b i om a s s a n d b i o e n e r g y 3 5 ( 2 0 1 1 ) 1 9 9 5e2 0 0 5

Avai lab le a t www.sc iencedi rec t .com

ht tp : / /www.e lsev ier . com/ loca te /b iombioe

Assessment of the availability of agricultural and forestresidues for bioenergy production in Romania

Nicolae Scarlat a,*, Viorel Blujdea b, Jean-Francois Dallemand a

a Institute for Energy, Joint Research Centre, European Commission, Via E. Fermi 2749, TP 450, 21027 Ispra (Va), Italyb Institute for Environment and Sustainability, Joint Research Centre, European Commission, Italy

a r t i c l e i n f o

Article history:

Received 24 July 2009

Received in revised form

24 January 2011

Accepted 28 January 2011

Available online 22 February 2011

Keywords:

Assessment

Agricultural residues

Forest and wood processing

residues

Biomass availability

Bioenergy

Romania

* Corresponding author. Tel.: þ39 (0) 3327865E-mail address: nicolae.scarlat@ec.europ

0961-9534/$ e see front matter ª 2011 Elsevdoi:10.1016/j.biombioe.2011.01.057

a b s t r a c t

This paper provides a resource-based assessment of availability of biomass resources for

energy production in Romania, at NUTS-3 level. The estimation of available biomass

includes the residues generated from crop production, pruning of vineyards and orchards,

forestry operations and wood processing. The estimation of crop residue availability

considers several site-specific factors such as crop yields, multi-annual yield variation,

environmental constraints and competitive uses. The evaluation of agricultural residues

was based on specific residue to product ratios, depending on crop type and crop yield. An

estimate of pruning residues is proposed, based on current orchard and vineyard areas and

specific ratios of residues. Woody biomass considers forest and forestry residues (including

firewood) and wood processing by-products, taking into account the type and share of the

unused part of the tree biomass and technical and economic aspects, including availability

and competitive use. The amount of agricultural and forest residues available for bioenergy

in Romania was estimated at 228.1 PJ on average, of which 137.1 PJ was from annual crop

residues, 17.3 PJ residues from permanent crops and 73.7 PJ/year from forestry residues,

firewood and wood processing by-products. The biomass availability shows large annual

and spatial variations, between 135.6 and 320.0 PJ, due to the variation in crop production

and forestry operations. This variation, which is even larger at the NUTS-3 level, if not

properly considered may result in shortages in biomass supply in some years, when

biomass is available in a lower amount than the average.

ª 2011 Elsevier Ltd. All rights reserved.

1. Introduction is a 24.0% share of energy from renewable sources in gross final

The energy from renewable sources in Romania contributed

187.5 PJ in 2005 and 195.0 PJ in 2007 [1]. Themost important part

came from biomass (64% of the renewable energy), of which

biomass used for heating represented 99.5% of renewable

energy used for heating, while biomass contribution to renew-

able electricity generation was insignificant in 2005. For

Romania, the target set by the Directive 2009/28/EC on the

promotionof theuseof energy fromrenewable sources for 2020

51; fax: þ39 (0) 332789992a.eu (N. Scarlat).ier Ltd. All rights reserved

consumption, which is an increase of 6.2% from 17.8% in the

2005 reference year. The National Renewable Action Plan [2],

developed according to the Renewable Energy Directive, esti-

mates that the gross final energy consumptionwill be 1268 PJ in

2020 in the additional energy efficiency scenario. Achieving the

overall national target for 2020 impliesa consumptionof energy

from renewable sources of 304 PJ. Biomasswill continue to play

a major role in achieving this target, although the contribution

of other renewables, such as wind, is expected to increase.

.

.

b i om a s s an d b i o e n e r g y 3 5 ( 2 0 1 1 ) 1 9 9 5e2 0 0 51996

From the point of view of existing potential, biomass repre-

sents a promising renewable energy source for Romania. Bio-

energy production represents one of the opportunities for

agriculture and rural development, providing alternative

options for using agriculture, forestry and wood processing

residues.The increasing roleofbiomass in futureenergysupply

requires the use of all available resources in a sustainable way,

without causing directly or indirectly negative impacts. The

Romanian Strategy for the valorisationof the renewable energy

sources, adopted by the Government Decision 1535/2003, esti-

mated the biomass potential at 318 PJ, of which: forest residues

and firewood (49.8 PJ/year), wood waste, such as sawdust and

other wood remains (20.4 PJ/year), agricultural wastes cereal

straw, maize stalks, trimming residues (200.9 PJ/year), biogas

(24.6 PJ/year) and municipal solid wastes (22.8 PJ/year).

The biomass from agriculture and forestry may constitute

a significant resource for bioenergy that could significantly

contribute to the total energy supply. However, the main

technical aspects of biomass residues utilisation for bioenergy

production relate to the resource availability at local level. A

better assessment of the biomass availability is therefore

needed at regional and local level, which can assist in the

identification of themost adequate locations and capacities of

biomass-based plants. Therefore, this paper provides a res-

ource-based assessment of the available agricultural and

forestry residues which can actually be used for energy

production in Romania at NUTS-3 (Nomenclature of Territo-

rial Units for Statistics) level, which corresponds to counties.

The annual variation in biomass production/availability for

bioenergy is a key factor to consider, since this can cause

shortages in supply in certain years, if not adequately taken

into account. This variability impacts on the location and

operation of bioenergy plants, transport and other logistics,

because the location of a bioenergy plant must consider the

minimum available resources in the area. Also, lower res-

ources available in the bioenergy plant area can lead to

logistical problems and decreased economics of the plant, due

to the increased collection area, longer transport routes and

increased biomass collection costs. Therefore, this paper

provides an estimate of the inter-annual variability of biomass

availability, to provide actual data on the biomass which is

available each year for energy generation.

