Economic Analysis of the Potential of Cellulosic Biomass Available in France from Agricultural Residue and Energy Crops

The objective of this research is to evaluate the feasibility and locations of using cellulosic biomass both from crop residues and from dedicated energy crops to supply 200-million-liter-biodiesel plants in France. The estimation of the potential amount of agricultural residue available in 2015 in each region of France is calculated. The residues considered in this study come from cereal straw and corn stover. Results show that eight out of the twenty one French regions have enough agricultural residues available to supply at least one 200 million liter biofuel plant. Region Centre has the largest potential, with enough residues to supply three to five plants. Finally, cost of supplying one biodiesel plant of 200 million liters in the region Centre is estimated. Results show that collection of biomass will be effective in an area with a radius of 58 Km to 168 Km depending of the raw material considered and its abundance. The cost of supplying a plant with miscanthus is much higher than with residues only. Thus, crop residues appear to offer a lower cost to produce biodiesel in the near term compared to a dedicated crop. Results show that production of biofuel from cellulosic biomass should not be limited by the supply of raw material, but costs of conversion to liquid fuels clearly will play a key role in the development of cellulosic biofuels. Energy prices and policies will have a significant impact on second generation biofuel development.     

Miscanthus as a Productive Biofuel Crop for Phytoremediation

There are many locations where soil quality improvements would be beneficial because of contamination, erosion, flooding, or past human activities. Miscanthus, a C-4 grass related to sugarcane, grows well in mildly contaminated soil and on sites where soil quality is poor, particularly with respect to nitrogen. Because of its high biomass yield, it is of interest as an energy crop, and as a plant to use for simultaneous crop production and phytoremediation. Here we review recent literature on using miscanthus for combined biomass production and phytoremediation of contaminated and marginal lands. We analyze both advantages and disadvantages for production of this crop along with phytoremediation of sites contaminated with metals and petroleum hydrocarbon. Reports of laboratory and field investigations, which use Miscanthus spp. for stabilizing and removing metals are considered. The potential for growing miscanthus commercially at contaminated and marginal sites in the regions of Central and Eastern Europe as well as the United States appears to be good because large quantities of biomass can be produced and effective phyto-stabilization can be achieved with very slow metal removal over time. In addition, soil quality is improved in many cases.     

Marginal lands for bioenergy in China; an outlook in status,potential and management

Energy consumption and CO₂ emissions have been increasing continuously over the past few decades in China and there is a pressing need to replace the fossil fuel‐based economy with an efficient low‐carbon system, tailor‐made to future requirements. China is starting an energy transition with the aim of building an energy system for the future. China has made tremendous progress in increasing the amount of renewable energy and reducing the cost of renewable energy over the last 20 years. According to the 14th 5 year plan, China aims to incorporate 20% of renewable energy to the primary energy mix and attain 27% reduction in CO₂ emissions. Bioenergy crops constitute a significant proportion of biomass‐based bioenergy and have recently been promoted by the Chinese Government to help overcome food and fuel conflict. Steps are being taken to promote bioenergy crops on marginal lands in China, and various regions across the country with soil marginality have been evaluated for bioenergy crop cultivation. The present paper reviews the status of bioenergy in China and the potential status of marginal lands from different regions of China. It also elaborates on some of the policies, subsidies and incentives allocated by the Chinese Government for the promotion of biomass‐based energy. Land management and plant improvement strategies were discussed, which are effective in making marginal lands suitable for bioenergy crop cultivation. Managing planting strategies, intercropping and crop rotation are effective management practices used in China for the utilization of marginal lands. A national investigation is desirable for creating an inventory of technical and economic potential of biomass feedstocks that could be planted on marginal lands. This would assist with highlighting the pros and cons of using marginal lands for bioenergy production and effective policy making.     

