The aim of this report is to demonstrate and evaluate the potential of tall wheatgrass (Elytrigia elongata) to avoid GHG emissions and obtain lower economic costs in marginal areas of Spain. Our research built scenarios based on experimental plots (2 and 3 years growth) in 3 locations of Spain with completely different climate conditions (provinces of Girona, Soria and Palencia). In our experiences, we achieved an adequate establishment and biomass production, and assumed a rank of biomass yields until the end of the life cycle that is usually accepted to be about 15 years in many other studies in United States, Argentina and Eastern Europe where tall wheatgrass is extensively cultivated in marginal areas for sheep livestock production. Using our experimental plots and statistical information for economic inputs costs, we built 5 different scenarios per region considering a large range of biomass yields of tall wheatgrass. The analysis included a comparison with annual grasses economic costs calculated for a wide range of biomass yields of a previous study. We estimated GHG emissions savings for tall wheatgrasses and used our previous study (which had GHG emissions savings as well). Savings were calculated replacing natural gas electricity with electricity from biomass combustion in real power plants in Spain. In a wide range of yields, the results suggest that marginal areas might present a better performance with tall wheatgrass compared to annual winter grasses (cereals whole plant cuttings), thus producing biomass yields with higher GHG savings and lower economic costs at the farm level.

1. Perennial energy crops for semiarid lands in the Mediterranean: Elytrigia
elongata, a C3 grass with summer dormancy to produce electricity in constraint
environments
Emiliano Maletta*1, Carlos Martin-Sastre2, Pilar Ciria1, Aranzazu del Val1, Annabel Salvado4,
Laura Rovira4, Rebeca Díez3, Joan Serra4, Yolanda González-Arechavala2 and Juan Carrasco1
1
CEDER-CIEMAT. Energy Department. Biomass Unit. Autovía de Navarra A-15, salida 56. 42290 Lubia
(Soria). Phone: +34 975281013
2
Institute for Research in Technology (IIT) - ICAI School of Engineering - Comillas Pontifical University - E-
28015, Madrid (SPAIN)
3
ITACyL. Biofuels and Bioproducts Resarch Centre, Pol. Agroindustrial Par.2-6 (24358), Leon, Spain. Phone/fax:
+34-987374554
4
IRTA, Mas Badia (17134) Girona, Spain. Phone: +34- 972780275, Fax: +34-972780517
* Corresponding author: emiliano.maletta@ciemat.es
The aim of this report is to demonstrate and evaluate the potential of tall wheatgrass (Elytrigia elongata) to avoid
GHG emissions and obtain lower economic costs in marginal areas of Spain. Our research built scenarios based on
experimental plots (2 and 3 years growth) in 3 locations of Spain with completely different climate conditions
(provinces of Girona, Soria and Palencia). In our experiences, we achieved an adequate establishment and biomass
production, and assumed a rank of biomass yields until the end of the life cycle that is usually accepted to be about
15 years in many other studies in United States, Argentina and Eastern Europe where tall wheatgrass is extensively
cultivated in marginal areas for sheep livestock production. Using our experimental plots and statistical information
for economic inputs costs, we built 5 different scenarios per region considering a large range of biomass yields of tall
wheatgrass. The analysis included a comparison with annual grasses economic costs calculated for a wide range of
biomass yields of a previous study. We estimated GHG emissions savings for tall wheatgrasses and used our previous
study (which had GHG emissions savings as well). Savings were calculated replacing natural gas electricity with
electricity from biomass combustion in real power plants in Spain. In a wide range of yields, the results suggest that
marginal areas might present a better performance with tall wheatgrass compared to annual winter grasses (cereals
whole plant cuttings), thus producing biomass yields with higher GHG savings and lower economic costs at the farm
level.
1 INTRODUCTION maize) and fibre sorghum (sorghum bicolor), are now
typical solid biofuels involved in private contracts
In Spain, a country with more than 4M ha with potential between farmers and energy companies. These contracts
for energy crops as a consequence of liberalization and often establish biomass prices as high as 85€/odt for
Common Agricultural Policy reforms [1], the square bales from these annual crops [4]. Therefore many
development of energy crops to produce biomass for stakeholders are developing a strong interest in new
heating or electric applications represents a major perennial energy crops that could produce lower biomass
challenge. The extensive semiarid rainfed areas of the costs in both irrigated and rain fed areas. Biomass yields
Mediterranean require species that tolerate severe per hectare are closely linked to biomass costs since
frequent droughts during late spring and summer and many areas have low yields as most Mediterranean
produce sufficiently high yields to obtain biomass with extensive rain fed areas have low competitive lands
low costs and high environmental benefits in relation (unfertile soils, scares rains in spring and summer, etc.).
with the used inputs and fossil energy. This consideration would be fundamental in order to
Economic constraints affecting renewable energies allow the economic feasibility of biomass power energy
are usually cited as important barriers when developing plants in Spain.
new activities in rural areas. Moreover, biomass Despite of economic considerations, energy crops
production marginal costs in Spain are still a major producing liquid or solid biofuels require to produce
constraint limiting the expansion of new facilities at the environmental benefits regarding global warming
time that recent measures have cut subsidies and financial potentials (GWP) and greenhouse gases emissions (GHG)
aid for private companies [2]. among many other impact categories often studied in Life
During the last decade, in Spain some new power cycle assessments (LCA) of energy crops and bioenergy
energy plants started to produce electricity from solid chains [5, 6]. Several studies have encouraged the
agricultural residues [3]. Biomass bales from herbaceous research and development of perennial species as energy
crops are currently used for co-firing to produce crops for marginal areas in order to produce biomass
electricity in power energy plants. The first raw materials yields with high energy balances and low environmental
considered were agricultural residues (mostly cereal straw impact regarding water, nitrogen use, erosion,
in square bales with less than 11% humidity) and biomass biodiversity and GHG emissions [7, 8].
