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To meet combustion quality requirements, Miscanthus is conventionally harvested in late winter/early spring after senescence due to a lowering of fuel nitrogen, chlorine and ash content. This can overcome combustion issues such as slagging, fouling and corrosion however there is a significant reduction in dry matter yields compared to early harvesting in the autumn. In this study, Miscanthus × giganteus harvested conventionally (after senescence) and early (green) have been pre-treated by hydrothermal carbonisation (HTC) at 200 °C and 250 °C. HTC at 200 °C improves the grindability of the biomass but results in limited energy densification. HTC at 250 °C results in increased energy densification producing a bio-coal with a HHV ranging from 27 to 28 MJ/kg for early and 25 to 26 MJ/kg for conventional harvesting; the Hardgrove Grindability Index (HGI) increases from 0 to 150. At higher HTC temperatures, the combustion profile of the bio-coal exhibits a ‘coal like’ single stage combustion profile. HTC results in a significant reduction in alkali metal content, increases safe combustion temperatures and reduces the theoretical propensity of the derived fuel to slag, foul and corrode. The results indicate that HTC can valorise both conventional and early harvested Miscanthus without producing any adverse effect on the yields and quality of the bio-coal. The challenges associated with early harvesting of Miscanthus appear to be largely overcome by HTC resulting in increased yields of up to 40% per hectare due to reduction in dry matter loss.

Des chaînes d'approvisionnement en biomasse respectueuses de l'environnement et économiquement compétitives sont un facteur clé de succès pour le développement de la bio-économie. Or Celui-ci est susceptible d'être entravé par la pénurie potentielle de biomasse lignocellulosique, matière première la plus demandée pour fabriquer des produits bio-sources. Des technologies innovantes pour la gestion des cultures, la récolte de biomasse et leur prétraitement, le stockage et le transport offrent de nombreuses possibilités pour augmenter l'offre en biomasse tout en réduisant les coûts et en minimisant les impacts négatifs sur l'environnement. Trois récents projets européens visaient à développer de telles technologies, l'ensemble des chaînes logistiques, et à évaluer leur viabilité et durabilité. Les sources de biomasse étudiées incluaient les rémanents forestiers, les résidus d'arboriculture ainsi que des cultures lignocellulosiques annuelles, pérennes et ligneuses. Des filières existantes dans différentes régions d'Europe ont servi de cas d'étude en vraie grandeur et de support pour des démonstrations à l'échelle commerciale. Les principaux verrous identifiés concernent le stockage de biomasse et la phase de production pour les cultures dédiées, et des leviers d'amélioration portant sur la densification de la biomasse, le développement de systèmes de récolte plus efficaces et les systèmes de production de biomasse ont permis de réduire les coûts, la consommation d'énergie et les émissions de gaz à effet de serre., Cost-efficient, environmental-friendly and socially sustainable biomass supply chains are urgently needed to achieve the 2020 and 2030 targets of the European Union. Optimized logistics are a key factor of success for bio-based value-chains, and there is currently ample room for improvement. Innovative techniques for crop management, biomass harvesting and pre-treatment, storage and transport offer a prime avenue to increase biomass supply while keeping costes down and minimizing adverse environmental impacts. This communication will draw on results from recent projects funded by the European Commission on the development of new or improved technologies for logistics chains, encompassing energy crops, forest and agricultural residues. It includes an assessment of their sustainability at supply-area level for small to large-scale bio-based projects. The main bottlenecks of logistics reside in storage capacity and feedstock production, and some promising avenues to alleviate include legume-lignocellulosics mixtures, decentralized densification via briquetting, more efficient harversting systems and a widening of harvesting time windows. In a case-study in Burgundy, reduction in costs of more than 30% could be achieved with these options, along with an abatement of 10 to 20 % of greenhouse gas emissions.

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Within the last few years Miscanthus has been shown as the most productive perennial grass under different climate conditions, resulting suited for biomass production both in northern and in southern countries of Europe. Factors which may affect the final yield are soil texture, fertilization rate, water availability and harvest time. In particular many authors stressed the fact that a late harvest, in the winter season, allows to obtain a better biomass quality (i.e. low moisture level and reduced ash content), even if considerable biomass losses could occur, in form of leaves and tops, respect to the yields that could be obtained with an early harvest in autumn. On the other hand, early harvest poses the problem of high moisture levels, which makes the biomass unsuited for baling shortly after cut. Thus the biomass requires to be left on the field for drying for a time span, between mowing and baling, that can vary from few to several days, depending on air temperature and rain. Within the LogistEC EU project, a set of field trials were conducted in order to assess the feasibly of early harvesting under different climate conditions, in Italy, France and UK. In Italy, a three-passage harvesting system, consisting in mowing, windrowing and baling, was adopted for early harvest and compared with a conventional winter harvest, carried out with a single-passage system (mowing and baling in one operation) at the end of the winter. In both harvest systems tractor power, as well as machinery types for mowing and baling were the same. Productivity, fuel consumption and biomass losses were measured. Preliminary results showed that fuel and operation times needed for the three passage system were significantly higher than for the single-passage system, while biomass losses were slightly lower in the early harvesting than in the late winter harvest. Our results allowed to conclude that early harvest, with the three-passages system, can help to extend the harvesting season also to the autumn period, especially in those regions where seasonal air temperature allow to bale the biomass at proper moisture content, where the risk of wet winters is high, wherever cultivated areas are small and widespread within the single farm and in the case expected yields should be low., Proceedings of the 23rd European Biomass Conference and Exhibition, 1-4 June 2015, Vienna, Austria, pp. 74-78

