**1. Introduction**

In EU directive 2003/30/EC biodiesel is defined as "methyl ester produced from vegetable or animal oil, of diesel quality, to be used as biofuel". The more recent EU directive 2009/28/EC has set the targets of achieving, by 2020, a 20% share of energy from renewable energy sources in the EU's overall energy consumption and a 10% share of energy from renewable sources in each member State's transport energy consumption. In this context special consideration is paid to the role played by the development of a sustainable and responsible biofuels production, with no impact on food chain.

Nowadays most biodiesel is produced through triglycerides transesterification of edible oils with methanol, in the presence of an alkaline catalyst (Lotero et al., 2005). The so obtained product has low viscosity and is a biofuel (fatty methyl ester) that can replace petroleum-based diesel fuel with no need of engine modifications (Suwannakarn et al., 2005). Furthermore, if compared to fossil fuel, the formed ester fuels are non-toxic, safe to handle, and biodegradable (Krawczyk, 1996). Glycerine is also obtained as by-product as shown in Fig. 1.

Fig. 1. Transesterification of a trygliceride.

C. Pirola1, D.C. Boffito1, A. Di Fronzo1, G. Carvoli1, D. Barnabè2, R. Bucchi2 and A. Rispoli2

*<sup>1</sup> Università degli Studi di Milano – Dipartimento di Chimica Fisica ed Elettrochimica, Milano, Italy, 2 Agri2000 Soc. Coop., Bologna, Italy.*

Non Edible Oils: Raw Materials for Sustainable Biodiesel 5

The authors present here preliminary results of a three years study about the feasibility of using new oilseed species for biodiesel production in Italy1. The intent is to propose an innovative agronomic solution that may affect the energy balance and the ability to achieve

A considerable amount of studies are available on mainstream and alternative crops for biodiesel feedstock. The authors made a selection of the most promising crops to be introduced in the Mediterranean zone, taking into account that currently the Mediterranean basin comprises not only temperate climate but also slightly-arid lands. Some of these are being effectively tested under the mentioned project as part of a unique rotation program. Among oil crops the Brassicaceae family has an outstanding position. Rapeseed (*Brassica napus*) is the third largest oil crop with 12% of the world plant oil market with best yields when cultivated in cold-temperate regions (Carlsson, 2009). Yet, the large biodiversity of Brassicaceae reveal incipient species, among which *Brassica juncea*, *Brassica nigra*, *Brassica rapa*, *Brassica carinata*, *Sinapis alba*, *Camelina sativa*, *Eruca sativa* ssp*. oleifera*, etc. Besides the potential as raw material for biodiesel, their high content of glucosinolates (GSL) make them able to recover soils made marginal by soil-borne pests as nematodes (e.g. galling nematodes from the *Meloidogyne* genus and cist nematodes from *Heterodera* and *Globodera* genera) (Romero et al., 2009; Curto & Lazzeri, 2006). Many researchers also report weedsuppressive effects of Brassicaceae (e.g. Al-Khatib, 1997; Krishnan, 1998) as well as filtering-

On the other side an unexpected source of oilseed seems to arise from the tobacco culture. In anticipation of changes in tobacco market, selections of new varieties destined for energy production are coming out. Tobacco, as drought resistant species, seems a good option to

The recent interest in *B. carinata* (also known as Ethiopian or Abyssinian mustard) is mainly a result of its high resistance to biotic and abiotic stresses such as drought tolerance. *Brassica carinata,* is an annual crop noted to be highly resistant to many rapeseed pests: blackleg (*Leptosphaeria maculans),* white rust (*Albugo candida), Sclerotinia* sp. and *Phyllotreta cruciferae* (Pan, 2009). According to Razon (2009), *B.carinata*, together with *E. sativa* ssp. *oleifera*, is the most promising oilseed for biodiesel purpose in temperate zones, not just for the yield but also for its adaptability to hard pedo-climatic conditions. It may be used in a crop rotation system with cereals and on low nutrient soils. Best results are achieved sowing on autumn (IENICA, 2004). Harvesting may be done with same equipment used for rapeseed with the advantage that *B. carinata* shows a good resistance to the dehiscence of mature siliquae. The vegetable oil obtained from *B.carinata* is characterized by the presence of erucic acid, making it unsuitable for human consumption. On the other hand, its physico-chemical properties meet the European

1 SUSBIOFUEL project ("Studio di fattibilità per la produzione di biocarburanti da semi oleosi di nuove specie e da sottoprodotti o materiali di scarto" – D.M. 27800/7303/09), financially supported by the

Ministry of Agricultural, Food and Forestry Policies – Italy.

face the shift of some previously fertile into arid lands caused by climate change.

