land.


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Energy crops - potential inthe near future in Europe

In 2008 the European Union ambitiouslycommitted to increase the proportion of

renewable energy to 20 % of total energyconsumption by 2020. It was also agreed that10 % of transportation fuel should be biofuelby 2020. The necessary growth of bioenergy

will mainly come from forestry, but eld crops will also be needed to reach the target.

Biomass produced from elds consists ofresidues (straw, tops etc.) and speci callycultivated crops (for example, miscanthus,poplar, willow, reed canary grass, rapeseed,maize). Not all residues are available forbioenergy production because they are neededfor livestock feed and litter and to maintainsoil fertility. In the EU-27 countries availablecrop residue potential is estimated to be 1 3 EJaccording to different studies (1 EJ = 1018 J).

The major part of this energy is contained instraw and the greatest potential is in Germany,France, Spain and Great Britain. Denmark isthe current leader in straw utilisation for energyproduction.

When estimating the potential of bioenergycrops it is rst necessary to approximate thearea needed for food production. In the EU-27 this is calculated to be about 111 millionha of arable land and about 69 million ha ofpermanent grassland. The population of EU-27is unlikely to increase rapidly in the near future.Holm Nielsen et al. (2007) estimated that if ourdiet were moderate (mixed vegetable-animalproducts), we would need about 62 % of thearable land to feed the population of EU-27. The world population is expected to exceed 9billion by 2050. To feed this population with amoderate diet would require 65% of all globallyavailable arable land. According to this study, we could use 10 30 % of arable land forbioenergy crops in EU-27. This would produce2 6 EJ of bioenergy if the yield were assumedto be 10 tdm/ha.

Pahkala et al. (2009) estimated that energy croppotential would be about 3 EJ by 2050 in EU-27if our diet were moderate. If our diet were rich(based heavily on animal products) there wouldnot be such marked potential. The greatestpossibilities to increase energy crop productionare in Eastern Europe where the food productyields are reaching the level of those of WesternEurope. The speci c bioenergy crops areunlikely to change from those currently in usebecause they have been intensively studied forseveral decades (miscanthus, reed canary grass, willows, poplar, maize and clovers for biogas, wheat and rapeseeds).

Crop residues and dedicated bioenergy cropstogether constitute 3 9 EJ of bioenergypotential. This is about 4 13 % of the estimated

total energy consumption in EU-27 for 2020.Biogas from manure is not included in thesegures, but biogas from energy crops is.

The perennial grass Miscanthus has high yield potential forenergy production. Unfortunately its frost durability is low.(Photo: Timo Ltjnen, MTT)


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Energy crop fuelcharacteristics

The best energy crops are durable, their drymatter yields are high and constant and their

production costs are low. A perennial growthhabit, low agrochemical requirements, effectiveconversion of solar energy to biomass and easeof conversion back to useful energy guaranteethat energy ef ciency of production is high andenvironmental impacts are low. For combustiblecrops it is practical if the crop can be harvested when it is dry. Transportation, storage andcombustion are easier and heating value is high.For biogas crops, a low moisture content isnot as important because the crops are usuallystored as silage. For biogas production the cropsshould be harvested when their gas productionis at an optimum level.

Unit Willow Hemp*(spring)

RCG(spring)

Poplar Soft Wood

Water content at harvest % 50 10-15 10-15 50-55 50Dry mass yield tdm/ha/year 6-10 5-10 4-10 10-20 3-5

Ash content (dry) % 2.9 1.5 1.0- 8.0 0.5-1.9 1-2Gross calorifc value (dry) MJ/kg 19.97 18.79 19.20 19.43 20.3Net calorifc value (dry) MJ/kg 18.62 17.48 17.28 18.72 18.10 18.97Carbon (C) % DM 49.8 47.3 48.6 39.7 50.6Hydrogen (H) % DM 6.26 6.0 6.1 7.7 6.24Sulphur (S) % DM 0.03 0.04 0.04 0.17 0.2 0.03Nitrogen (N) % DM 0.39 0.7 0.3 2.0 0.9 0.1Chlorine (Cl) % DM 0.03 0.01 0.01 0.09 0.04 0.01

Aluminium (Al) g/kg of ash 2.2 2.1 2.8 16,7 16.0Calcium (Ca) g/kg of ash 243.0 240 66.5 189.3 238.8Potassium (K) g/kg of ash 123.3 44.7 129.5 28.6 80.7Magnesium (Mg) g/kg of ash 23.4 24.0 21.7 42.9 31.4Sodium (Na) g/kg of ash 2.5 3.5 7.0 3.6 4.6Phosphorus (P) g/kg of ash 36.9 49.3 32.3 17.9 12.4

Silicon (Si) g/kg of ash 93.3 160 218.3 178 73.9 Ash smelting point,(DT/A)

C 1490 1610 ~1400 1160 1200

It is advantageous if an energy crop is suitedto existing power plants and is co-combustible. This keeps investment costs low, requiring,for example, only crushing and feeding linesfor biomass bales. Ash content should be low,ash smelting point should be high enough andcombustion should occur without productionof harmful elements such as chlorine andheavy metals. Chopped energy crops are usuallysuitable for co-combustion with wood chips,peat or coal. For example, reed canary grass,hemp and straw have higher chlorine contentand lower ash smelting points than wood-basedfuels, a fact that has to be taken into account when fuel mixture ratios are being planned.Differences in heating values are minor if drymatter contents of biofuels are considered(table 1). In practice, the water content of thebiofuel re ects its heating value.

Table 1. Typical values of fuel characteristics (Strmberg 2006, Alakangas 2000, Finell, Xiong & Olsson, 20062007, VTT & Vapo 2009). In practice, the variation can be high.

* Only one study from northern Sweden, harvested in May 2005.


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Top incentive schemes(support systems)

Because energy crop chains, from cultivation topower plant, are quite complex and investment

costs for the plants are higher than for fossilfuel plants, it is clear that utilisation of energycrops cannot be pro table without nancialsupport. Different countries have adopteddifferent kinds of support systems, which arebrie y discussed.

In Finland agricultural subsidies for cultivatingreed canary grass are the same as the subsidiesfor other eld crops (500 700 /ha/year).

This is essential for the economy of the RCGfuel-chain. On the other hand, because thesubsidy is the same for all crops, the systemdoes not encourage farmers to cultivate RCGif the fuel price is low. Establishing energy cropplantations or using energy crops for energyproduction is not supported in Finland. Thepower plants can get investment support (e.g.15 30 % of investment costs) and they canavoid emission trade fees by using biofuels inplace of fossil fuels.

Willow is a popular energy crop in Sweden, where the farmers receive a subsidy for establishment costs of th(Photo: Timo Ltjnen, MTT)

In Italy, since January 2009, a new supportscheme has updated the green certi catemechanism that supports production ofelectrical energy only from utilisation ofbiofuels: small plants (< 1MW) receive a tariffof 0.22 /kWh, whereas bigger plants receivethe green certi cates (based on a variablemarket price), plus an additional 10 % bonus.

In Spain, top incentives include mainly theregulated tariff, using energy crops forelectricity generation. According to this theregulated tariff for the 2MW producer for the

rst 15 years is 0.1696 /kWh and 0.1559 /kWh for the >2MW producer.

In Sweden, taxes, subsidies and support schemesfor using renewable energy have been appliedsince the early 1990s. The most signi cantcomponent is taxation on the emission ofcarbon dioxide from combustion of fossil fuelsto produce heat, which was rst introduced in1991. The users of renewable sources, such asbiofuels, are exempted from the carbon tax.