from energy crops were then also included. Winter In 2009, the Renewable Energy Directive (RED)
annual crops like triticale (triticosecale sp.), oats (Avena established increasingly restrictive minimum GHG
sativa), peas (Pisum sativum) and rye (Secale cereale) emissions savings for biofuels replacing fossil reference
but also warm annual grasses like fodder maize (Zea fuels for transport. This minimums savings are 35%

2. (from 2009) and will become in 50% in 2017 and 60% metabolism pathway, usually known as “warm grasses”)
from 1stJanurary of 2018 [9]. Since then, several studies these crops have yields reported to be higher than 20
have provided evidences that marginal areas might odt/ha per year during their lifetime [4, ]. Nevertheless
produce also marginal biomass yields or have logistics most of them require irrigation for rhizome propagation
implications producing low or none environmental or event direct sowings in most agricultural lands at least
benefits from feedstock, residues and energy crops [5, 8, during the establishment (spring) when drought events
10]. The RED also established a methodological are very frequent in Spain limiting their viability to the
approach for LCA for biofuels, nevertheless solid irrigation arable surface. Additionally, even when they
biomass standards and a sustainability criteria for them produce much more biomass yields, in some cases have a
have not been addressed sufficiently at the time that many higher establishment cost reported to be as high as
debates, recommendations on methods and discussions 2000€/ha in Miscanthus [19, 20].
on land use changes effects on GHG calculations are Perennial C3 grasses (three-carbon photosynthetic
currently taking place [11]. Recent significant metabolism pathway) also called “cool grasses” can be
advancements have added new principles such as those established without irrigation during autumn or early
from the Roundtable on Sustainable Biofuels (RSB) for spring and may produce forage in successive years with
certification schemes. The RSB included a new harvests during late summer when less precipitation
certification scheme for most biomass and biofuel occur in the Mediterranean. Forage traditional crops like
feedstock and established a calculation method for GHG reed canary grass (Phalaris sp), tall fescue (Festuca
emissions from agriculture considering CO2, NOx, N2O, arundinacea) or perennial ryegrass (Lolium perenne)
nitrates and Ammonia derived from fertilizers have been extensively used in Europe for livestock
production, application and dynamics in the soil [12]. production and also as new energy crops [21].
In Spain electricity from lignocellulosic energy crops Nevertheless, in Mediterranean and semiarid areas most
may replace electricity from natural gas, the cleanest species produce too low yields or do not re-grow after the
substituted fossil source as suggested by RSB and RED. extreme summer drought events. Other best suited C3
In Spain only few publications on LCA have addressed energy grass is giant reed (Arundo donax) with very high
lignocellulosic energy crops [13, 14] and there is a lack yields but require rhizomes or shoots for propagation and
of information on C3 or C4 perennial grasses scenarios even irrigation or some rains during establishment [20].
producing energy. In a previous study [13], we analysed Then most of these grasses are best suited for sub-humid
GHG emissions from triticale, oats and rye cultivated in areas in northern regions of Spain, not allowing most rain
continental rain fed areas in Spain in a wide range of fed low competitive cereal regions to produce biomass
biomass yields from different species and varieties. Our from perennial species.
results suggested that cereal bales (grain+straw) have to Elytrigia elongata (Host) which common name is
outreach a yield of about 8 odt/ha in order to accomplish “Tall wheatgrass”, is also known as Thinopyrum
similar sustainability criteria established for liquid ponticum (Podp), Agropyron elongatum (Host); Elymus
biofuels in the RED (from 2018, 60% of GHG savings elongatus (Host) var.ponticum. It is a summer dormant
compared to the fossil substituted reference). Therefore, cool season perennial grass native from Eurasia and has
those results suggested to condition sustainability of been cultivated in constraints environments all over the
biomass in most agricultural arable lands in Spain that world [22]. Among many other similar wheatgrasses such
have semiarid climate conditions and produce an average as Elymus lancelolatus, Pascopyron smithii, Agropyron
national grain yield of 1,8 t/ha; whole plant biomass cristatum, A. intermedium and A. sibericum, tall
yields of 4 odt/ha considering local harvest indexes wheatgrass is probably the latest-maturing wheatgrass
reported from experimental networks [15]. adapted to the temperate areas of North America and
Additionally, many reports strongly suggest that Europe and probably the most productive of all [22]. The
Common Agricultural Reforms (CAP) for 2014 health species is adapted to range sites receiving at least 300mm
check, should encourage perennial grasses and renewable of annual precipitation and is particularly noted for its
energy alternatives at the time cereals and dairy milk capacity to produce forage and persist in areas that are
quota would have shorten subsidies for farmers [16]. too alkaline or saline for other productive crops [22, 23].
Spain as one of the member countries with more Thus, it is a good source of pasture and hay during the
abandoned and low competitive cereal lands of Europe late summer, when forage often is in short supply. It also
might require new alternative crops to be cultivated under has been used successfully as a silage crop. Tall
rain fed conditions and produce biomass. There is a wheatgrass has large seed that is easy to harvest and
current need for additional plots and LCA with perennial plant. It has good seedling vigour, and established plants
species suited for marginal lands or in those areas where have an exceptionally deep root system, which
traditional agriculture and livestock production have low contributes to its resistance to drought [23]. Its
and very low competitiveness [17]. palatability for livestock is low at the same time that it
Among several alternative crops, many perennial could have acceptable characteristics to use for
grasses have been studied as energy crops and may combustion in industrial boilers to produce electricity
produce high environmental benefits and low biomass power. Some recent European studies have analysed Tall
costs at the farm level that are relevant for their wheatgrass and encourage its consideration for semiarid
consideration on bioenergy chains [4, 5, 6, 7]. areas as a novel energy crop [24].