**2. Agronomical aspects** 

**2.1.1** *Brassica carinata*

a high level of sustainability in the oilseeds production.

**2.1 Non edible oil crops in the Mediterranean basin** 

buffering effects against heavy metals pollution (Palmer et al., 2001).

Refined, low acidity oilseeds (e.g. those derived from sunflower, soybean, rapeseed, tobacco etc.) may be easily converted into biodiesel, but their exploitation significantly raises the production costs, resulting in a biofuel that is not competitive with the petroleum-based diesel (Loreto et al., 2005). Presumably, as the market increases and technology is improved, costs will be driven down. In any case, the raw materials constitute a large portion of the manufacturing cost of biodiesel (up to 80%) (Bender, 1999).

Current oilseeds production systems raise environmental concerns because lands are intensively cultivated requiring high fertilizer and water inputs. These practices, aiming to increase yield, must be reduced or carefully regulated to prevent emissions of greenhouse gases or other environmental impacts. To do this, improved agronomic practices as the use of mixed species or crop rotation undoubtedly play a key role in mitigating negative impacts and enhancing biodiversity. A deep understanding of the microbial diversity of soils, its impacts on nutrient uptake and therefore on yield is crucial for sustainable cropping systems (The Royal Society, 2008).

Energy crops for industrial destination may represent a strategic opportunity in land use and income generation. However, in addition to the environmental aspects, economical concerns exist regarding the subtraction of lands for food cultivation. In a high market tension, it could have major impact on food/feed prices, increasing inequality, especially in developing countries. In addition, increased demand for food can result in the slowdown in biodiesel production due to reduced raw material availability. This was noticed in 2007 with industrial plants exploiting only 50% of their production capacity (Carvoli et al., 2008).

For all these reasons, it is highly desirable to produce biodiesel from crops specifically selected for their high productivity and characterized by low input requirements, or from low-cost feedstock such as waste cooking oil (WCO), animal fats and greases (Canakci et al., 2005; Zhang et. al, 2003).

While edible crops available for biodiesel production are restricted to few species (mainly palm/ soybean in the U.S. and palm/ rapeseed in the E.U.), the intent of using dedicated alternative feedstock opens a wide choice for new species that may be more suitable for specific conditions resulting on high yields.

The high WCO potential is recognized also by the EU directive 2009/28/EC, where waste vegetable or animal oil biodiesel is reported to save about the 88% of greenhouse emissions, a quite high value if compared to biodiesel from common vegetable oils, whose greenhouse emission savings range from 36 to 62%. The main issue posed by such a raw material is the need of its standardization, especially with regard to acidity decrease. Several methods have been proposed to solve this problem. Among them it is worth mentioning, besides the cited alkali refining method, addition of excess catalyst (Ono & Yoshiharu, 1979), extraction with a solvent (Rao et al., 2009), distillation refining process (Xingzhong et al., 2008) and preesterification method (Loreto et al., 2005; Pirola et al., 2010; Bianchi et. al, 2010; Parodi and Martini, 2008). This last seems to be the most attractive approach and has recently received much attention.

In the following paragraphs, the authors expose how it is possible to exploit waste materials or oils derived from crops not addressed to the food as potential raw materials for biodiesel production. Both the agronomic and chemical aspects deriving from the experimental work of the authors will be displayed.

