Europe biomass overview; how main

species are currently grown

Jos Iglesias Martnez de Antoana

Abstract

This text aims to explain the actual situation of the biomass scenario in Europe, using

the literature survey. Compiling and comparing how main European species are

commonly harvested. Their methods of planting, silvicultural treatments, and

therefore, all the practices for each species. And reporting the currently situation in

the different countries, using the information available from researches, studies, and

other publications.

Keywords

Biomass, countries, harvesting methods, main species, Willow, Poplar, Eucalyptus.

Index

1 Introduction ......................................................................................................... 6

2 Methodology.............................................................................................................7

3 General knowledge ..................................................................................................8

3.1 Little history of biomass ................................................................................... 8

3.2 A renewable source of energy........................................................................... 9

3.3 Biomass fuels classification............................................................................. 12

3.4 Primary forest biomass for energy use .......................................................... 12

3.5 Fuels Standars and fuels types ....................................................................... 13

3.5.1 Moisture content .......................................................................................... 14

3.5.2 Ash content................................................................................................... 14

3.5.3 Calorific value .............................................................................................. 15

3.5.4 Additional information ................................................................................ 15

3.5.5 Determination of properties ........................................................................ 15

3.5.6 Quality assurance for the standards ........................................................... 16

3.6 Utilization of Biomass Energy ........................................................................ 17

3.6.1 Types of biofuels .......................................................................................... 17

3.6.1.1 Firewood .................................................................................................... 17

3.6.1.2 Chips .......................................................................................................... 18

3.6.1.4 Briquettes .................................................................................................. 23

3.7 Technologies for getting biomass fuels ........................................................... 24

3.7.1 Pelletization .................................................................................................. 24

3.7.2 Gasification .................................................................................................. 24

3.7.3 Biological Methods ....................................................................................... 24

3.7.4 Briquetization .............................................................................................. 25

3.7.5 Torrefaction ................................................................................................. 25

3.7.6 Hydrothermal carbonization ....................................................................... 25

3.7.7 Pyrolysis ....................................................................................................... 26

3.8 Biomass scenario ............................................................................................. 28

4 Short Rotation coppice crops................................................................................31

4.1 What is a short rotation coppice crop? .......................................................... 31

4.2.1 Poplar ........................................................................................................... 34

4.2.1.1 Hybrids ...................................................................................................... 36

4.2.1.2 Growing procedures ................................................................................ 40

4.2.1.2.1 Levelling ................................................................................................. 40

4.2.1.2.2 Ploughing the field ................................................................................. 40

4.2.1.2.3 Weed control .......................................................................................... 40

4.2.1.2.4 Planting .................................................................................................. 42

4.2.1.2.5 Planting machinery ................................................................................ 43

4.2.1.2.6 Fertilization ............................................................................................ 44

4.2.1.2.7 Replanting .............................................................................................. 45

4.2.1.2.8 Parcel protection .................................................................................... 45

4.2.1.2.9 Watering ................................................................................................. 45

4.2.1.2.10 Harvesting ............................................................................................ 46

4.2.1.2.11 Harvesting machines ............................................................................ 46

4.2.1.2.12 Direct chipping harvest machinery ..................................................... 47

4.2.1.2.13 Whole plant harvest machinery ........................................................... 47

4.2.1.3 Countries ................................................................................................... 48

4.2.2 Eucalyptus .................................................................................................... 50

4.2.2.1 Eucalyptus species ..................................................................................... 52

4.2.2.2 Growing procedures ................................................................................. 54

4.2.2.3 Countries ................................................................................................... 56

4.2.3.1 Species ....................................................................................................... 60

4.2.3.2 Growing procedures ................................................................................. 60

4.2.3.2.1 Planting .................................................................................................. 61

4.2.3.2.2 After planting ......................................................................................... 63

4.2.3.2.4 Whole-shoot harvesting ......................................................................... 64

4.2.3.2.6 Cut-and-billet ......................................................................................... 66

4.2.3.2.7 Regrowth ................................................................................................ 66

4.2.3.2.8 Fertilizing and watering ......................................................................... 66

4.2.4 Birch ............................................................................................................. 69

4.2.5 Alder ............................................................................................................. 70

4.2.7 Spanish broom ............................................................................................. 72

4.2.8 Paulownia ..................................................................................................... 72

4.2.9 Leucaena....................................................................................................... 73

4.2.10 Stump harvesting ....................................................................................... 73

5 Conclusions.......................................................................................................................75

6 Bibliography.....................................................................................................................77

6

1 Introduction

According to many sources of information biomass could be defined as:

1. Total dried matter of all the living species (animal, vegetable, etc) that live in a

determined placed, expressed in dried weight per unit area or volume.

2 Organic matter originated in a biological process, induced or spontaneous, usable

as an energy source.

The first definition is commonly used in ecology. The second meaning is more

restricted. Refers to the 'useful' biomass in energetic terms. Plants transform the sun's

radiant energy into chemical energy through photosynthesis, part of that chemical

energy, is stored in the form of organic matter (chemical energy). Chemical energy

from biomass can be recovered burning it directly or transforming it into fuel.

Therefore we accept the second definition including materials resulting from the

natural or artificial transformation.

One common mistake is to use biomass as a synonym of the useful energy that can

be extracted from it, leading to some confusion because the relation between useful

energy and biomass is highly variable and depends on many factors. To begin, the

useful energy may be extracted by direct combustion of biomass (wood, animal

excrement, etc.), but also of the combustion of fuels derived from it by physical or

chemical transformations (methane of organic waste, for example) in process which

'always' lost something original useful energy.

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2 Methodology

The purpose of this part is explaining the actual situation of the forestry biomass

scenario in Europe.

At first, it is necessary to get an overall point of view of the biomass sector. What

includes legality, type of fuels that are used, processes of getting this fuels, biomass

problems, etc. Because this information is useful to understand the nowadays

biomass situation.

Secondly, It is focused on how biomass sources are obtained (what type of

machinery is used and how), the properties of the different biomass plant species

(heating value, yield of production, selection of clones, suitability of this clones etc),

the silvicultural treatments that are commonly done(type of cutting, time in which is

done, etc), the main structure of this crops (spacing of plants).

Aiming at giving a comparison of how biomass crops are developed in the different

countries.

This explained scenario will make an idea about the economic sector situation. In

which it is remarked some aspects about the biomass market. And finally a

conclusion, in which it is explained how biomass sector will develop on the future.

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3 General knowledge

The documentation used to make this book is wide, books, newspapers articles,

thesis, websites. Forestry and therefore biomass sector, have a complete set of

researches. All the media what I have used to make this book has been correctly

mentioned.

3.1 Little history of biomass

1812. A gas company in London, England, demonstrates the first commercial use of

pyrolysis, heating biomass in an oxygen-free environment to produce a liquid oil.

1840. First commercially used biomass gasifier is built in France.

1860s. Wood is the primary fuel for heating and cooking in homes and businesses,

and is used for steam in industry, trains and boats.

1870s. Gasifiers are used with engines for power generation

1876. The Otto Cycle, invented by German scientist Nicolaus August Otto, is the

first combustion engine to use ethanol-blended gasoline.

1880s. Henry Ford uses ethanol to fuel one of his first automobiles, the quadricycle.

1890s. Coal begins to displace wood used in steam generation.

1900. Vegetable oil is used as a diesel fuel when German inventor Rudolf Diesel

demonstrates that a diesel engine can run on peanut oil.

1908. When designing his Model T car, Henry Ford expects ethanol to be the major

fuel used by motorists. He builds an ethanol fermentation plant in Atchison, Kansas,

to manufacture ethanol for motor fuels.

1910s. Although wood remains the fuel of choice in rural homes in North America,

coal begins to replace the use of wood in city homes.

1930s. Kerosene and fuel oil begin to replace wood as primary energy source.

In the United States, ethanol is used to fuel cars well into the 1920s and 1930s.

During the

1930s. for example, more than 2,000 service stations in the U.S. Midwest sell

gasohol (ethanol made from corn).

