Comparison between Annual and Perennial Energy Crops

Transcription

1 Comparison between Annual and Perennial Energy Crops * E. ALEXOPOULOU 1, T. GEMTOS 2, A. L. FERNANDO 3, Y. PAPATHEOHARI 4, S. L. COSENTINO 5 1 CRES, 19th Km Marathonos Avenue, 19009, Pikermi Attikis, GREECE, 2 University of Thessaly, 3 FCT UNL, 4 AUA, 5 UNICT ealex@cres.gr Abstract: The EU biobased economy needs sustainable supply of biomass for multiple uses: pharma, food, feed, bio-based materials and bioenergy. The yielding potential of the energy crops (annual and perennial ones) has to be as effiecient as possible in order to minimize the competition for land. The last two decades several energy crops (and/or non-food crops) have been tested at European level in the framework of several RTD projects. In the framework of EU project 4FCROPS ( a list of 15 non-food crops have been selected as the most promising ones and the selected crops were categorized in five groups according to main product (oil, fiber, lignocelluloses, sugar and wood). In EU project EUROBIOREF ( several annual oil crops (cuphea, safflower, lesquerella, castor, crambe and lonestry) tested and compared with the tranditional oil ones cultivated in EU (rapeseed & sunflower), while the perennial crops that were selected and compared were giant reed, switchgrass, miscanthus and poplar. In the Greek research project THALIS ( sweet sorghum, kenaf, rapeseed and sunflower are being testing in rotation systems for a period of four years with several tranditional winter and spring crops. The main advantage of the annual energy crops is their agronomic management can be easily adapted from their more traditional cultivation practices and they fit in current (rotation) farming systems. The main advantages of perennial energy crops that are being developed for biomass production and their great production potential lies in their low production costs, suitability to marginal and erosive lands, relative low water needs, low nutrient and agrochemical requirements, and positive environmental benefits. It is estimated that with the progress of the advanced biofuels the perennial energy crops will became quite an important source of feedstock, especially if the establishment costs will be reduced and the perennial grasses will domesticated and will be genetically improved. Key words: annual energy crops, perennial grasses, SRC crops, bioenergy, rotation INTRODUCTION The area of the cultivation of the energy crops is affected by the CAP 2020 and by the market needs. The EU target for 10% biofuels by 2020 is expected to lead to the cultivation of 25 Mha energy crops (European Biomass Association, 15 Mha will be used for liquids biofuels (biodiesel and bioethanol) and 5 Mha for biogas and 5Mha for solid biofuels. In 2007 the total biomass consumption to primary energy consumption in the EU was 89 million tons oil equivalent. Reagrding the annual energy crops it is very important how these crops can be inserted in the exististed agricultural systems in order to form the future intergrated agricultural systems. The scientific basis on how to implement these systems, which is essential to decision-makers and to secure policy support, is still relatively scarce. Emphasis should be given to depict farm-scale rotational schemes of food and non-food crops as well as on rotation schemes and on the possibility to use the arginal/abandoned/surplus lands for the cultivation of energy crops following the principles of precision and sustainable agriculture. Agricultural land use in the EU is already intensive in most regions and increased production of crops for nonfood uses could cause additional pressures on agricultural biodiversity, on soil and water resources and on the food/feed markets. At current market prices the effect of competition between bioenergy-biobased materials and food production for domestic food supply would be limited but would become more important with the assumed rise of the combined carbon permit and energy prices. The land available for growing bioenergy crops will be largely determined by the Utilized 330