Social assessment of miscanthus cultivation in Croatia: Assessing farmers' preferences and willingness to cultivate the crop

Social aspects of miscanthus cultivation have been investigated in a limited way in the scientific literature. Adopting existing frameworks for social life-cycle assessment enables assessments to include numerous social aspects; however, the relevance of these aspects depends on the local context. This study aims to identify the most relevant social aspects from the farmers' perspective using a previously proposed framework for the assessment of the stakeholder ‘farmer’. It is based on a case study for miscanthus production in Sisak Moslavina in Croatia. The existence of abandoned lands in Croatia presents an opportunity for the cultivation of miscanthus as a potential source of biomass for the production of bio-based materials and fuels. The study seeks to assess the feasibility of cultivating miscanthus in the region, taking into account potential challenges and opportunities, as well as farmers' willingness to adopt the crop, and to understand the reasons behind land abandonment. We conducted a survey among 44 farmers in the region and used a scoring method to identify the most relevant social aspects. The aspects most valued by the farmers were health and safety, access to water, land consolidation and rights, income and local employment, and food security. Responses to the question of whether they would adopt the crop highlight the importance of an established market, good trading conditions and profitability of cultivation. The survey also enabled an understanding of farmers' preferences with respect to the production conditions of crops. The farmers regarded the provision of subsidies as one of the main factors that render a crop attractive. Opportunities for the adoption of the miscanthus cultivation include high yields and low input requirements. Barriers include land conflicts and land availability. Despite the opportunities for miscanthus development in the region, there are important challenges to consider for successful implementation of the crop.     

Genetic Engineering of Energy Crops: A Strategy for Biofuel Production in China Free Access

Biomass utilization is increasingly considered as a practical way for sustainable energy supply and long‐term environment care around the world. In concerns with food security in China, starch or sugar‐based bioethanol and edible‐oil‐derived biodiesel are harshly restricted for large scale production. However, conversion of lignocellulosic residues from food crops is a potential alternative. Because of its recalcitrance, current biomass process is unacceptably expensive, but genetic breeding of energy crops is a promising solution. To meet the need, energy crops are defined with a high yield for both food and biofuel purposes. In this review, main grasses (rice, wheat, maize, sorghum and miscanthus) are evaluated for high biomass production, the principles are discussed on modification of plant cell walls that lead to efficient biomass degradation and conversion, and the related biotechnologies are proposed in terms of energy crop selection.     

Determining spatially varying profit-maximizing management practices for miscanthus and switchgrass production in the rainfed United States

Determining optimal management practices for the profitable production of perennial energy crops is critical for scaling up production beyond experimental levels. Although many experimental field studies have examined the effects of management practices on the performance of miscanthus and switchgrass, there are no recommendations for economically optimal nitrogen (N) application rates and how they should vary spatially and with the age of the energy crop as well as on optimal rotation age of the energy crop to maximize profits. We develop a modeling framework to determine economically optimal crop management decisions and simulate the variability under various scenarios for miscanthus and switchgrass production across 2287 counties in the rainfed United States. We find that profit-maximizing N recommendations for these crops vary across maturity stages and regions and can increase the landowner's profits compared with a uniform N rate across ages and regions. We also find that the optimal rotation for these crops is shorter than the productive physical lifespan (15–20 and 10 years for miscanthus and switchgrass, respectively). Specifically, the N rate that maximizes the economic returns is negligible for miscanthus and 111 kg ha⁻¹ for switchgrass production at age 2. The mean profit-maximizing N rate increases with age for miscanthus, peaking at 151 kg ha⁻¹ at age 11 before declining to 114 kg ha⁻¹ at the optimal rotation age of 13 years while that for switchgrass is 150 kg ha⁻¹ for middle-aged stands and declines to 114 kg ha⁻¹ at the optimal rotation of 8–9 years. We find that miscanthus is the most profitable energy crop in the northern region of the rainfed United States while switchgrass is most profitable in the south of the rainfed United States. Our findings are useful for improving assessments of the profitability of energy crops and guiding future management decisions by landowners.     

