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Abstract: Once again Swedish forest industries are supposed to face a new threatening shortage of wood. Therefore, demonstration of new ideas of producing wood for pulp and fuels (heat, ethanol, hydrogen gas, dimethylether, electricity) in the most southern part of Sweden was very welcome. One example of new ideas is that some farmers planted hybrid poplars on abandoned farming land at Sångletorp (33ha), Johannesholm (15ha), Kadesjö (11ha) and Näsbyholm (2ha) in the southernmost part of Sweden in 1991. Some of these plantations were harvested in 2004, but some are still growing. The harvested wood had been used for pulp and fuel. The results of the harvest and of the plantations that are still growing are analysed here from an economic, ecologic and energy point of view. [Copyright &y& Elsevier]

The aim of the present paper is to evaluate the most intensive demonstration of harvesting of olive tree prunings (OTP) ever occurred in Greece. In Agios Konstantinos, an integrated shredder was used to harvest the local olive groves. The harvesting campaign was performed for two consecutive years. In total, for both years, the harvesting campaign lasted for 20 days where around 81 ha of olive groves were harvested, that amounted to 252 dry Mg of harvested prunings. The aim of the paper is to evaluate an agricultural residue mobilization value chain in terms of performance, economics and fuel analyses of the harvested OTP. Via detailed monitoring, the present paper compares the harvesting demonstration results for both years. In brief, the average material capacity increased from 2.2 dry Mg/h (first year) to 2.4 dry Mg/h (second year), whereas the corresponding harvesting and haulage costs of these harvesting campaigns were calculated at 62.3 €/Mg (dry basis) and 63.7 €/Mg (dry basis), with an estimated commercial operation cost at 46.0 €/Mg (dry basis). Finally, from 49 samples of OTP collected, the average moisture content was at 27.5% (as received), ash content at 4.5% (dry basis) and the average LHV at 12.2 MJ/kg (as received). [Display omitted] • Detailed monitoring of a two-year mechanized harvesting and haulage of olive prunings. • Material Capacities at 2.2 dry Mg/h and 2.4 dry Mg/h in two consecutive years. • Estimated commercial cost of harvesting and haulage at 46.0 €/dry Mg olive pruning. • Harvested prunings averaged 12.2 MJ/kg LHV, 27.5% moisture and 4.5% ash content. • Mechanized harvesting of olive prunings (<3 Mg/ha) proved to be economical feasible. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents a snapshot speculative analysis of some possible effects of the massive windthrow in south Sweden on January 8–9, 2005. Hurricane Gudrun damaged buildings and blocked roads, making large areas inaccessible except by helicopter. Electricity and telecommunications were shambolic. Around 70 million cubic metres were windthrown, equalling a ‘normal’ Swedish annual felling––a gross value exceeding €20,000,000,000. The paper presents the subsequent restoration work that has placed a special focus on the forest sector. In south Sweden, logging work will last for a couple of years. The roundwood market will be severely strained. For individual forest owners, the economic effects of the storm are often disastrous. To ensure that forest owners will retrieve at least part of the pre-storm forest value, restoration aims at the salvaging of maximum value. Sawmills try to store the most valuable timber for years to come, decreasing the risk of painful capacity adjustments and protecting export opportunities. Forest fuel value is low compared to sawlogs and pulpwood. Thus, the forest energy sector has received little attention. Forest chippers normally contribute important marginal quantities of wood fuels, but since no logging residues will be harvested from the windthrown forests for a period of 2–3 years, they are put out of business and may disappear from the market. Heating and power plants will receive an abundance of industrial by-products in the coming 2–3 years, followed by a period of expected shortage of woody biomass for energy production. With few forest chippers left, the situation will be troublesome. [Copyright &y& Elsevier]

In this paper, we address a corn-stover harvest scheduling problem (CSHSP) that arises when a cellulosic ethanol plant contracts with farmers to harvest corn stover after the grain harvest has been completed. The plant contracts a fleet of harvesting crews, which must be assigned by the plant scheduler to harvest fields as they are called in by the farmers over the harvest season. First, we study the static CSHSP, in which the call in times for the fields are assumed known at the beginning of the season, and propose a mathematical programming-based approach that we show to generate solutions with an average optimality gap of only 6.1% for real-life-inspired instances. We also consider the dynamic CSHSP, in which the call in times are not known at the beginning of the harvest season and the requests arrive randomly over time. The method that we develop for the solution of this problem incurs costs that are about 4.8% higher, on average, than those incurred for the static case. These results exhibit the proposed approach to be robust for use by a plant scheduler in his/her efforts to optimize harvest scheduling as the actual season unfolds. Our proposed approach can also effectively deal with uncertainties encountered in a commercial harvest. [ABSTRACT FROM AUTHOR]