1940s. After World War II, the ethanol fuel industry closes down in the United

States, with the arrival of low-priced, abundant petroleum fuels.

1950s. Electricity and natural gas displace wood heat in most homes and commercial

buildings.

1970s. Concerns about crude oil supplies and environmental quality lead to renewed

interest in ethanol and other biomass energy sources. Governments begin to fund

research into converting biomass into useful energy and fuels.

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1980s. Companies such as Chevron, Texaco and Amoco Oil Company begin to

market ethanol-blended fuels to U.S. consumers.

High energy prices create new interest in biomass energy in Canada. In Atlantic

Canada, for example, large institutions and schools modify district heating systems to

run on wood wastes.

1970s.Biomass power plants are built in North America.

A large biomass power industry quickly develops in California. By 1985, the state

has 850 megawatts of installed biomass power capacity.1

1990s. As public concerns about environmental issues such as air pollution and

climate change grow, governments in Canada and elsewhere take a greater interest in

using renewable energy, such as biomass, to decrease. 2

Various materials can be used for the energy supply. Of these, the wood products

have been the main source of renewable energy used by man until the industrial

revolution, even today, for 2,500 million people still be the main source of energy.

3.2 A renewable source of energy

The production of energy obtained from fossil materials, predominantly, is associated

with the release of a large quantity of emissions whose action has multiple and

significant negative effects on ecosystems. And for which, as for CO2 and nuclear

waste of power plants, there are no solutions for treatment and elimination.

Biomass as a way of power generation plays an important role here because of it can

directly intervene not only in control, by reducing the amount of CO2 released to the

atmosphere by the energy sector, being the sump on the man can act with greater

success.

The main characteristic of biomass is that form a closed energy cycle, that is why this

energy could be call as a renewable energy source.

Green plants and algae, through photosynthesis process used atmospherical CO2 for

the production of its own tissues, so that CO2 is temporarily fixed (sink effect). Later

this CO2 is returned to the atmosphere as a result of plant respiration, and by the

decomposition of dead parts of plants. Therefore, unlike fossil fuels, biomass is a

renewable resource that has a CO2 balance of zero, which is one of the useful

reasons for its use.

1 (http://www.centreforenergy.com/AboutEnergy/Biomass/History.asp) 2 http://wdronline.worldbank.org

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To explain what happen with biomass cycle at a high level. Biomass cycle regulates

the amount of atmospherical carbon. Biosphere effectively acts like a carbon sponge.

This sponge effect, however, is limited. Just as a sponge at home, biomass can only

absorb so much carbon at a time.

When is too much carbon in the atmosphere, one solution is to make the sponge

small, as we do with deforestation, or finally the carbon balance is lost, and no more

will be absorbed.

If there is too much carbon in the atmosphere earth heats up. It happens when

greenhouse gases (carbon dioxide, water vapour, nitrous oxide, methane, etc.) trap

heat and light from the sun in the earths atmosphere.

The fundamental process that explains the warming of the earth's surface is the

greenhouse effect. Which is the accumulation of heat in the lower atmospheric

layers, by the intervention of greenhouse gases. These gases have the capacity to be

nearly transparent to short wave radiation that comes from the sun, but opaque to

long wave radiation emitted from the Earth.

The average temperature on Earth has already warmed by close to 1C since the

beginning of the industrial period. In the words of the Fourth Assessment Report of

the Intergovernmental Panel on Climate Change (IPCC), a consensus document

produced by over 2,000 scientists representing every country in the United Nations:

Warming of the climate system is unequivocal. Global atmospheric concentrations of CO2, the most important greenhouse gas, ranged between 200 and 300 parts per

million (ppm.) for 800,000 years, but shot up to about 387 ppm. Over the past 150

years, mainly because of the burning of fossil fuels and, to a lesser extent, agriculture

and changing land use.3 A decade after the Kyoto Protocol set limits on international

carbon emissions, the developed countries enter the first period of rigorous

accounting of their emissions, but greenhouse gases in the atmosphere are still

increasing. Worse, they are increasing at an accelerating rate.

At the Convention of the United Nations Framework on Climate Change (1992),

scientific community alerted of the problem of global warming and climate change.

Since then, and after successive meetings, in 1997, in the United Nations Framework

Conference on Climate Change, it was signed the Kyoto Protocol, which was ratified

in 2002 by the European Union. Trying to reach the objective of that industrialized

countries reduce its emissions by an 8% below the 1990 volume.

In Article 10 of the Kyoto Protocol, there were adopted procedures for afforestation

and reforestation, as good development mechanism during in the first period (20082012). Countries participating in these projects must follow the Guide to Good

Practice for Land Use, Land Change and Forestry, made by the IPCC

(Intergovernmental Panel on Climate Change).

3 http://www.biomassenergycentre.org.uk

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In addition, due to the growing importance of CO2, in Kyoto Protocol is considered

the possibility of using forests as carbon sinks. Contributing to increase the CO2 fixation, originated by burning fossils fuels, and change of use to from forestry to

farm forestry. Reducing the negative effects on climate change. Therefore it is

important to get knowledge of atmospheric CO2 sequestration by tree biomass.

The effects of climate change are already visible in higher air and ocean

temperatures, widespread melting of snow and ice, and rising of the sea levels. Cold

days, cold nights, and frosts have become less frequent while heat waves, heavy

rainfall and floods are more common, and the damage and probably the intensity of

storms and tropical cyclones have increased. This transcends negatively in many

aspects of human activities, and thus constitutes one of the main concerns of this

time.

There are some other substances that are liberated to the atmosphere by the smoke

produced in the firing, but instead a common firing, in a biomass heating system

polluted gases has to pass through some filters in order to get free to the atmosphere.

The production of CO2 and other greenhouse gases, as the residues from nuclear

power plants are increasing. It is for this reason that the wider adoption of renewable

energy is present as an essential element to improve fuel independence and thus

avoid such undesirable and unsustainable effects that occur on environment.

Biomass as a power generation plays an important role here and which can directly

intervene not only in control, what is more, in reducing the amount of CO2 released

into the atmosphere by the energy sector, being the sump on the man can act with

greater ease.

Biomass relies on sustainable forest management, and does not mean over-

exploitation of the forests. Most forest biomass is produced from material that would

have no other use such as sawmill residues, forest thinnings and forest wastes, such

as tops, branches, and low quality logs left over after higher quality logs have been

removed. Now, instead of being wasted, forest biomass is used to replace fossil fuels,

besides it delivers socioeconomic benefits in rural communities.

Over-exploitation of this resource with annual harvest levels above annual growth is

an unsustainable short-term practice that will drain the forest resource over time.

Sustainable forest management involves good silvicultural practices which improve

forest growth and prevent fires, insect attacks and other disruptive events. And it can

also involve harvesting in forest areas killed or heavily affected. Such practices

maintain or improve overall carbon stocks.

Sustainable biomass can and must make a meaningful contribution if society is to

achieve its ambitions on renewable energy and climate change mitigation. Choosing

fossil fuels over biomass does irreversible damage to our climate and limits societys opportunities to switch to renewable energy. Leaving unmanaged forests, however, is

12

a poor option as it would deepen the carbon debt created by prolonged burning of

fossil fuels and will not develop local sustainable industries and managed in a

credible and efficient manner.

3.3 Biomass fuels classification

Woodfuel by origin are classified as:

-Direct woodfuels (primary biomass):

They are made of wood and wood products extracted directly from the forest and

agroforestry lands.

-Indirect woodfuels:

Subproducts derived from wood primary industries (that process directly the tree or

log that comes from the mountain) and secondary industries (process the wood

elaborated on primary industries, can produce residues with additives and glues).

- Recovered woodfuels:

Derivatives of all economic and social activities non related with the forestry sector,

such as construction waste, demolition of buildings, pallets, containers, wooden

boxes, etc.

3.4 Primary forest biomass for energy use

Primary forest biomass is the biodegradable part of products and waste generated in

the forest, and energy crops, that are processed for the purpose of obtaining energy.