2 Agricultural Area (UAA), including set-aside that will be released from food and fodder production, as a consequence of a further reform of the common agricultural policy and productivity increases. It is reported (EnCrop Project) that in EU27 a total area between 50,000 and 60,000 ha occupied with energy crops for solid biofuels. At the same time the cultivation area for energy crops for liquid biofuels is quite bigger and came up to 2.5 million ha. The need of producing 5.75% biofuels by 2010 (of the total liquid fuels) was the main reason for the cultivation of the crops for liquid biofuels in 2.5 million ha (Figure 1). The area of the energy crops cultivated in Europe is occupied by annual energy crops (such as cereals and rapeseed for bioethanol and biodiesel, respectively). According to Handbook that was compiled in the framework of the EnCrop project the largest areas of energy crops for solid biofuels located for miscanthus in UK, Germany Spain and Italy; for reed canary grass in Sweden and Finland; for willow in UK, Sweden and Germany and poplar in Spain and Italy. Statistics of energy crop plantations for solid biofuels are almost inexistent in many European countries (EnCrop project). MATERIALS and METHOD The last two decades several energy crops (and/or non-food crops) have been tested at European level in the framework of several RTD projects. In the framework of 4FCROPS project (Future Crops for Food, Feed, Fiber and Fuel, ( ) a list of 15 non-food crops have been selected as the most promising ones and the selected crops were categorized in five groups according to main product (oil, fiber, lignocelluloses, sugar and wood) (Table 1 & 2). Table 1. Selected annual crops per end product and climatic area (source: 4FCROPS) Climatic area Oil Fiber Sugar Nemoral Rapeseed Hemp - Continental Rapeseed Flax Sugar beets Atlantic central Rapeseed Flax Sugar beets Atlantic north Rapeseed Hemp - Lusitanian Rapeseed Hemp Sweet sorghum Mediterranean North Sunflower Hemp Sweet sorghum Mediterranean South Ethiopian mustard Flax Sweet sorghum Figure 1. Area of the cultivation of energy crops from 2003 to 2007 (EU). As different sectors food, feed, fiber, and fuels compete for land, the yielding potential of the future non-food crops has to be as efficient as possible in order to minimize the competition for land. In the long term, bioenergy crops provide the largest potential. This development will be driven by: additional productivity increases, further liberalization of agricultural markets and the introduction of high-yield bioenergy crops. The aim of this study is to carry out a comparion between annual and perennial energy crops based on- EU going projects or recently completed. Table 2. Selected perennial crops per end product and climatic area (source: 4FCROPS) Climatic area Lignocellulosic SRC crops Nemoral Reed canary Poplar grass Continental Miscanthus Willow Atlantic central Miscanthus Poplar Switchgrass Atlantic north Miscanthus Willow Switchgrass Lusitanian Miscanthus Willow, Eucalyptus Mediterranean Giant reed Poplar North Mediterranean South Cardoon Eucalyptus In EU project EUROBIOREF ( several annual oil crops (cuphea, safflower, lesquerella, castor, crambe and lonestry) tested and compared with the tranditional oil ones cultivated in EU (rapeseed & sunflower), while the perennial crops that were selected and compared were giant reed, switchgrass, miscanthus and poplar ( ). 331

3 In the Greek research project THALIS ( ) ( sweet sorghum, kenaf, rapeseed and sunflower are being testing in rotation systems for a period of four years with several tranditional winter and spring crops. The results of the comparison of annual and perennial energy crops are presented below. RESULTS and DISCUSSION Annual energy crops In 4FCROPS project the selected annual energy crops were: a) oil crops for biodiesel production, b) sugar crops for bioethanol production and c) fiber crops for both bioenergy and biobased products. In Table 3 the water requirements of the annual energy crops as well as the frost and water resistance are presented. Oil Crops: Currently, the most important oil crop for biodiesel production in Europe is rapeseed, while quite important is sunflower for the south Europe. The total production of rapeseed in EU28 is 21.5 million tons (2009) with an oil production 8.9 million tons (2009) ( The mean seed yields in Europe of the crop of rapeseed is 2500 kg/ha (Figure 2). The main rapeseed producers are France and Germany, while important also considered Poland and UK. Sunflower is the second important oil crop for biodiesel production in Europe with a total production of 6.9 millions tons (2009) of seeds and 2.6 millions tons of oil ( while the mean seed yields 1900 kg seeds/ha. Rapeseed is being cultivated as an annual winter crop, while sunflower is an annual spring crop. The most important characteristics in terms of oil crops are the oil content of the seeds and the chemical composition of the oil. Rapeseed and Ethiopian mustard produce seeds with quite high oil content that for most of varieties and hybrids is higher than 40%. Both crops produce oils that are in fully accordance with the biodiesel standards. Sunflower seeds have oil content from 25 to 40 % but recently the new varieties that have been developed produce seeds with higher oil content (more than 40%). In the framework of EUROBIOREF project apart from rapeseed and sunflower emphasis was given on other oil crops; cuphea, lesquerella, castor, safflower, lunaria and crambe. After four years of experimentation it was found that safflower, castor and crambe have good adaptability in EU and high yields, while further research is needed in order increased the seed yields. Regarding cuphea and lesquerella more research is needed compared to the previous mentioned crops in order to record the realistic potential of these crops when cultivated in EU, while the yields of lunaria were quite poor. Figure 2. Yields (t/ha) of rapeseed in several climatic areas in EU (in marginal and agricultural lands with low and high inputs) Sugar Crops: Sweet sorghum and sugar beets considered as the important crops for bioethanol production (first generation biofuels). Sweet sorghum is an annual spring crop with quite high biomass yields that has been investigated the last two decades in several European research projects. Its yields can reach 40 t/ha dry matter yields and fresh biomass yields up 140 t/ha (Figure 3). Currently, it was invesitigated in the view of SWEETFUEL project ( The stems of sweet sorghum stems have high content in sugars that according to the variety and the harvesting time varies from 10 to 15%. Figure 3. Yields (t/ha) of sweet sorghum in several climatic areas in EU (in marginal and agricultural lands with low and high inputs) 332