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The level of the carbon tax has increased fromabout 0.025 (0.25 SEK) per kg CO2 in the early1990s to 0.063 (0.63 SEK) in 2002, and on topof which another 0.006 (0.06 SEK) per kgCO2 was added in 2007. Sizeable subsides havebeen available for development of CHP plantsusing biofuels since the 1980s. For example,Enkping CHP plant received subsides of400 (4000 SEK) per kW of electricity generatingcapacity, about 40 % of the total investment. Inaddition, CHP plants using biofuels can be alsosupported through other schemes such as theGreen Electricity Certi cate, Emission Trading,Program for Energy Ef ciency in industry(PFE), etc. To encourage farmers to start inthe willow production business, a programmehas been in operation since the end of 1980s.Farmers currently get subsidies of about 5000SEK (about 500 ) from the government,although it was 10,000 SEK at the start of theprogramme. Unfortunately there is no similarsubsidy available for establishment of otherenergy crops.

In Austria, for electricity production from biogas,a xed feed-in tariff of between 11.30 cent/kWh(power > 1000 kW) and 16.95 cent/kWh (power< 100 kW) is guaranteed over 10 years. In year 11the plant owner gets 75 % of this feed-in tariffand in year 12, 50 %. Due to high substrate costsfor energy crops, the Austrian plant owners gotan additional commodity bonus of 4 cent/kWhin 2008. This government aid for new biogasplants is limited to 5.1 M per year.

References :

AEBIOM 2007. New dedicated energy cropsfor solid biofuels. www.aebiom.org. 16 p.

Alakangas, E. 2000. Suomessa kytettvienpolttoaineiden ominaisuuksia. Properties offuels used in Finland. VTT Tiedotteita 2045.

Edwards, R.A.H., ri, M., Huld, T.A. &Dallemand, J.F. 2005. GIS-based assessmentof cereal straw energy resource in the

European Union. Proceedings of 14thEuropean Biomass Conference & Exhibition.

Ericsson K., Huttunen S., Nilsson, L.J. &Svenningsson, P. 2004. Bioenergy policy andmarket development in Finland and Sweden.

Energy Policy 32: 1707-1721.Finell, M., Xiong S., Olsson, R. 2006.Multifunktionell industrihampa fr norraSverige BTK-rapport 2006:13

Holm Nielsen, J. B., Oleskowicz-Popiel, P.& Al Seadi, T. 2007. Energy crop potentialsfor bioenergy in EU-27. Proceedings of 15thEuropean Biomass Conference & Exhibition:94 103.

Kopetz, H., Jossart, J.M., Ragossnig, H.& Metschina, C. 2007. European biomassstatistics 2007. European Biomass Association(Aebiom). 73 p.

Le colture dedicate ad uso energetico: ilprogetto Bioenergy Farm Quaderno Arsia6/2004.

McCormick, K. & Kberger, T. 2005.Exploring a pioneering bioenergy system: The case of Enkping in Sweden. Journal ofCleaner Production 13: 1003-1014.

Pahkala, K., Hakala, K., Kontturi, M. &Niemelinen, O. 2009. Peltobiomassatglobaalina energianlhteen. Field crops asglobal energy source. Maa- ja elintarviketalous137. 48 p. + 3 appendix.

Phyllis, database for biomass and waste, www.ecn.nl/phyllis

Strmberg, B. 2006. Fuel Handbook. Vrmeforsk. ISSN 0282-3772.

VTT & Vapo 2009. Local fuels, Properties,classi cations and environmental impacts. Inpress.


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Current production andpotential in the nearfuture

Production of reed canary grass (RCG) forenergy production has increased rapidly inFinland during the past decade. In 2008 theproduction area of RCG was about 20,000 hain Finland. In Sweden the production area is

under 1,000 ha. In other EU-countries RCGis not cultivated with the exception of smallexperimental plots. RCG is well suited to theNordic countries, where the winter is cold.Crop quality improves during the winter andthe spring harvest method produces dry, highquality fuel.

Reed canarygrass in Finland2

Reed canary grass is a well suited energy crop for Finlandand northern Sweden, where the winters are cold.(Photo: Timo Ltjnen, MTT)

The Ministry of Agriculture and Forestry ofFinland has set a target to increase the eld areaof energy crops to 100,000 ha before 2016.In Finland about 1.8 million ha is needed fordomestic food and feed consumption. Thusit would be possible to use about 0.5 millionha for other purposes such as energy use. Inaddition, there exist dozens of power plants inFinland that could use RCG in bales or as afuel-mix.

The realistic yield level of RCG in Finlandis 4 7 tdm/ha, when harvest losses are takeninto account. Fields have produced 10 tdm/hayields, but especially young RCG elds haveproduced only 3 tdm/ha. Because the energycontent of RCG is about 4.5 MWh/tdm, currentproduction is about 450 GWh/year, if the yieldlevel is assumed to be 5 tdm/ha. If the RCGarea were increased to 100,000 ha, annualenergy production would be about 2.25 TWh. This represents about 0.6 % of total energyconsumption in Finland.

Technologies in cultivationand harvesting

Cultivation of reed canary grass

Reed canary grass is a winterhardy, highlyproductive and durable grass crop. The oldestexperimental elds have been productivemore than 15 years in Finland. An RCG plantdevelops its root system during two summersand the rst yield is harvested two years aftersowing. The crop produces the best yields whenit is older than three years.

RCG grows well in all soil types, but the bestyields have been recorded from moist moldand ne sand soils. Fields for RCG should be

at and stone-free so that is possible to cut

Timo Ltjnen, Katri Pahkala,Petri Vesanto & Matti Hiltunen


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the crop close to the soil surface, leaving ashort stubble. Couch grass and old ley haveto be destroyed during the previous summerin a eld intended for RCG because a youngRCG crop is a very poor competitor against weeds. RCG is sown like forage grasses, but

the best results have been achieved withoutcover crops. The crop is fertilised in springafter harvest at 60 80 kg N/ha. Even oldpeat bogs are suitable for RCG cultivationafter adequate liming and fertilisation.

The plantation can be broken up quite easily ifthe farmer wants to change a crop. Glyphosateis sprayed during June-July and the eld isploughed in autumn. In the following springa competitive crop (e.g. oats) is sown andharvested in autumn. Subsequently glyphosateis sprayed again and the eld is ploughed. The RCG should then have been removedcompletely.

Yield quality

In Finland and Sweden RCG is harvested inspring after the snow melts because the cropis then dry and fuel quality is high. In thespring-harvested crop ash content is lowerand ash smelting point is higher than in anautumn-harvested crop. Also Cl, K, Ca, N andP contents have decreased during the winter. Ash content can range between 2 % and 10 %according to fertilisation and soils. Ash contentis lower in stems compared with leaves. Atspring harvest up to 70 % of the biomass canbe represented by stems.

Harvest of reed canary grass

The rst crop can be harvested two years aftersowing. Subsequently the crop is harvestedannually during AprilMay. If there is groundfrost, RCG can be harvested immediately afterthe snow melts. If there is no ground frost the

Disc mower with conditioner mowing RCG in spring. The snow has pressed the crop very near to the soil surfimportant to set stubble height as short as possible. (Photo: Timo Ltjnen, MTT)


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soil has to be dry enough to bear the combineharvester. RCG should be harvested before thenew growth exceeds 10 15 cm. Cutting greenbiomass decreases the fuel quality and delaysgrowth of the new crop. Moisture content ofRCG is usually 10 15 % during spring harvest.Contractors are often used to harvest the cropbecause harvest machinery is expensive.