Impact of drought stress on growth and quality of miscanthus for biofuel production

Miscanthus has a high potential as a biomass feedstock for biofuel production. Drought tolerance is an important breeding goal in miscanthus as water deficit is a common abiotic stress and crop irrigation is in most cases uneconomical. Drought may not only severely reduce biomass yields, but also affect biomass quality for biofuel production as cell wall remodeling is a common plant response to abiotic stresses. The quality and plant weight of 50 diverse miscanthus genotypes were evaluated under control and drought conditions (28 days no water) in a glasshouse experiment. Overall, drought treatment decreased plant weight by 45%. Drought tolerance – as defined by maintenance of plant weight – varied extensively among the tested miscanthus genotypes and ranged from 30% to 110%. Biomass composition was drastically altered due to drought stress, with large reductions in cell wall and cellulose content and a substantial increase in hemicellulosic polysaccharides. Stress had only a small effect on lignin content. Cell wall structural rigidity was also affected by drought conditions; substantially higher cellulose conversion rates were observed upon enzymatic saccharification of drought‐treated samples with respect to controls. Both cell wall composition and the extent of cell wall plasticity under drought varied extensively among all genotypes, but only weak correlations were found with the level of drought tolerance, suggesting their independent genetic control. High drought tolerance and biomass quality can thus potentially be advanced simultaneously. The extensive genotypic variation found for most traits in the evaluated miscanthus germplasm provides ample scope for breeding of drought‐tolerant varieties that are able to produce substantial yields of high‐quality biomass under water deficit conditions. The higher degradability of drought‐treated samples makes miscanthus an interesting crop for the production of second‐generation biofuels in marginal soils.     

Economic and environmental performance of miscanthus cultivated on marginal land for biogas production

Environmental issues surrounding conventional annual biogas crops have led to growing interest in alternative crops, such as miscanthus. In addition to the better environmental performance, miscanthus can be grown on marginal land where no competition with feed and food crops is anticipated. On marginal land however, biomass yields are significantly lower than on good agricultural land. This raises the question of the economic and environmental sustainability of miscanthus cultivated on marginal land for biogas production. This study assessed the environmental and economic performance of miscanthus cultivated on marginal land for biogas production by conducting a Life‐Cycle Assessment and complementary Life‐Cycle Cost analysis. The functional unit chosen was 1 GJ of electricity (GJ_el.). The substitution of a fossil reference was included using a system expansion approach. Electricity generated by the combustion of miscanthus‐based biogas in a combined heat and power has considerably lower impacts on the environment than the fossil reference in most of the categories assessed. In the impact category “climate change”, the substitution of the marginal German electricity mix leads to a carbon mitigation potential of 256 kg CO₂e/GJ_el.. At 45.12 €/GJ_el., the costs of miscanthus‐based biogas generation and utilization are considerably lower than those of maize (61.30 €/GJ_el.). The results of this study clearly show that it can make economic and environmental sense to cultivate miscanthus on marginal land as a substrate for biogas production. The economic sustainability is however limited by the biomass yield. By contrast, there are no clear thresholds limiting the environmental performance. The decision needs to be made on a case‐by‐case basis depending on site‐specific conditions such as local biodiversity.     

西北干旱区利用间套作促进能源植物的高产高效

在全球性能源紧缺和我国能源植物大规模种植困难等大背景下,优质、充足的原料供应已成为制约生物质能源产业发展的主要限制因素。在确保能源植物高效生产和克服"与粮争地、与人争粮"现实的同时,挖掘我国边际土壤高产高效生产能源植物的土地优势和增产潜力。通过筛选评价适宜西北干旱地区高抗逆的新型能源植物种类,开发应用能源植物与粮经作物间套作栽培技术,实现新型能源植物对逆境资源的高效利用和可持续规模化种植,提高能源植物的生产力和优化能源物种的区域配置,增加土地产值和农民收入,缓解能源紧缺,达到经济、生态和社会效益多赢,为我国能源和粮食安全提供技术支撑。     

Switchgrass and Giant Miscanthus Biomass and Theoretical Ethanol Production from Reclaimed Mine Lands