Nevertheless, early autumn and spring rains in the The aim of this report, is to use current experimental
Mediterranean regions are very scarce and in most plots in three regions of Spain established two (2010) and
regions they limit the adequate establishment and annual three years (2009) ago for building scenarios considering
productivity of best suited energy crops like Panicum their expected lifetime. We compared tall wheatgrass and
virgatum, Arundo donax or Miscanthus giganteum. As previously reported annual grasses performance on GHG
many other C4 grasses (four carbon photosynthetic emissions savings when producing electricity in existing

3. Spanish power energy plants and their economic costs at highest is 23ºC. Extreme temperatures rarely are below
the farm level in a wide assumed range of yields in the 0ºC or exceed 40°C. There are generally soft winters and
three study regions. hot-drought summers, which generates a lot of
accumulation of water vapor in the atmosphere which
produce “cold drop” in autumn (weather phenomenon
2 MATERIALS AND METHODS associated with the Mediterranean area characterized by
heavy rains, hail and electrical storms). The average
2.1 Location, climate and soil of the experimental plots rainfall values are between 600-750mm. May occur
used for scenarios building torrential rains in spring, but especially in autumn. This
Two groups of parcels were established with tall location has less dry months than other locations of these
wheatgrass in the provinces of Girona (located in the climate characteristics. The province of Palencia, is
region of Catalonia), and Soria and Palencia (in the characterized by a Continental Mediterranean climate.
region of Castilla y Leon). All plots were cultivated Rainfalls range between 350 and 600 mm, the maximum
under rain fed conditions in 2009 and 2010 (Figure 1). is in spring and autumn (minimum in winter and
summer). The monthly mean temperature is between 7ºC
and 19 °C with cold winters (between 5 and -10 ° C), and
Girona dry and hot summers (between 20 and 27 ° C average
temperature). Figure 2 shows Ombrothermic diagram –
average temperature (ºC) against precipitation (mm)-
from September 2010 to August 2011.
Palencia Soria
Girona
70 140
Temperature (ºC)
60 120
Precipitation (mm)
50 100
40 80
30 60
20 40
10 20
Figure 1: Plots with Tall Wheatgrass (Elytrigia 0 0
elongata) in the three study regions in Spain Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug
Months
The experimental plots took place in very different Palencia
soils (Table 1). The plots in Soria were on a loam sandy
70 140
texture soil (sand 75-85%, lime less than 10% and clay
60 120
Precipitation (mm)
less than 15%) with organic matter about 0.6% and pH of
Temperature (ºC)
50 100
6.8. This soil is light, with good drainage. The deeper
40 80
texture is sandy or sandy loam. The soil in the plots of 30 60
Palencia was the richest in P with moderately high 20 40
organic matter (1.37) and the highest pH (8.5). The plots 10 20
in the province of Girona have highest organic matter 0 0
contents (1.65%). Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug
Months
Table I: Soil characteristics in 0-30 cm layer of the three Soria
sites used for scenario building in this study
P K Organic 70 140
pH N (%) Texture
Temperature (ºC)
60 120
(mg/kg) (mg/kg) Matter (%)
50 100
Girona 8,2 0,11 28 192 1,65 loam 40 80
Palencia 8,5 0,09 50,4 0,22 1,37 Franc 30 60
Soria 6,8 0,03 6,6 61,2 0,6 sandy 20 40
10 20
0 0
Regarding climate conditions, the region of Soria is Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug
characterized by fairly hot summers, with temperatures Months
sometimes reaching 30 ºC, and cold winters, with Average Temperature (ºC) Precipitation (mm)
temperatures falling below 0 ºC and frequent frosts; in
Figure 2: Ombrothermic diagram for the period
2010 the first autumn frost occurred on September 27th (–
September 2010-August 2011 in all three sites
0.4 ºC), whereas the last spring frost in 2011 took place
on March 22nd (–0.4 ºC).
2.2 Experimental plots used for scenario building
The province of Girona is characterized by a Coastal
The experimental parcels were established in autumn
Mediterranean climate. These characteristics give to this
2009 and 2010, and in both cases they had no harvests
location more moderate temperatures with no prolonged
during the establishment year.
periods of extremely high or low temperatures. The
average annual temperature is between 15-16° C, the
minimum annual average is 7°C and the
Table II: Experimental plots from different trials (established in 2009 and 2010) in the three study regions

4. Regions Soria Palencia Girona
Management and inputs 2009 2010 2009 2010 2009 2010
Experimental plot Strips Strips small plots Strips small plots small plots
Plot size (total in m2) 5000 4500 225 135 90 90
Tillage operations Chisel, harrowing, rotary tiller
Base (NPK in kg/ha) 350 500 none
Top fertilizers NAC27% (kg/ha)
1st year none none none
Succesive years 250 300 0 250
Sowing rate 40 20 30 20 20
Sowing date Nov.2009 Nov.2010 Oct.2009 Oct.2010 Oct.2009 Oct.2010
Herbicides
pre-emergence none Glifosate none
post-emergence none 2-4D 2-4D and MCPA
Weed control mowings 2010 2010 2009 and 2010 2010 and 2011
Cut numbers 1 1 1 1 2 (june - Oct) 1
Biomass yield range (odt/ha) 2.5 - 6 4 - 10 5 - 12 5 - 12 12 - 39 10 - 40
Note: Yields from 2012 were estimated before harvest (June 2012). Maximum and minimum values correspond to the
extreme values of replicates in the first and second year, and in the third year in the case of trials established in 2009
Both trials (2009 and 2010) followed similar the third years were based on observations and height in
management techniques. Operations for tillage soil June 2012.