Mowing and windrowing

Disc mowers with or without a conditionerare commonly used to mow RCG. For springharvest the stubble height has to be set as shortas possible. Mowing a badly lodged crop caneasily leave the stubble too long and harvestlosses increase. If a conditioner is used, it isimportant to adjust the conditioner tender toavoid draught losses in a very dry crop. If adisc mower without a conditioner is used, thegrowth has to be windrowed before harvest. The same rotary rakes as used to rake silageare suitable.

Bale harvest

In Finland round balers are the most commonlyused to harvest RCG. Round balers are cheaperand lighter than large square balers. However,

Advantages of a large square baler are the tight and well-shaped bales. (Photo: Timo Ltjnen, MTT)

large square balers have higher capacity,produce tighter bales and are of a better shapethan those produced by round balers. It ispossible to make 30 50 % heavier loads fortransportation by using good large square balesrather than round bales. For these reasons useof large square balers is becoming increasinglycommon for RCG harvesting.

The target for baling has to be very dense and well-shaped bales of suitable dimensions fortransportation. Bale dimensions are de ned when making the contract for growing RCG.Dry RCG is not very easy to compress, thusadjustments to the balers have to be made toget tight, compact bales. Normally density ofgood round bales is 130 150 kg dm/m3 anddensity of large square bales 170 200 kg dm/m3.Round balers use bale net or rope for tying andlarge square balers use only rope.

Loose harvest The advantage of loose harvest is that itproduces a short chop already during theharvest, which is suitable for feeding lines in

power plants. Crushing the bales is not needed with loose harvest. The loose harvest methodis suitable if the distance from the RGC elds


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to the power plant or to a fuel terminal is10 15 km at most. Using this method theRCG is harvested by a self-propelled or atractor-powered silage chopper. The chop istransported by tractors to storage areas and theheap is covered with a tarpaulin. Afterwards thechop is mixed with fuel peat or wood chips andtransported to the power plant.

Field transport andintermediate storage

Reed canary grass bales have to be transportedfrom the eld to intermediate storage to await

truck transport or have to be placed in terminalstorage. If the elds are near to the power plant(< 30 km), the bales can be transported directlyfrom the eld to storage at the power plant.Short-distance transport is normally performedusing front-loader tractors and trailers.

It is important that bales keep their shapeand do not break up during short-distancetransport. Shapeless bales will cause problemsduring loading on to trucks and when feedingthe bale crusher. It is wise to make the bale heapas high as possible and to cover the heap withtarpaulin to protect the bales against moisture.It is worthwhile weighing down tarpaulinedges with a layer of soil to keep the tarpaulinin place. Working phases from cultivation tointermediate storage are usually the farmersresponsibility.

Long distance transportand logistics

RCG is usually transported in bales or mixed with the principal fuel because the density ofRCG chop is very low (70 kg dm/m3 ). A full150 m3 truckload is only about 10 tonnes ifloose RCG chop is transported. The truckloads

Typical RCG production chains in Finland. (Picture: Jyvskyl Innovation Ltd).


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can be 15 18 tonnes with round bales and20 25 tonnes with large square bales. RCG inbales is pro table to transport up to distances of70 80 km.

Density of RCG can also be improved by

pelletizing or briquetting. Transport andcombustion of pellets and briquets are easyand effective. However, the high costs ofpelletizing and briquetting are the reasons thatthese technologies are not usually used withRCG in Finland.

Typical production chains of RCG in Finlandare indicated:

Production chain 1 (Bale chain): mowing,baling, intermediate storage, long-distancetransport, automatic crushing, automaticmixing, combustion

Production chain 2 (Combined baleand loose chop chain): mowing, baling,transport to terminal, terminal storage,crushing, mixing with main fuel, long-distance transport, combustion

Production chain 3 (Loose harvestchain): mowing, loose harvest, transportto terminal, terminal storage, mixing with main fuel, long-distance transport,combustion

Energy productiontechnologies

Reed canary grass as a fuel

In Finland RCG is used in a mix with a mainfuel in CHP plants. The main fuel is peat inmost cases, which is mixed with RCG chopbefore feeding into the boiler. The main fuelcan also be wood or a mix of wood and peat.RCG is transported to power plant in bales, inloose chop or as a complete mix. For feedinginto the boiler, RCG chop must be < 50 mm toprevent blockage problems in feeding lines.

At the moment there are no power plantsdesigned originally for RCG ring. RCG has lowdensity, higher chlorine and alkali content andlower ash smelting point compared with typicalsolid fuels like peat, wood or coal. For thesereasons the RCG proportion is usually limitedto 10 20 % of total energy content of the fuelmix. This represents a 20 40 % proportion in volume of an RCG-peat-mix. Firing pure RCG would lead to corrosion risks, boiler fouling and

ash smelting, which can cause malfunctions inthe boiler. Probably ring of pure RCG wouldbe possible in boilers designed for ring straw. There is no yet practical evidence of this.

Preparation of reed canary grasspeat wood mix with a wood crusher on the yard of a power plant.(Photo: Timo Ltjnen, MTT)


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Preparation of fuel mix

The simplest way to mix RCG with the mainfuel is to spread peat or wood chips and RCG inlayers by wheel loader and to load the fuel bedinto the storage heap, transport truck or directlyfeed it into the boiler. However the mixing resultis often uneven when this method is used.

RCG is thoroughly mixed with wood chips ifthe bales are crushed together with the woodusing a wood crusher. The crusher can bemobile or part of a feeding line of a powerplant. However, RCG decreases crushingcapacity compared with pure wood crushing.

If there is only a bale crusher line for RCGbales, the RCG chop can be fed on to the mainfuel conveyor as the fuels are being mixed orthe RCG chop can be fed directly into the boilerpneumatically via a pipeline. The pneumaticfeed system has to be planned carefully in orderto get the RCG suf ciently well mixed to forma uidized bed and avoid separate and rapidcombustion of RCG in the feed area.

Combustion technologies

In Finland there are mainly three types ofboiler used in CHP plants and heating plants: grate boilers bubbling uidised bed boilers circulating uidised bed boilers

The grate system is typically used for a rangeof boilers, from 10 kW heating boilers to 25MW industrial and district heating boilers. Inthe simplest case the grate is an inclined re-grate, but in the bigger boilers the grate isusually moves mechanically. In Finland grateboilers are often designed to use wood chips,bark, sawdust and sod peat. The feed systemsof grate boilers do not suit feeding light RCGchop, thus RCG has to be mixed thoroughly with the main fuel. If the mixing is uneven

RCG chop easily ies away with ue gasesand the fuel bed becomes cratered, leading todif culties in controlling the combustion. Thegrate should move to prevent an ash smelting

problem. In straw boilers these challenges aresolved because straw is even more dif cult afuel to combust than RCG.

Bubbling uidised bed boilers are multifuelboilers that can use biofuels, peat and even

sludges. In these boilers the fuel is combustedon a very hot sand bed at the bottom of theboiler. Combustion air is blown through thesand bed. Output capacity varies between5250 MW. The circulating uidised bed boilersare normally even larger, 20550 MW. They arealso multifuel boilers, which can use biofuelsand peat, but also coal. Hot sand circulates inthe boiler and fuel is red in the sand. Controlof combustion and emissions is very good.

The uidised bed boilers are well suited to burnRCG if it is mixed with the main fuel and theproportion of RCG is relatively small. Peat isa very good main fuel to use with RCG whencombusted in uidised bed boiler.

Reed canary grass in uidisedbed combustion

RCG is as reactive fuel as other biofuels andcombustion is rapid and complete. RCG hashigher chlorine content than peat or woodand during combustion chlorine salts areproduced with potassium and calcium, whichcan lead to boiler fouling and corrosion risks insuperheaters. In addition, the ash smelting pointof RCG can be low in certain circumstances. In

uidised bed boilers bed-sand uidization is animportant factor in usability, good combustion

and emissions. Agglomeration or sintering ofbed sand is not desirable and in peat ring itis exceptional. If pure wood or RCG is used,there is a risk of sintering. When RCG is co-

red with wood, there is a risk that silicate(SiO2 ) of RCG ash reacts with the potassiumfrom wood ash and generates sticky glass.