#### **2. Agronomical aspects**

4 Biodiesel – Feedstocks and Processing Technologies

Refined, low acidity oilseeds (e.g. those derived from sunflower, soybean, rapeseed, tobacco etc.) may be easily converted into biodiesel, but their exploitation significantly raises the production costs, resulting in a biofuel that is not competitive with the petroleum-based diesel (Loreto et al., 2005). Presumably, as the market increases and technology is improved, costs will be driven down. In any case, the raw materials constitute a large portion of the

Current oilseeds production systems raise environmental concerns because lands are intensively cultivated requiring high fertilizer and water inputs. These practices, aiming to increase yield, must be reduced or carefully regulated to prevent emissions of greenhouse gases or other environmental impacts. To do this, improved agronomic practices as the use of mixed species or crop rotation undoubtedly play a key role in mitigating negative impacts and enhancing biodiversity. A deep understanding of the microbial diversity of soils, its impacts on nutrient uptake and therefore on yield is crucial for sustainable

Energy crops for industrial destination may represent a strategic opportunity in land use and income generation. However, in addition to the environmental aspects, economical concerns exist regarding the subtraction of lands for food cultivation. In a high market tension, it could have major impact on food/feed prices, increasing inequality, especially in developing countries. In addition, increased demand for food can result in the slowdown in biodiesel production due to reduced raw material availability. This was noticed in 2007 with industrial plants exploiting only 50% of their production capacity (Carvoli et

For all these reasons, it is highly desirable to produce biodiesel from crops specifically selected for their high productivity and characterized by low input requirements, or from low-cost feedstock such as waste cooking oil (WCO), animal fats and greases (Canakci et al.,

While edible crops available for biodiesel production are restricted to few species (mainly palm/ soybean in the U.S. and palm/ rapeseed in the E.U.), the intent of using dedicated alternative feedstock opens a wide choice for new species that may be more suitable for

The high WCO potential is recognized also by the EU directive 2009/28/EC, where waste vegetable or animal oil biodiesel is reported to save about the 88% of greenhouse emissions, a quite high value if compared to biodiesel from common vegetable oils, whose greenhouse emission savings range from 36 to 62%. The main issue posed by such a raw material is the need of its standardization, especially with regard to acidity decrease. Several methods have been proposed to solve this problem. Among them it is worth mentioning, besides the cited alkali refining method, addition of excess catalyst (Ono & Yoshiharu, 1979), extraction with a solvent (Rao et al., 2009), distillation refining process (Xingzhong et al., 2008) and preesterification method (Loreto et al., 2005; Pirola et al., 2010; Bianchi et. al, 2010; Parodi and Martini, 2008). This last seems to be the most attractive approach and has recently received

In the following paragraphs, the authors expose how it is possible to exploit waste materials or oils derived from crops not addressed to the food as potential raw materials for biodiesel production. Both the agronomic and chemical aspects deriving from the experimental work

manufacturing cost of biodiesel (up to 80%) (Bender, 1999).

cropping systems (The Royal Society, 2008).

specific conditions resulting on high yields.

al., 2008).

2005; Zhang et. al, 2003).

much attention.

of the authors will be displayed.

The authors present here preliminary results of a three years study about the feasibility of using new oilseed species for biodiesel production in Italy1. The intent is to propose an innovative agronomic solution that may affect the energy balance and the ability to achieve a high level of sustainability in the oilseeds production.

#### **2.1 Non edible oil crops in the Mediterranean basin**

A considerable amount of studies are available on mainstream and alternative crops for biodiesel feedstock. The authors made a selection of the most promising crops to be introduced in the Mediterranean zone, taking into account that currently the Mediterranean basin comprises not only temperate climate but also slightly-arid lands. Some of these are being effectively tested under the mentioned project as part of a unique rotation program.

Among oil crops the Brassicaceae family has an outstanding position. Rapeseed (*Brassica napus*) is the third largest oil crop with 12% of the world plant oil market with best yields when cultivated in cold-temperate regions (Carlsson, 2009). Yet, the large biodiversity of Brassicaceae reveal incipient species, among which *Brassica juncea*, *Brassica nigra*, *Brassica rapa*, *Brassica carinata*, *Sinapis alba*, *Camelina sativa*, *Eruca sativa* ssp*. oleifera*, etc. Besides the potential as raw material for biodiesel, their high content of glucosinolates (GSL) make them able to recover soils made marginal by soil-borne pests as nematodes (e.g. galling nematodes from the *Meloidogyne* genus and cist nematodes from *Heterodera* and *Globodera* genera) (Romero et al., 2009; Curto & Lazzeri, 2006). Many researchers also report weedsuppressive effects of Brassicaceae (e.g. Al-Khatib, 1997; Krishnan, 1998) as well as filteringbuffering effects against heavy metals pollution (Palmer et al., 2001).