2. Methods, data and assumptions

This paper aims to produce a resource based assessment of

biomass availability for bioenergy production, providing

conservative estimates, in compliance with agro-environ-

mental constraints and current competitive uses. The esti-

mation ismade both at national and county (i.e. NUTS-3) level,

for which sound statistics are currently available. Biomass

availability depends on the supply costs, and therefore,

increased public supportmechanisms improve the economics

of bioenergy production and increase resource availability.

This analysis concentrated on the estimation of the natural

capital without integrating full mobilisation costs and public

support mechanisms.

The paper considers the residues generated from agricul-

tural crop production, pruning of vineyards and orchards,

forestry operations and wood processing. The residues (straw,

stalks, stems and cobs) generated from the main agricultural

crops, which could be used for energy production, are

included in the estimation: wheat, barley, oats, rye, rice, and

maize, sunflower and oilseed rape. The assessment of the

agricultural crop residues availability considers several site-

specific factors such as crops yields, multi-annual yield vari-

ation, environmental constraints and competitive uses. The

estimation of agricultural residues is based on specific total

residue to product ratios, depending on the crop type and crop

yield. The estimates of pruning residues from fruit tree plan-

tations and vineyards are based on current orchard and

vineyard areas and specific ratios of residues. Forest residues

included in the estimates consider forestry residues, firewood

andwood processing by-products. Estimations of their annual

availability are based on the time series harvested quota,

types of operations (final cut, forest thinning and cleaning

operations) and on species/group of species (coniferous,

beech, oak.), at NUTS-3 level. The estimates took into

account their availability, forest accessibility, type and share

of the commercially unused part of the tree biomass and

technical and economic aspects of their collection. Wood

processing residues (sawdust, shavings, bark, wood remains,

etc.) estimations are based on the by-products fraction, taking

into consideration the technological process.

The estimates of the total biomass potentially available for

bioenergy production are given as the average, maximum and

minimum amounts at NUTS-3 level, thus considering their

annual variations. Key data is provided by national statistics

[1], providing complete, detailed and spatially disaggregated

time series. The period from 2000 to 2006 is selected as

a reference for the study. The availability of biomass at local

level and the distribution of the biomass resources over the

land area are essential for bioenergy production. Therefore,

the density of biomass resources per land area was estimated

as an adequate criterion for comparing available resources

between regions and counties and as a key factor in the

economics of a bioenergy plant. This provides an indication of

on the areas which are the most adequate and cost-effective

for bioenergy production and where the collection cost of

biomass is the lowest.

2.1. Agricultural land and forest land in Romania

From the total area of Romania (23.8 Mha), the utilised agri-

cultural area covers, on average, 10.3 Mha, (43.4% of the total

area) out of which arable land is 6.6 Mha (Fig. 1). Cereals have

the highest share of agricultural production, with a produc-

tion of 10.5Mt in 2000 and 15.8Mt in 2006, peaking at 24.4Mt in

2004. The rapeseed production increased steadily in the last

years, from 76,100 t in 2000 to 361,500 t in 2007, due to the

increased use of rapeseed oil for biofuels production [1].

Romania is also an important producer of sunflower, with

a production ranging from0.7Mt in 2000 to 1.5Mt in 2006. Fruit

production covers an area of 207,000 ha and reaches almost

1.5 Mt/year. Vineyards cover about 185,000 ha, with a grape

production of about 1.2 Mt/year [1].

Romania has an area of about 6.4 million ha covered by

forests, with 29.9% coniferous, 49.5% non-coniferous (31.5%

beech and 18.0% oak), 15.7% various hardwood species and

Fig. 1 e Distribution of agricultural and forest land in Romania.

b i om a s s a n d b i o e n e r g y 3 5 ( 2 0 1 1 ) 1 9 9 5e2 0 0 5 1997

4.9% various softwood species. Of the total forest area, 66% are

in the mountain areas, 24% are in hilly areas and 10% in the

plains. The total standing wood volume was estimated to

about 1350 million m3, of which 39% is coniferous, 37% beech,

13% oak and 11% other species. The average standing wood

volume per hectare is 217 m3, but there are forests in the hill

and mountain areas with a higher wood volume per hectare,

of 900e1300 m3/ha. The average increment is about 5.6 m3/ha

per year and the wood increment of the entire forest area

represents 35 million m3 of wood per year [3].

2.2. Agricultural crop residues

Significant agricultural residues are generated from agricul-

tural crops (e.g. wheat, barley, oats, rye, rice, maize, sunflower

or oilseed rape), like straw and stover (i.e. stalks, ears, leaves,

cobs). The estimation of agricultural residues in this study

takes into account: a) annual grain/seed yields for different

types of crops; b) variation of the crop area; c) crop residue to

yield ratios for different types of crops; d) residue removal

rates according to the environmental and economic

constraints and agricultural technology used; e) competitive

wheat and barleyy = -0.3186Ln(x) + 1.503

R2 = 0.2883maize

y = -0.1807Ln(x) + 1.3373R2 = 0.1732

oats and ryey = -0.2073Ln(x) + 1.3466

R2 = 0.2163

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0

Yield [t/ha]

Rat

io s

traw

:gra

in [

-]

wheat and barley maize oats and rye

Fig. 2 e Straw to grain ratio for cereals.

use of crop residues (i.e. for animal bedding, mushroom

farming) [4].

The crop residue yields vary evenmore than the crop yields

[5,6] and is therefore difficult to account for, as it depends on

plant variety, location, climate conditions, farming practices

and other effects [7,8]. The values for residue to yield ratios,

dependent on crop types, were obtained from a literature

survey. Frequently, in different studies, a constant crop to

residue production ratio is assumed [9e11], which might not

be valid as the ratio varies greatly across different sites/

climates, plant varieties, farming practices, annual yields, etc.