The main materials that constitute the primary forest biomass are:

- Derivatives of silvicultural treatments:

Branches and twigs from pruning jobs. Trees cut from thinnings, phytosanitary

logging or trees affected by forests fires.

-Remains of logging:

Branches and tops from final fellings and intermediate cuts.

-Firewood from pollarding and non-timber trees:

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Branches and trunks from non healthy trees.

-Woody and herbaceous energy crops:

Plantings are made with high density and very short rotation, selecting the species

according to the amount of biomass produced.

-Brush clearing:

Cleaning shrubs in forest. All these products are supplied through the works of

forestry companies, obtained from sustainable forest management.

The management of primary forest biomass since its collection until it turns into

energy, is a costly process that requires a correct planning and the use of new

technologies to achieve optimization. The low bulk density makes forest biomass

transportation difficult and very expensive. What is more it requires large storage

spaces. Therefore it is necessary to get products more compact and easy to use. The

heterogeneity of the biomass and the application that it is going to be given,

determines the treatment required. The pre-treatment processes biomass, both in field

and factory are:

- Drying: natural or forced.

- Chipping, grinding or milling.

- Densification: pellets, briquettes, packaged.

To obtain other fuels like bio-ethanol or biodiesel or black liquors the wood will

suffer physical and chemical transformations.

3.5 Fuels Standards and fuels types

Before defining the biomass combustion sources it is necessary to understand that it

has to be given in a determined way, under standardisation it is possible to confer a

determined economic value to a type of fuel.

Standardisation aims at removing trade and application barriers by establishing

unification (of concepts, procedures and products) within a national or international

community of concerned stakeholders. Standards increase economization,

compatibility, user-friendliness and security in the application and exchange of

products and services

The fuel specifications and class standards simply set out which properties of

different kinds of fuels need to be stated when selling that fuel, and how the values

are given (normative properties). As well as these properties, it also sets out another

set of properties (informative) that may need to be given in some situations, or which

may be given as supplementary information.

The European Commission in 2002 asked the Committee European of Normalisation

(CEN) to establish some standards about the residues derived fuels. Then, CEN

created the following technical committees:

14

TC335 about solid biofuels and TC343 about solid recovered fuels (SRF).

TC335(European committee) creates BS EN 14961-1, which last actualization was in

2010, and that sets out the general requirements and lists of what properties must be

stated for each solid biofuel type (wood pellets, briquettes, chips, firewood and non-

woody pellets). EN 14961 parts 2 to 6 each then apply to an individual solid biofuel

type and describe specific classes of that fuel, such as an A1 wood pellet, or a B2

wood chip, with particular combinations of properties. The properties that need to be

stated for most forms of solid biofuels are:

Biomass origin i.e. what is it made of and where does it come from tree (stemwood, branches, stumps), waste wood, straw, etc.

Dimensions (diameter, length, proportions of chips in different size ranges, etc.). Moisture content. Ash content. 4

3.5.1 Moisture content

The moisture content is especially important because of it is heavily related with the

fuel calorific power.

Moisture content is usually specified as the percentage of the total weight of the

(wet) sample, i.e. wet basis. However, it can also be quoted on dry basis as (i.e. U25

25%) with the weight of water given as a percentage of the mass of dry biomass. Although both values are equally valid, and can be readily converted from one to

another, it important always to be clear which basis has been used. Not only must

moisture content be measured correctly and accurately, product sampling is

particularly important when measuring moisture content as it is a parameter that can

vary considerably within a pile of woodchips and within a single log.

3.5.2 Ash content

Ash comprises the non combustible mineral content of the fuel and predominantly

consists of oxides of alkali and alkaline earth metals, such as potassium, calcium and

magnesium. The ash content of biomass can vary considerably, with very low levels

in heartwood, and much higher levels in bark.

Cereal straw tends to be much higher still. Some boilers and stoves are designed to

be able to burn high ash content fuels, but some cannot do so. In addition to the

quantity of ash, some ash tends to melt at a lower temperature, which can give rise to

the formation of lumps of clinker or slagging. This can block air flow through the

grate.

4 http://www.biomassenergycentre.org.uk

15

3.5.3 Calorific value

Calorific value (CV.) is the energy content of the fuel. While provision of the

calorific value (Q.) of the fuel is not an essential requirement of the standards (i.e. it

is informative rather than normative) we suggest that provision of this information, particularly when dealing with woodchips, is beneficial. The calorific

value of most forms of wood is similar based on the same weight and moisture

content but the density of different tree species does affect the volume energy

density. Broadleaf wood by volume generally has >30% greater energy content than

softwood.

Broadleaf species may appear to grow much slower than conifer species on the same

site but when the calorific value is considered the difference is much less. This can

be particularly important when considering the value of traditional coppice

management of broadleaf species like sweet chestnut.

By definition net calorific value is defined as the energy content per unit weight (Q.).

It is also possible to specify energy density (E.), which is energy content per unit

volume. The net CV. of woodfuel is highly dependent on moisture content, and

consequently some people prefer to buy by volume rather than weight, which is

much less sensitive to moisture content.

3.5.4 Additional information

In addition to the main parameters described above, other properties may only need

to be specified in certain cases, for example nitrogen, chlorine or sulphur content

where the origin is chemically treated biomass, or bulk density in the case of wood

chips sold by volume.

There are also a number of parameters that are included as informative. These are only required to be given in certain circumstances, such as when there may be some

reason why the value might be higher than the typical range. This might apply to

biomass grown on land with high natural levels of metal ores, or where chlorine

levels might be high as a result of growing near to the sea, or where the land might

be contaminated with industrial waste or sewage sludge.

3.5.5 Determination of properties

What the majority of the standards do is set out how each property must be

measured. If the parameters are to be regarded as absolute values, independently

verifiable and comparable between different measurements, there has to be a

standardized protocol. Of the suite of 30 or so standards, 20 are concerned with the

determination of the parameters outlined in the previous section. Each one sets out

16

the equipment to be used, the procedures to be employed, the level of precision, etc.

for the determination of one or a number of parameters. Many of these are only of

relevance to test laboratories and cannot be performed without specialist equipment

and facilities; however these are for the most part determinations that will not be

required for the majority of biofuel sold.

Where they are required it may simply be necessary to perform an occasional

measurement on a representative sample to determine that it is within the normal

range.

There are, however, a few measurements which it is possible for the fuel supplier to

perform for themselves without excessive expenditure or technical expertise. And

these, fortunately, are the ones that it is most important to monitor on a routine basis.

Although BS EN 14774-2:2009 sets out how moisture content should be measured

using specialist equipment, it can also be measured reasonably accurately using a

domestic oven. It is also possible to use a hand held, electrical resistance type

moisture meter to measure the moisture content of a firewood log, provided it is

referenced back to the oven dry method in the standards. Considerable care must be

taken when doing this as there are a number of factors that can give an incorrect

measurement. Many such meters give dry basis moisture content so it is important to

be sure which basis is being used.

Analysis of samples for concentration of heavy metals and other chemical species

does require a specialist test laboratory, however, this is unlikely to be necessary for

most fuel suppliers except possibly on an occasional basis.

3.5.6 Quality assurance for the standards

Because the end user needs a fuel that works properly, the standards for a particular

class not only shows the working properties. All points along the supply chain must

be monitored and, where necessary, documented to ensure that standards are met.

In addition, it must ensure that contamination is avoided, processes perform their role

properly and, if there are any subsequent concerns about fuel quality it is relatively

straightforward to identify where and when any slipping of standards might have

occurred and how many other users of the fuel might potentially be affected. The

aim of the QA standards is to guarantee the fuel quality through the whole supply

chain, from the origin and source to the delivery of the solid biofuel and provide

adequate confidence that specified quality requirements are fulfilled.

It is an explicit aim of the standards that: Quality assurance measures shall establish confidence in the fuel through systems that are simple to operate and do not cause

undue bureaucracy. It is the duty of the fuel supplier to check levels and report if

necessary.