On the other side an unexpected source of oilseed seems to arise from the tobacco culture. In anticipation of changes in tobacco market, selections of new varieties destined for energy production are coming out. Tobacco, as drought resistant species, seems a good option to face the shift of some previously fertile into arid lands caused by climate change.

#### **2.1.1** *Brassica carinata*

The recent interest in *B. carinata* (also known as Ethiopian or Abyssinian mustard) is mainly a result of its high resistance to biotic and abiotic stresses such as drought tolerance. *Brassica carinata,* is an annual crop noted to be highly resistant to many rapeseed pests: blackleg (*Leptosphaeria maculans),* white rust (*Albugo candida), Sclerotinia* sp. and *Phyllotreta cruciferae* (Pan, 2009). According to Razon (2009), *B.carinata*, together with *E. sativa* ssp. *oleifera*, is the most promising oilseed for biodiesel purpose in temperate zones, not just for the yield but also for its adaptability to hard pedo-climatic conditions. It may be used in a crop rotation system with cereals and on low nutrient soils. Best results are achieved sowing on autumn (IENICA, 2004). Harvesting may be done with same equipment used for rapeseed with the advantage that *B. carinata* shows a good resistance to the dehiscence of mature siliquae. The vegetable oil obtained from *B.carinata* is characterized by the presence of erucic acid, making it unsuitable for human consumption. On the other hand, its physico-chemical properties meet the European

<sup>1</sup> SUSBIOFUEL project ("Studio di fattibilità per la produzione di biocarburanti da semi oleosi di nuove specie e da sottoprodotti o materiali di scarto" – D.M. 27800/7303/09), financially supported by the Ministry of Agricultural, Food and Forestry Policies – Italy.

Non Edible Oils: Raw Materials for Sustainable Biodiesel 7

*brasiliensis*) and physic nut (*Jatropha curcas*). Among non-edible oils, the one extracted from castor bean is the most used for a wide variety of industrial purposes. Its oil is primarily of economic interest having cosmetic, medical and chemical applications. The presence of a high proportion of ricin oleic acid makes it suitable for the production of high-quality lubricants (Sanzone & Sortino, 2010). The use of castor oil is particularly supported in Brazil, with attempts to extract the ethyl esters using ethanol from sugarcane fermentation (although less reactive than methanol), making it a complete natural and renewable product (Pinto et al., 2005). Albeit the actual productivity is not very high, between 600 and 1,000 kg seeds/ha year, this value could triplicate with genetic improvement (Holanda, 2004). With the recent report on the draft genome sequence of castor bean revealing some key genes involved in oil synthesis (Chan et al., 2010), this possibility becomes even more palpable. In addition to this, the ease with which it can be cultivated in unfavorable environments contributes to its appeal as a raw material for sustainable biodiesel. In agreement to this, a two years field experiment conducted in south Italy using local ecotypes yielded around 2.3 t/ha of seeds, with up to 38% oil content, a quite high number for the dry conditions of the region (Sanzone & Sortino, 2010). The main limitation is the hand harvest, the current practice in the biggest producer countries as India, Brazil and China. However mechanization of harvesting is recently available for the collection of dwarf hybrid plants

Among the species of interest for the production of biodiesel, the cardoon or artichoke thistle (*C. cardunculus*) is an important resource to be exploited, particularly in light of its adaptability to different soils. *Cinara cardunculus* is a perennial herbaceous species belonging to the family Asteraceae. Its deep root system allows the plant to extract water and nutrients from very deep soil zones revealing a plant with a small demand for fertilization and extremely resistant to drought. This characteristic makes it suitable to be grown on dry marginal or abandoned lands in the Mediterranean basin. Production reaches 30-35 t/ha per year, with about 2 tons of seeds; the seeds contain up to 25 % oil, with a similar composition to sunflower oil (Pasqualino, 2006). Recently, studies have been conducted within the EU project "Biocard - Global Process to Improve *C. cardunculus*". In the framework of this project, a research on the harvesting procedures, i.e. a crucial point of the cultivation of the thistle has also been conducted. As an example, a combine prototype designed to separate and thresh the capitula and to drop the biomass proved to be feasible, with a good