Values of the ratio reported in the relevant literature [6e27]

were compiled for different agricultural crops and the

average dependence of the residue to yield to crop biomass for

each type of cropwas established (Figs. 2 and 3). The residue to

grain ratios vs. crop yield were plotted and yield to residue

ratios curves were produced for each type of crop, depending

on the crop yield. The values used in the estimation and other

data used in the calculations are presented in Table 1. In the

estimations of crop residue available for energy, a lower

heating value for crop residues of 14.5 MJ/kg was considered,

determined from a dry matter heating value of 17.5 MJ/kg.

rapeseedy = -0.452Ln(x) + 2.0475

R2 = 0.1669

sunflowery = -0.9356Ln(x) + 3.152

R2 = 0.1931

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0

Yield [t/ha]

Rat

io s

traw

:see

d [-

]

rapeseed sunflower

Fig. 3 e Straw to grain ratio for rapeseed and sunflower.

Table 1 e Main characteristics of agricultural residues used in this study.

Crop type Residue toyield ratio

Availability[%]

Seed moisturecontent [%]

Straw moisturecontent [%]

Wheat and barley 1.05e1.78 40 15 15

Rye and oat 1.08e1.42 40 15 15

Maize 1.04e1.52 50 15 30

Rapeseed 1.20e1.98 50 15 50

Sunflower 2.20e3.50 50 15 40

Source: [33e35].

Table 2 e Residue to fruit yields obtained for pruning.

Crop Residue tofruit yields

Moisture[%]

Availability[%]

Apple trees 0.2e0.5 40 80

Pear trees 0.2e0.5 40 80

Peach trees 0.4e0.6 40 80

Apricots 0.4e0.6 40 80

Cherry trees 0.4e0.6 40 80

Plum trees 0.8e1.2 40 80

Nut trees 0.6e1.8 40 80

Vineyards 0.3e1.0 40 80

Source: [37].

b i om a s s an d b i o e n e r g y 3 5 ( 2 0 1 1 ) 1 9 9 5e2 0 0 51998

As a result of varying local conditions, the estimates of the

amount of residues that may be removed vary widely and

have a high degree of uncertainty. Several studies proposed

different values for sustainable removal rates of crop residues.

Walsh et al. [9] and Van der Sluis et al. [28] suggested biomass

removal rates of between 30 and 40% of the residue without

reducing soil productivity. Some authors proposed a sustain-

able removal rate of 40e50% for wheat straw andmaize stover

[7,8,15], while Glassner [29] estimated that 20e60% of maize

stover can be sustainably harvested. Low tillage farming with

high crop yields could lead to a higher removal rate, increasing

the availability of straw for other uses [14], up to 68e75% of the

maize residue [15], or even 76e82% [15,29]. In this study,

removal rates of 40% for wheat, barley and oats and 50% for

maize, sunflower and rapeseed were considered.

The estimates of the available crop residues must include

the consideration of competing uses. Animal breeding is the

most important competitive use of straw and stover, which

are used mostly for feeding and bedding [30]. Straw is also

used in agriculture and gardening, for crop protection, mainly

in cold climates [7]. Straw is used as substrate for mushroom

production, together with horse manure or poultry litter. The

spent compost can be used for other activities or used as soil

conditioner, fertiliser and in bioremediation.

The amount of crop residues used for different purposes

was calculated based on animal population (cattle, horses and

sheep) and mushroom production in each county. For esti-

mating the use for animals, it is important to determine the

amount of livestock in a specific region and how many use

some form of a bedding system. The amount of straw used

depends on the straw availability, on the type of farms and

farming systems [31]; therefore, the exact amount of residues

used is difficult to establish. In this study, a consumption of

1.5 kg of straw/day per head was considered for the use of

straw for cattle bedding (for a quarter of the cattle population),

as well as for equines (horses, mules). For sheep, an average

consumption on 0.1 kg straw/day per head was used. For the

use of straw for pigs, a consumption of 0.5 kg of straw/day per

head of pig, (one eight of the pigs population using straw) was

considered [31,32].

2.3. Pruning residues

Orchards and vineyards require annual pruning operations,

which produce large amounts of biomass, which might

potentially be available as a bioenergy source. The residues

generated from the pruning of orchards (apples, pears, plums,

peaches, apricots and cherry trees) and vineyards, consist of

small branches and biomass resulted from regular and clea-

ning operations.

Little data is available on pruning residues. However,

several studies proposed some figures for the ratios of residue

to product yields for pruning [33e36]. These data show certain

scattering and must be used with caution. The available data

was compiled and conservative data were used in the com-

putation of the available biomass from pruning. Based on our

own survey and on the data reported in different studies

[33e36] we proposed data to be used to establish the average,

the minimum and maximum amount of annual trimming

residues (Table 2). Not all of the residues are available for use

and losses from the collection must be considered; an avail-

ability factor of 80% was considered.

2.4. Wood residues

The wood residues included in the assessment are: forest

residues, firewood and wood processing residues. The avail-

able forest biomass is determined by the types of operations

(final felling, forest thinning and cleaning operations) and on

species/group of species (coniferous, beech, oaks, softwood

and hardwood) at NUTS III (county) level. The estimates are

based on the percentage of branches, crown tops and bark for

coniferous and deciduous trees depending on the forest

operation (final felling, forest thinning or cleaning). The esti-

mates of the forest residues and wood industry by-products

are based on current annual felling rates for the selected

reference period in this study. Wood harvesting rates are

considered sustainable and reflect the accessibility and the

current potential of forests. However, total annual felling

represents only around 45% of the annual increment in forest

Table 3 e Forest residues from harvesting operations.

Operation/biomass included Share of forestry residues (% of stand volume)

Coniferous Beech Oak Hardwood Softwood

Final cuts/tree biomass (<5 cm diametera) 4 4 5 6 6

Secondary cuts/tree biomass(<5 cm diameter) 1 13 11 19 12

Secondary cuts/firewoodb (>5 cm diameter) 20 52 55 50 63

a Trees tops, branches, usually left in the forest, never harvested.

b Firewood is part of the tree which is not usable from technological point of view (i.e. small branches, defects). It does not include trees tops

and branches under 5 cm diameter.