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3.6 Utilization of Biomass Energy

The use of forest biomass with energy purpose require in most cases a previous

transformation. In order to get the most suitable products for use as fuel.

The main problem of biomass fuels is its price. Which is expensive based on their

supply in comparison with conventional fossil fuels (mainly diesel and gas). The

drawbacks of its supply are related with the lowest calorific power of biofuels per

m.3, that make its transport expensive.

In the majority of countries of the European Union the use of biomass is not

generalised yet (because of there are not enough companies of manufacturing and

distribution, and in so much cases they are rural).

3.6.1 Types of biofuels

FAO defines wood energy as the energy obtained from solid biofuels, liquid and

gas derived from primary and secondary forests, trees and other vegetation on forest.

The classification of products according to the Unified Wood Energy Terminology

(UWET) is: firewood, wood chips, wood pellets, charcoal briquettes, charcoal, black

liquor, and other wood fuels.

3.6.1.1 Firewood

The term firewood includes all wood obtained from forests or other source which its

original format is the timber.

Firewood dried as round wood in long lengths for example will dry by evaporation

from the ends so will exhibit a very significant variation in moisture content from a

maximum in the middle to a minimum at each end. Firewood recently cut from such

a long length will show considerable variability between logs as a result.

The firewood firing is the most traditional form and can be obtained from any woody

species, both forest and agricultural. It is cylindrical or conical, very heterogeneous

in size with a low density. It is used to split it up in order to get a better storage and

conservation. And because it is necessary to get it with the ideal properties for its

use. Thats why the firewood must be dry correctly because of the greater the moisture contents the lower the power calorific. Thereof, the tree species is close

related in this aspect.

To avoid the problems of burning wood without previous drying we must place in a

moisture content close to 15%, taking into consideration that the firewood with high

18

moisture slows and hinders the combustion, produce condensation and tar in the flues

and reduces its calorific value.

One of the key things a customer needs to know is if the logs will fit in their wood

stove or boiler. Therefore, the maximum length (or length range) and range of

diameters are both stated.

For example, a delivery of L25 logs would all be less than 25 centimetres long; and D10 logs would have a diameter of between 5 and 10 centimetres.

One of the key things for firewood that a customer needs to know is if the logs fit in

their wood stove or boiler. Hence the maximum length (or length range) and range of

diameters are both stated. For example, to delivery of 'L25' logs would all be less

than 25 centimetres long, and 'D10' logs would have a diameter of 10 centimetres.

The important issue is to describe the product. The CEN standards (EN14961-2)

provides a simple method of doing this.

Firewood is given a quality code of A1, A2 or B. the main characteristics of each are:

A1 logs will be more than 90% split and will have no visible decay; A2 logs will be more than 50% split and may have up to 5% decay; and B logs will be less well seasoned with more than 25% moisture content by overall weight and tend to be larger.

5

3.6.1.2 Chips

The chips are a result of crushing of the wood, producing irregular pieces, having a

thickness of about 2 cm. and varying sizes that will normally not exceed 10 cm. in

length.

Chips have a low density and a much higher surface area than firewood, so starts

quickly the time of combustion. The drying process is expensive but increases the

calorific power.

The chips that provide forests is completely natural and contains no additives,

obtaining a clean biofuel that faces the greenhouse gas emissions

Wood chips standard (EN 14588- 4.183), establish parameters for chipped woody

biomass in the form of pieces, with a defined particle size produced by mechanical

treatment with sharp tools such as knives.

5 http://www.biomassenergycentre.org.uk

19

Hog fuel standard (EN 14588 4.94). Is provided by Crushing/ shredding wood in the form of pieces of varying size and shape and produced by crushing with blunt

tools such as rollers, hammers, or flails.

Its very difficult to ensure a whole load of woodchips are of the same size, just because of the way they are produced. So the dimensions of wood chips are specified

in terms of the range of sizes of 75% of the sample, measured using sieves.

While woodfuelled systems can be designed to burn a variety of woodchip sizes

many modern systems have been designed to deliver very high efficiencies in

converting the energy stored in the wood into heat. To work well they need

woodchips of the correct size, generally with a low proportion of small, or fine,

material which would reduce the efficiency of the combustion and a low proportion

of larger pieces which could jam the feed system.

The CEN standards use simple calibrated sieves to assess the composition of

particular samples:

A common specification is likely to be P16 and this will comprise:

75% of the total volume of woodchips being between 3.15mm. and 16mm. Less than 12% of the total volume of woodchips will be less than 3.15mm. in size; For P16A no more than 3% will be more than 16mm. and all will be less than 31.5mm.

OR for P16B no more than 3% will be more than 45mm. and all will be less than

120mm. 6

3.6.1.3 Pellets

Pellets are particles pressed from wood dried splinters. The wood usually comes

from pruning and cleaning of forests, residues from sawmills and forest or forestry

crowns industries. But in some countries like in the north of Europe are obtained

directly from the main logs. Pellets need to undergo a process of chipping, grinding

and compression in small cylinders from 6 to 10mm, having a diameter between 10

to 30mm. normally. Have a 650700kg./m.3 density, a calorific value of 40004500 kcal./kg. (2 kg. of pellets are equivalent to 1 litre of diesel) and with a moisture

content of 712%. Their great advantage is its easy storage, transport and dosing, what is more pellets behaves like a fluid.

The pellet manufacturing history is more recent than briquettes. Pelleting presses

were used to manufacture animal feed. It was not until 1961 when he began his

densification for energy. That year, the company Sprout-Waldron Co., press

manufacturer, created a complete installation for granulate oak bark in Tennessee

(USA).

6 Luis Ortz, Alejandro Tejada, Antonio Vzquez, Aprovechamiento de la Biomasa Forestal producida

por la Cadena Monte-Industria, CIS-Madera magazine.

20

In 1967, the forestry research laboratory associated with the University of Oregon,

made 200 trials about to bark granulation.

In 1977, Gunneman created the Bio Solar Research in Eugenia, Oregon, and

launched a trial in Browneville (Oregon). In the same year, registered a granulation

patent called Woodex. It is remarked that the material must be ground (particle size

must be less of the 85% of the minimum size of the pellets), dry or humidified

(moisture content between 16 and 28%).7

In the case of pellets, and particularly non-woody pellets, the ash melting behaviour

is also important and included as informative. In the case of grasses and cereals ash

melting point can be significantly lower than for wood and this can cause slagging

problems (formation of solid lumps of ash melted together in the grate) in many

boilers and stoves. Specific forms of biomass may also require additional properties

to be stated, such as mechanical durability, bulk density and percentage of fines

(dust) for pellets, any additives and net calorific value for pellets and briquettes,

particle density for briquettes, etc.8

Existing coal crusher can easily disintegrate the pellet since it is composed of ground

particles. But over time, pellets can absorb moisture, swell and disintegrate resulting

in increased dust formation and mechanical strength against crushing. Biological

degradation can also occur. Hence, pellets are required to be stored in a dry place,

which is hazardous due to the potential for heat generation in the pellet piles.

Therefore, there is need to impart hydrophobic property to pellets.

The calorific power of pellets can be increased by combining some technologies like

torrefaction with pelletization. Torrefaction pellets have some added advantages over

conventional biomass-based pellets including improved durability, grindability,

hydrophobicity, and coal-like combustion. Energy and environmental performances

of torrefaction pellets power generation has not yet been analyzed.

The process of combined torrefaction and pelletization imparts this property. During

this process, biomass slightly decomposes, retaining 7080% of the original mass as solid products and releasing the rest as torrefied gas.

Note that, the solid and volatile fractions contain almost 90% and10% of the initial

biomass energy content, respectively. Hence, torrefaction pellets demonstrates a

higher energy density compared to that of conventional bio-pellets and primary

densified biomass.9

The big advantage of this product is its quality and that is a manufactured product so

it can be delivered to remote areas from the production site. Pellets are the biomass

fuel that is more generalized, and therefore has the least supply problems.

Quality is a central issue for the further development of pellet markets.