4 Sugar beet is a traditional biennial crop. In EU27 the total harvested area in 2007 was million ha and the top four producers countries by descending order were Germany million ha, France million ha, Poland million ha and UK million ha. The mean yields in EU are kg/ha. Sugar beet is a traditional crop that is mainly cultivated for sugar production. From 100kg fresh sugar beets can be extracted 12 to 15 kg sucrose, 3.5 kg molasses and 4.5 kg dried pulp. Fibre crops: The most important bast fibre crops for Europe are flax and hemp. Another important crop is cotton that is cultivated in South Europe. Kenaf is a bast fibre crop that was cultivated for few years in north of Italy (around Bologna) and the harvesting material was delivered to Company KEFITALIA in order to produce insulations mats from this crop. Fibrous flax cultivated in a total area of ha in Europe in Its yields are 10 t/ha in experimental fields and the long fibre yields were 2.8 t/ha and 0.7 t/ha of the short fibre yields. The realistic yields are 30 to 35% lower compared to the ones recorded in experimental fields (Figure 4). Figure 4. Yields (t/ha) of fiber flax in several climatic areas in EU (in marginal and agricultural lands with low and high inputs) Hemp is being cultivated in quite small area compared to flax. In 2012, its cultivation area is around 14,000. France is the main hemp producer the last 30 years. Hemp yields varies according to the variety and the area of the cultivation and its stem yields can be ranged from 8 to 12 t/ha. Perennial energy crops In 4FCROPS project the selected perennial crops were: a) perennial lignocellulosic crops and b) short rotation forestry crops. In Table 3 the water requirements of the perennial energy crops as well as the frost and water resistance are presented. Table 3. Water requirements, frost and drough resistance of the selected crops Crop Water requirement Frost resistance Drought Annual energy crops Rapeseed Medium High Medium E. mustard Low Low High Sunflower Medium Low Medium Hemp High Medium Medium Flax Medium Medium Medium Sorghum spp Medium Low High Perennial energy crops (SRC, perennial grasses) Willow High High Low Poplar Medium Medium Medium Eucalyptus High Low High Reed canary High High Low grass Switchgrass Medium High Med/High Miscanthus High Medium Low Giant reed Medium Low Med / High Cardoon Low Low High Lignocellulosic crops: Lignocellulosic crops are important non-food crops for both solid biofuels and for second generation biofuels (advanced biofuels). In this study were selected: reed canary grass, cardoon, switchgrass, miscanthus and giant reed. Reed canary grass is a perennial crop for northern Europe. It is the cultivated commercial in Finland with a total cultivated area around 20,000 ha and 1,000 ha in Sweden. Its realistic yields varied from 4 to 7 t/ha. In Finland has been set a target for 100,000 ha of reed canary grass by The ash content of reed canary grass varies from 1 to 8% and the net caloric value is 4300 kcal/kg. Miscanthus is considered as the most important perennial grass crop in Europe. Ican be cultivated in whole Europe with yields that can reach 30 t/ha. Its crop realistic yields varied from 15 to 20 t/ha (Figure 5). It s a crop that needs water and thus it is not the best choice for the regions in Southern Europe with limited water irrigation. The crop has the lower ash content of the perennial grasses (3%) and net calorific value around 4400 kcal/kg. Switchgrass is a perennial crop with many varieties (upland and lowland ones) that can be cultivated successfully in whole Europe and can replace miscanthus in areas in areas that there is no 333