Biogas production is mainly based on the anaerobic digestion of cereals silages and maize silage is the most utilized. Regarding biogas production, the most important portion of the plant is the ear. The corn ear, due to high starch content, is characterized by a higher biogas production compared to the silage of the whole plant. In this paper, we present the results of experimental field tests carried out in Northern Italy that aim to evaluate the anaerobic methane potential (BMP) of different portions of ensiled maize hybrids. The BMP production is evaluated considering the possibility of harvesting and ensiling: the whole plant; the plant cut at 75 cm of height; the ear only; the plant without the ear. For the different solutions, the results are reported as specific BMP and as average biogas production achievable per hectare. The methane production by harvesting and ensiling the whole plant (10,212 and 10,605 m³ ha-1, for maize class 600 and 700, respectively) is higher than the ones achievable by the other plant portions (7961 and 7707 m³ ha-1, from the ear; 9523 and 9784 m³ ha-1, from the plant cut at 75 cm; 3328 and 3554 m³ ha-1, from the plant without the ear, for maize class 600 and 700, respectively). The harvest of the whole plant, although it is the most productive solution, could not be the best solution under an economic and environmental point of view. Harvesting only the ear can be interesting considering the new Italian subsidy framework and for the biogas plants fed by biomass transported over long distances. [ABSTRACT FROM AUTHOR]

Abstract: Agricultural residues, particularly corn stover, are a promising feedstock for bioenergy systems. To analyze these systems in a life cycle framework, environmental impacts from cultivation and harvest must be allocated to the resulting products, corn grain and stover. This paper explores three approaches to allocation for corn and stover: economic and energy-based allocation, as well as a subdivision approach, which assigns to stover only those additional activities caused by its harvest. This study develops a life cycle inventory for corn production based on average U.S. agronomic data and then applies the three allocation methods to produce a life cycle inventory for stover. This inventory contains over 1100 environmental flows and is available in the online Supplementary material. This analysis shows that economic allocation and subdivision assign the least impact to stover (14–15%), energy-based allocation the most (30%). One hectare of corn and stover production emits approximately 2.5 tonnes of carbon equivalent and requires approximately 23 GJ of fossil energy. Value-based allocation methods, like energy and economic allocation, may be most appropriate when they reflect the goals of the production system. In addition, value-based methods are typically simple to apply, and thus may be more transparent for those interpreting a study. Subdivision, as applied in this study, reflects the consequences of changing the existing corn production systems, may require more data, and might be most appropriate for near-term prospective analyses; such as those that question whether adding cellulosic ethanol production to existing corn production systems yields environmental benefits. Thus, the selection of an allocation approach should hinge on the intent of the study. [Copyright &y& Elsevier]

Abstract: Based on literature and six country studies (Belgium, Denmark, Finland, Netherlands, Sweden, Slovakia) this paper discusses the compatibility of the EU 2020 targets for renewable energy with conservation of biodiversity. We conclude that increased demand for biomass for bioenergy purposes may lead to a continued conversion of valuable habitats into productive lands and to intensification, which both have negative effects on biodiversity. On the other hand, increased demand for biomass also provides opportunities for biodiversity, both within existing productive lands and in abandoned or degraded lands. Perennial crops may lead to increased diversity in crop patterns, lower input uses, and higher landscape structural diversity which may all have positive effects on biodiversity. In production forest opportunities exist to harvest primary wood residues. Removal of these forest residues under strict sustainability conditions may become economically attractive with increased biomass demand. An additional biomass potential is represented by recreation areas, road-side verges, semi-natural and natural areas and lands which have no other use because they have been abandoned, polluted or degraded. Whether effects of cropping of biomass and/or removal of biomass has positive or negative impact on biodiversity depends strongly on specific regional circumstances, the type of land and land use shifts involved and the associated management practices in general. However, it is clear that in the six countries studied certain types of biomass crops are likely to be more sustainable than others. [Copyright &y& Elsevier]