7 http://www.biomassenergycentre.org.uk 8 Xun Luo, 2011, Torrefaction of biomass, a comparative and kinetic study of thermal decomposition

for Norway spruce stump, poplar and fuel tree chips. 9 Wolfgang Hiegl, Rainer Janssen, 2009, Advancement of pellet-related European standars,

www.pelletatlas.info

21

Especially the residential heating sector depends on reliable fuel quality since it is

crucial for a reliable and economic use of small-scale pellet heating systems.

Several European countries such as Austria (NORM M 7315), Sweden (SS

187120) and Germany (DIN 51731), that was set out in 1996, have introduced pellet-

related standards in the past, but experiences in these countries showed that standards

need to be accompanied by a control system that certifies pellet production and

minimum pellet quality. In Austria, for example, the pellet standard is connected to a

certification label (NORM tested) that certifies pellet producers and guarantees unproblematic pellet usage for the end-consumer.

This did not work in Germany where production in agreement with DIN standards is

usually certified by the DIN tested label. However, this label is granted without external controls at the production site. Furthermore, the minimum requirements of

DIN 51731, developed by (Deutsches Institute fr Normungare) not always strict

enough for unproblematic pellet combustion in small-scale applications. This

standard also lacks a threshold for mechanical durability.10

This led to the development of the standard-independent certification scheme for

wood pellets DINplus by DIN CERTCO Which combine features of the German and

the Austrian standard, Including external controls and strict quality requirements.

There is a new standard called EN Plus that is generalizing now. New certificate is

definitely in the European pellet market new standards and enhancing

transparency. This system has been agreed upon by the European Pellet Council in

January 2011 With "ENplus" European standard EN 14961-2 is

implemented. ENplus future goes beyond pure product standard and integrates the

entire supply chain in its certification system.

ENplus with the wood pellets are divides into three classes. For consumers, the class

A1 will be important because it is based on the absolute strictest criteria. A2 with a

wide range of raw materials. And B for the pellet with an industrial purpose, with

less strict requirements. The bulk density is the same for the three categories but and

ash melting behaviour differs (> 1200 C for A 1,> 1100 C for A2 and B).11

ENplus certification differs from EN 14961-2 in the following parts:

Raw material basis (no chemically treated wood is allowed in class B in EN certification).

Ash melting behaviour is mandatory (voluntary in EN 14961-2). Ash used for determining the ash deformation temperature (DT) is to be produced at 815 C.

12

Wood pellets of the EN-B class cannot be sold as bagged pellets.

10 http://www.biomassenergycentre.org.uk 11 European Pellet Council, Handbook for the Certification of Wood Pellets for Heating purposes,

2011, http://www.pelletcouncil.eu 12 http://www.primeenergysolutions.ie

22

The European Biomass Association (AEBIOM) together with 10 national pellet

associations as well as an industry representative (Laborelec) have established this

IEE funded project to develop ENplus and implement the certification all over

Europe (with Germany, Austria, Spain, Italy and Finland leading the way). The

project started in May 2011 and will run for 3 years).

No matter which pellet quality standard will receive eventually a higher level of

acceptance, the necessity to certificate biomass pellets quality must be of highest

concern so as to enhance the commercial potential of the produced pellets in the

developing world biofuel market.

In several countries, additional environmental quality labels or pellets for pellet

heating or Have Been published. In Some Countries These quality labels as a

substitute functions for the Lack of a national standard, while in others they work as

a supplement the national standard.

Austria: The Federal Ministry for the Environment has devised a special label for

biomass fuels environment, where only raw materials from natural wood are

allowed. At present no Austrian pellet manufacturer has applied for this label.

Sweden: The Swedish wood pellets trade body, Pellsam, Consists of manufactures

and suppliers of pellet heating equipment. Pellsam offers its member companies a

competitive advantage in the form of a 6 year full insurance cover for unexpected

break-down or damage to the equipment pellet.

UK: The Department of Trade and Industry Codes of Good have produced for

Biofuel pellets and Practice. These codes are adopted by British BioGen members as

a standard for products and services. The Codes of good practice will be superseded

by the European Standards for Solid Biofuels once they are published.

France: The Association for Professionals Bioenergy Pellet has created a club,

which aim is to Promote the quality of fuels and have Established a quality label for

this purpose. It faces specific advice on determining a quality pellet for various uses

stoves, boilers, heating large scale power plants.

Denmark: A national standard for pellets have been in great demand for the Danish

consumers and suppliers. As a substitute three quality labels from respectively Force

Technology, Teknologisk Institute and soon the Danish environment label

Svanemrket" have entered the market and offer quality certifications for pellet

manufactures and suppliers.13

In addition to that, it is remarkable that too many companies have started to accredit

pellets making essays and giving a certification. Such as Intertek, Hetas,

Woodsureson.

13 http://gasification.askdefine.com/

23

3.6.1.4 Briquettes

The term briquette is a clear term for on the other side and confusing. It is a clear

term because a briquette can not be confused with other fuel. But it is unclear that the

briquette can be made of very different compacted materials.

Thus, the raw material can be biomass provided by silvicultural treatments, biomass

waste from wood mills (sawmills, doors, furniture factories, particle board plants,

etc), residual industrial biomass, urban waste biomass, charcoal or simply a mixture

of all them. The composition of the briquettes varies by area due to the availability

of raw materials.

The raw materials are gathered and compressed into briquette in order to burn longer

and make transportation of the goods easier. These briquettes are very different from

charcoal because they do not have large concentrations of carbonaceous substances

and added materials. Compared to fossil fuels, the briquettes produce low net total

greenhouse gas emissions because the materials used are already a part of the carbon

cycle.

The common feature of all is briquetted its high density. Its shape is generally

cylindrical, but not so long (octagonal, rectangular with rounded corners). For

example, coal-briquettes are produced compacting coal dust or granulated coal is

shaped, and its shape is like and egg or a hazel of 12-20 cm. long.

One of the most common variables of the biomass briquette production process is

the way the biomass is dried out. Manufacturers can use torrefaction, carbonization,

or varying degrees of pyrolysis. Researchers concluded that torrefaction and

carbonization are the most efficient forms of drying out biomass, but the use of the

briquette determines which method should be used.

Compaction is another factor affecting production. Some materials burn more

efficiently if compacted at low pressures, such as corn stover grind. Other materials

such as wheat and barley-straw require high amounts of pressure to produce

heat. The standard briquettes parameters in many standards like 14961-3, BS EN

15210-1:2009, CEN/TS 15210-2: 2005. Extendedly used in the third World.

24

3.7 Technologies for getting biomass fuels

3.7.1 Pelletization

Pelletization involves compressing dried and ground biomass and extruding it under

high pressure to produce cylindrical pieces. Through palletization, bulk density can

be increased up to 410 times. Since densified biomass is tenacious and fibrous in nature with a large particle size, they are difficult to grind in a coal-fired power plant

using existing coal crusher.

3.7.2 Gasification

Gasification is a process that converts carbonaceous fossil organic based materials on

carbon monoxide, hydrogen and carbon dioxide. This is achieved by reacting the

material at high temperatures (> 700 C), without combustion, with a controlled

amount of oxygen or steam. The resulting gas mixture is called synthesis. The power

derived from the gasification and combustion of the resulting gas is considered to be

a source of renewable energy, if gasified compounds were obtained from biomass.

The advantage of gasification is that using the synthesis gas is potentially more

efficient than direct combustion of the original fuel, besides it can burn at higher

temperatures, or even in the fuel cell, so that the higher thermodynamic limit of

efficiency defined by Carnot's rule is higher or not applicable. The synthesis gas can

be burned directly in gas engines, which is used to produce methanol and hydrogen,

or converted via the Fischer-Tropsch process, into synthetic fuel. Gasification can

also begin with a material that would otherwise have been removed as biodegradable

waste. Furthermore, the high temperature process refines corrosive ash elements such

as chloride and potassium. Gasification fossil fuels are widely used in industrial

scales to generate electricity.14

3.7.3 Biological Methods

It is an alcoholic fermentation which transforms the biomass to ethanol (biofuel).