Source: [37]

b i om a s s a n d b i o e n e r g y 3 5 ( 2 0 1 1 ) 1 9 9 5e2 0 0 5 1999

biomass, which is amongst the lowest in Europe. Therefore,

this study provides data only on the presently available forest

residues and not the whole potential.

Under economical, social and environmental constraints,

it is considered that only a part of forest residues can be

removed from the land to be used for energy production (up to

80% in the plains and 50e70% in the mountain areas),

depending on the availability, general/local topography, forest

accessibility and technical and economic difficulties of

biomass collection. The major part of the logging residues

resulting from the main felling is currently left in the forest.

However in mountain areas, only a part of the residues can be

collected from the technical and economic point of view

(30e50%), depending on the terrain type, slope and accessi-

bility of the area. In the plain and hilly area, at least 80% of the

residues can be made available for bioenergy production.

About 50e60% of the residues are already removed from

forests and used for energy production in the plain and hilly

areas, while in mountain areas the whole amount is unused

for the moment [37,38] Table 3.

Biomass available for bioenergy is that which has no tech-

nological purposes, like: tops, branches, bark, or damaged and

imperfect wood. In the final cuts, branches, which account for

amaximumof4%inconiferousand19%innon-coniferousstand

volumes, are currently left in the forest, thus they are practically

available. In the final cuts, firewood amounts to about 20% in

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

Alb

aA

rad

Arg

esB

acau

Bih

orB

istr

ita-

Bot

osan

iB

raso

vB

raila

Buz

auC

aras

-Sev

erin

Cal

aras

iC

luj

Con

stan

taC

ovas

naD

ambo

vita

Dol

jG

alat

iG

iurg

iu

Agr

icul

tura

l res

idue

s [M

t dry

/yea

r]

Min Ave

Fig. 4 e Production of agricultura

coniferous forests and 10% in non-coniferous forests, while in

secondary cuts, it ranges from 20% in coniferous to 52e63% in

oak, beech, softwood and hardwood harvest. Firewood is

entirelyharvested,andcurrentlyusedforheating inhouseholds.

Wood residues are generated from roundwood processing:

sawdust, shavings, bark, wood remains, etc. The fraction of

available by-products varies depending on the processing

technology: a part of by-products (sawdust, wood remains,

etc.) are used to produce other wood based products: particle-

board, plywood, fibreboard, etc. The processing efficiency of

wood varies between 52 and 65% for timber, to 80% for veneer

production, plywood, etc., depending on the species/group of

species. On average, around three quarters of the felled

roundwood is transformed into final products [38]. The

remaining by-products (bark, sawdust, wood chips, shavings,

etc.) might be available for energy generation. A survey [38]

undertaken at companies involved in the wood processing

residues revealed that almost all the wood residues generated

in the wood processing industry are presently used for the

production of energy needed in their own technological

process. These residues are however included in the estimates

of forest biomass available for energy production. The esti-

mations of wood residues available for energy production are

basedona lowerheatingvalue (LHV)of 10.4GJ/m3andadensity

of 570 kg/m3 for deciduous trees and a lower heating value of

7.6 GJ/m3 and a density of 400 kg/m3 for coniferous trees.

Gor

jH

argh

itaH

uned

oara

Ialo

mita Iasi

Ilfo

vM

aram

ures

Meh

edin

tiM

ures

Nea

mt

Olt

Prah

ova

Satu

Mar

eSa

laj

Sibi

uSu

ceav

aT

eleo

rman

Tim

isT

ulce

aV

aslu

iV

alce

aV

ranc

ea

rage Max

l crop residues per counties.

0.000

0.050

0.100

0.150

0.200

0.250

0.300

0.350

0.400

0.450

0.500

Alb

aA

rad

Arg

esB

acau

Bih

orB

istr

ita-

Bot

osan

iB

raso

vB

raila

Buz

auC

aras

-Sev

erin

Cal

aras

iC

luj

Con

stan

taC

ovas

naD

ambo

vita

Dol

jG

alat

iG

iurg

iuG

orj

Har

ghita

Hun

edoa

raIa

lom

ita Iasi

Ilfo

vM

aram

ures

Meh

edin

tiM

ures

Nea

mt

Olt

Prah

ova

Satu

Mar

eSa

laj

Sibi

uSu

ceav

aT

eleo

rman

Tim

isT

ulce

aV

aslu

iV

alce

aV

ranc

ea

Woo

d re

sidu

es [

Mt d

ry/y

ear]

Min Average Max

Fig. 5 e Available woody biomass residues from forestry and wood processing industry per counties.

0

20

40

60

80

100

120

140

160

180

200

trimmingresidues

crop residues forestryresidues

firewood woodprocessing

Res

idue

s [P

J/ye

ar]

Min Average Max

Fig. 6 e Available biomass residues in Romania.

b i om a s s an d b i o e n e r g y 3 5 ( 2 0 1 1 ) 1 9 9 5e2 0 0 52000

3. Biomass resource availability forbioenergy

3.1. Availability of agricultural crop residues

The total amount of agricultural annual and permanent crop

residues is estimated at NUTS-3 level, as average amount,

over the reference period selected for the study. Annual crop

residues production amounts on average 19.2 Mt dry/year,

ranging from 10.2 to 27.0 Mt dry/year. Only a part of these

annual residues can be collected, if considering the various

agro-environmental constraints. The collectable annual crop

residues are, on average 8.9 Mt dry/year (ranging from 4.7 to

12.6 Mt dry/year). Comparatively, the annual production of

trimming residues is much lower, on average 1.1 Mt dry/year

(ranging from 0.6 to 1.4 Mt dry/year), of which only 80% can be

collected: 0.9 Mt dry/year (varying from 0.5 Mt to 1.2 Mt dry/

year). Thus, the collectable agricultural residues from annual

and permanent crops, are 9.8 Mt dry/year on average,

(between 2.2 and 13.8 Mt dry/year), with large variations from

one region to another (Fig. 4). The main uses of crop residues

amount to around 1.3 Mt/year, of which: cattle 0.4 Mt/year,

horses 0.5 Mt/year, sheep 0.3 Mt/year, pigs 0.1 Mt/year, while

mushroom production uses a very low amount (6000 t/year),

due to the very low production of mushrooms.

