A case study on the costs and the fuel consumption of harvesting,transporting, and chipping chains for logging residues in Japan

The objective of this study is to examine the feasibility of a harvesting and transporting system for logging residues including the cost, energy, and carbon dioxide (CO₂) effectiveness of fossil energy substitution with logging residues in Japan. “A harvesting and transporting system for logging residues” was constructed with reference to some European countries, where the utilization of bioenergy is making steady progress, and examined based on field experiments in Japanese forestry. The feasibility of the system was discussed from the standpoints of cost, energy, and CO₂, and the system was compared with those of European countries. Concerning the system, it is desirable that the process of chipper comminuting should be incorporated into the system as early as possible. Although such a system is not particularly feasible in Japan from the standpoint of cost, it is suggested that it should be possible for Japan to reduce the domestic CO₂ emissions by utilizing logging residues as alternative energy resources. A comparison with the European countries and a preliminary sensitivity analysis to the system demonstrate that the technical development to reduce the total cost, e.g., improving the forwarding and transporting efficiency, is essential for realizing bioenergy utilization in Japan.     

A harvest and transport cost model for Eucalyptus spp. fast-growing short rotation plantations

This project developed a cost model for the mechanical harvesting of fast-growing Eucalyptus plantations. With such a model, forest managers can check the profitability of a prospective operation under different work conditions and assess the competitiveness of alternative options, which in turn will lead to supply chain optimization. The model is based on mathematical relationships that return machine productivity as a function of operational conditions. These relationships were calculated on data obtained from detailed time studies, conducted on all the main equipment types used in Eucalyptus plantations. Tests were conducted on 11 different machines that harvested a total 2465 oven-dry tonnes over 23 ha on 12 sites in 3 countries. The time study sessions lasted 250 h. Both the Cut-to-Length (CTL) system and the Whole-Tree (WT) system were studied. The model was validated with success and was used to make a number of different simulations. Simulation results show that the WT system allows cheaper harvesting and transport than the CTL system for a range of conditions. Under the conditions of our simulations and in favourable terrain, WT harvesting results in a delivered cost of about 20 euro/green tonne of bark-free pulp chips, whereas CTL harvesting results in a cost between 25 and over 30 euro/green tonne of debarked pulp roundwood.     

Criteria and indicators for sustainable forest fuel production and harvesting: A review of current standards for sustainable forest management

Forest biomass is increasingly being considered as a source of sustainable energy. It is crucial, however, that this biomass be grown and harvested in a sustainable manner.International processes and certification systems have been developed to ensure sustainable forest management (SFM) in general, but it is important to consider if they adequately address specific impacts of intensified production and harvesting methods related to forest fuels. To explore how existing SFM frameworks address sustainable forest fuel production, criteria and indicators (C&I) from 10 different international processes and organizations and 157 international, national and sub-national forest management certification standards under the Forest Stewardship Council (FSC) and the Programme for the Endorsement of Forest Certification (PEFC) were reviewed. International processes include indicators that require identification or reporting of availability, harvested amounts, value, or share in energy consumption of forest fuels. Forest certification standards address several specific woodfuel issues, but not always in a consistent manner. It seems that developed countries more frequently address environmental consequences of harvesting residues or whole trees on soil fertility and biodiversity, while developing countries more frequently address social issues, such as local people’s access to firewood and working conditions in charcoal production. Based on findings, options to improve SFM standards for sustainable forest fuel production are discussed. These options include clarification of terminology, systematic inclusion of important management impacts unique to forest fuel production, coordination of efforts with other related governance processes, including tools promoting sustainability at more integrated levels, such as landscape, supply chain and global levels.     

Energy wood harvesting productivity of three harvesting methods in first thinning of scots pine (Pinus sylvestris L.)

Energy wood harvesting in young forests presents an economical challenge and has been dependent on subsidies in Finland. Whole-tree harvesting systems have proved to be most productive when carrying out energy wood harvesting in cleanings and early thinnings in young forests. The application of integrated energy wood and pulpwood harvesting is less common.It was hypothesized that multi-tree harvesting (MTH) with the OM-Waratah 745 single grip harvester head could change harvesting logistics and improve productivity for integrated energy wood and pulpwood thinnings. Two variations of MTH were compared with single-tree harvesting (STH). The logging methods studied were: (1) conventional single-tree harvesting with pulpwood and energy wood processed at the strip road; (2) multi-tree harvesting with pulpwood and energy wood processing along the strip road (MTH1); and (3) multi-tree harvesting at the stump where the aim was to leave the logging residues distributed evenly over the harvesting area and not on the strip roads (MTH2).MTH methods were 28-35% more productive than the single-tree harvesting. The biggest differences in work stages were found in the felling and delimbing stages. In single-tree harvesting felling was 9-26% and delimbing 14-27% slower than in multi-tree harvesting.MTH2 distributed 13% of residues further than 7 m from the strip road center. With STH and MTH1 only a good 1.2-1.7% was placed this far, and 74.4 and 62.0% respectively within 3 m.     