5 enough water for irrigation. Its ash content is between 4 and 5% and the net calorific value is like reed canary grass (4300 kcal/kg). Figure 5. Yields (t/ha) of miscanthus in several climatic areas in EU (in marginal and agricultural lands with low and high inputs) Giant reed is a perennial crop with quite high yields up to 35 t/ha for Southern Europe and with realistic yields between t/ha. It has been exploited only in small and large experimental fields and it is considered as an excellent source for second generation biofuels. Currently, it has been announced that a large area of giant reed will be established in northern Italy by company Chemtex. Its ash content is between 4 and 4.5% and the net calorific value is like reed canary grass and switchgrass (4300 kcal/kg). Cardoon is a perennial crop that can be used for both solid biofuels for whole crop and oil production from its seeds, while the whole crop could be exploited for second generation biofuels. It is a crop for the South Europe with dry yields that could reach 25 t/ha, while it s realistic yields are t/ha. Cardoon has high ash content that varied from 8 to 12% and its net calorific value is low that the other perennial crops presented above and varied from 3800 to 3900 kcal/kg. Figure 6. Yields (t/ha) of poplar in several climatic areas in EU (in marginal and agricultural lands with low and high inputs) SRC crops: The most important crops for short rotation coppice are: willow, poplar and eucalyptus. It is reported ha of willow in Sweden and 6000 ha in Poland, while the yields varied from 8-10 ton/ha/year. Commercial fields of poplar has been reported in Italy (5700 ha) and Spain (18000 ha). The yields of poplar in several climatic EU areas are presented in Figure 6. The ash content of willow had been reported to be 2.9% and the net calorific value MJ/kg. The corresponding values were for poplar % and 18.1 MJ/kg. The potential yields of this crop are quite high. It has been reported yields 20 t/ha/y in experimental fields. Eucalyptus is also an important crop for SRC in Europe with potential yields of 32 t/ha per year. In Europe is being cultivated for paper and pulp production (mainly Portugal and Spain). For Eucalyptus it has been reported that the ash varies from 2-3% and the net calorific value for the eucalyptus wood is MJ/kg, while for the bark MJ/kg. It s should be mentioned that for soft woods the ash content varies from 1-2%, while the net calorific value is MJ/kg. Comparison between annual and perennial energy crops The main advantage of the annual energy crops is their agronomic management can be easily adapted from their more traditional cultivation practices and they fit in current (rotation) farming systems. On the other hand the perennial grasses are grass crops that are being developed for biomass production in Europe and North America. Their great production potential lies in their low production costs, suitability to marginal and erosive lands, relative low water needs, low nutrient and agrochemical requirements, and positive environmental benefits (e.g. potential for carbon storage through their deep and well-developed root system, high water use efficiency) (Zegada- Lizarazu et al. 2010). The annual energy crops are mainly used for the production of first generation biofuels (bioethanol and biodiesel), while some of them can be used alternative for food production or fiber production. 334

6 The perennials have a great potential as source for second generation biofuels. Most of the perennial grasses are undomesticated and are in the early stages of development and management. The investment in research and development of these crops will result in larger improvements than with traditional crops. Moreover, these crops show some advantages over annual crops in terms of agricultural inputs, yields, production costs, food security, reduced GHG emissions, and environmental sustainability. The annual energy crops because they can easily fit to the conventional agricultural systems and they can be insert in the existing rotation systems as well as they can easily established by seed and can be cultivated with existing machinery used for other conventional crops after some adjustments have high farmers and public perception. On the contrary, the perennial grasses needs a long term commitment of the land that will be established and in some of them the establishment taking place by rhizomes and/or plants that makes it more expensive than the establishment by seed and thus they have lower farmer/public perception compared to the annual energy crops. According to 4FCROPS the most suitable energy crops in terms of agronomic management, climatic adaptability, and potential biomass production in northern Europe are some fast-growing trees and perennial grasses such as poplar, willow, reed canarygrass, switchgrass and miscanthus. In the Mediterranean climate of southern Europe eucalyptus, sweet sorghum, giant reed and cardoon are promising energy crops. The energy crops that could provide feedstock for second-generation biofuels (such as perennial grasses and woody crops) are largely undomesticated and are in the early stages of development and management. Thus, investment in research and development of these crops will result in larger improvements than with traditional crops. It is estimated that with the progress of the second generation biofuels the perennial energy crops will became quite an important source of feedstock, especially if the establishment costs will be reduced and the perennial grasses will domesticated and will be genetically improved. It was found that the perennial crops (www4fcrops.eu) may be better planted in surplus land, although their financial best was achieved when cultivated on good agricultural lands in spite of their increased land rent. In all cases it was revealed that the increase in productivity due to more fertile soil and increased level of inputs is more than compensated by the sales of higher output. Recently, three European research projects funding the research and development of perennial grasses at European level (with the contribution of partners outside of Europe) which are: OPTIMA, OPTIMISC and GRASS MARGIN. These projects started in autumn 2011 and will conclude in the beginning of Links among the three projects have been established from the very beginning of the projects and some activities will be carried out in common such as common workshops, conferences, etc. A final conference will be organised at the end of the projects in Brussels in which the results of the three projects will be presented to the relevant stakeholders. CONCLUSIONS With the progress of the second generation biofuels the perennial energy crops will become quite an important source of feedstock, especially if the establishment costs will be reduced and the perennial grasses will be domesticated and will be genetically improved. Currently, the perennial grasses are being investigated in three EU projects and it is expected that quite important findings to be realised at the end of the projects in On the other hand the annual energy crops can be inserted in the existing agricultural systems easily and thus they have high public acceptance. There is lack of information regarding the rotation systems that have been followed in the future integrated agricultural systems. ACKNOWLEDGMENTS This work was funded by the FP7 projects 4FCROPS EUROBIOREF, OPTIMA & by Thalis project (Environmental friendly biomass production). REFERENCES Zegada-Lizarazu W, Elbersen W, Cosentino SL, Zatta A, Alexopoulou E, Monti A, Agronomic aspects of future energy crops in Europe. Biofuels, BIOPROD. BIOREF. 4(6),