The available annual crop residues for energy generation

amount on average 137.1 PJ (ranging from 63.6 to 202.0 PJ),

while trimming residues amount on average 17.3 PJ (ranging

from 9.6 to 22.3 PJ). The total agricultural residues available for

bioenergy production amount on average 154.4 PJ, but vary

from 73.2 to 224.2 PJ. This variation is due to the crop pro-

duction and especially due to the yield variation in different

years, while the crop area is rather constant. Better farming

practices and the use of new plant varieties, resistant to

adverse climate conditions and drought might reduce this

variability. A significant non-uniform regional distribution of

the available agricultural biomass was revealed. The large

variation of agricultural crop residues between counties is

mainly due to the differences in crop area, but also due to yield

variation between different regions. Thus, most of the annual

crop residues are available in the counties from the Southern

Plain (Calarasi, Constanta, Teleorman, Dolj, Ialomita, Olt,

Braila) and from the West plain (Timis), while residues from

permanent crops are only available in a few counties from

hilly areas (Vrancea, Arges, Dambovita, Iasi). The distribution

of agricultural residues in the country is shown in Fig. 4.

3.2. Availability of woody biomass resources

The estimation of annual woody biomass available is 3.8 Mt

dry/year on average, varying within a range of 3.2e5.0 Mt dry/

year. The bioenergy related potential of available woody

biomass was estimated at 73.7 PJ/year, from 62.4 to

95.8 PJ/year. This data represents the amount that can actually

be used at the present for bioenergy and not the theoretical

potential related to the biomass increment in forests. In

comparison, the theoretical potential according to the total

biomass increment in Romanian forests is around 332 PJ. If

forest harvesting will increase from the current share of 45%

of annual increment (thus “under harvested”), to a higher rate

(70e80% in Nordic countries), the availability of wood residues

0

2

4

6

8

10

12

Alb

aA

rad

Arg

esB

acau

Bih

orB

istr

ita-

Bot

osan

iB

raso

vB

raila

Buz

auC

aras

-Sev

erin

Cal

aras

iC

luj

Con

stan

taC

ovas

naD

ambo

vita

Dol

jG

alat

iG

iurg

iuG

orj

Har

ghita

Hun

edoa

raIa

lom

ita Iasi

Ilfo

vM

aram

ures

Meh

edin

tiM

ures

Nea

mt

Olt

Prah

ova

Satu

Mar

eSa

laj

Sibi

uSu

ceav

aT

eleo

rman

Tim

isT

ulce

aV

aslu

iV

alce

aV

ranc

ea

Ave

rage

res

ourc

es [

PJ/y

ear]

Permanent crop residues Annual crop residues Forestry residues Firewood Wood processing residues

Fig. 7 e Total biomass available resources per counties.

b i om a s s a n d b i o e n e r g y 3 5 ( 2 0 1 1 ) 1 9 9 5e2 0 0 5 2001

might increase accordingly. This depends, however, on the

improvement in forest management techniques, improve-

ment in forest biomass mobilisation and forest accessibility.

The forest biomass distribution in the country depends on the

forest distribution and the share of forest in each NUTS 3 unit,

but also on the type and characteristics of the forests (Fig. 5).

This shows that currently, forest biomass is mainly available

in the most forested, mountain regions (counties Suceava,

Bacau, Neamt, Caras-Severin, but also in Arad, Arges, Brasov,

Maramures, Mures, Harghita, Hunedoara).

3.3. Availability of biomass for bioenergy use

This study reveals significant biomass, 228.1 PJ on average,

available for energy production, coming from agricultural and

forest residues. Overall, bioenergy potential from annual crop

residues has the highest share (60.1%), followed by firewood

(16.2%), wood processing residues (11.8%), permanent crop

0

2

4

6

8

10

12

14

16

Alb

aA

rad

Arg

esB

acau

Bih

orB

istr

ita-

Bot

osan

iB

raso

vB

raila

Buz

auC

aras

-Sev

erin

Cal

aras

iC

luj

Con

stan

taC

ovas

naD

ambo

vita

Dol

jG

alat

iG

iurg

iu

Ava

ilabl

e bi

omas

s [P

J]

Min A

Fig. 8 e Variation of biomass ava

residues (7.6%) and forestry residues (4.4%) (Fig. 6). However,

the available biomass ranges from 135.6 to 320.0 PJ, depending

on the variation of crop production and forestry activities. The

following amount of biomass from the analysed sources is

available in the present for bioenergy:

� 73.7 PJ (variation from 62.4 to 95.8 PJ) from forest, forestry

and wood processing;

� 154.4 PJ (variation from 73.2 to 224.2 PJ) from agricultural

annual and permanent crops.

The results from this study show that the estimates of

average available resources from agriculture and woody

biomass (228.1 PJ) are lower than the potential estimated in

the Romanian Strategy for the valorisation of the renewable

energy sources, adopted by the Government Decision 1535/

2003. The Romanian Strategy estimated the biomass potential

at 318 PJ for Romania, of which agricultural andwood biomass

Gor

jH

argh

itaH

uned

oara

Ialo

mita Iasi

Ilfo

vM

aram

ures

Meh

edin

tiM

ures

Nea

mt

Olt

Prah

ova

Satu

Mar

eSa

laj

Sibi

uSu

ceav

aT

eleo

rman

Tim

isT

ulce

aV

aslu

iV

alce

aV

ranc

ea

verage Max

ilable resources per counties.