Abstract: Wood chips need to fulfill specific quality parameters in order to be used as fuel for industrial or residential use. Moisture content and chip size distribution are recognized as the main physical characteristics affecting energy conversion efficiency. Objective of the study was to evaluate the effects of harvesting mode on the quality of wood chips, under the typical conditions offered by SRC poplar grown in Central Italy. Single-pass and two-pass harvesting were compared. Standing stems and cut windrowed stems were harvested using two modified foragers alternately equipped with a drum or a disc chipper, allowing a further comparison of different chipping devices. Data were obtained from 3 fields in Central Italy and allowed analyzing the drying process occurring when stems are felled and stored in the field as windrows. The mean water content at the time of cutting was 59% , which was reduced below 30% after about 100 days of storage in the windrows. Regression analysis of storage duration and moisture content showed that air temperature is the main driver of the drying process, under the typical conditions of a Mediterranean climate. Harvest mode (single-pass or two-pass) and chipping device (drum or disc) have a significant effect on particle-size distribution. The incidence of accept particle was higher when chipping windrowed stems or using the drum chipper. The paper discusses the advantages of two-pass harvesting and emphasizes the importance of flexibility when choosing harvest mode and chipper type. [Copyright &y& Elsevier]

Abstract: Finland and Sweden have been forerunners in the development of wood harvesting machinery and methods. In both countries, small- and large-scale supply systems for wood chips have been in operation for several decades. More recently, the production and use of forest chips from logging residues and small diameter trees has been growing rapidly. The European Union (EU) has set ambitious targets for the use of renewable energy to mitigate climate change and to increase domestic energy security and self-sufficiency. The largest unutilised source for renewable energy in the EU is forest biomass. European forests could fulfill one third of the goal set for biomass-based energy production in the EU’s Biomass Action Plan. In addition, member countries have started national programmes to promote the use of biomass for energy. As a result, interest in Nordic forest energy technology has been increasing rapidly in other parts of the EU. The Finnish Forest Research Institute and its collaborators have been running a technology transfer project in ten European countries, with the goal of tailoring and adapting Nordic forest technology to local conditions through analysing the applicability, costs and overall competitiveness of selected feedstock supply technologies. This paper summarizes the findings of feasibility studies carried out in Poland and Scotland and gives an overview of the current situation and development trends of forest energy in the European Union. [Copyright &y& Elsevier]

Abstract: Reed canary grass (Phalaris arundinacea L.) samples of the Palaton variety grown at 10 different locations in northern Europe were analyzed and the effect of growing location and soil type on the carbohydrate composition and lignin content were investigated. The results showed that the major carbohydrate components in delayed harvested reed canary grass were glucose and xylose. Some growing locations and soil types significantly influenced the carbohydrate composition of the grass. Soils with both high organic and clay content produced lower glucose and xylose contents but an increased lignin content. A soil rich in sand gave higher glucose, xylose and arabinose content. Reed canary grass is a perennial rhizome grass that has shown potential as an energy crop for solid bio-fuel production and as a short fibre raw material for the pulp and paper industry. This study showed that delayed harvested reed canary grass can also be a potential new raw material for ethanol production. [Copyright &y& Elsevier]

Abstract: This paper, which illustrates some results of the project SO.L.E.AGRI. (“Wood-energy chain sustainability in agricultural sector”) funded by Provincia di Siena and of the PRIN 2005–2006 “Study of the biomass-energy chains in Italy” funded by the Italian Ministry of Instruction, University and Research, highlights that the use of agricultural residuals as renewable energy source is economically and environmentally convenient. This work firstly looks at the energy use of agricultural residuals harvested, and then it considers their packaging and supply management. The main objective of the production of the solid bio-fuels originated from pruning residuals is the reduction of harvesting and transport costs; therefore, experimental tests have been carried out in different farms using an innovative shredding machine that simultaneously permits harvesting, shredding and packaging of pruning residuals. These trials have been undertaken in olive groves and vineyards, on stony and hilly terrain. The machine has obtained good results under different operative conditions: intensive mechanisation of harvesting implies lower costs and simultaneous packaging assures a better organisation of the whole energy chain. [Copyright &y& Elsevier]