preparation were similar to those usually implemented
with cereals and annual grasses in Spain, including two 2.3. Scenarios definition
passes of chisel, one with harrow disks, rotary tiller and
ring roller. Then, a base fertilization was usually utilized Management, machinery operations and raw materials
before sowing in autumn except in Girona were soils are
richer enough and typical management considers weed Scenarios definition followed several assumptions for
competition as favoured when nitrogen fertilizers are the total expected lifetime of tall wheatgrass. There are
applied during crop establishment (table II). Sowing rates very few studies with evaluations of tall wheatgrass in a
were adjusted in relation to the germination rates and long period of time especially without grazing
seed viability from previous tests (data not shown). management (only grass cuttings). Many evaluations on
Herbicides and weed control operations (mowing) during tall wheatgrass were intended for forage production under
establishment were followed when needed. extreme alkaline soil conditions that are very different
from the areas under study (mostly arable lands with low
cereal yields). Based on specific studies in other
countries, lifetime of tall wheatgrass in this assessment
was assumed to be 15 years [24]. Following this report
and our experimental plots, we assumed no harvest in the
first year, as well as a maximum yield after the third year
to be maintained for 7 years and a progressive decrease
starting after the crops has 10 years old.
Before establishment, machinery labour included
tillage operations and base broadcasting fertilizations
with NPK fertilizer in Palencia (500kg/ha). Considering
our plots in Soria, Palencia and Girona, once tall
wheatgrass was established we assumed mowing
operations during next spring in order to avoid weed
competition which is also a recommended management to
avoid excessive evapotranspiration during summer in the
Figure 3: Trials plots in Soria (2009) with tall first year [22]. Thus, by letting the biomass on the ground
wheatgrass during bailing in the second year in the first year no baling was considered.
Machinery equipment and tractors weights and
Sampling methods were used to evaluate the lifetime as well as diesel consumptions were taken from
production in each replicate when trials were cultivated the Spanish Ministry of Agriculture [25]. This
as small plots (Girona and Palencia). Biomass yields information was taken into account for the LCA and
including harvest losses evaluation were registered in the economic costs analysis considering the number of times
grass strips of Soria by mowing and baling operations of all operations during the assumed lifetime.
(Figure 2). Biomass yields reported considered the Fertilization during spring was also different among
variation among trials and repetitions or replicates as well the defined scenarios. Based on our experience in Soria,
as an estimation of the expected biomass yield to be no top fertilization in spring was done in the
achieved in summer 2012. Biomass yields assumed for establishment year. Fertilization with Calcium Ammonia

5. Nitrate (CAN) 27% doses were assumed to be 300, 250 assumed to be linked with soil and climate variations
and 150 kg/ha for Palencia, Girona and Soria based on (climatic year and site dependent).
the soil characteristics and yield expectancy considering
climate conditions. Additionally, a nutrient restitution to 2.4 Life Cycle Assessment methodologies
the soil with NPK was assumed to be 50kg/ha in Palencia
and Girona, and 80kg/ha in Soria 6 times in the 15 years Life Cycle Assessment (LCA) is the environmental
lifetime of tall wheatgrass. tool we selected to determine the energetic and
Other inputs like herbicides where assumed based on environmental performance of Tall wheatgrass to produce
the plots of the three study regions as well. Thus, the lignocellulosic biomass for electricity generation.
scenario considers a pre-emergence glyphosate (1 l/ha) in LCA is a systematic set of procedures for compiling
Palencia, and broadleaf herbicides 2-4D and dicamba (1 and examining the inputs and outputs of materials and
l/ha) in Soria and Palencia during the first year. A final energy and the associated environmental impacts directly
herbicide spreading (two passes) was also assumed for attributable to the functioning of a product or service
the end of the lifetime to allow a new crop establishment system throughout its life cycle [28]. This environmental
(glyphosate, 1 l/ha). assessment tool is regulated by ISO 14040 [28] and ISO
14044 [29] standards, and according to this, LCAs
Table III: Machinery equipment and number of should follow four steps: (1) goal and definition, (2)
operations involved in the lifetime (15years) of tall inventory analysis, (3) impact assessment and (4)
wheatgrass interpretation.
Weight Lifetime Palencia Girona Soria Simapro 7.2 [30,31] software tool and Ecoinvent 2.2
Machinery operations for lifetime (kg) (h) (times)
Chisel ploughing (50cm) 750 1200 1
[32,33] European database have been selected for the
Harrowing by disks 1800 1200 2 2 LCAs.
Ring roller 1500 400 1 Also a rough nitrogen balance was made considering
Chisel ploughing (25cm) 750 1200 1
Rotary tiller 1400 1200 2 2
nitrogen supply by fertilizers and measuring the amount
Base fertilizer application (establishment) 700 400 1 0 0 of nitrogen contended in the crops as the nitrogen
Restitution NPK fertilizer (spreader) 700 400 6 6 6 extracted.
Sowing 810 750 1 1 1
Herbicides spreader (pre-emergence) 600 500 1 0 0
Top fertilizer application (spring) 700 400 15 15 14 2.4.1 Goal and Scope definition
Herbicides spreader (post-emergence) 600 500 1 1 1 The aim of this study is to evaluate the energy
Mowing 2400 667 15 16 15
Baling (250kg bales) 9000 2308 14 14 14
balance and environmental impacts of the 15 scenarios
Bales loading 2500 1333 14 14 14 defined in the above sections for growing tall wheatgrass
Last herbicide (End-life application) 600 500 2 2 2 as energy crop in Spain for electricity generation and
Tractor 1 (120HP) 4320 12000
Tractor 2 (150HP) 5400 10000
compare them with electricity generation from natural
gas, as a reference for generation from non-renewable
Yields fossil sources.