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Alb

aA

rad

Arg

esB

acau

Bih

orB

istr

ita-

Bot

osan

iB

raso

vB

raila

Buz

auC

aras

-Sev

erin

Cal

aras

iC

luj

Con

stan

taC

ovas

naD

ambo

vita

Dol

jG

alat

iG

iurg

iuG

orj

Har

ghita

Hun

edoa

raIa

lom

ita Iasi

Ilfo

vM

aram

ures

Meh

edin

tiM

ures

Nea

mt

Olt

Prah

ova

Satu

Mar

eSa

laj

Sibi

uSu

ceav

aT

eleo

rman

Tim

isT

ulce

aV

aslu

iV

alce

aV

ranc

ea

Bio

mas

s de

nsity

[T

J/km

2]

Min Average Max

Fig. 9 e Density of biomass residues available for bioenergy per counties.

b i om a s s an d b i o e n e r g y 3 5 ( 2 0 1 1 ) 1 9 9 5e2 0 0 52002

potential is 271 PJ. In addition, it includes the categories of

biogas and municipal solid wastes that were not addressed in

this paper. Thus, the National Strategy indicates the following

biomass potential for Romania: 49.8 PJ from forest residues

and firewood, 20.4 PJ/year from wood waste, such as sawdust

and other wood remains, 200.9 PJ/year from agricultural

wastes, such as cereal straw, maize stalks, 24.6 PJ from trim-

ming residues and 22.8 PJ from biogas and municipal solid

wastes. Compared to this potential, in our assessment we

provide the actual available biomass, considering present

conditions, such as existing agricultural practices, current

crop production and yields, current forest fellings, as well as

various technical and environmental constraints. In the

conditions of increased agricultural production and forest

fellings, according to the forest biomass increment, coupled

with increased biomass mobilisation, it might be possible to

reach the potential indicated in the Romanian Strategy.

The current study shows a high variability of biomass

availability between different NUTS-3 areas (counties). A

higher amount of biomass resources can be made available

from agriculture in several areas, whereas in hilly and

mountain areas, less suitable for agriculture, the proportion of

wood residues is higher (Fig. 7). The counties with the highest

available biomass are Calarasi, Timis, Constanta, Dolj, Tele-

orman, Arad. The current study also revealed a high vari-

ability of biomass availability from one year to another.

Therefore, the average, minimum and maximum amount of

biomass available was established to accommodate the vari-

ation in residues availability (Fig. 8).

Table 4 e Biomass use in energy balance in Romania.

2000 2001

Final energy consumption [PJ] 942 963

Gross biomass consumption [PJ] 117 88

Biomass in gross energy consumption [%] 7.5 5.8

RES in final energy consumption [%] 18.0 14.9

Biomass in final energy consumption [%] 12.2 9.2

The density of biomass resources per land area is presented

inFig. 9 for comparingavailable resourcesbetweenregionsand

counties. Several counties show a higher density of biomass

available for energy situated in agricultural areas (Calarasi,

Ialomita, Teleorman, Braila, Galati, Giurgiu, Constanta, Olt),

while several counties in rich forest areas, show a lower

density of biomass resources. The lowest level of biomass

resources is in Harghita, Hunedoara, Alba, Salaj, Sibiu, which

are areas with low agricultural activity.

3.4. Present use of biomass in Romania

A part of the biomass residues, mainly firewood, forestry and

wood processing residues and residues from agriculture is

currently used in Romania (Table 4), amounting to 116 PJ on

average [1]. Biomass plays an important role in the residential

sector for space heating in households, tertiary sector- hotels,

schools and other public buildings mainly in the mountain

areas and to a lesser extent for district heating and for process

heat in wood processing. Traditional wood heating is well-

developed, especially in rural areas, for direct burning

(in stoves and ovens), for space heating, cooking and hotwater

preparation. Firewood is mainly used in the areas where is

easily available, especially in themountain and hilly areas, but

also in areas with lowwood resources, at large distances from

the harvesting areas. A large share of firewood (95%) is used in

the residential sector, for residential heating purposes. Other

uses of firewood (5%) are for process heat generation, space

heating in industrial and public buildings, from mountainous

2002 2003 2004 2005 2006

963 1013 1093 1051 1034

100 84 130 134 134

6.1 7.2 8.0 8.2 7.9

16.3 16.6 17.5 19.7 19.4

9.9 11.7 11.7 12.7 12.4

-4

-2

0

2

4

6

8

10

12

Alb

aA

rad

Arg

esB

acau

Bih

orB

istr

ita-

Bot

osan

iB

raso

vB

raila

Buz

auC

aras

-Sev

erin

Cal

aras

iC

luj

Con

stan

taC

ovas

naD

ambo

vita

Dol

jG

alat

iG

iurg

iuG

orj

Har

ghita

Hun

edoa

raIa

lom

ita Iasi

Ilfo

vM

aram

ures

Meh

edin

tiM

ures

Nea

mt

Olt

Prah

ova

Satu

Mar

eSa

laj

Sibi

uSu

ceav

aT

eleo

rman

Tim

isT

ulce

aV

aslu

iV

alce

aV

ranc

ea

Unu

sed

biom

ass

[PJ]

Min Average Max

Fig. 10 e Biomass remaining available for bioenergy in Romania.

b i om a s s a n d b i o e n e r g y 3 5 ( 2 0 1 1 ) 1 9 9 5e2 0 0 5 2003

areas. Residues fromwoodprocessing are used on a large scale

by industrial companies to generate heat; however, there is

a very limited number of cogeneration capacity. These plants

generally use a mixture of fuels: sawdust, shavings and wood

chips. They are small capacity boilers, between0.3 and5MWth,

withmaximum10MWth, and the total installed thermal power

of about 1200 MWth. Several biomass district-heating plants,

with a capacity between 1 and 7 MWth (total 45 MWth), are

located in the mountain and hilly areas, in high density forest

areas, where large quantities of wood and wood residues are

available. Five new district heating plants have been recently

commissioned inGheorghieni, VatraDornei,Vlahita, Intorsura

Buzaului, Gura Humorului for using wood residues (wood

remains, wood chips, sawdust, etc.) with a capacity ranging

from 4 MWth to 12 MWth [39].