Verification Theory and Approximate Optimal Harvesting Strategy for a Stochastic Competitive Ecosystem Subject to Lévy Noise

This work focuses on optimal harvesting problems for a stochastic competitive ecosystem subject to Lévy noise. A verification theorem for corresponding harvesting strategy is established, which offers sufficient conditions for deriving an optimal harvesting strategy and an upper bound of the value function. For a given instantaneous marginal yields function, a concrete upper bound of value function is constructed by applying the verification theorem obtained in this paper. Meanwhile, the monotonicity of value function is investigated. Also, an ε-optimal harvesting strategy is designed to find an approximate optimal harvesting strategy for those harvesting problems with no exact optimal harvesting strategy. Finally, by choosing appropriately Markov decision process defined on a discrete state space, a computational method for an optimal harvesting strategy is designed and a concrete example is also given to show the implementation of the algorithm.     

Feasibility of the Nordic forest energy harvesting technology in Poland and Scotland

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.     

Depletion of forest resources in Sudan: Intervention options for optimal control

Agricultural expansion and over-cutting of trees for fuelwood are important causes of deforestation in arid and semi-arid countries such as Sudan. The consequence is increased desertification and high erosion and loss of soil nutrients leading to declining agricultural productivity. However, the social costs of the deforestation externality are not taken into account in present forest management and land use planning in Sudan leading to under-pricing and over-exploitation of the country's forest resources. This study evaluated the suitability of approaches commonly used by most forest resource management agencies for prediction of the state and control of harvesting of forest resources against alternative empirical simulation models using relevant information about economic behaviour of trading agents in the fuelwood market. Results showed the clear superiority of models integrating market behaviour over current approaches in the ability to better simulate real trends of wood consumption and hence depletion rates. The study also adopted an optimal control model to derive socially optimal forest harvesting regimes. The results showed that current rates of forest resource rent recovery and reforestation efforts are very far from optimal. Results also suggest that, in addition to optimal pricing and higher reforestation efforts, promotion and availability of fuel substitutes and investment in wood energy conversion efficiencies have a strong potential for curbing the problem of deforestation in Sudan.     

The long-term effects of logging residue removal on forest floor nutrient capital, foliar chemistry and growth of a Norway spruce stand

This study compared the nutrient capital of the forest floor, the nutrient status of trees, and the growth of a stand of Norway spruce (Picea abies L. (Karst.)) planted on a whole-tree harvesting treatment (needles left on site) with a conventional stem-only harvesting treatment 30 years after clearcutting. No significant treatment effects were detected in the amount of organic matter, the amounts of nutrients in the forest floor, or the concentrations of foliar nutrients. The results indicate that whole-tree harvesting with the needles left on the site did not reduce the long-term nutrient capital of the forest floor or the nutritional status of trees. Whole-tree harvesting significantly reduced the height of dominant spruce compared to stem-only harvesting, however the stem volume of dominant spruce did not differ between the harvesting treatments. The greater height growth of the dominant trees in the stem-only harvesting treatment could be attributed to indirect factors other than changes in site resource availability (e.g. protection against frost damage), and hence the effect of whole-tree harvesting on potential site productivity was inconclusive due to the confounding effect of site factors. In the whole-tree harvesting treatment, the total stem volume of the stand and, consequently, the actual site productivity, was lower when compared to stem-only harvesting due to the lower density of naturally regenerated seedlings.     

Integrated harvesting systems

The evolution of integrated harvesting systems is examined and progress recorded from early systems studies, through development of optimal allocation models to the uptake of integrated systems in commercial harvesting operations. The progress that has been made in the introduction of integrated harvesting systems has been as a result of technological improvements to the harvesting equipment, and to supply incentives which have raised delivered wood fuel prices. The introduction of integrated harvesting operations has realised benefits to the forest stand in terms of stand health and reduced fire hazard.     

Integrated harvesting of energy wood and pulpwood in first thinnings using the two-pile cutting method

In order to increase the harvesting volumes of energy wood and pulpwood from first thinnings, harvesting costs have to be reduced significantly. Metsäteho Oy studied the integrated harvesting of pulpwood and energy wood based on a two-pile method, where industrial roundwood (pulpwood) and energy wood fractions are stacked into two separate piles when cutting a first-thinning stand. The productivity and cost levels of the integrated, two-pile cutting method were determined, and the harvesting costs of the two-pile method were compared with those of conventional separate wood harvesting methods.In the time studies, when the size of removal was 50 dm³, the productivity in conventional whole-tree cutting was 6% higher than in integrated cutting. With a stem size of 100 dm³, the productivity of whole-tree cutting was 7% higher than in integrated cutting. The results indicated, however, that integrated harvesting based on the two-pile cutting method enables harvesting costs to be decreased to below the current cost level of separate pulpwood harvesting in first-thinning stands. The greatest cost-saving potential lies in small-sized (d_1.3 = 7-11 cm) first thinnings. The costs of forest haulage after integrated pulpwood and energy wood cutting were higher than those of separate wood harvesting because of lower removals in integrated harvesting. The results showed that when integrated wood harvesting is based on the two-pile cutting method, the removals of both energy wood and pulpwood should be more than 20-25 m³ ha⁻¹ at the integrated harvesting sites in order to achieve economically viable integrated procurement.     