The rationale of this proposal consists in the use of non-edible crops on soils no longer suitable for food production due to infestation by nematodes. The authors tested the possibility to rescue marginal soil fertility in consequence of the cultivation and the green manure of a naturally biocidal crop (*B. juncea* and *B. carinata*). Thanks to this practice the soil could be quickly good enough to produce oilseeds with satisfying yields for industrial destination. Furthermore a reduction in inputs of fertilizers is also expected due to preservation of organic matter content of soil. This practice offers the possibility to rescue soils availability for food production. Indeed, after some cycles of this rotation, the pest

(Clixoo, 2010).

**2.1.5** *Cynara cardunculus*

cost/working capacity relation (Pari et al., 2008).

**2.2 A new proposal for biodiesel production** 

specifications defined for biodiesel destination by the normative EN 14214:2002. Beyond its oil production capabilities, it was pointed out that the *B. carinata*'s lignocellulosic biomass can also be used to generate power and especially heat (Gasola et al., 2007), revealing an even greater potential.

#### **2.1.2** *Brassica juncea*

*Brassica juncea* (also known as wild mustard or Indian mustard) varieties are grown for edible leaves or for condiment mustard only in some countries, while its use as an oilseed crop is increasingly growing. Canadian plant breeders have developed *B. juncea* cultivars with canola characteristics (Potts et al., 1999). As a result, canola varieties of *B. napus* and canola-type *B. juncea* have similar compositional characteristics. The key differences between *B. napus* and canola-type *B. juncea* lie in their agronomic characteristics. *Brassica juncea* tolerates high temperatures and drought better than *B. napus*, and thus it is better suited for the warmer, drier climates as the Upper Plains of the U.S. or the Mediterranean area. Green manure of *B.juncea* is a current practice in some countries (e.g. Italy and U.S.) making use of the GSL-Myrosinase system as a natural biofumigant. At the same time, this practice supplies organic matter to soil. To make the most of its biocidal activity against soilborne pests and diseases, the mulching and incorporation to soil must be done at flowering time (Curto & Lazzeri, 2006).

#### **2.1.3** *Nicotiana tabacum*

The tobacco (*N. tabacum*) is an annual herbaceous plant belonging to the Solanaceae family, widespread in North and South America, commonly grown for the collection of leaves. The seeds are very small (up to 10,000/g) and contain 36 to 39% of oil having a high percentage of linoleic acid (Giannelos et al., 2002). Currently, the common varieties directed to leaf production reach the modest order of 1 to 1.2 t seeds/ha (Patel, 1998, as cited in Usta, 2005) as a result of selection to reduce the amount of seed produced. Recently researchers were able to over express, through genetic engineering, genes responsible for the oil production in the leaves (Andrianov et al., 2010). However, the seeds potential for oil production is much higher. In this sense, another recent outcome on tobacco improvement is a variety that can at least triple seed (up to 5 t/ha) and oil production. The energy tobacco varieties exist both in the non GMO and the GMO version for resistance factors against herbicides and insects (Fogher, 2008). Its high oil yield makes it very competitive in front of mainstream oil crops as rapeseed, sunflower and soybean. The remaining meal revealed to be relevant for combustion or to be used as a protein source for livestock. Tests with pigs demonstrated its palatability to animals, a good conversion rate and therefore its equivalence to the soybean meal (Fogher, 2002). In addition, the presence of consolidate agricultural practices and know-how make clear the advantage of using a well-known species as tobacco as alternative feedstock for biodiesel. The research on Energy Tobacco has also found new economies for the transplant management as well as direct sowing techniques are currently under test. Combineharvesters for the harvest of the whole inflorescences are available.