The estimates [39,40] show that, out of the total biomass

consumption for energy in Romania of 116 PJ, about 64.5 PJ is

derived from wood residues and 53.5 PJ from agricultural

residues. Thus, practically almost all the available quantity of

firewood and wood processing residues is already used. There

are some areas with higher biomass consumption than

available resources, where biomass is supplied from areas

with higher available resources (Fig. 10).

4. Conclusions and recommendations

The high amount of biomass available from agriculture and

forestry may constitute a significant resource for bioenergy

that could contribute significantly to the total energy supply in

Romania. This estimation considers various environmental

and economical constraints for making available agricultural

crop residues andwood residues and taking into account their

competitive uses.

This study revealed a relatively high degree of uncertainty

related to the biomass availability in a specific year, due to

annual variation of crop production and current annual wood

harvesting. The available annual crop residues for energy

amounts onaverage 137.1 PJ, ranging from63.6 to 202.0 PJ,while

the available residues from permanent crops amounts on

average 17.3 PJ, ranging from 9.6 to 22.3 PJ. Therefore, the

availableagricultural residues forbioenergyproductionamount

onaverage 154.4 PJ, ranging from73.2 to 224.2 PJ. The totalwood

residues resulting from the forest industry including forestry

residues, firewood and wood processing by-products, available

for bioenergy production was estimated at 73.7 PJ/year, from

62.4 PJ/year to amaximumof 95.8 PJ/year. This study shows the

existence of important resources potentially available for bio-

energy production: 228.1 PJ on average, ranging from 135.6 to

320.0 PJ, with agriculture being the main source for biomass.

The large annual variations in biomass production/avail-

ability for bioenergy represent a key factor to consider, since

this can cause shortages in supply in certain years, if this is

not adequately taken into account. This variability impacts on

the location and operation of bioenergy plants, transport and

other logistics. Therefore, the location of a bioenergy plant

must consider the minimum available resources in the area.

The lower available resources in the bioenergy plant area also

leads to logistical problems and reduced economic viability of

the plant, due to the increased collection area, longer trans-

port routes and increased biomass collection costs. Therefore,

this paper provides estimates of the average, minimum and

maximum amount of available biomass resources, which

could be more useful when planning a biomass plant.

Crop and wood residues are unevenly distributed over the

country, as directly correlated with crop production and forest

areas. The results showed a large variation at NUTS-3 level

under specific local conditions, types of crops, crops and forest

shares. Most of the annual crop residues are available in

counties from the Southern and Western plains. Most of the

residues from permanent crops (orchards and vineyards) are

available in a few counties in the hilly areas, which are impor-

tant fruit and grape producers.Wood resources are available in

mountain and hilly areas, where the forest share is high,

providing apredictable and stable resource. Themain technical

aspects of biomass residues utilisation for bioenergy produc-

tionrelate to theavailabilityof resources ina specific regionand

the density of biomass per area. The density of resources per

b i om a s s an d b i o e n e r g y 3 5 ( 2 0 1 1 ) 1 9 9 5e2 0 0 52004

area is a key factor, determining the collection radius of the

biomass and the cost of collection, which is an important

limiting factor. A combination of a high plant capacity and low

density of biomass increases the transport capacity and road

traffic, which can be limited in some areas by the local road

infrastructure. A solution to solve this problem is the diversifi-

cation of biomass feedstock to reduce the collection distance

and compensate for yield variability. The setting up of a bio-

energyplantdependsultimatelyontheresourceavailabilitybut

it should meanwhile match the energy (heat) demand in that

area. Thus, the plant location is amatter of optimisation, as the

energy demand and biomass supply issue influence the logis-

tics of the plant, the biomass collection distance and transport

costs.

A part of the biomass residues available, mainly firewood,

forestry and wood processing residues and residues from agri-

culture is currently used in Romania. Thus, it is estimated that

54% of energy production from biomass is presently derived

fromwoodresiduesand46% isderived fromagriculturalwastes

and residues [38,39,41]. Almost all of the available firewood and

wood residue is already used in Romania. A large part of the

biomass isused inhouseholds, instovesandkilns,with lowfuel

efficiency. There is large amount of biomass available still

unused. Biomass could be better used in cogeneration, district

heating plants, in advanced systems, which are already avail-

able on the market, operating with high efficiency. Small

capacity plantswill make better, more effective use of the local

resources and thus would limit the total biomass required and

better match supply with demand. A more detailed analysis at

the local level will decide on the exact location of the plant

based on the resources available in that area.

This study was performed as a technical input to the

preparation of the National Renewable Action Plan of

Romania within the framework of the Directive 2009/28/EC on

the promotion of the use of energy from renewable sources.

r e f e r e n c e s

[1] National Institute of Statistics http://www.insse.ro/cms/rw/pages/index.ro.do.

[2] Romania. National renewable energy action plan inaccordance with Directive 2009/28/EC on the promotion ofthe use of energy from renewable sources; 2010.

[3] National Forest Administration http://www.rosilva.ro/categorie.php?id¼4

[4] Edwards R, �Suri M, Huld T, Dallemand JF. GIS-basedassessment of cereal straw energy resource in the EU. 14thEuropean biomass for energy industry & climate protectionconference, Paris; 2005.

[5] Summers MD, Jenkins BM. Biomass production andallocation in rice with implications for straw harvesting andutilization. Biomass Bioenergy 2003;24:163e73.

[6] Hamelinck C, van den Broek R, Rice B, Gilbert A, Ragwitz M,Toro F. Liquid biofuels strategy study for ireland, reportprepared for sustainable energy Ireland; 2004.

[7] Panoutsou C, Labalette F. Cereals straw for bioenergy andcompetitive uses, Proceedings of the cereals straw resourcesfor bioenergy in the European Union, Pamplona, 18e19October 2006.

[8] Patterson PE, Makus L, Momont P, Robertson L. Theavailability, alternative uses and value of straw in Idaho,

final report of the Project BD-K251. Idaho WheatCommission; 1995.

[9] Walsh ME, Perlack RL, Turhollow A, de la Torre Ugarte D,Becker DA, Graham RL, et al. Biomass feedstock availabilityin the US; 1999. State Level Analysis.