In order to build scenarios assuming normal large-sized 2.4.2. Functional unit
plots with tall wheatgrass in the study regions, we used The functional unit chosen is 1 TJ of electrical energy
the information from our management techniques and generated from biomass for the studied system and from
results in small and medium sized (strips) plots. Based on natural gas for the reference system. This amount of
similar practices and yields in other reports from electrical energy is a round number corresponding to 12
Argentina [26], United States [27] and Hungary [24] we hours of functioning of the 25Mw power plant selected
defined five yield scenarios for each region: very low, for this study (see 2.4.5).
low, middle, high and very high (Table IV). These The electricity production per hectare of tall
different yields assumed no substantial changes in wheatgrass trials is the product of the crop yield (see
fertilization or cultivation techniques. Therefore we Table IV) at 12 % humidity by the net calorific value at
assumed that variation in yields is mostly caused by soil 12 % humidity [27] and by the efficiency of the biomass
and climate variability among years and specific site conversion process into electricity (29.5 % for this case
(parcels) of each region. Yields defined in scenarios for study).
large plots considered the typical differences that small
plots have because of border effects (usually large plots 2.4.3 Systems description
present 25-50% lower yields compared to small plots The bioenergy systems analyzed includes three
depending on boarders and plot shape). subsystems: agricultural biomass production, electricity
generation and the transport of products and raw
Table IV: Yield scenarios for the three study regions materials.
Yield scenarios (mean value for lifetime)
Agricultural system
Regions Very low Low Middle High Very High
Palencia (odt/ha) 4,1 5,8 7,0 8,2 10,2
The agricultural system could be described by the
Girona (odt/ha) 6,2 8,1 9,5 10,9 12,8 crop schemes followed, the machinery used and the
Soria (odt/ha) 2,4 3,9 5,0 6,1 7,0 inputs consumed.
The three agronomic management patterns (one per Biomass power plant system
region) and five yield levels of our three regions reported
then a total of 15 scenarios for which economic and LCA All the data considered to model the biomass power
was carried out. The five yield levels reflect variations plant system are real data from a 25 MW biomass plant

6. located in northern Spain. This plant consumes biomass Biomass, ash and slag means of transport and distances
at an average humidity of 12% and produces electricity were provided by company in charge of the biomass
with a conversion efficiency of 29.5%. The plant power plant.
consumes natural gas for maintenance operations and
pre-heating and produces ashes and slag from biomass as Natural gas system
residues. The average consumption of natural gas and the The natural gas system includes the gas field
productions of ashes and slag per kilogram of burned operations for extraction, the losses, the emissions and
biomass are shown in Table V. the purification of the main exporter counties of natural
gas to Spain (Algeria 73 % and Norway 27 %). Also
Table V: Biomass power plant consumptions and includes the long distance and local transport of gas to
residues produced the power plant in Spain, considering the energy
Consumed or produced consumption, loses and emissions for distribution.
Amount
substances Finally the substances needed and the average efficiency
Natural gas consumption 0.0342 of Spanish natural gas power plants to produce electricity
(MJ Kg-1 Wet Biomass Burned) are taken into account [35].
Slag production
82.47
(g Kg-1 Wet Biomass Burned)
2.4.4 Life cycle inventory analysis
Ashes production 8.25
(g Kg-1 Wet Biomass Burned) The inventories used to consider natural gas
consumption [35] of the biomass power plant, transports
The emissions of the plant into the air are submitted [36] of agricultural inputs, and biomass and power plant
regularly to the local government. The emissions residues are taken from Ecoinvent.
accounted are only those which affect the global warming The methods used for the inventory analysis of the
potential (GWP). In the power plant studied these agricultural system mainly follow that proposed on Life
emissions come from gas natural combustion (see Table cycle inventories of agricultural production systems [34].
VI). Carbon dioxide emitted from biomass combustion To consider N2O emissions we follow the formula
was not considered because it was previously fixed from proposed by de RSB GHG Calculation Methodology v
the air by the crop. 2.0 [12]. This formula is basically based on the formula
proposed in the Ecoinvent Agricultural Report [34], that
considers the new IPCC guidelines [37]. Also we
Table VI: Biomass power plant aerial emissions
Substance Origin Amount
consider the nitrate emissions affecting to Global
(g Kg-1 Wet Biomass Warning Potential as the RSB purposes [12], making and
Burned) estimation of them by means of nitrogen balance, the soil
Fossil carbon and crop characteristics and the rainfall of the zone.
Natural gas 1.94
dioxide
Fertilizers productions
Table VII: Transport system summary The fertilizer inventories consider the different steps
Material From To Distance Vehicle of the production processes, such as the use of raw
Processing Lorry materials and semi-finished products, the energy used in
Seed Field 30 km
center 20-28t the process, the transport of raw materials and
Processing Regional Lorry intermediate products, and the relevant emissions [34].
100 km
center storehouse 20-28t The production of calcium ammonium nitrate starts
Regional Demonstratio Lorry
10 km with the production of the ammonium nitrate by the
storehouse n parcel 16-32t
Fertilizers neutralization of ammonia with nitric acid. The final
Regional product is then obtained by adding dolomite or limestone
and Manufacturer 600 km Train
storehouse to the solution before drying and granulation [38].
herbicides
Lorry No inventories are given in Ecoivent for multinutrient
100 km
>16t fertilizers due to the amount different possible ways to
Regional Demonstratio Lorry mix nitrogen, phosphorous and potassium compounds to
10 km
storehouse n parcel 16-32t produce NPK fertilizers [38]. The modeling of NPK
Demonstratio Lorry fertilizer inventories has been approximated by
Biomass Biomass plant 60 km
n parcel 16-32t
combining inventories of single fertilizers according to
Ash and Lorry
Biomass plant Disposal 37 km multinutrient fertilizer specific contents of N, P 2O5 and
slag 16-32t
K2O, as well as the form of the nitrogen provided
Transport system (ammonium, nitrate or urea) [38].