Peat is a very good main fuel with RCG becausepeat ash does not react appreciably with RCG

ash, but the sulphur in peat reacts with potassiumin RCG to generate potassium sulphate, whichprevents formation of corrosive potassiumchloride.


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Fuel mixture Max. proportion of RCG ofenergy content

Max. proportion of RCG of volume

Reed canary grass and peat 20 % about 40 %

Reed canary grass and wood chips

10 % about 20 %

Reed canary grass, peatand wood chips; proportionof peat > 50 %

15 % about 30 %

Table 2. Recommended maximum proportions of RCG together with wood or peat when a fuel-mix is used boiler. (Source: Vapo Ltd, Novox Ltd.).

Biofuel Energy balanceGJinput/ GJ output

Greenhouse gas balance,tonne CO2-ekv/GJoutput

RCG, harvest and transport asloose chop, CHP

0.078 0.015

RCG, harvest and transport asbales, CHP

0.077 0.015

Wood chips from loggingresiduals, CHP

0.025-0.027 0.002

Wood chips from stumps, CHP 0.038 0.003 Wood chips from small diam.trees, CHP

0.036 0.003

Ethanol from barley 0.8 0.105

Biodiesel from rape seed 0.5 0.11Fisher-Tropsch-diesel 0.5 0.02-0.03

Table 3. Energy and greenhouse gas balances for different biofuels. Energy balance should be clearly < 1 anbalance should be clearly < 0.1 (balance of petrol) for biofuel use to represent a sensible option. CO2, CH 4 and N 2 O have beentaken in account in calculating greenhouse gas balances. (Source: Mkinen et al. 2006)


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Good case example

The power plant of Kokkolan Voima Ltd. wascommissioned in 2001. The uidised bed boiler with steam turbine can produce 20 MW ofelectricity and 50 MW of district heat. During2008 the plant used peat for about 170 GWh,residues from the forest industry for 50 GWh, wood chips for 95 GWh and RCG for 5 GWh.During 2006 2007 the company built a newcrushing and feeding system for eld biomass. The system consists of a storage hall, a crushingline for the bales and a pneumatic feeding lineto the boiler.

Crushing technology is based on the methoddeveloped by the Danish Reka company, which was designed originally to crush straw in largesquare bales. Nominal capacity of the crusheris 1000 kg/h. The system includes a nearly50 m long bale conveyor on which the bales

Power plant of Kokkolan Voima Ltd. Reed canary grass chop is transported pneumatically to the boiler via thleft. (Photo: Timo Ltjnen, MTT).

are loaded twice a day. The remainder of thetime the crusher works automatically and isunmanned. As the crusher is a low speed type,the crushing does not cause dust problemsand thus represents a reduced re hazard andthe environment stays cleaner. The crushercan accommodate both large square bales andround bales.

The screw below the crusher drum movesRCG chop into a pneumatic pipeline through afeeder device. The diameter of the pneumaticpipeline is 100 mm and its length from thecrusher to the boiler is more than 100 m. Thefeeding point for the RCG is at the same leveland on the same side of boiler as the feed forthe main fuel.

The system is designed to process 15 GWheld biomass annually, which is about 5 % of

total energy used on the plant. RCG is mainly


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bought from about 50 contract farmers. TheRCG cultivation area is about 600 ha. Farmersfrom the neighbouring area transport the balesdirectly to the storage facility of the powerplant. The RCG produced far from the plantis stored near the elds and transported to the

plant with logging residue trucks, which cantake about 70 round bales (15 tonnes). By usinglarge square bales the load mass can be higher.Purchasing RCG directly from farmers involvessigni cant administrative work for the plant.

Pros and cons:+ RCG is transported in bales to the plant

effective transport logistics+ Covered storage assures high fuel quality

and independence from transport logistics+ Quality of crushing is high and energy

ef cient+ Using this method RCG does not cause

problems in treatment and feeding theother fuels

- The method requires investment andsuf cient space at the power plant

References:

Alakangas, E. 2000. Suomessa kytettvienpolttoaineiden ominaisuuksia. Properties offuels used in Finland. VTT Tiedotteita 2045.172 p. + 17 p. appendix. www.vtt. /inf/pdf/tiedotteet/2000/T2045.pdf

Burvall, J. 1997. In uence of harvest timeand soil type on fuel quality in reed canarygrass (phalaris arundinacea l.). Biomass andBioenergy 12: 149-154.

Larsson, S., rberg, H., Kaln, G. & Thyrel,M. 2006. Rr en som energigrda. Reedcanary grass as an energy crop. BTK-rapport2006:11. Sveriges Lantbruksuniversitet,

Enheten fr Biomassateknologi och Kemi.Ume: SLU. 43 p.

Mkinen, T., Soimakallio, S., Paappanen, T.,Pahkala, K., Mikkola, H.J. 2006. Liikenteenbiopolttoaineiden ja peltoenergiankasvihuonekaasutaseet ja uudetliiketoimintakonseptit. VTT tiedotteita 2357:134 p. + 19 p. appendix. www.vtt. /inf/pdf/

tiedotteet/2006/T2357.pdf Paappanen, T., Lindh, T., Krki. J.,Impola, R., Taipale, R., Leino, T., Rinne,S., Ltjnen, T. & Kirkkari, A-M. 2008.Ruokohelven polttoaineketjun kehittminenliiketoimintamahdollisuuksien parantamiseksi.Development of reed canary grass fuelchain. VTT Tiedotteita 2452. 158 p.+ 9 p. appendix. www.vtt. /inf/pdf/

tiedotteet/2008/T2452.pdfPellervon taloudellinen tutkimuslaitos, 2006.Suomi bioenergian edellkvijmaana. Finlandis leading way in bioenergy. PTT-katsaus, Vol.27: 2. 47 p.

Saijonkari-Pahkala, K. 2001. Non-woodplants as raw material for pulp and paper. Agricultural and food science in Finland, Vol.

10 : supplement 1 (Academic Dissertation).101 p. www.mtt. /afs/pdf/afsf10_suppl1.pdf

Vapo 2008. Ruokohelpi polttoaineena.Reed canary grass as fuel. Vapo paikallisetpolttoaineet. 4 p. www.vapo. /

lebank/3260-polttoesite.pdf


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Willow Willow (Salix spp.) includes several tree andshrub species, some of which grow fast andhave been cultivated for energy generation inenergy forests in Sweden since the rst oilcrisis in the 1970s. Clones of Salix viminalisare mainly used in the energy forests. Otherspecies such as Salix dasyclados have also beencultivated, but to a much more limited extent. Willow has almost the same net heating valueas the wood fuels, approximately 18.6 MJ/kg dm (see comparison with other biofuels and energycrops in Table 1 of Introduction).

Current production andpotential in the near future

Willow is mostly cultivated in the elds

of southern Sweden, where about 1,250farmers work with commercial plantationscurrently totalling about 13,500 hectares. Theestablishment period and intervals betweenharvests are 3 5 years and the yield can reachabout 8 10 tonnes dry mater per hectare

Willow and hempin Sweden3

per annum, but signi cant variation occursaccording to region and year.

Currently about 20 % of total energyconsumption in Sweden is from bioenergy. The biofuels from direct bioenergy farmingmake a very small contribution (< 1 TWh in2008, not including crops produced for biogas),compared with those from wood industryresidues. There is a great untapped potential,

however, and bioenergy could contribute upto 220 TWh, 10 % of it coming from long-term energy farming. To date, willow chipsfor direct combustion are the most commonlyused products on the market.