Fibre sorghum and miscanthus are recognized as two of the most promising crops for providing dry biomass suited for thermo-chemical conversion processes. Despite their high biomass yield potential, several concerns may arise related to their economic sustainability. Operation costs for harvesting and handling, as well as biomass losses (i.e. quantity and quality decrease) along the supply chain can significantly affect final biofuel price, making biomass less attractive in relation to other renewable energy sources. Therefore, optimizing logistics of biomass energy chains is a key factor for reducing costs of biofuel production from energy crops. LogistEC project addresses this question through different demonstration cases linked to real industrial plants in different European locations: a biomass power plant conducted by Acciona company in Extremadura region (Spain) and a pellet production plant owned by Bourgogne Pellet and located in Burgundy region (France)., Proceedings of the 23rd European Biomass Conference and Exhibition, 1-4 June 2015, Vienna, Austria, pp. 187-192

Willows (Salix spp.) are a very diverse group of catkin‐bearing trees and shrubs that are widely distributed across temperate regions of the globe. Some species respond well to being grown in short rotation coppice (SRC) cycles, which are much shorter than conventional forestry. Coppicing reinvigorates growth and the biomass rapidly accumulated can be used as a source of renewable carbon for bioenergy and biofuels. As SRC willows re‐distribute nutrients during the perennial cycle they require only minimal nitrogen fertilizer for growth. This results in fuel chains with potentially high greenhouse gas reductions. To exploit their potential for renewable energy, willows need to be kept free of pests and diseases and yields need to be improved without significantly increasing the requirements for fertilizers and water. The biomass composition needs to be optimized for different end‐uses. Yields also need to be sustainable on land less productive for food crops to reduce conflicts over land use. Advances in understanding the physiology and growth of willow, and in the identification of genes underlying key traits, are now at the stage where they can start to be used in breeding programs to help achieve these goals.

In this study the effect of the application of different fertilizer on the fuel and combustion characteristics of SRC willow is investigated. The willow has been sampled in autumn and spring for two years and their combustion characteristics and their corresponding combustion properties and ash related problems have been studied. N as NH4(NO3) was applied to two of the treatments with K in the form of K2O added to one and SO3 in the form of (NH4)2SO4 added to the other. Sewage pellets were applied to the third treatment since willow has the tendency to remediate sewage sludge. In general the N, S and ash contents and the alkali index for the leaves was higher than the stems. The potassium concentrations in the ash are higher in the stems than the leaves but the reverse is true for sodium concentration. However the alkali index for leaves was higher because of the higher ash content. Initial conclusions can be made that later harvest times are desirable for ash-related problems but not for NOx formation., Proceedings of the 18th European Biomass Conference and Exhibition, 3-7 May 2010, Lyon, France, pp. 1117-1121

Recent research has indicated that the leading perennial energy grasses, Miscanthus giganteus and switchgrass (Panicum virgatum) may be utilized for non-thermal energy conversion. The feedstock requirements for these conversion technologies would allow the crops to be harvested early, prior to senescence, to exploit the greater higher biomass yields that occur during the autumn. Miscanthus grown at three locations in Europe was continually harvested early and maintained its high peak yield when compared to the conventional spring post-senescence yield. At one site, where the crop was continually harvested for 6 years, the early harvest yield began to decline after four years although this yield decline did not occur when the crop was adequately supplied with additional nitrogen. The two ecoptypes of switchgrass grown at locations in Europe, responded very differently to an early harvest. Lowland switchgrass at two locations could not maintain the high peak yield even with a moderate application of nitrogen. Upland switchgrass examined at one location did sustain high peak yields for 5 years of continuous early harvest without the need for additional nitrogen. The results of this study have indicated that a continual early harvest of both miscanthus and switchgrass is possible but replacement plant nutrients must be applied to the crop to revent or limit the extent of any yield decline., Proceedings of the 23rd European Biomass Conference and Exhibition, 1-4 June 2015, Vienna, Austria, pp. 61-67

The Rothamsted Research­based Salix spp. breeding programme has been in operation since 2003. This paper reports on the yields of the second round of yield trials that have progressed through its willow breeding pipeline. The material tested was bred in January 2005 and 2006 and has been through three rounds of selection within the willow breeding pipeline prior to inclusion in the yield trials. The multi­site yield trials were present at six sites and each trial contained three replicates of each variety in a randomised block design. Trials were planted in spring 2011, cutback after an establishment year in February 2012 and yield was assessed in winter 2013/14. Trials contained two commercial SRC variety yield standards and twelve breeding lines produced at Rothamsted Research. ­1 ­1 Two of these breeding lines have been selected from these trials. RR006202 produced 11.39 t d.m. hayr at the ­1 ­1 RRes site and proved highly rust resistant in high rust pressure trials and RR06103 yielded 13.82 t d.m. hayr at the RRes site. Both have been selected from this round of trials for submission for DUS testing and registration with the CPVO for plant breeder’s rights and will be released to interested partners for multiplication., Proceedings of the 22nd European Biomass Conference and Exhibition, 23-26 June 2014, Hamburg, Germany, pp. 116-121