#### **2.1.4** *Ricinus communis*

*Ricinus communis* (castor bean) is an oilseed crop that belongs to the Euphorbiaceae family, which includes other energy crops as cassava (*Manihot esculenta*), rubber tree (*Hevea* 

specifications defined for biodiesel destination by the normative EN 14214:2002. Beyond its oil production capabilities, it was pointed out that the *B. carinata*'s lignocellulosic biomass can also be used to generate power and especially heat (Gasola et al., 2007),

*Brassica juncea* (also known as wild mustard or Indian mustard) varieties are grown for edible leaves or for condiment mustard only in some countries, while its use as an oilseed crop is increasingly growing. Canadian plant breeders have developed *B. juncea* cultivars with canola characteristics (Potts et al., 1999). As a result, canola varieties of *B. napus* and canola-type *B. juncea* have similar compositional characteristics. The key differences between *B. napus* and canola-type *B. juncea* lie in their agronomic characteristics. *Brassica juncea* tolerates high temperatures and drought better than *B. napus*, and thus it is better suited for the warmer, drier climates as the Upper Plains of the U.S. or the Mediterranean area. Green manure of *B.juncea* is a current practice in some countries (e.g. Italy and U.S.) making use of the GSL-Myrosinase system as a natural biofumigant. At the same time, this practice supplies organic matter to soil. To make the most of its biocidal activity against soilborne pests and diseases, the mulching and incorporation to soil must be done at flowering

The tobacco (*N. tabacum*) is an annual herbaceous plant belonging to the Solanaceae family, widespread in North and South America, commonly grown for the collection of leaves. The seeds are very small (up to 10,000/g) and contain 36 to 39% of oil having a high percentage of linoleic acid (Giannelos et al., 2002). Currently, the common varieties directed to leaf production reach the modest order of 1 to 1.2 t seeds/ha (Patel, 1998, as cited in Usta, 2005) as a result of selection to reduce the amount of seed produced. Recently researchers were able to over express, through genetic engineering, genes responsible for the oil production in the leaves (Andrianov et al., 2010). However, the seeds potential for oil production is much higher. In this sense, another recent outcome on tobacco improvement is a variety that can at least triple seed (up to 5 t/ha) and oil production. The energy tobacco varieties exist both in the non GMO and the GMO version for resistance factors against herbicides and insects (Fogher, 2008). Its high oil yield makes it very competitive in front of mainstream oil crops as rapeseed, sunflower and soybean. The remaining meal revealed to be relevant for combustion or to be used as a protein source for livestock. Tests with pigs demonstrated its palatability to animals, a good conversion rate and therefore its equivalence to the soybean meal (Fogher, 2002). In addition, the presence of consolidate agricultural practices and know-how make clear the advantage of using a well-known species as tobacco as alternative feedstock for biodiesel. The research on Energy Tobacco has also found new economies for the transplant management as well as direct sowing techniques are currently under test. Combine-

*Ricinus communis* (castor bean) is an oilseed crop that belongs to the Euphorbiaceae family, which includes other energy crops as cassava (*Manihot esculenta*), rubber tree (*Hevea* 

harvesters for the harvest of the whole inflorescences are available.

revealing an even greater potential.

**2.1.2** *Brassica juncea*

time (Curto & Lazzeri, 2006).

**2.1.3** *Nicotiana tabacum*

**2.1.4** *Ricinus communis*

*brasiliensis*) and physic nut (*Jatropha curcas*). Among non-edible oils, the one extracted from castor bean is the most used for a wide variety of industrial purposes. Its oil is primarily of economic interest having cosmetic, medical and chemical applications. The presence of a high proportion of ricin oleic acid makes it suitable for the production of high-quality lubricants (Sanzone & Sortino, 2010). The use of castor oil is particularly supported in Brazil, with attempts to extract the ethyl esters using ethanol from sugarcane fermentation (although less reactive than methanol), making it a complete natural and renewable product (Pinto et al., 2005). Albeit the actual productivity is not very high, between 600 and 1,000 kg seeds/ha year, this value could triplicate with genetic improvement (Holanda, 2004). With the recent report on the draft genome sequence of castor bean revealing some key genes involved in oil synthesis (Chan et al., 2010), this possibility becomes even more palpable. In addition to this, the ease with which it can be cultivated in unfavorable environments contributes to its appeal as a raw material for sustainable biodiesel. In agreement to this, a two years field experiment conducted in south Italy using local ecotypes yielded around 2.3 t/ha of seeds, with up to 38% oil content, a quite high number for the dry conditions of the region (Sanzone & Sortino, 2010). The main limitation is the hand harvest, the current practice in the biggest producer countries as India, Brazil and China. However mechanization of harvesting is recently available for the collection of dwarf hybrid plants (Clixoo, 2010).