Technologies in cultivationand harvesting Willow plantations are established fromcuttings during spring. Planting materialshould be bought from a reputable source toensure good stock quality. Willow is usuallysupplied as 2 3 meter long branches that arecut between December and March when thebuds are fully dormant. These can be planted

immediately or carefully stored in coolconditions (-2 -4C) until they areused. It is necessary to protect the

planting material from moisture lossand during storage prior to planting.Cuttings with burst buds should notbe planted because they will not rooteasily.

Special designs (twin rows) andtechniques for willow plantationestablishment have been developed. Willow branches 2 3 m length are cutinto 15 20 cm sections immediatelybefore planting. The twin-row designallows a spacing of 0.75 m betweenrows and 1.5 m between twin rows,

Twin row design for establishment of willow using a Step Planter.(Photo: Lantmnnen Agroenergy AB)

Shaojun Xiong & Michael Finell


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leading to a planting density of about 13,000cuttings per hectare.

Weed control during the rst year is veryimportant. The willow root system establishesin the rst year, during which it is not tolerant

of weed competition. Measures that can ensure weed-free sites at planting have to be taken toachieve successful establishment. The site mustbe prepared using a deep plough in the previousautumn. Broad spectrum contact herbicides,such as glyphosate (a type Roundup Bio), areoften used to control perennial weeds beforeany cultivation and even 2 3 weeks afterwards.Mechanical weed control is an alternative. Inaddition, residual soil-acting herbicides canbe also used to control germinating weeds.Detailed recommendations can be obtainedby contacting a dealer such as Lantmnnen Agroenergi in Sweden. The willow crop foliagecan shade out the weeds when it is well-established.

Willow plantations are very demanding of water and nutrients, generally requiring 3

5 mm of water per day during the growingseason. The demand for nutrients variesaccording to age of the plantation and stageof crop development. For example, no Nfertilisation is recommended in Sweden duringthe year of establishment, but 45 kg N perhectare should be applied during the second(i.e. the rst harvest) year, and 100 150 kg Nduring the third and fourth years. Studies havesuggested that an economic and environmentalbene t may result from using waste water forirrigation, and sludge together with ash frombiofuel combustion as fertiliser. Research hasalso demonstrated that willow can remediatesoil contaminated by organic pollutants andheavy metals.

Pest and disease control has to be managed.Fungal pathogens and leaf-eating insects candamage willow. Planting mixtures of different varieties or species is always recommended.Research has led to development of new vigorous willow varieties with increasedresistance to diseases such as melampsora rust

and damage by insects including the willowbeetle. Chemicals control of insects is notrecommended from an environmental point of view, but a limited application of insecticidescan be allowed to control willow beetle insome cases.

Willow is preferably harvested during the winter when the ground is frozen and themoisture content in the biomass is at its lowest(ca. 50 %). Willow is harvested after 3 5 yearsof growth. Harvesters that can cut-and-chipin one or two operations and are capable ofcutting two rows in one pass (i.e. suitable fortwin row design) are mostly used in Sweden.

Logistics Willow biomass is usually harvested directlyby cutting and chipping in the eld. The chipsare then transported to district heating or CHPplants where they are stored and used. Thesame equipment can be used for producingand supplying willow chips for a CHP plant asis used to produce conventional wood chips.

There is no major difference either in storageconditions used for willow or conventional wood chips. Willow can be stored in bundlesover a longer time period without signi cantreduction in quality.

Energy productiontechnologies

Willow chips are mostly used as solid fuel fordirect combustion in heating or CHP boilers.However, they currently contribute up to20 % of fuel mixtures because willow containselevated levels of problematic elements forcombustion (such as K, Cl, Na, N, Mg etc.) incomparison with other wood fuels, leading to ahigher risk of corrosion, slagging etc. In otherrespects willow chips are used in the same wayas wood chips and have similar calori c values.Studies testing combustion of willow powderand pellets or briquettes have been conductedand it is expected that a co- ring willow andother fuel types will be studied in the future.


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National law and incentivesprogrammesIn Sweden, as in other European countries,energy farming is encouraged to promotesustainable development. Therefore, energyfarming of willow has been required to haveno deleterious effects on food safety andsecurity for future generations and if possible willow should be rotated with food and otherindustrial crops without lowering productioncapacity. There should be no disturbance to thesoil and landscape characteristics, the ecologyof the production area should not be disturbedunduly and the production process should be

in line with urban environmental aims. To reach these goals, some restrictive rulesand regulations must be adhered to in willowproduction management:

Willow harvesting (Photo: Theo Verwijst)

Sludge and other solid organic componentsmust be used carefully

Nitrogen run-off should not exceed 10 kg/ha/year

Phosphorus loss to watercourses shouldnot exceed 0.2 kg/ha/year

Agrochemicals application for pest/disease/ weed management cannot exceed 0.7 kg/ha/year

No activities are allowed that could increasein heavy metal content of the soil.

When the willow biomass is used as a carbonneutral biofuel and has low sulphur emissions,the user can be rewarded by state policies andincentives. The most important state policyin Sweden to promote the use of biofuels istaxation on the emission of carbon dioxide. This has been in operation since 1991. Biofuelsare exempt from the carbon tax. CHP plants


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using biofuels may be also supported throughother schemes such as the Green ElectricityCerti cate, Emission Trading, Program forenergy ef ciency in industry (PFE), etc.

To encourage farmers to start the willowbusiness, some incentive programmes havebeen implemented since the end of 1980s.Currently farmers can get subsidies of about5,000 SEK (about 500 ) from the governmentto establish willow plantations.

The eld energy crops can be transformed ef ciently to energy in uidised bed combustion at CHP-plant.(Photo: Timo Ltjnen, MTT).


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Schematic layout of cycling in Enkping.

Good case example

The multifunctional willow plantation inEnkping is one of the most successful casesof large-scale energy farming. Wastewater

treatment, sludge recycling, leakage waterltration and heavy metal puri cation arecombined with willow biomass production. The biomass of willow is then supplied inchips to the ENA Energys CHP plant inEnkping, which has the capacity to produce23 MW of electricity and 55 MW of heat. Itgenerates 350 GWh (100 GWh electricity, 250GWh heat) every year.

The original concept comprises about 80hectares of willow plantation, an irrigationsystem and 3 ponds connected to the muncipal waste-water treatment plant. Each year,approximately 200,000 m3 of nutrient-rich water, after a conventional purifying process, isdistributed through the 350 km irrigation pipesto the 80 hectares of willow plantation. Theplanning was initiated in 1993 1994 and the

system was ready to use in 2001.Bene ts of the ENA Energy concept can besummarised: Use of a local energy resource - shorter

distances and lower expenses fortransporting fuel

The waste from society can be recycledas fertiliser reduces uses of commercialfertilisers and environmental problems

Reduction of nitrogen leakage into theBaltic Sea also minimises environmentalrisks

Saves the costs for building conventionalnitrogen removal facilities

Saves energy used in waste handling Improvement of soil environment

through remediation by willow


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HempHemp (Cannabis sativa L.) is an annual,dioecious, herb. It is a multi-purpose plant thathas been domesticated for the bast ber in thestem, a xed oil in the seeds, and an intoxicating

resin secreted by epidermal glands. Most ofthe hemp grown in Europe is used for breproduction. The bres are used in the pulp andpaper industry and the residual shives are usedas animal bedding. Energy production in theform of solid fuel from the whole hemp stemis a relatively new use for the crop.