This alcohol is produced by the fermentation of sugars.

Another biological method is the methane fermentation, which is the anaerobic

digestion of the biomass by bacteria. It is typically used for the transformation of wet

biomass. In the fermenters, or digesters. Cellulose is the substance that is going to be

degraded as a gas, which contains about 60% methane and 40% carbon dioxide. For

14 http://www.sector-project.eu

25

this process requires a temperature between 3035 C. These digesters for its high autonomy have a favourable option for intensive livestock farms.

3.7.4 Briquetization

There are also different press technologies that can be used. A piston press is used to

create solid briquettes for a wide array of purposes. Screw extrusion is used to

compact biomass into loose, homogeneous briquettes that are substituted for coal in

cofiring. This technology creates a toroidal, or doughnut-like, briquette. The hole in

the centre of the briquette allows for a larger surface area, creating a higher

combustion rate.

3.7.5 Torrefaction

Torrefaction is a mild pyrolysis process performed between 250 and 320 C at

atmospheric pressure in the absence of oxygen. Torrefaction combined with

pelletization improves biomass fuel qualities. Size reduction of torrefied biomass

requires 5085% less electrical energy than size reduction of fresh biomass. Torrefied pellet production consists of initial heating, drying, torrefaction, cooling,

size reduction, and pelletization.

One of the key advantages of this process is that, utility fuel consumption in biomass

drying is either eliminated or substantially minimized through the utilization of

torrefaction gas (Uslu et al., 2008). The moisture content of torrefied pellets was

considered to be 3 wt.%.15

3.7.6 Hydrothermal carbonization

Is a new biomass conversion process. Organic materials becomes a product similar to

lignite by a heat treatment under pressure of the material in aqueous suspension at

temperatures of 180220 o C. The resulting char is CO2 neutral, and can be incinerated or used for all industrial applications traditionally reserved to lignite. The

process transforms all the carbon present in the plant residues into coal (100%

efficiency in the use of carbon). All of this process is developed without releasing

CO2 or methane. If used as a component of products to improve soil, char

contributes to improve the arid soils. Furthermore, char produced catch CO2 in the

soil, contributing to the removal of greenhouse gases in the atmosphere over time.

15 Hydrothermal carbonization of biomass residuals: a comparative review of the chemistry, processes

and applications of wet and dry pyrolysis

26

The carbonization hydrothermal conversion of biomass produces CO2 neutral coal

through a chemical process anaerobic. The process separates hydroxide anions (HO-)

and hydrogen cations (H +) from the organic molecules, which become water (H2O).

The dried organic molecules are combined to form a number of different carbon

compounds. This process is very similar to the naturally carbonization. As H2O is a

very stable molecule, every time you remove a molecule of water of all these organic

molecules also releases energy. This makes the process is HTC effective and highly

exothermic.16

17

18

3.7.7 Pyrolysis

Pyrolysis is thermal decomposition occurring in the absence of oxygen. It is always

also the first step in combustion and gasification processes where it is followed by

total or partial oxidation of the primary products. Lower process temperature and

longer vapour residence times favour the production of charcoal. High temperature

and longer residence time increase the biomass conversion to gas and moderate

temperature and short vapour residence time are optimum for producing liquids. The

product distribution obtained from different modes of pyrolysis process are

summarised in the table below. Fast pyrolysis for liquids production is of particular

interest currently as the liquids are transportable and storage.19

Typical product yields (dry wood basis) obtained by different modes of pyrolysis of

wood20

Mode Conditions Wt% Liquid Char Gas

Fast ~500

oC, short hot vapour residence time

~1 s 75% 12% 13%

Intermediate ~500

oC, hot vapour residence time ~10-

30 s 50% 25% 25%

Slow - Torrefaction ~290oC, solids residence time ~30 mins -

82%

solid 18%

Slow -

Carbonisation

~400oC, long vapour residence time hrs -

> days 30% 35% 35%

Gasification ~800oC 5% 10% 85%

16 http://www.bioenergyinternational.es 17 Joaqun Mas, 2011, Biomasa Forestal de la Comunidad Valenciana: Estado Actual y Futuro 18 Alain Damien, Biomasa: Fundamentos ,Tecnologas y Aplicaciones 19 http://www.pyne.co.uk 20 http://eur-lex.europa.eu

27

Fast pyrolysis occurs in a time of few seconds or less. Therefore, not only chemical

reaction kinetics but also heat and mass transfer processes, as well as phase transition

phenomena, play important roles.

The critical issue is to bring the reacting biomass particle to the optimum process

temperature and minimize its exposure to the intermediate (lower) temperatures that

favour formation of charcoal. One way this objective can be achieved is by using

small particles, for example in the fluidised bed processes that are described later.

Another possibility is to transfer heat very fast only to the particle surface that

contacts the heat source, which is applied in ablative processes.

In fast pyrolysis biomass decomposes to generate mostly vapours and aerosols and

some charcoal. After cooling and condensation, a dark brown mobile liquid is formed

which has a heating value about half that of conventional fuel oil. While it is related

to the traditional pyrolysis processes for making charcoal, fast pyrolysis is an

advanced process, with carefully controlled parameters to give high yields of

liquid. The essential features of a fast pyrolysis process for producing liquids are:

Very high heating and heat transfer rates at the reaction interface, which

usually requires a finely ground biomass feed.

Carefully controlled pyrolysis reaction temperature of around 500oC and

vapour phase temperature of 400-450oC.

Short vapour residence times of typically less than 2 seconds.

Rapid cooling of the pyrolysis vapours to give the bio-oil product.

The main product, bio-oil, is obtained in yields of up to 75% weight on dry feed

basis, together with by-product char and gas which are used within the process to

provide the process heat requirements so there are no waste streams other than flue

gas and ash. A fast pyrolysis process includes drying the feed to typically less than

10% water in order to minimise the water in the product liquid oil (although up to

15% can be acceptable), grinding the feed (to around 2 mm in the case of fluid bed

reactors) to give sufficiently small particles to ensure rapid reaction, pyrolysis

reaction, separation of solids (char), quenching and collection of the liquid product

(bio-oil). Virtually any form of biomass can be considered for fast pyrolysis. While

most work has been carried out on wood due to its consistency, and comparability

between tests, nearly 100 different biomass types have been tested by many

laboratories ranging from agricultural wastes such as straw, olive pits and nut shells

to energy crops such as Miscanthus and Sorghum, forestry wastes such as bark and

solid wastes such as sewage sludge and leather wastes.

At the heart of a fast pyrolysis process is the reactor. Although it probably represents

at most only about 1015% of the total capital cost of an integrated system, most research and development has focused on the reactor, although increasing attention is

now being paid to control and improvement of liquid quality including improvement

of collection systems. The rest of the process consists of biomass reception, storage

and handling, biomass drying and grinding, product collection, storage and, when

relevant, upgrading.

28

3.8 Biomass scenario

The directive 28/2009/CE aims to develop the use of biofuels and other sources of

renewable energy in all the European members. And derogates the Directive

2003/30/CE that was set out in order to promote the use of renewable fuels in the

transport.

Directives 2001/77/EC and 2003/30/EC set indicative targets for 2010 for all State

Members, and some measures were planned for the growth and development of

renewable energy. In addition, in 2005 was adopted a biomass action plan with 31

measures to promote biomass, and were it aims to the MS to have national action

plans.

Nonetheless, in January 2007, several reports showed that Member States will not

achieve its objectives for 2010, so EU does not reach the goals. The Commission

therefore proposed a new more rigorous framework to promote the development of

renewable energies for 2020.