#### **2.1.5** *Cynara cardunculus*

Among the species of interest for the production of biodiesel, the cardoon or artichoke thistle (*C. cardunculus*) is an important resource to be exploited, particularly in light of its adaptability to different soils. *Cinara cardunculus* is a perennial herbaceous species belonging to the family Asteraceae. Its deep root system allows the plant to extract water and nutrients from very deep soil zones revealing a plant with a small demand for fertilization and extremely resistant to drought. This characteristic makes it suitable to be grown on dry marginal or abandoned lands in the Mediterranean basin. Production reaches 30-35 t/ha per year, with about 2 tons of seeds; the seeds contain up to 25 % oil, with a similar composition to sunflower oil (Pasqualino, 2006). Recently, studies have been conducted within the EU project "Biocard - Global Process to Improve *C. cardunculus*". In the framework of this project, a research on the harvesting procedures, i.e. a crucial point of the cultivation of the thistle has also been conducted. As an example, a combine prototype designed to separate and thresh the capitula and to drop the biomass proved to be feasible, with a good cost/working capacity relation (Pari et al., 2008).

#### **2.2 A new proposal for biodiesel production**

The rationale of this proposal consists in the use of non-edible crops on soils no longer suitable for food production due to infestation by nematodes. The authors tested the possibility to rescue marginal soil fertility in consequence of the cultivation and the green manure of a naturally biocidal crop (*B. juncea* and *B. carinata*). Thanks to this practice the soil could be quickly good enough to produce oilseeds with satisfying yields for industrial destination. Furthermore a reduction in inputs of fertilizers is also expected due to preservation of organic matter content of soil. This practice offers the possibility to rescue soils availability for food production. Indeed, after some cycles of this rotation, the pest

Non Edible Oils: Raw Materials for Sustainable Biodiesel 9

In table 2 the mean percentage increasing of biomass of *B. napus*, *H. annus*, *G. max*, and

*N. tabacum* % 21 *B. napus* % 15 *H. annus* % 26 *G. max* % 28 Table 2. Increasing of biomass of oilseed crops produced after green manuring of B. *juncea.*

**3. Chemical aspects: Standardization of the raw materials and biodiesel** 

parameters for starting oil that can affect the quality of the final biodiesel.

Oil characterization before proceeding with the standardization of the raw material is a very important issue. Some properties remain in fact unchanged from the starting material to the finished biodiesel, or they are anyway predetermined. It is so important to check that the values of such chemical and physical oil properties are in range with those required by the standard regulations (see Table 3). The experimental procedures to get the values of such properties are also standardized and are indicated in the regulations. The following are

High sulphur and phosphorous content in the fuels cause greater engine wear and in particular shorten the life of the catalyst. Biodiesel derived from soybean, rapeseed, sunflower and tobacco oils are known to contain virtually no sulphur (Radich, 2004;

The authors have nevertheless found that the oil obtained from *B.juncea* seeds may contain high concentrations of sulphur due to the presence in the plant's tissues of glucosinolates,

Soybean, sunflower, peanut and rapeseed oils contain a high proportion of linoleic fatty acids, so affecting the properties of the derived ester with a low melting point and cetane number. Quantitative determination of linoleic acid methyl ester is accomplished by gas chromatography with the use of an internal standard after the substrate has been transesterificated and allows also the quantification of the other acid methyl esters (Environment Australia, 2003). The super-critical chromatography is another useful

**Crop Unit Biomass increasing** 

**Element Unit Value Standard Test Method**  sulphur mg/kg 112 UNI EN 20846:2005 nitrogen % (mass) 0,35 ASTM D5291-09 phosphorus mg/kg < 4 UNI EN 14107:2003

Table 1. Nitrogen, sulphur and phosphor content in *B. juncea* oil.

**production** 

**3.1 Oil characterization** 

Zhiyuan et al., 2008).

**Sulfur and phosphorous content:** 

the molecules responsible for the biofumigation effect. **Linoleic acid methyl ester, iodine value and viscosity** 

analytical technique, suitable for the direct analysis of the oils.

*N*. *tabacum* produced after green manuring of *B. juncea* is summarized.

control and the progressive increase of organic matter should make the soil eligible again for quality productions.