Abstract: In order to fulfil the targets set by the Kyoto protocol, Belgium established a series of regulations for renewable electricity and put in place a virtual market of green certificates. Their attribution is correlated to the reduction of fossil CO2 emissions. For biomass, emissions occurring during harvest have a significant impact. This paper proposes a model to estimate CO2 emissions during this step and applies it to the chipping of poplar forest residues in Southern Belgium. The factors entering into the CO2 ratio per MWh of biofuel are modelled according to the most influential characteristic of forest residues, i.e. mean initial diameter. The results show that if the diameter of the chipped material increased from 4 to 16cm (factor 4), the CO2 emissions per MWh decreased by a factor 7. This stresses the value of modelling the emissions in order to identify the most critical supply routes for attribution and valuation of the green certificates. [Copyright &y& Elsevier]

Abstract: Renewable energy sources have been identified to play an important role in mitigating climate change. The main reason is that carbon dioxide emission is avoided when fossil fuels are replaced. This paper presents a study focusing on direct and indirect greenhouse gas emissions from fuel chip production in Finland. The fuel chips studied were produced from logging residue at final harvest. Five different fuel production chains were considered. The calculations showed that fuel chip production from the residues of final harvest is very efficient from the viewpoint of energy use during collection, chipping and transportation. Only an input of 2–3% of the produced energy is needed, which means that roughly 30 to 50 units of bioenergy is produced for every unit of (fossil) energy consumed. The emissions from collecting, chipping and transporting the residues were evaluated to be about 4–7kg depending on harvesting and chipping methods and transportation distance. Emissions of greenhouse gases (other than ) from burning forest residues in a modern CHP-plant were evaluated to be small, about 2kg . If nitrogen losses are compensated for with fertilisation, the additional greenhouse gas emissions were calculated to be about . The calculations showed that in a favourable situation as much as 97–98% of the greenhouse gas emissions could be avoided by substituting a fossil fuel with wood fuel, but even in an unfavourable situation the amount avoided should be higher than 75%. [Copyright &y& Elsevier]

This paper presents the methods used to establish a wood-fuel supply chain for coal-fired power plants taking into account wood resources, potential suppliers and financial, economic and environmental constraints.The first step is a quantitative and qualitative evaluation of forest residues around the power plants. At the next stage, the supply chain characteristics are analyzed. Finally, a combination of forest residue sources and supply chains is selected under the constraints of the multiple criteria of the energy producers. In the present case study, the conclusion of the analysis is that an optimal strategy includes three levels: one base level made up of large-scale loggers harvesting softwood from final cuts, one top level made up of medium-scale loggers mainly harvesting hardwoods, and a reserve level made up of small-scale loggers and farmers. Detailed characteristics of these levels are given. [Copyright &y& Elsevier]

The Swedish forest industry sector produces timber, energy and other commodities, but has to consider the vested interests of other parties. This paper adopts a perspective whereby the modern forest industry sector is regarded as a system for the production of energy products, and where traditional forest industry products are seen as commodities that are released as energy at the end of their lives. Assisted by a review of the literature, the market forces affecting forest fuels are assessed from the perspectives of forest owners, machine contractors and purchasers of forest fuels.Present-day forest operations are highly efficient in terms of invested and inherent energy in harvested timber. There are also markets, methods and technology for the production of biofuels. However this harvest entails economic and environmental costs. The markets for biofuels seem to be growing, and bioenergy from forests competes with energy produced by other actors. Designing systems that provide a profitable flow of bioenergy from forestry without risking the sustainable use of forests as regards the long-term supply of nutrients and maintaining biological diversity constitutes a challenge for scientists and practitioners working in the sector. The author suggests existing systems for environmental and forest certification as a means of safeguarding and confirming that the harvest and trade of forest fuels comply with standards for ensuring sustainable forestry. [Copyright &y& Elsevier]

More than 216 million t (238 million tons) of corn stover (dry basis) is produced annually in the USA of which a portion could possibly be collected for conversion to ethanol and other industrial products. This paper examines published data on collecting corn stover using field machinery, including moisture content, mass fractions, and the amount of stover removed from the field. It is shown that a typical sequence of shredding, windrowing and round baling operations may result in a collection efficiency of <40%. Other factors such as weather, season, and leaving stover for environmental reasons may also reduce the amount of stover collected per unit area. Collection cost would depend on the amount of stover collected per unit area, the number of operations, machine efficiency in each operation, and bulk density. A typical cost calculated for round baling and delivering the bales to a storage 8 km (5 miles) away from a harvested field amounted to $21.60/dry t ($19.70/dry ton). [Copyright &y& Elsevier]