Directive 2009/28/EC is part of the package about European Energy and Climate

Change, which provides the basis for the EU to achieve its objectives for 2020: a

20% improving of energy efficiency, renewable energy contribution of 20% and a

reduction of emissions of greenhouse gases (GHG) of 20%. However, taking into

account the conclusions adopted by the Heads of State and Government of the

European Union, could happen a GHG reduction target to reach 30% in 2020. 21

In Europe, 54% of primary energy from renewable sources comes from biomass, go

However, it represents only the 4% of the total energy. Specifically, according to

data of the European renewable energy EurObserv'ER in 2010 primary energy

production due to biomass was quantified at 78.8 Mtoe. Most were consumed in

house heating, and district heating. Overall, around 83% is for thermal uses and 17%

of electricity production. Germany, with 11.690 Mtoe. heads the production,

followed by France and the Scandinavian countries, which are considered the true

leaders in line with its population since. 22

A report from EurObserv'ER suggests that if most populous countries of the

continent, those with significant forest resources, such as France, Germany, Spain

and Italy, intensify their efforts in this area can reach the target. The White Paper

expects biomass to be the leader of European renewable energy development. If all

these good intentions are realized, the contribution of biomass at the end of the

century could reach a quarter of global energy production.

21 EurObserv'ER, December 2012, Solid Biomass barometer 22 http://www.ieabioenergy.com

29

IEA Bioenergy is an organisation set up in 1978 by the International Energy Agency

(IEA) with the aim of improving cooperation and information exchange between

countries that have national programmes in bioenergy research, development and

deployment.

The International Energy Agency acts as energy policy advisor to 28 Member

Countries plus the European Commission, in their effort to ensure reliable,

affordable, and clean energy for their citizens. Founded during the oil crisis of 1973-

74, the IEAs initial role was to co-ordinate measures in times of oil supply emergencies. As energy markets have changed, so has the IEA. Its mandate has

broadened to incorporate the Three Es of balanced energy policy making: energy security, economic development, and environmental protection. Current work

focuses on climate change policies, market reform, energy technology collaboration

and outreach to the rest of the world, especially major producers and consumers of

energy like China, India, Russia and the OPEC countries.23

Activities are set up under Implementing Agreements. These are independent bodies

operating in a framework provided by the IEA. There are 42 currently active

Implementing Agreements, one of which is IEA Bioenergy.

The Intelligent Energy Europe (IEE) programme is giving a boost to clean and sustainable solutions. It supports their use and dissemination and the Europe-wide

exchange of related knowledge and know-how.

The Seventh Framework Programme (FP7) bundles all research-related EU

initiatives together under a common roof playing a crucial role in reaching the goals

of growth, competitiveness and employment; along with a new Competitiveness and

Innovation Framework Programme (CIP), Education and Training programmes, and

Structural and Cohesion Funds for regional convergence and competitiveness. It is

also a key pillar for the European Research Area (ERA).

The broad objectives of FP7 have been grouped into four categories. This are

cooperation, ideas, people and capacities. For each type of objective, there is a

specific programme corresponding to the main areas of EU research policy. All

specific programmes work together to promote and encourage the creation of

European poles of (scientific) excellence.24

For example, Finland biomass energy provides 50% of heating, and 20% primary

energy consumption. However, the current rate of growth in production from

biomass will make impossible to deal with the objectives set out in the White paper

on renewable energy. The European Commission emitted a communication to the

Council and the European Parliament, in which, they confirmed that the development

of technologies related to biomass suffered from poor coordination of policies and

insufficient financial support.

According to the Commission, only Denmark, Finland and the UK experiment a

growing of biomass energy source. However, they concluded, in most of the new

23 http://cordis.europa.eu 24 http://www.fao.org

30

Member States there is significant potential of using biomass to generate both

electricity and heat.

Biomass stimulates forest development. Wood demand generates investments in

forest management and new forest plantations. The forest stock in Europe is steadily

increasing. In the last 20 years, the European carbon stock increased by 26%25

due to

an increased forest area (an additional 3.5 million hectares between 2000 and 2010)26

and harvesting at levels well below the annual growth (only 63% of the annual

growth is harvested). Statistics show steadily growing forests, although the use of

bioenergy has been increasing at the same time.

It is incorrect to suggest that increased bioenergy adoption will lead to increased

harvesting of our forests. Bioenergy uses waste and residue streams from well

established sustainable harvesting practices. Maybe, it is not economically feasible

for the energy sector to cut down trees in order to turn them into pellets or chips, and

this is not expected to change in the foreseeable future.

Europe faces the threefold challenge of meeting increasing energy demands while

reducing its dependency on fossil fuels and mitigating climate change. To effectively

address these challenges, the European Union (EU) aims to support the development

of renewable energy sources. This is embodied in Directive 2009/29/EC, which

states that at least 20% of total energy consumption should be met by renewables by

2020 (10% in the transport sector).

25 http://epp.eurostat.ec.europa.eu 26 http://www.unece.org/

31

4 Short rotation coppice crops

4.1 What is a short rotation coppice crop?

Despite these high expectations, the development of energy crops is relatively small

in relation to the expected energy objectives. However this situation is differs on the

type of crop. Thus, agricultural crops for the production of first generation biofuels

have gained a significant level of development, and now constitute the most dynamic

sector in the biomass sector, due to certainly that suppose to the farmer of being

traditional agricultural species. And because have there existed incentives for

commercial establishment. In contrast to this, the lignocellulosic energy crop type,

among which include herbaceous and woody species do not have similar measures.

In practice, this has delayed the necessary technological development that requires

this type of crop, because there are new species; or known species, whose cropping

conditions are different from the traditional. This unsatisfactory state of

lignocellulosic energy crops has been analyzed at the level of the EU.

Because of the expected increase in biomass it is possible that in the future we can

attend a state incentive and support for their development and commercial

deployment.

Lignocellulosic biomass production by the method of coppicing has been used by

man since ancient times, providing contributions of this raw material concentrated in

both space and time. In the last decade, short-rotation tree crops (Short Rotation

Forestry, SRF, in British terminology) become relevant, to be an adequate way of

providing raw material in relatively short time. Your destination can be mainly the

energy production by different processing methods (currently thermal and electrical

applications).

Crops are considered short-rotation forestry (SRF) those used in the fast-growing

species under intensive management system and a short shift between 2 and 10 years.

Potential species considered for biomass production by the SRC must possess a

number of important characteristics, including

-Possess high energy potential and be a quality fuel.

-Ensuring high yields of biomass dry weight.

-Fast youth growth.

-Show good re-growth capacity.

-Have narrow crown or wide sized leaves.

-Provide great adaptability to different sites and resistance to biotic and abiotic stress,

among others.27

27 H.Sixto, M.J. Hernndez, M. Barrio, J. Carrasco, I. Canellas, 2007, Plantaciones del gnero Populus

para la produccin de biomasa con fines energticos: revisin

32

It is recommended that in dryer places the species will be perennial, because annual

species do not provide a good soil protection. Biomass SRC crops also act as

effective windbreaks, and provide shelter to wildlife, it has been reported a high

richness of species diversity.

In this way, it is considered that the biodiversity in these plantations is significantly

higher than in substitute crops. The ability to regenerate after the cut reports other

advantages, for example, the low installation cost of the following one. This makes

possible to combine productive and environmental aims. By contrast, the need for

irrigation in these crops is common in lower latitudes, despite being much lower than

other traditional crops such as corn, is a drawback that should be solved by applying

waterings and using highly water efficient plant material.

The species chosen usually have a broad genetic base, short improvement cycles,

easy vegetative propagation, ability to sprout after cutting, etc.

Currently, European countries such as Denmark, Britain and Sweden, (the last with

more than 13,000 ha. of SRF), are leading in commercial applications short-rotation

forestry crops, developing and implementing an active investigation. That is is

promoted using an incentive policy.28

The three effects that seem to be important in deciding plantations designs and

management of SRC are:

1) The law of constant production end, which explains that the performance of a crop

rise when density is increased, although from a density yielding became to be

independent thereof. This may be used to determine the maximum number of

cuttings per hectare in SRF plantations.

2) Competition between individuals is a fact, so it makes to be dominant and

dominated trees. Turn be established based on this competition time, to prevent loss

of strain viability.