Switchgrass (Panicum virgatum L.) and giant miscanthus (Miscanthus x giganteus Greef & Deuter ex Hodkinson & Renvoize) are productive on marginal lands in the eastern USA, but their productivity and composition have not been compared on mine lands. Our objectives were to compare biomass production, composition, and theoretical ethanol yield (TEY) and production (TEP) of these grasses on a reclaimed mined site. Following 25 years of herbaceous cover, vegetation was killed and plots of switchgrass cultivars Kanlow and BoMaster and miscanthus lines Illinois and MBX-002 were planted in five replications. Annual switchgrass and miscanthus yields averaged 5.8 and 8.9 Mg dry matter ha^?1, respectively, during 2011 to 2015. Cell wall carbohydrate composition was analyzed via near-infrared reflectance spectroscopy with models based on switchgrass or mixed herbaceous samples including switchgrass and miscanthus. Concentrations were higher for glucan and lower for xylan in miscanthus than in switchgrass but TEY did not differ (453 and 450 L Mg^?1, respectively). In response to biomass production, total ethanol production was greater for miscanthus than for switchgrass (5594 vs 3699 L ha^?1), did not differ between Kanlow and BoMaster switchgrass (3880 and 3517 L ha^?1, respectively), and was higher for MBX-002 than for Illinois miscanthus (6496 vs 4692 L ha^?1). Relative to the mixed feedstocks model, the switchgrass model slightly underpredicted glucan and slightly overpredicted xylan concentrations. Estimated TEY was slightly lower from the switchgrass model but both models distinguished genotype, year, and interaction effects similarly. Biomass productivity and TEP were similar to those from agricultural sites with marginal soils.     

An integrated biogeochemical and economic analysis of bioenergy crops in the Midwestern United States

This study integrates a biophysical model with a county‐specific economic analysis of breakeven prices of bioenergy crop production to assess the biophysical and economic potential of biofuel production in the Midwestern United States. The bioenergy crops considered in this study include a genotype of Miscanthus, Miscanthus×giganteus, and the Cave‐in‐Rock breed of switchgrass (Panicum virgatum). The estimated average peak biomass yield for miscanthus in the Midwestern states ranges between 7 and 48 metric tons dry matter per hectare per year ( t DM ha^?1 yr^?1), while that for switchgrass is between 10 and 16 t DM ha^?1 yr^?1. With the exception of Minnesota and Wisconsin, where miscanthus yields are likely to be low due to cold soil temperatures, the yield of miscanthus is on average more than two times higher than yield of switchgrass. We find that the breakeven price, which includes the cost of producing the crop and the opportunity cost of land, of producing miscanthus ranges from $53 t^?1 DM in Missouri to $153 t^?1 DM in Minnesota in the low‐cost scenario. Corresponding costs for switchgrass are $88 t^?1 DM in Missouri to $144 t^?1 DM in Minnesota. In the high‐cost scenario, the lowest cost for miscanthus is $85 t^?1 DM and for switchgrass is $118 t^?1 DM, both in Missouri. These two scenarios differ in their assumptions about ease of establishing the perennial crops, nutrient requirements and harvesting costs and losses. The differences in the breakeven prices across states and across crops are mainly driven by bioenergy and row crop yields per hectare. Our results suggest that while high yields per unit of land of bioenergy crops are critical for the competitiveness of bioenergy feedstocks, the yields of the row crops they seek to displace are also an important consideration. Even high yielding crops, such as miscanthus, are likely to be economically attractive only in some locations in the Midwest given the high yields of corn and soybean in the region.     