The transport system is summarized in Table VII.
This table shows all modes of transport used and the Herbicides production
distances between origin and destination points for every The data related to emissions, energy and substance
transport in the LCAs carried out. consumption in the production of the herbicides sprayed
The transportation means and distances for the is taken from Ecoinvent [39]. The quantities of active
transport of agricultural inputs until the regional matters considered are taken from the formulations of the
storehouse are taken from the Ecoinvent database [34]. commercial fertilizers used.
The distance from the regional store house to plots was
10 km approximately. The transport of workers to the Seed production
parcel has not been considered because of the highly Tall wheatgrass seeds can be produced in Spain under
variability of transport distances depending on cases. similar conditions compared to the operations of fertilizer
and management practices used for forage cultivation.

7. Tall wheatgrass seeds are frequently produced under land. Indirect land use change is a complex process that
irrigation in high quality soils under contract with real is not fully understood by the scientific community and
farmers, thus their normal operations and yield so is not included in this study [43].
production were assumed to be similar to that of the local
common management practices considered in this study. 2.4.5 Life cycle impact assessment
Then, a grain production yield of 0.8 odt ha-1 was Life Cycle Impact Assessment (LCIA) is the phase in
considered as suggested by other studies [25,26,27]. an LCA where the inputs and outputs of elementary flows
The energy consumption for cleaning, drying, seed that have been collected and reported in the inventory are
dressing, and bag filling of the Tall wheatgrass seed in translated into impact indicator results [44].
the processing plant has been estimated in 32.8 kWh t- LCIA is composed of mandatory and optional steps.
1
[40]. Mandatory steps of classification and characterization
have been carried out and optional steps normalization
Diesel consumption and combustion emissions of and weighting have been avoided in order to make results
agricultural machinery more comparable and to avoid introducing value choices.
The diesel consumption of agricultural machinery In the classification steps elementary flows shall be
was obtained from the Spanish Ministry of Agriculture assigned to those one or more impact categories to which
[25]. The inventories for the extraction, transport of they contribute. In the characterization steps each
petrol, the transformation into diesel and its distribution quantitative characterization factor shall be assigned to
are taken from Ecoinvent [41]. The exhaust emissions of all elementary flows of the inventory for the categories
diesel in agricultural machinery engines are also that have been included in the classification [44].
considered [41].
Environmental impact assessment method
Agricultural machinery manufacture We have selected the software tool Simapro 7.2 [45]
The inventories for agricultural machinery and the impact assessment method of the IPCC 2007 [46]
manufacture are specific to the different types of to assess the 100 years’ period horizon Global Warming
machinery (tractors, harvesters, tillage implements or Potential (GWP).
general implements).
The amount of machinery (AM) needed for a specific Energy assessment method
process was calculated multiplying the weight (W) of the In order to assess the energy consumed to generate
machinery by the operation time (OT) and dividing the electricity from tall wheatgrass biomass and from natural
result by the lifetime of the machinery (LT) [34]: gas, we have selected the software tool Simapro 7.2 [45]
and the Cumulative Energy Requirement Analysis
AM (kg FU-1) = W (kg) OT (h FU-1) LT-1(h); (CERA) [48]. This method aims to investigate the energy
use throughout the life cycle of a good or service. The
Where FU (See 2.4.2) is the functional unit of the primary fossil energy (FOSE) has been obtained using
LCA. The life time was obtained from the Spanish this method.
Ministery of Agriculture (see Table III) [25].
2.5. Comparison between tall wheatgrass and winter
Nitrous oxide emissions cereals from previous studies
The calculation of the N2O emissions [12] is based A previous study data and results from two
on the formula in Nemecek et Kägi [34] and adopts the experimental plots with triticale (Triticosecale sp.), oats
new IPCC guidelines [37]: (Avena sativa), lopsided oats (Avena strigosa L.) and rye
(Secale cereale) was utilized in order to make
N2O= comparisons with tall wheatgrass scenarios performance.
44/28∙(EF1∙(Ntot+Ncr)+EF4∙14/17∙NH3+EF5∙14/62∙NO3-) The 15 scenarios of tall wheatgrass were based in a
similar range of biomass yields compared to the cited
With: research in which GHG emissions savings when
N2O = emissions of N2O [kg N2O ha-1] substituting natural gas electricity by combusting biomass
EF1 = 0.01 (IPCC proposed factor [37]) in a 25MW boiler. The mentioned study considered two
Ntot = total nitrogen input [kg N ha-1] sites with experimental plots located in two Spanish
Ncr = nitrogen contained in the crop residues [kg N ha-1] provinces in Castilla y León (Soria and León). The power
EF4 = 0.01 (IPCC proposed factor [37]) energy plant and transport systems cited in tables V and
NH3 = losses of nitrogen in the form of ammonia [kg VI, were the same for both studies [13].
NH3 ha-1]. Calculated as proposed in the RSB [12] and
Nemecek et Kägi [34] methodologies. 2.6 Economic costs at the farm level
14/17= conversion of kg NH3 in kg NH3-N In order to calculate costs for biomass production at
EF5 = 0.0075 (IPCC proposed factor [37]) the farm level, the 15 scenarios defined for tall
NO3- = losses of nitrogen in the form of nitrate [kg NO3 wheatgrass in above sections were analysed together with
ha-1]. They were estimated through the RSB formula [12] the winter cereal trials analysed in previous studies [13].
which considers nitrogen supply, the nitrogen uptake, the Winter cereals costs included two regions as defined in
soil and crop characteristics and the local rainfall. our previous study (Soria and León) which were assumed
14/62= conversion of kg NO3- in kg NO3-N. to explore enough yield and be management
representative for typical cereal areas in central Spain.