[10] Nelson RG. Resource assessment and removal analysis forcorn stover and wheat straw in the Eastern and MidwesternUnited States. Biomass Bioenergy 2002;22:349e63.

[11] Ericsson K. and Nilsson L.J. Assessment of the potentialbiomass supply in Europe using a resource focussedapproach, Lund University Gerdagatan 13, S-223 62 Lund,Sweden.

[12] Wilhelm W, Johnson JMF, Hatfield JL, Voorhees WB,Linden DR. Crop and soil productivity response to cornresidue removal: a literature review. Agron J 2004;96:1e17.

[13] USDA-NRCS. White paper crop residue removal for biomassenergy production: effects on soils and recommendations;2006.

[14] Johnson JMF, Allmaras RR, Reicosky DC. Estimating sourcecarbon from crop residues, roots and rhizodeposits using thegrain-yield database. Agron J 2006;98:622e36.

[15] Kadam KL, McMillan JD. Availability of corn stover asa sustainable feedstock for bioethanol production. BioresourTechnol 2003;88:17e25.

[16] Graham RL, Nelson R, Sheehan J, Perlack RD, Wright LL.Current and potential U.S. corn stover supplies. Agron J 2007;99:1e11.

[17] Lee C. and Grove J. Straw yields from six small grain varieties2003e2004 and 2004e2005 growing seasons, University ofKentucky.

[18] Diamantidis ND, Koukios G. Agricultural crops and residuesas feedstocks for non-food products in Western Europe. IndCrops Prod; 2000:97e106.

[19] Koukios EG. Agriculture as a source of biomass in WesternEurope, report for biomass for greenhouse gas emissionreduction (BRED) project; 1998.

[20] Katterer T, Andren O, Persson J. The impact of alteredmanagement on long-term agricultural soil carbon stocks-a Swedish case study. Nutrient Cycling in Agroecosystems2004;70:179e87.

[21] Gallagher P., Dikeman M., Fritz J., Wailes E., Gauther W.,Shapouri H. Biomass from crop residues: cost and supplyestimates, AER-819.

[22] Sokhansanj S, Turhollow A, Cushman J, Cundiff J.Engineering aspects of collecting corn stover for bioenergy.Biomass Bioenergy 2002;23:347e55.

[23] Aboudrare A, Debaeke P, Bouaziz A, Chekli H. Effects of soiltillage and fallow management on soil water storage andsun-flower production in a semi-arid Mediterranean climate.Agr Water Manag 2006;83:183e96.

[24] Petersen CT, Jørgensen U, Svendsen H, Hansen S, Jensen HE,Nielsen NE. Parameter assessment for simulation of biomassproduction and nitrogen uptake in winter rape. Eur. J. Agron1995;4:77e89.

[25] Rathke GW, Christen O, Diepenbrock W. Effects of nitrogensource and rate on productivity and quality of winter oilseedrape grown in different crop rotations. Field Crop Res 2005;94:103e13.

[26] Rinaldi M, Losavio N, Flagella Z. Evaluation and applicationof the oilcropesun model for sunflower in southern Italy.Agric Syst 2003;78:17e30.

[27] Soriano MA, Orgaz F, Villalobos FJ, Fereres E. Efficiency ofwater use of early plantings of sunflower. Eur. J. Agron 2004;21:465e76.

[28] Van der Sluis E, Shane R, Stearns L. Local biomass feedstocksavailability for fuelling ethanol production. Biofuels, foodand feed tradeoffs conference, April 12e13, 2007, St. Louis,Missouri; 2007.

b i om a s s a n d b i o e n e r g y 3 5 ( 2 0 1 1 ) 1 9 9 5e2 0 0 5 2005

[29] Glassner DA, Hettenhaus JR, Schechinger TM. Corn stovercollection project, BioEnergy’98: expanding BioEnergypartnerships; 1998.

[30] Powlson D., Using straw for energy-implications for soils &agriculture, Workshop Proceedings cereals straw andagricultural residues for bioenergy in New Member Statesand Candidate countries, Novi Sad, 2e3 Oct. 2007.

[31] Rps-Mcos. An assessment of the renewable energy resourcepotential of dry agricultural residues in and, Report forSustainable Energy Ireland; 2004.

[32] Tuyttens FAM. The importance of straw for pig and cattlewelfare: a review. Appl Anim Behav Sci 2005;92:261e82.

[33] Esteban LS, Ciria P, Carrasco JE. An assessment of relevantmethodological elements and criteria for surveyingsustainable agricultural and forestry biomass byproducts forenergy purposes. Bioresources 2008;3:910e28.

[34] Nikolaou A, Lychanaras V, Panoutsou C. Characteristics andgeographical distribution of agricultural residues for energyproduction in Greece, 12th European conference of biomassfor energy, industry and climate protection, Amsterdam;17e21 June 2002.

[35] Di Blasi C, Tanzi V, Lanzetta M. A study on the production ofagricultural residues in Italy. Biomass Bioenergy 1997;12:321e31.

[36] Jolli D, Giljum S. Unused biomass extraction in agriculture,forestry and fishery, Seri Report Nr. 3; 2005.

[37] Blujdea V. Contribution of wood to the national energysecurity e structure and evolution of wood consumption inRomania, Forest Research and Management Institute Report;2008.

[38] Scarlat N, Mihai M. Research and experiments for woodresidues and biomass use for energy production, ReportS4-12-97; 1997.

[39] Ionescu L. Renewable energy sources: a continuouschallenge for Romania. Timisoara: Modern Wood EnergySystems and Markets; 16e17 September 2008.

[40] Tantareanu C. Country survey-Romania, ERA bioenergystrategy e short term measures to develop the Europeanresearch area for bioenergy RTD, AG Meeting; 7 October 2002.

[41] Scarlat N. Romanian energy situation and biofuel market,international workshop wood fuel e an energy source fortomorrow’s Europe,May, 18e19th; 2004. Pamporovo, Bulgaria.