Current production and

potential in near futureHemp is currently only grown on a small scalefor energy production in Sweden. Farmers,however, are interested in this crop because it isan annual and allows more exibility in croppingsystems than perennials such as willow or reedcanary-grass.

Hemp is also interesting from an organic

farming point of view because it usually requires

13 570 13 240 13 264 13 314 13 254 13 011

534 625163 181

657 780

34 144 310 478

811390

0

2 000

4 000

6 000

8 000

10 000

12 000

14 000

2003 2004 2005 2006 2007 2008

A r e a u s e

d f o r e n e r g y c r o p p r o

d u c t i o n

( h a

)

Year

Willow

RCG

Hemp

Willow, reed canary-grass and hemp production in Sweden from 2003 to 2008.

no pesticide or fungicide application. Hemp canbe used for weed control as a dense hemp stand will shade out competing weeds. The goal ofthe government is that at least 20 % of Swedishfarming should be certi ed organic by 2010.Hemp is considered an interesting componentfor crop rotations in organic farming.

The enclosed gure shows the area used for willow, RCG and hemp production in Swedenfrom 2003 to 2008. There was a steady increasein hemp cultivation from 2003 to 2007, reachinga maximum of about 800 ha. In 2008, howeveronly half of that area (about 400 ha) was usedfor hemp production.

Technologies used incultivationand harvesting To make full use of the growing season hempshould be sown as early in the spring as is possible.Seed is best sown at 2 3 cm depth and at arow distance of 25 cm. Although the seedlings will germinate and survive at temperatures just

above freezing, soil temperatures of 8 10 C


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are optimal. Good soil moisture is necessaryfor seed germination, and adequate rainfall isneeded for good growth, especially during the

rst 6 weeks. For energy purposes a seeding rateof 20 40 kg/ha is recommended. Growinghemp may require addition of up to 110 kg/ha of nitrogen, and 40 90 kg/ha of potash.Nitrogen fertilisation in excess 200 kg/ha hashowever been tested with good results.

Hemp is harvested for energy use as wilted,dry material in late winter or spring after thegrowing season. This means that the wholegrowing season is used, giving a high biomassyield. During winter the leaves fall off and theash content is lowered. Some of the unwantedelements (N, S, Cl) are leached out of thematerial during winter, which produces betterfuel than grass.

Hemp can be harvested by cutting and baling orcan be cut by a precision chopper and collected

Demonstration of a newly developed small, exible harvester for hemp in Grstorp, Sweden, April 2009.(Photo: M. Finell, SLU).

as loose material. Bales can be stored indoorsor in a covered pile to protect them from rain.Loose material can be stored in covered silos orin tubes. Harvesting hemp with conventionalmachinery can sometimes be troublesomebecause the strong bres have a tendency to get

stuck in rotating machine parts. The enclosedpicture shows hemp harvesting equipment.

Logistics As with other energy materials, including reedcanary grass and straw, logistics are challenging. The crop is only harvested once a year, oftenin spring when the need for raw material byheating and power plants is low. This means

that storage of the harvested material is oftenrequired.

Baling offers an effective means to collect,handle and store the material, but it is also asigni cant cost item in the production chain.


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Using hemp in large-scale heating and powerplants requires that the material is cut and mixed with other fuels before combustion. This hasled to a focus on loose handling of hemp. Theenclosed photo shows trials for compressinghemp to improve transport.

Different methods for compacting loose hempmaterial have been studied to improve transportof the material. It is suggested that the materialis collected at terminals where chopped hempis mixed with other fuels such as wood chips,bark or peat. The mixture is then transportedto a heating and power plant for combustion.In this way the dry hemp material could beused to improve the energy value of very moistmaterials (e.g. bark).

Compressing trials with spring-harvested hemp using a Roll-pac on.(Photo: Y. Sderstrm, vik Energi AB).

Energy productiontechnologiesHemp can be re ned into briquettes or pelletsto increase the energy density and to improvehandling characteristics. This material can beused for heat production by the general public(burner, stoves and boilers) or in larger scaleheating and power plants.

When using hemp in larger scale heating andpower plants, briquetting and/or pelletisingof the material is often not necessary. Loosehandling and mixing with other fuels in similar ways as for reed canary grass and willow is

currently being investigated.


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In many combustion applications, ash relatedproblems, such as slagging tendency, areimportant. In enclosed gure some new fuels,including hemp with a high (ha) and low (la)ash content are compared with sawdust forash-forming tendency.

0

20

40

60

80

100

Wheatstraw

Reedcanarygrass(ha)

Reedcanary

grass (la)

Hemp(ha)

Hemp(la)

Salix Barkspruce

Barkpine

Barkbirch

Loggingresidues(stored)

Loggingresidues(fresh)

Sawdust

F r a c

t i o n o

f f u e

l a s

h t h a

t f o r m s s

l a g

( w t % )

Nonexistent

4

2

4 4

2

1-2

2

2

3

4

3

Fraction of fuel ash that forms slag for some different fuels. Categories of sintering are speci ed abovbars: Category 1, non-sintered ash residue, i.e. non-fused ash 1, non-sintered ash i.e. non-fused ash; Csintered ash, i.e. particles contained clearly fused ash; Category 3, mostly sintered ash, i.e. the deposiinto smaller blocks; and Category 4, totally sintered ash, i.e. the deposited ash was totally fused int (Source: hman et al. 2006)

National laws andincentive programmesIn Sweden, hemp has been grown as an energycrop since 2003. The difference with othercrops is that only EU certi ed industrial

hemp varieties can be used. The certi ed varieties have a tetrahydrocannabiol (THC)content of less than 0.20 %. A subsidy of 45 /ha is available for hemp, as for other energycrops in Sweden, but this will probably bediscontinued beyond 2009.


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Good case example The cultivation of hemp is limited to small-scale trials in Sweden. A good example ofsmall-scale hemp production for bioenergyis Gudhems Kungsgrd in Falkping. At this

family-owned farm about 100 ha of hemp isgrown and re ned into biofuel briquettes. Hempbriquette production started there in 2004. Thebriquettes are sold in the surrounding area tolocal end users. The farm reports a biomassyield of about 10 tons/ha at a moisture contentof 11 %. Hemp is harvested in winter/spring with a self-propelling precision chopper (Claas Jaguar). The chopped material is then storedindoors and/or fed directly to the briquettepress. The briquette press is a German madeRUF with a capacity of 300 kg/h for hemp. The hemp briquettes are sold in small (15 kg)and large packs (600 700 kg) and the price tothe consumer is between 1.50 and 3 SEK/kg.

References: Aronsson, P.G. & Bergstrm, L.F. 2001.Nitrate leaching from lysimeter-grownshort-rotation willow coppice in relationto N-application, irrigation and soil type.Biomass and Bioenergy 21: 155164.

Berndes, G. & Brjesson, P. 2007.Multifunctional bioenergy systems. AGS

Pathways report 2007: EU1. AGS Of ce atChalmers. ISBN 978-91-633-0270-1.

BIONIC Scandinavia, www.bionic.nu

Gilbe, C., et al. 2008. Slagging Characteristicsduring Residential Combustion of BiomassPellets. Energy & Fuels 2008, 22, 35363543.

McCormick, K. & Kberger T. 2005.Exploring a pioneering bioenergy system: The case of Enkping in Sweden. Journal ofCleaner Production 13, 1003-1014.

Nutek (Nrings- och teknikutvecklingsverket)1994. Energigrdor. R 1994:16.Strmberg, B. 2006. Fuel Handbook. Vrmeforsk. ISSN 0282-3772.

Pasila, A. The dry-line method in bast bre

production. Academic dissertation, Universityof Helsinki. Yliopistopaino, Helsinki 2004.