Water and energy footprints of bioenergy crop production on marginal lands

Water and energy demands associated with bioenergy crop production on marginal lands are inextricably linked with land quality and land use history. To illustrate the effect of land marginality on bioenergy crop yield and associated water and energy footprints, we analyzed seven large‐scale sites (9–21 ha) converted from either Conservation Reserve Program (CRP) or conventional agricultural land use to no‐till soybean for biofuel production. Unmanaged CRP grassland at the same location was used as a reference site. Sites were rated using a land marginality index (LMI) based on land capability classes, slope, soil erodibility, soil hydraulic conductivity, and soil tolerance factors extracted from a soil survey (SSURGO) database. Principal components analysis was used to develop a soil quality index (SQI) for the study sites based on 12 soil physical and chemical properties. The water and energy footprints on these sites were estimated using eddy‐covariance flux techniques. Aboveground net primary productivity was inversely related to LMI and positively related to SQI. Water and energy footprints increased with LMI and decreased with SQI. The water footprints for grain, biomass and energy production were higher on lands converted from agricultural land use compared with those converted from the CRP land. The sites which were previously in the CRP had higher SQI than those under agricultural land use, showing that land management affects water footprints through soil quality effects. The analysis of biophysical characteristics of the sites in relation to water and energy use suggests that crops and management systems similar to CRP grasslands may provide a potential strategy to grow biofuels that would minimize environmental degradation while improving the productivity of marginal lands.     

Life cycle assessment of ethanol production from miscanthus: A comparison of production pathways at two European sites

Lignocellulosic ethanol represents a renewable alternative to petrol. Miscanthus, a perennial plant that grows on marginal land, is characterized by efficient use of resources and is considered a promising source of lignocellulosic biomass. A life cycle assessment (LCA) was performed to determine the environmental impacts of ethanol production from miscanthus grown on marginal land in Great Britain (Aberystwyth) and an average‐yield site in Germany (Stuttgart; functional unit: 1 GJ). As the conversion process has substantial influence on the overall environmental performance, the comparison examined three pretreatment options for miscanthus. Overall, results indicate lower impacts for the production in Stuttgart in comparison with the corresponding pathways in Aberystwyth across the analysed categories. Disparities between the sites were mainly attributed to differences in biomass yield. When comparing the conversion options, liquid hot water treatment resulted in the lowest impacts, followed by dilute sulphuric acid. Dilute sodium hydroxide pretreatment represented the least favourable option. Site‐dependent variation in biomass composition and degradability did not have substantial influence on the environmental performance of the analysed pathways. Additionally, implications of replacing petrol with miscanthus ethanol were examined. Ethanol derived from miscanthus resulted in lower impacts with respect to greenhouse gas emissions, fossil resource depletion, natural land transformation and ozone depletion. However, for other categories, including toxicity, eutrophication and agricultural land occupation, net scores were substantially higher than for the fossil reference. Nevertheless, the results indicate that miscanthus ethanol produced via dilute acid and liquid hot water treatment at the site in Stuttgart has the potential to comply with the requirements of the European Renewable energy directive for greenhouse gas emission reduction. For ethanol production at the marginal site, carbon sequestration needs to be considered in order to meet the requirements for greenhouse gas mitigation.     

我国优势油脂类生物柴油植物蓖麻的种质资源发掘和生物柴油利用

发展可再生生物质能源是解决人类能源危机和环境污染的重要途径。利用边际土地发展油脂类生物质能是生物质能的重要组成部分。蓖麻因为适应性强和油脂成份独特被誉为"理想的生物柴油植物"。蓖麻是我国优势油脂类能源植物,利用边际土地,发展蓖麻产业为我国生物柴油产业化提供原料,是我国现阶段生物柴油产业化发展的相对理想而又现实的选择,而且具有重要的发展前景和巨大的发掘潜力。立足我国现阶段生物柴油产业化的瓶颈问题,着重阐述了蓖麻种质资源发掘的现状、优良品种培育的途径和发展前景,以及利用蓖麻种子油生产商业化生物柴油的现状,以期推动我国利用边际土地发展蓖麻产业以及生物柴油商业化生产。     

Bioethanol potential from miscanthus with low ILUC risk in the province of Lublin,Poland