Land use changes Rental land costs in Soria were assumed to be 90€/ha per
Direct land used change does not take place because year when cropping Tall wheatgrass. Winter cereals
the parcel selected was previously a winter cereal crop rental land costs were assumed to be an average value for

8. the region of Castilla y León (119€/ha.year). Both tall Total mean costs per hectare considering 15 years
wheatgrass and winter cereals used economic data from lifetime of Tall wheatrgrass, were much higher that
MARM (2012)[25] and local information for fertilizer, winter cereals in all scenarios (Table VIII). The higher
herbicides and tall wheatgrass seeds prices. costs of winter cereals might be explained mainly because
of a higher contribution of establishment (machinery
2.7. Nitrogen balances operations, base fertilization and sowing). Rental lands
A rough nitrogen balance was made. This estimation contribution, top fertilization and harvest operations
considers nitrogen supplied in base and top fertilizations (mowing, baling and loading) are major costs affecting
as the entrance of the system and total nitrogen content of Tall wheatgrass.
rye aerial biomass trials as exit of the system. The total
amount of nitrogen extracted and exported by the crop 3.2. Global warming potential
harvest is calculated by multiplying the yield of each
scenario (see Table IV) by its respective biomass Increasing yields reflect a remarkable reduction in
nitrogen content [27]. As roots remain into the soil we GHG emissions when producing electricity in a power
assumed that all nitrogen from roots return to the soil. energy plant. Nevertheless, winter cereals had higher
Therefore we did not take into account any proportion of GWP at similar yields at the farm level compared to Tall
root nitrogen content as extracted nitrogen. wheatgrass. As reflected with mean production costs,
lower yields achieved higher GWP per TJ in winter
3 RESULTS AND DISCUSSION annual grasses compared to Tall wheatgrass (Figure 5).
3.1 Economic assessment 120
Oat
100 Lopsided Oat
Costs at the farm level resulted to be much higher for
GWP (Mg CO2 eq TJ electrcity-1)
biomass production from winter cereals compared to Tall 80
Rye
wheatgrass (Figure 4). Triticale
60
Tall wheatgrass
(Soria)
240
Tall wheatgrass Palencia Tall wheatgrass
220 40 (Palencia)
200 Tall wheatgrass Soria
Tall wheatgrass
(Gerona)
180 20
Tall wheatgrass Girona
Mean biomass cost (€/odt)
160
Triticale
140 0
Rye 2000 4000 6000 8000 10000 12000 14000
120
Oat Yield (kg d.m. ha-1)
100
80 Lopsided Oat Figure 5: Global warming potentials as function of
60 biomass yields per hectare in winter cereals and Tall
40
wheatgrass scenarios.
20
0
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 90%
Oat
GHG Savings (%) Biomass Compared to electricity
Biomass yield (odt/ha.year)
80%
Lopsided Oat
from Natural Gas as fossil reference
Figure 4: Biomass costs production at the farm level in 70% Rye
Tall wheatgrass and winter cereals 60% Triticale
50% Tall wheatgrass
(Soria)
Table VIII: main costs for biomass from three scenarios 40% Tall wheatgrass
of Tall wheatgrass and for winter cereals considered in 30%
(Palencia)
Tall wheatgrass
this study (Gerona)
20% Tall wheatgrass
Winter cereals
Tall wheatgrass (€/ha.y-1)
€/ha.y-1 10%
Regions/inputs Palencia Girona Soria (Soria and León) 0%
2000 4000 6000 8000 10000 12000 14000
Field works 19 18 16 164
Yield (kg d.m. ha-1)
base fertilization 13 0 0 157
Top fertilization 70 54 35 70 Figure 6: GHG emissions savings of Tall wheatgrass and
Pre emergence herbicides 1 8 13 0 winter cereals producing electricity from biomass as a
Reposition fertilization 8 2 0 0
Post emergence herbicides 1 2 1 51 function of biomass yield.
Final herbicides 2 2 2 0
Rental land 119 174 90 119
Mowing, baling and loading 156 153 153 163
Seeds 5 5 5 114
Total 393,58 418,53 314,18 838,00
Considering the biomass yields explored range in our
scenarios, Tall wheatgrass produced lower costs at all
yields but differences were higher (as much as 124€/odt)
when biomass yield was lower (below 4odt/ha). Highest
yields showed a lower cost for Tall wheatgrass (around
36€/odt) suggesting that more productive areas may be
also better suited for the perennial grass.

9. 0,6
wheatgrass biomass used for electricity might be suitable
Palencia 2,3
5,2%
1,5%
0,2
0,4% for areas with lower potential yields achieving similar
limitations stated in the sustainability criteria established
3,5
for biofuels in the RED.
8,0% As shown in Figure 7, most important inputs causing
GWP are fertilizer production and those derived from
fertilizer use (nitrous oxide), accounting in total for
21,7
50,2%
89.9% in Palencia, 78.4% in Soria and 80.7% in Girona.
15,0
Differences are linked to the nitrogen fertilizer doses for
34,7% each case (see table II).