Rolandsson, H. Swedish Board of Agriculture. Personal communication.

Small, E. and Marcus, D. Hemp: A New Crop with New Uses for North America. Trends innew crops and new uses. 2002. J. Janick and A. Whipkey (eds.). ASHS Press, Alexandria, VA.

Sundberg, M and Westlin, H. Hampa sombrnslerbvara, frstudie. JTI-rapport 341,Lantbruk & Industri. ISSN 1401-4963.

Svebio (Swedish bioenergy association) 2003.Bioenergy- A review. Focus Bioenergy No 12003.

Svensson, S.E., Diedrichs, H., Halleflt, F. &Hansson, P.A. 1997. Kretsloppsanpassning

av energiodling en orienterande studie.Rapport frn Vattenfall Utveckling AB,Projekt Bioenergi, UB 1997/3.

Swedish Energy Agency 2004. Syntes avforskning rrande Willow inom programmetfasta biobrnslen frn jordbruksmark. ER 30:2004.

Swedish Energy Agency 2008. Energilget2008.

Sderstrm, Y. vik Energi AB. Personalcommunication.


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Current production andpotential in the near future

Poplar (Populus spp.) is a tree belonging tothe Salicaceae family widely used in traditionalarboriculture and forestry. It is tolerant of a wide range of soil conditions, but generallygrows in deep fertile soils and it is best suitedto the Mediterranean climate since it is verysensitive to frost. Under optimal conditionsSRF (short rotation forestry) poplar plantationscan reach a productivity level of about 20 tdm/ha/year.

Poplar is currently the most important speciesfor SRF in Italy. All the existing commercial

Poplar in Spainand Italy4

plantations are based on poplar clones grownin the northern regions of Italy (Lombardia,Piemonte, Veneto, Friuli, Emilia Romagna)and to a less extent in central Italy (Marche,Umbria, Lazio and Toscana) with a totalestimated harvested area of about 5,700 ha.

The rst commercial experiences with SRFbegan in early 2000 in Lombardia thanks tothe availability of Rural Development Program

funds and additional regional subsidies. Initiallythe Swedish model was adopted, (density ofplantations, harvested each year) and results were encouraging, but suffered from lack ofbest practice knowledge by farmers, who oftendedicated only marginal lands to SRF and didnot put enough effort into maintenance andfertilisation of the plantations.

The presence of large operators willing toinvest in biomass power plants will lead to astrong potential market for wood-fuel in thenear future. However, the interest of farmers inSRF has declined during the last two years dueto uctuations in pro tability of cereal crops.SRF remains pro table, but is not consideredcompetitive in comparison with traditionalcrops at this point in time. Possible solutionsin Italy to further promote the cultivation and

utilisation of wood-fuel from energy cropsare:1. Negotiation of improved contract

conditions and incentives withfarmers.

2. Maximisation of energyef ciency through:

Combined Heat and Power nsteadof power generation only

Promotion of local small-mediumscale supply chains for districtheating and CHP to reducetransportation costs

Mature poplar plantation in the spring time just before harvest.(Photo: L. Corbella & M. Cocchi, ETA)

Lorenzo Corbella, Maurizio Cocchi & Margarita Salve Diaz Miquel


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In Spain, the ON CULTIVOS Project (2005 2012) represents the principal national

initiative where, energy crops include: carinata(Brassica carinata), poplar (Populus spp),forage sorghum (Sorghum bicolor) as well ascereals for bioethanol production and rapeseed(Brassica napus) (table 4).

The estimated demonstration area at the end ofthe project is about 10,000 ha involving regionsin north (Navarra, Aragon, Catalua, Castilla yLeon), central (Castilla la Mancha, Madrid) andsouth-eastern (Andalusia, Extremadura) Spain. Applications under this initiative include energyproduction for heating, power generation,development of biofuels and gasi cation.

The aim of studying Populus clones andhybrids is to generate knowledge andexperience for sustainable production in theSpanish context. Ef ciency of utilisation of

scarce resources, such as water, optimisationof production regarding spacing/rotation,selection and monitoring of machineryadapted to harvesting and associated logistics,and economic, energy and environmentalequilibria are of major interest for promotionof poplar as an energy crop.

The objectives for biomass production in theSpanish Renewable Energy Plan specify 40%for energy crops. According to the plan theymust reach 1.9 Mtoe per year in electrical andthermal applications by 2010 and 2.2 Mtoe peryear as biofuels.

Table 4. Demonstration areas for energy crops in Spain,2006-2007. Source: Ciemat.web: www.oncultivos.es

ENERGY CROP Hectares

SORGHUM 104

BRASSICA NAPUS 348BRASSICA CARINATA 23POPULUS SPP. 18MAIZE 31 WHEAT 15BARLEY 16.5

Technologies forcultivation and harvesting

Research on SRF in Italy has been on-goingsince the early stages of bioenergy crop

production using poplar and has mainly focusedon genetic improvement and clone selection,optimised cultivation techniques, harvestingand mechanisation and storage and logistics ofbiomass production. Research efforts duringrecent years have yielded important results.

Regarding the optimisation of the cultivationtechniques, some important steps forward weretaken in the following elds:

Establishment of plantations: plantationsare established with cuttings (20 30cm in length) during spring. Research onmechanisation has led to optimisation of amechanised transplanting unit (developedby the Italian company Spapperi), which hasa working capacity of up to 35,000 cuttingsper day under optimal conditions;

Identi cation of optimal coppice rotation:research con rmed that under optimalpedo-climatic conditions one harvest everyother year yields better results in the longterm than annual harvesting. Under lessfavourable conditions, 3-5 year rotations aremore sustainable.

Plantation density: from the initial Swedishmodel, based on one year harvest cyclesand 10,000 to 15,000 plants per hectare, thetrend is now to aim for a density of 7,000 to10,000 plants/hectare for 2 3 year harvestcycles and 2 3,000 for 5 years cycles. Treesare planted in single rows instead of doublerows.

Fertilisation: initial fertilisation beforeplanting is suggested and can be done witha combination of mineral fertilisers andorganic fertilisers in order to achieve slowrelease of nutrients. Depending on theexpected target productivity, it is also possibleto apply nitrogen fertilisers periodicallyamong rows (around 60 80 kg/ha N) soon


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Poplar plantations are established with cuttings semi-automatically.(Photo: L. Corbella & M. Cocchi, ETA)

after harvesting, in order to promote rapidgrowth of the new shoots. Removal of the plantation: at the end

of the cycle (10 12 years) SRF poplarplantations can be easily removed at lowcost (around 300 /ha) using traditionalforestry machinery (milling cutter); poplarroots contain a substantial amount of waterand roots tissues are relatively soft.

Research on mechanisation of SRF has beenextensive. Concerning harvesting, initially theonly available means for harvesting SRF wasby using a Claas Jaguar self-propelled harvester.From the start two main limiting factors wereevident: the high cost of the harvester ledto the need for larger plantations to increasethe annual number of working hours of themachine and reduce unit costs, and the dif culty

for the Jaguar to harvest trees more than 6 cmdiameter, which were common in 2-3 year oldcoppice plantations.

During recent years three main harvestingmodels were identi ed that have overcomethese problems:

Fully mechanised harvesting with a self-propelled Claas Jaguar harvester anda modi ed GBE harvesting head: theBIOMASSE EUROPA GROUP developeda new harvesting head (GBE-1) suitablefor Claas combine harvesters that works well in 2-3 year coppices and is affordable;

Fully mechanised tractor-poweredSPAPPERI harvesters. These are lessexpensive machines, ideal for small andmedium scale plantation extensions and 2 3 year coppice cycles;

Salixphere Bender VI, is non-row-speci c and allows cutting and chipping in

any plantation of 2 3 year rotations. Thedevice is well adapted to irregular soils withcosts intermediate between those for Claasand Spapperi harvesters;


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3 step harvesting with traditional forestry

techniques and equipment, ideal for longercycles (3 5 year harvest cycles). In thiscase the plantation density is reduced andtree height at harvesting exceeds that in2 year coppices. Trees can be harvestedfollowing a 3 step model: felling (withcutters or by hand with chainsaw), stackinglogs in the eld with tractors and forklifts,and successive chipping with individualchipping units.