Increasing production of biofuels has led to concerns about indirect land‐use change (ILUC). So far, significant efforts have been made to assess potential ILUC effects. But limited attention has been paid to strategies for reducing the extent of ILUC and controlling the type of LUC. This case study assesses five key ILUC mitigation measures to quantify the low‐ILUC‐risk production potential of miscanthus‐based bioethanol in Lublin province (Poland) in 2020. In 2020, a total area of 196 to 818 thousand hectare of agricultural land could be made available for biomass production by realizing above‐baseline yield developments (95–413 thousand ha), increased food chain efficiencies (9–30 thousand ha) and biofuel feedstock production on underutilized lands (92–375 thousand ha). However, a maximum 203–269 thousand hectare is considered legally available (not protected) and biophysically suitable for miscanthus production. The resulting low‐ILUC‐risk bioethanol production potential ranges from 12 to 35 PJ per year. The potential from this region alone is higher than the national Polish target for second‐generation bioethanol consumption of 9 PJ in 2020. Although the sustainable implementation potential may be lower, the province of Lublin could play a key role in achieving this target. This study shows that the mitigation or prevention of ILUC from bioenergy is only possible when an integrated perspective is adopted on the agricultural and bioenergy sectors. Governance and policies on planning and implementing ILUC mitigation are considered vital for realizing a significant bioenergy potential with low ILUC risk. One important aspect in this regard is monitoring the risk of ILUC and the implementation of ILUC mitigation measures. Key parameters for monitoring are land use, land cover and crop yields.     

A multiple species approach to biomass production from native herbaceous perennial feedstocks

Due to the rapid rate of worldwide consumption of nonrenewable fossil fuels, production of biofuels from cellulosic sources is receiving increased research emphasis. Here, we review the feasibility to produce lignocellulosic biomass on marginal lands that are not well-suited for conventional crop production. Large areas of these marginal lands are located in the central prairies of North America once dominated by tallgrass species. In this article, we review the existing literature, current work, and potential of two native species of the tallgrass prairie, prairie cordgrass (Spartina pectinata), and little bluestem (Schizachyrium scoparium) as candidates for commercial production of biofuel. Based on the existing literature, we discuss the need to accelerate research in the areas of agronomy, breeding, genetics, and potential pathogens. Cropping systems based on maintaining biodiversity across landscapes are essential for a sustainable production and to mitigate impact of pathogens and pests.     

Importance of biophysical effects on climate warming mitigation potential of biofuel crops over the conterminous United States

Current quantification of climate warming mitigation potential (CWMP) of biomass‐derived energy has focused primarily on its biogeochemical effects. This study used site‐level observations of carbon, water, and energy fluxes of biofuel crops to parameterize and evaluate the community land model (CLM) and estimate CO₂ fluxes, surface energy balance, soil carbon dynamics of corn (Zea mays), switchgrass (Panicum virgatum), and miscanthus (Miscanthus × giganteus) ecosystems across the conterminous United States considering different agricultural management practices and land‐use scenarios. We find that neglecting biophysical effects underestimates the CWMP of transitioning from croplands and marginal lands to energy crops. Biogeochemical effects alone result in changes in carbon storage of ?1.9, 49.1, and 69.3 g C m^?2 y^?1 compared to 20.5, 78.5, and 96.2 g C m^?2 y^?1 when considering both biophysical and biogeochemical effects for corn, switchgrass, and miscanthus, respectively. The biophysical contribution to CWMP is dominated by changes in latent heat fluxes. Using the model to optimize growth conditions through fertilization and irrigation increases the CWMP further to 79.6, 98.3, and 118.8 g C m^?2 y^?1, respectively, representing the upper threshold for CWMP. Results also show that the CWMP over marginal lands is lower than that over croplands. This study highlights that neglecting the biophysical effects of altered surface energy and water balance underestimates the CWMP of transitioning to bioenergy crops at regional scales.     