3.3. Energy balances
Seed and Pesticides Fertilizers Energy yields increased significantly with biomass
Nitrous Oxide Field Works production per hectare as most inputs variation is lower
Biomass transport Power Plant Operation than outputs, suggesting that specific conditions could be
(yearly climate differences or soil variability) could
2,3
0,6
1,8%
0,2
0,6%
Soria generate different energy balance scenarios. Therefore,
climate and soil conditions determining yields might
6,4%
cause large variations on energy balances as well. Tall
wheatgrass originate a similar response compared to
4,6 winter cereals, but with a parallel higher response when
12,9%
14,5
correlating energy yields at the power energy plant with
40,8% biomass yields in the field (figure 9).
8,0
Oat
Energy output per fossil energy inputs (TJ electricty
7,0
13,4 Lopsided Oat
37,6% 6,0
TJ fossil energy-1)
5,0 Rye
Seed and Pesticides Fertilizers 4,0
Triticale
Nitrous Oxide Field Works 3,0
Biomass transport Power Plant Operation Tall wheatgrass
(Soria)
2,0
Tall wheatgrass
0,6 0,1 1,0
2,3% 0,4% Girona 0,0
(Palencia)
Tall wheatgrass
2000 4000 6000 8000 10000 12000 14000 (Gerona)
Yield (kg d.m. ha-1)
2,3
8,0% Figure 9: Energy ratios for electricity production from
2,4
8,6% biomass of Tall wheatgrass and winter cereals scenarios
12,8
as a function of biomass yield
45,3%
The scenario for the region of Soria clearly has a
higher energy yield at similar biomass yields in the farm
10,0
35,4% probably explained by lower fertilizer uses (figure 10).
Most important fossil input contributions were
fertilizers. Fossil energy inputs were mostly caused by
Seed and Pesticides Fertilizers fertilizers: 46%, 59.8 and 50.7 in Soria, Palencia and
Nitrous Oxide Field Works Girona respectively. Secondly, machinery fossil inputs
Biomass transport Power Plant Operation and raw materials (pesticides and seeds) were affecting
energy ratios as well.
Figure 7: Different contributions to the global warming
potentials for tall electric production (TJe) from biomass 3.4. Soil nitrogen balance
of wheatgrass in the three study regions Nitrogen balances in the soil changed dramatically in
the scenarios assumed for tall wheatgrass as a function of
Higher yields produced a higher emission reduction biomass yield (Figure 11). A clear negative relationship
when comparing GWP of electricity from biomass in the between soil nitrogen balance and biomass yield seems to
25MW power energy plant, with natural gas electricity in be explained as nitrogen fertilizer uptakes are higher to
Spain (figure 6). As suggested in previous studies, winter nitrogen applications then suggesting a necessarily soil
cereals low biomass yields at the farm level determine nitrogen extraction from the soil nitrogen stock. As
higher GWP and lower emissions reductions replacing management scenarios defined in this study considered
the fossil reference. Even under extremely low yield same nitrogen doses for five different biomass yields,
scenarios (below 4odt/ha) calculated GHG emissions higher biomass yields imply a higher nitrogen uptake
savings were always higher than 50% and low and compared to lower yields (figure 12). This result suggest
medium yields scenarios in both Palencia and Soria, were that yields between 6 and 8 odt/ha resulted in assumed no
always above 60%. These results suggest that Tall changes in soil nitrogen.

10. 0,002 60
0,011
5,0%
1,0%
Soria Tall
wheatgrass
Nitrogen Balance (kg N ha-1)
40 (Soria)
0,035 20 Tall
16,5%
wheatgrass
(Palencia)
0,098 0
46,0%
Tall
-20 wheatgrass
(Gerona)
-40
0,067
31,5%
-60
-80
Seed and Pesticides Fertilizers 0 2000 4000 6000 8000 10000 12000 14000
Field Works Biomass transport Yield (kg d.m. ha-1)
Power Plant Operation Figure 11: Soil nitrogen balances in the three regions
0,011
0,002 scenarios as a function of its biomass yields.
4,4%
0,8%
Palencia
As mentioned in above sections, obtaining high GHG
0,035 emissions savings would probably mean that Tall
14,4%
wheatgrass had enough high biomass (energy output) and
energy yield, compared to the GHG emissions incurred
for crop and post-harvest transport and processing
0,051
producing electricity. Nevertheless, our results indicate
20,7% 0,146 that producing more biomass implies more nitrogen
59,8%
uptake and a potential excessive soil nitrogen depletion
that should be addressed in a bioenergy sustainable
production. In Girona for instance, only very low yields
extracted less nitrogen than that supplied to the crop.
Seed and Pesticides Fertilizers
Highest GHG emission reductions coincide with soil
Field Works Biomass transport
nitrogen depletion suggesting that an adequate nitrogen
Power Plant Operation management should be consider (more nitrogen fertilizers
0,001 may cause higher fossil inputs and lower emission
0,7%
reductions but may allow soil nitrogen stability).
Girona 0,011
6,4%
90%
NITROGEN DEFICIT NITROGEN SURPLUS Tall
85% wheatgrass
GHG Savings (%) Compared to electricity from
0,035 (Soria)
21,0% 80%
Natural Gas as fossil reference)
75% Tall
wheatgrass
0,085 70%
(Palencia)
50,7%
65% Tall
wheatgrass
60% (Gerona)
0,036 55%
21,3%
50%
45%
Seed and Pesticides Fertilizers 40%
-80 -60 -40 -20 0 20 40 60
Field Works Biomass transport Nitrogen Balance (kg N ha-1)
Power Plant Operation Figure 12: GHG emissions savings as a function of soil
nitrogen balances.
Figure 10: Different contribution for energy fossil inputs
per TJe in the three study regions with Tall wheatgrass

11. 4 CONCLUSIONS Available (in Spanish) at:
http://www.boe.es/boe/dias/2012/01/28/pdfs/BOE-A-
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