In this work, the productivity and work quality of different types of chipping machines used for biomass comminution produced by dedicated plantations were evaluated. Drum and disc chippers with different powers were compared with feller-chippers and grinders. Machines were tested using only one tree species (poplar) and two different feedstocks: branchwood (seven-year-old treetops and biomass produced by a vSRC) and whole-trees (materials produced by an SRC). This study showed a similar performance for all types of machines tested in terms of working rate using different feeding systems, i.e., automatic and forestry crane. However, different results were obtained for woodchip quality. The whole tree comminution was able to guarantee the best woodchips, and chippers produced better wood chips in comparison to grinders. The results obtained indicate that productivity is linked to engine power and that feedstock size can influence wood chip quality. Furthermore, feller-chippers are able to guarantee the same productivity and wood chip quality as “conventional” chippers. [ABSTRACT FROM AUTHOR]

Abstract: The authors tested a 409 kW forager turned into an industrial chipper through a special conversion kit. Conversion was temporary, and the forager could be returned to its original occupation with one day of work. The converted forager proved as effective as a dedicated chipper of the same power. Net chipping productivity varied between 25 and 33 green t h−1. Productivity was highest with poplar tops and lowest with pine tops. Fuel consumption ranged from 1.6 to 1.8 l green t−1. Fuel consumption did not change with tree species, but increased significantly with knife wear. Temporary conversion allowed a better depreciation of the invested capital and resulted in a 25% reduction of unit chipping cost. The converted forager proved an ideal solution wherever the production of wood chips was a complementary business within the scope of a larger agricultural economy. In technical terms, this machine offered the combined advantages of road-capability and good off-road mobility, allowing low-cost independent relocation and effective in-field chipping. [Copyright &y& Elsevier]

Abstract: A commercial drum chipper was fed alternately and piecewise with poplar stems and poplar tops, in order to determine the effect of piece size and tree part on machine performance. Chipping stems required most of the available power (231 kW) delivered by the tractor, whereas chipping tops took about half that much. However, productivity was twice as high with stems, compared to tops (i.e. 25 and 11 t h−1 of oven dry wood, respectively). As a consequence, specific fuel consumption per unit product was 15% lower with stems, compared to tops – i.e. 0.61 and 0.72 L m−3, respectively. Mean feeding speed was 0.37 m s−1 for stems and 0.41 m s−1 for tops, but the difference was not significant (p = 0.1677). Productivity and fuel consumption were strongly related to piece size, but tree part had its own additional effect, independent from size and possibly related to form. When chipping tops it is advisable to feed more pieces at a time, in order to partly compensate for the effect of piece size. Operators expecting to chip primarily small-size materials may acquire special chipper versions with wider drums and additional side rollers, for smoother mass feeding. [Copyright &y& Elsevier]

In the second paper in this series factorial combinations of two short rotation coppice (SRC) willow varieties (S. viminalis cv. Jorunn and S. x dasyclados) and five planting densities (10,000/111,000 plantsha-1) were compared at a site in Cambridgshire, UK. Frequent measurements of above-ground and below-ground biomass accumulation (AGBA and BGBA), canopy radiation interception (I), green leaf areaindex (GLAI), radiation use efficiency (RUE), and attenuation coefficient (k) were made in 1997, 1998 and 1999 in order to explain density, variety and harvest interval related yield effects. At full canopy, the highest GLAIs attained, usually by the highest plant density, were in the range 5/6.5. GLAI declined rapidly once this peak had beenattained. GLAI decreased following canopy closure (radiation interception >90%), due to loss of leaves lower down the canopy profile. Despite a more rapid loss of leaf area by the highest planting density, GLAD values were consistently greater at the highest planting density(P>0.05), and GLAD for S. dasyclados was significantly greater than S. viminalis in each year (P<0.05). GLAD was related to final dry matter production. Higher planting densities also had earlier dates of canopy closure, which were correlated with increased final yield. k values were in the range -0.2/-0.51, indicating differences in morphology between the varieties although no consistent trends could be determined. Patterns of AGBA mirrored canopy development. Peak AGBA in thefirst season was 19 and 14 tha-1 for S. viminalis and S. x dasyclados, respectively. End of season yield was significantly lower (11.5 and 12.9 tha-1 for S. viminalis and S. x dasyclados, respectively) due to leaf fall and carbohydrate movement. End of season yields followed a clear, significant trend of increased yield with increasing plant density in the case of S. viminalis. This trendwas not apparent with S. x dasyclados after the first season. RUE values [ABSTRACT FROM AUTHOR]