The economic performance of jatropha,cassava and Eucalyptus production systems for energy in an East African smallholder setting

This study evaluates the potential economic feasibility of three smallholder energy crop production systems (jatropha, cassava and eucalyptus) under typical semi‐arid conditions in Eastern Africa. This feasibility is determined by assessing net present values (NPV), internal rates of return (IRR), benefit‐cost ratios (BCR) and payback periods (PBP). In addition, the production costs are compared to the costs of reference energy systems, petrol, diesel and pellets. Low and intermediate input systems are considered and specific attention is paid to the opportunity cost of labour, by considering both family labour (no labour costs) and hired labour. The results show that all family labour settings have positive NPVs and high IRR and BCR values. Moreover, cassava has the highest family labour NPV (2900–5800USThis study evaluates the potential economic feasibility of three smallholder energy crop production systems (jatropha, cassava and eucalyptus) under typical semi‐arid conditions in Eastern Africa. This feasibility is determined by assessing net present values (NPV), internal rates of return (IRR), benefit‐cost ratios (BCR) and payback periods (PBP). In addition, the production costs are compared to the costs of reference energy systems, petrol, diesel and pellets. Low and intermediate input systems are considered and specific attention is paid to the opportunity cost of labour, by considering both family labour (no labour costs) and hired labour. The results show that all family labour settings have positive NPVs and high IRR and BCR values. Moreover, cassava has the highest family labour NPV (2900–5800US$ ha^?1) and the shortest PBP, but the required investment costs are high in comparision with the other crops. If hired labour is used, the NPV of eucalyptus is highest (380–1400$/ha^?1), and it is also the least sensitive to changes in wages and yields. Jatropha performs best only for the indicator IRR and only with family labour or low labour opportunity costs. The analysis and comparison of bioenergy production costs shows that eucalyptus pellets (2.6–3.1$ GJ^?1) are competitive compared with reference pellets at current market prices (5$ GJ^?1). Jatropha SVO (19$ GJ^?1) and cassava ethanol (19–36$ GJ^?1) are only competitive with fossil diesel (21$ GJ^?1) and petrol (25$ GJ^?1) in a family labour setting. At current values jatropha biodiesel (24–37$ GJ^?1) is not competitive. The economic performance is sensitive to variations in crop yields and yield data are highly uncertain. However, this study demonstrates that there is considerable potential for increasing the economic performance by further improvements in yield, harvesting efficiency and conversion efficiency as well as reductions in transport and packaging costs.     

Toward the domestication of lignocellulosic energy crops: learning from food crop domestication

Domestication of cereal crops has provided a stable source of food for thousands of years. The extent to which lignocellulosic crops will contribute to the world's renewable energy depends largely on how the new crops will be domesticated. Growing miscanthus as biofuel feedstocks on marginal and degraded land in northern and northwestern China offers an example for developing theoretical framework and practical strategies for energy crop domestication. The domestication should incorporate the highest possible genetic diversity from wild species, focus on the improvement of drought and cold tolerance especially in the stage of crop establishment, increase the efficiencies of water and nutrient uses and photosynthesis, adjust vegetative growing season according to local temperature and precipitation, and reduce or prevent seed production. Positive ecological effects on soil conservation, landscape restoration, carbon sequestration, and hydrological cycles should be maximized, while negative impact on biodiversity needs to be minimized. With the development of other sources of renewable energy, the role of lignocellulosic crops may evolve from primarily energy production to increasingly ecological restoration and biomaterial development. The integration of this new cropping system into the existing agriculture may open a new avenue to the long-term sustainability of our society.     

The relationship between the soil water storage and water-use efficiency of seven energy crops

The aim of this work was to determine two types of photosynthetic water-use efficiency in order to examine their utility as selection criteria for tolerance of energy crops to soil water deficit. Furthermore, effects of crop cultivation on soil water content and storage were investigated. Seven energy crops were examined: miscanthus, prairie cordgrass, willow, thorn-free rose, Virginia mallow, Bohemian knotweed, and topinambour. The highest values of instantaneous (WUE) and intrinsic (WUE_i) water-use efficiencies were found for miscanthus and prairie cordgrass. The reduction of WUE and/or WUE_i was caused mainly by a rapid rise in the transpiration rate and a greater stomatal conductance, respectively. Principal component analysis showed that neither WUE nor WUE_i could be recommended as universal selection criteria for the drought tolerance in different energy crops. The proper localization of soil with a good supply of water is most the important condition for energy crop plantations.