Logistics

Energy crops are generally distributed by localcompanies in the proximity of the energyconversion plant and can be used in theexisting systems for other biomass (herbaceousor woody) processing. Plantations are often inlocations close to an energy plant to reduceroad transport costs. The maximum capacity

of trucks is 90 m3

.

Storage

Poplar grown as an energy crop is seasonalregarding production and harvest, while theenergy plant runs throughout the year. It istherefore necessary to store the biomass toensure a reliable supply of wood. Long periodsof storage affect the cost, quality (calori c value, moisture, mould, ash) and reduction indry matter.

Storage can take place at different sites (closeto the production area, close to the plant, at an

intermediate location).Table 5. Storage options for poplar biomass.

A modi ed self-propelled forage chopper cuts the poplars, makes woodchips and blows the chips into a transp(Photo: L. Corbella & M. Cocchi, ETA)

Open air storage

Piles of chipsPiles of bundlesPiles of balesShelter (semi-covered)

Enclosed warehouse(i.e. as pellets)Enclosed and ventilated warehouseSilo


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The moisture content of fresh poplar biomass atharvest is around 55%. For this reason outdoorstorage in large bulk piles of woodchips canlead to fermentation and subsequent loss ofdry matter of up to 5% per month.

To overcome this problem, research is activelyseeking to identify the best storage solutions.Current trends are: Storage under cover (feasible only for small

volumes of woodchips)

Identi cation of optimal pile dimensions.Pile dimension in uences the balancebetween evaporation and rainwaterabsorption capacity

Use of canvas (plastic net) or special fabrics(Top Tex) that let moisture out but areimpermeable to rainwater (this looks like a

very ef cient solution at present).

For long periods of storage the bundlerformat is more convenient than chips, as itreduces biological activity and degradationassociated with green woody biomass (table 5).

Poplar chips are stored here in an open concrete silo. This type of storage is suitable only for short-term stmoisture content of fresh poplar chips is high. (Photo: L. Corbella & M. Cocchi, ETA)

Energy production

technologies The OCR turbines are able to produce heat andelectricity for small to medium scale systems(from 200 kW e up to 2 MW e per unit) by usingthe technology of the Rankine cycle. Theturbo-generator coupled with a diatermic oilboiler is a perfect example of a highly ef cientCHP plant (18 % for electricity and 79 % for

thermal output). The diatermic oil boiler, fed with woody biomass, heats the oil up to 300C,providing the required heat for the turbo-generator, which produces electric energy anda thermal output of 90 C.

These systems are suitable for case studies where the local biomass availability is limitedand the reduced plant size, apart from reducingthe general plant complexity and optimising thecosts for storage, transport and logistics, permitsenhanced utilisation of the co-generated heat with clear environmental, energy and economicbene ts.


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Organic Rankine Cycle (ORC), heat and energy production from a biomass powered boiler. (Source: Turbode

Direct co-combustion with coal in a 50 MW eplant in northern Spain using Technology Atmospheric Fluidized Bed Combustion(AFBC),at a thermal ef ciency of 82.59 %,

uses 59.8 % rejected coal, 35.3 % coal, and4.9% wood biomass. The absorbent material islimestone (95.5 % CaCO3 ). Fuel consumption isaround 64 t/hour and absorbent consumption5 t/hour. Woody residual biomass and energycrops represent advantages at the plant sitein terms of forest valuation, CO2 emissionreduction and increased local employment.

Energy and greenhousegas balances

The utilisation of biomass for energy mustcomply with environmental sustainability criteriaand each step of the production, conversion andutilisation process has to be evaluated in orderto assess accurately the energy and emissioncontributions. In the table 6 the resulting CO2 emissions for the production of one TJ in theentire cycle for different fuels is reported. The

CO 2 Emissions(kg/Tj of usable energy)

Woody biomass Diesel fuel Natural gas

Emissions due tocombustion

150000 78700 57700

Emissions due to the procurement of fuels

-148000 11900 7900

Indirect emissions relatedto the construction andmanagement of the plant

1460 1370 771

Total 3460 91970 66371

Table 6. CO2 emissions from wood biomass fuel compared with fossil fuels according to Italian data.


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impact of woody fuels is markedly lower incomparison with diesel fuel and natural gas.

Experiments in northern Spain with poplarSRF indicate very positive energy balances asseen in the table 7.

The energy inputs are estimated at between 2%and 7% of the energy produced.

The use of mineral fertilisers and herbicides(production and application) are the most criticalenvironmental costs for the system, representing40% to 96% of the total environmental impactof the categories analysed.

The utilisation of solid biomass in a large powerplant for the production of electrical energydemands the use of lters for near completereduction in emission of ne particles. Italiantechnical regulations clearly de ne strictemission limits and lter technologies are welldeveloped from a technical point of view andare economically viable.

Markets and economicsof productionIn Italy there are currently two markets forbiomass from SRF poplar plantations:

Biomass power plants and small to mediumsized CHP/district heating

Industry for panel production and timberfor furniture

There are around ve operating biomassplants in northern and central Italy that accept woodchips from SRF (almost 60 MW e installedcapacity). For the near future some important

Table 7. Poplar crop energy balance (AGROSOST project 2004 2007. UAB, ARU, CIEMAT, Spain)

Type of energy MJ produced MJ consumedDirect energy stored in biomass 18200 368Calori c energy production (85%) 15470Electric energy production (27%) 4910

(*) Main energy consumption stages include agrochemical production (42%); transport (39%)

operators have expressed interest in supplyingbiomass power plants with woodchips fromSRF plantations. In particular:

ENEL: the largest national energy companyand electricity provider plans to introduceco- ring with biomass from SRF in fourof its coal plants;

POWERCROP: a company of the Eridania-Sadam Group (sugar industry) plans tocommission 4 biomass power plants by2011 after decommissioning sugar plantsfollowing sugar policy reforms.

SOME FIGURES for Italy:

Average fuelwood price: 40-50 /t biomassdelivered to plant gate (40 % moisture)

Average price paid to farmers for standingtrees: 18-20 /t fresh biomass (harvestingand transportation costs excluded, paid bybuyer)

Average revenues for 35 t fresh biomass/ha:630-700 /ha per year

Average annual plantation costs (includingplantation establishment): 350-500 /ha peryear

Grants from Rural Development Programavailable for initial establishment ofplantation (around 40 % of direct costs)

There is not a clearly established Spanishmarket as energy crop production is still at an

early stage. Some important Spanish companieshave shown interest in using woody biomassfrom SRF plantations alone or mixed withother fuels:


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pure vegetable oil or anaerobic digestion.In most regional plans, grants are allowedalso for the establishment of permanentplantations of energy crops such as SRFof poplar or other species, as well as forbuying harvesters and other machinery orequipment.

Measures of the RegionalOperative Programmes The European Regional DevelopmentFund (ERDF) established according to Reg.EC 1783/99 is another EC structural fundaimed at increased social and economiccohesion among the different Europeanregions.

National measures and incentivesfor green electricity The Italian legislation for incentives forgreen electricity is evolving. As far as

the electricity produced from biomass isconcerned, two dist

handbook for energy producers_www version[1]

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