3) Under the clearing law of Yoda et al. (1963) total biomass per unit increases

exponentially without mortality until canopy closure.29

For a determined density there is an optimum turn in which maximum soil resources

are exploited, shortening the turn when the initial densities are high. However, this

does not mean that shorter turn always is going to be the best, because the best turn

will be that for which the plant successfully exploit all the resources optimally, and

from which production decay happens after that.

At higher densities, the number of branches and leaves is smaller, so that, the

percentage of usable woody biomass increases as well as helping reducing

competition from weeds, but once you have closed cups, there are few differences in

production compared to other crops made with larger frames. Also it should be noted

28 http://www.aebiom.org 29 H.Sixto, M.J. Hernndez, M. Barrio, J. Carrasco, I. Canellas, 2007, Plantaciones del gnero Populus

para la produccin de biomasa con fines energticos: revisin

33

drawbacks to plantations high density, such as an increase in bark percentage, resins

and other chemicals biomass which may be undesirable for subsequent energy use.

In addition to this, it must be added an increase establishment cost.

Bullard et al. (2002) compared willow plantations with densities between 10,000 and

the 111,000 stems/ha. and realised that were not obtained a density from which

production began to decrease.30

There are various references that report bigger productions in the second rotation and

successive from the first cut. Due to the high number of shoots per strain, and

especially strains that already have developed root system. They reach the crown

closing faster. Thereby it is achieved a more effective control of herbaceous

competition and therefore a more efficient use of the resources available for

plantation development.31

Therefore, it is possible to consider the desirability of make a cut in the first year,

seeking greater production supported by a shoot with an installed root system. At the

same time, this first harvesting allows initial a more effective intervention in weed

controlling plantations in case of poorly installed plantations. And may involve also a

big source supply of clonal material for successive time plantations.

The current trend is the application of reduced turn and the realization of a more

intensive crop. It is supported by the different studies that have found increases of

production reducing turns while increasing density. But still many questions about

turn and optimal frames for a clone or species planted at a site.

It is required a research effort to determine the maximum annual increase in biomass

by species and ecological conditions (climate and soil). As only in this way, can be

determined the turn and optimal framing for each condition.

The choice of plant species depends apart from the end-use, the ease of bio-

conversion of this species (combustion, gasication, pyrolysis, fermentation or mechanical extraction of oils). Some plant species are good for all of the potential

conversion technologies. For example rapeseed oil can be processed via combustion,

gasication, pyrolysis or mechanical extraction, while others such as wood and cereal crops are suitable mainly for combustion, gasication, pyrolysis and fermentation.

It is important to note that, while particular plant species may have specic benets for subsequent processing technologies, the amount of potential energy available

from a given biomass source is the same, independently of the conversion technology

used.

30 H.Sixto, M.J. Hernndez, M. Barrio, J. Carrasco, I. Canellas, 2007, Plantaciones del gnero Populus

para la produccin de biomasa con fines energticos: revisin 31 Elizabethh E.Hood, Peter Nelson, Randall Power, 2011, Plant biomass conversion

34

What will vary between conversion technologies is the actual amount of energy

recovered from the biomass source and the form of that energy.

The attention paid to particular woody/herbaceous plant species varies around the

world, taking account of the soil and climatic factors that affects growth. In the

context of northern Europe, much attention has been focused on the C3 woody

species, especially those grown as short rotation coppice (SRC) for example willow

and poplar and forestry residues.

4.2 European main biomass species

4.2.1 Poplar

Naturally poplar is a tree that reaches 2530m. high at ten years. It has a height of 1517 m., with an average diameter of 1113 cm. It has a fast growing, 6meters in the first 6 months. It has a wood density between

0.45 and 0.75t./m3, a 1015% bark rate and a 4550% of dry matter. The optimum

temperature is between 15C25C, tolerating between -10C y 40C. Needs at least a 600mm. precipitation.

The genus has over 40 species with a wide range of variability. It has high capacity

for inter-specific hybridization, which has been linked with his great ability to adapt

to different environmental conditions.32

33

It springs from strain and more difficult from root.

Poplar is principally attacked by Marssonina brunnea, Melampsora larici-populina,

Melampsora allii-populina, Dothichiza, Xanthomonas populi and Rosellinia

necatrix.

Poplar has been investigated in central European countries and in the U.K. for

many years, but the information on poplar still appears rather scattered and not

as focused on energy use as for willow. But there are possibilities of transferring

information and breeding material between countries. Poplar seems to be more

resistant to pests and diseases in comparison with willow.

The poplar is adapted to wet and temperate climate. The altitude range for growing

poplar is very broad and it generally grows well until 1000 m. altitude.

32 Alain Damien, Biomasa: Fundamentos ,Tecnologas y Aplicaciones 33 Hortensia Sixto Blanco, M Jos Hernandez Garasa, M Pilar Ciria Ciria, Juan Esteban Carrasco

Garca, Isabel Caellas Rey de vias, 2010, Manual de cultivo de Populus spp. para la produccin de

biomasa con fines energticos, INIA

35

Is necessary the presence of land with at least 80 cm. deep for the proper

development of roots, with a pH between 6 and 8. Avoiding sandy soils. Poplar

cultivation requires loose soil, well aerated, deep, low clay (less than 15%), with

more than a 2% contents of organic matter, active lime concentrations below 6% and

without salinity. It prefers loamy textures, or sandy loam, with slimes and with high

retention capacity. Short floods winter has no bad consequences. But poplar can not

suffer frequent waterlogging, what causes root suffocation. It Requires the irrigation

application in most arid places, unless in specific local conditions, continuous rainfall

and/ or the existence of groundwater that ensure water supply needed for its growth. 34

35

For each species of Populus, hybrids and clones could find different tolerances to

different soil parameters, resistance to pests and diseases, re-growth capacity after

cutting or yields. It must be taken into account when making the choice of the most

suitable plant material.

The International Poplar Commission defined in 1985 the clone capable of being

used ideally in short turns in culture and was characterized, among other things, by

presenting a juvenile fast growth, high continuous production of shoots, ability to

grow in high densities, extensive vegetative period and positive response to cultural

treatments, among others.

For example there are clones that stand out of others in the first rotation which may

have a lower yields in the successive, due to their different response to coppicing. 36

The poplar is highly appreciated by the paper industry ,which values its good

delignification and its ability to get bleached and performance.

EUBIA conditions for biomass crops, are recommended to have a density of 10.000

to 15.000 stems/ha., 1 3 year rotation, 25cm. mean diameter harvest, 2.57.5 m. average height and a production 2045 t./ha. Is harvested, with a humidity of 5055%.37

The humidity is variable (5055%). The composition is 42 to 56% cellulose, 1825% hemicellulose and 2123% lignin. The ash content varies from 1.6% to 3%. The composition of the whole plant, in % over DM. (dry matter) is: 81.57% volatile

matter, 16.8% carbon, 0.06% sulphur, 0.39% nitrogen and chlorine < 0.1%.

Has a NCV of 18.7 MJ./kg.DM.(dry matter), yielding 916 (t. DM./ha. Year). Giving us energy per unit area of 170300 (GJ./ha.). 38

34 http://hybridpoplar.com 35 http://www.extension.umn.edu/distribution/naturalresources/components/00095part3.pdf 36 http://www.fao.org 37 http://www.eubia.org/ 38 Alain Damien, Biomasa: Fundamentos ,Tecnologas y Aplicaciones

36

4.2.1.1 Hybrids

Poplars of Tacamahacan section and hybrids from Tacamahacan x Aigeiros shown

very good potential for growth in SRC at a high density. It has young vigorous

growth that depends on the species and clone used.

The species belonging to Aigeiros section (P. nigra, P. deltoides and P. angulata).

Present a maximum annual average growth at 1015 years. Although do not suited to high density crops. Species Tacamahacan section (P. maximiczii, P. trichocarpa, P.

balsamifera) have a maximum annual average growth at 410 years, Trepidae subsection (P. tremula, P. tremuloides, P. grandidentata ) occurs between 1015 years.

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All these clones known as interamerican arise from crossing two American species (Populus deltoides and Populus trichoc