Supply assessment of forest biomass – A bottom-up approach for Sweden

As there is increasing interest in the use of biomass for energy in Sweden, the potential availability and harvesting costs of forest roundwood, harvesting residues and stumps were estimated up to the year 2069 in 10-year intervals, using a high spatial resolution GIS. In each individual forest area, an average harvesting cost per forest assortment was estimated, based on the geographic and other properties of the area. Using cost structure and resource availability, marginal cost curves were constructed to allow analyses of the effects of changing market conditions and different policy frameworks. Based on geographically explicit data, the results indicated that the average harvesting costs would be 21–24 € m⁻³ for roundwood, depending on the type of harvesting and extraction operation. The corresponding cost estimate for harvesting residues was 23–25 € m⁻³ and 35 € m⁻³ for stumps. The harvesting cost estimates lie on the steeper part of the marginal cost curve, suggesting that increases in the supply of woody biomass can only occur at significantly higher harvesting costs. From a policy perspective, this suggests that subsidies aimed at reducing the harvesting costs will only have limited success in increasing the harvested volumes, given current technology. Therefore, for future development in the supply of forest assortments for energy generation, it is important to consider not only the supply potential, but also the integration of improvements in harvesting and transportation systems.     

Energy harvesting from pavements and roadways: A comprehensive review of technologies,materials, and challenges

Energy harvesting from pavements has been a topic of extensive research in the recent past. This domain has attracted not only the research community but also the industry and governmental authorities. The various sources exploited for energy harvesting from pavements and roadways are solar radiation, mechanical energy dissipated due to moving vehicles and pedestrians, geothermal energy, rainwater, and wind. This article presents an exhaustive and updated review of all potential means of energy harvesting from these sources. Following the introductory section, the article sequentially covers the energy harvesting methods and their research progress, materials, development of practical systems, commercial status, comparison of technologies, challenges, and concluding remarks. This study reveals that there is wide scope for further research and feasibility studies, which could lead to a wide‐spread implementation of the various technologies for energy harvesting from pavements and roads.     

Harvesting operations and energetics of tall grasses for biomass energy production: A case study

The U.S.A. imports about 50% of its energy needs while Florida imports about 85%. Among the renewable energy sources available, biomass appears promising especially in the southeast which includes Florida because of a favorable environment for production and the available methods to convert biomass to energy. Optimal production of biomass requires the identification and management of high yielding persistent perennial cultivars. Elephantgrass (Pennisetum purpureum Schum.) and energycane (Saccharum spontaneum L.) are two tall grasses that meet these requirements. To optimize the supply of convertible biomass, suitable methods of harvesting the crop must be available. The purpose of this research was to study the feasibility and energetics of harvesting, drying, and baling tall grasses with conventional farm machinery.

A Mathews rotary scythe and a New Holland 849 Auto Wrap large round baler were determined to provide a practical harvesting system for baled biomass averaging 15–27 Mg ha⁻¹. The rotary scythe can be used for harvesting and fluffing or turning a windrow over to expedite drying. This harvesting system requires about 3 kg diesel fuel Mg⁻¹ dry biomass (DB), 25 min of time Mg⁻¹ DB, and a cost of about $10 to 12 Mg⁻¹ DB. Energy requirements of harvesting operations would be about 300–375 MJ Mg⁻¹ DB, and primary energy requirements for production and harvesting are about 1100–1500 MJ Mg⁻¹ DB. For each unit of fossil fuel invested in the total production and harvesting system, 12–15 units would be returned in biomass.     

Prospects for green cane harvesting and cane residue use in Brazil

Mechanisation of sugarcane harvesting is growing rapidly in Southern Brazil where nearly 80% of Brazil’s crop is cultivated. Currently a maximum of 20% of the cane is mechanically harvested and the proportion is expected to rise to about 50% by 2005. However, most of the cane is burned prior to harvesting and less than 2% is harvested green. Issues such as topography, crop cultivation and management methods, labour costs, machine performance, environmental legislation and markets for sugarcane residues will influence the increase in mechanical harvesting of burned or green cane. This paper discusses the prospects for green cane harvesting technology, with emphasis on Southern Brazil, and compares harvesting technologies which are being commercialised today. The paper also addresses the recovery of cane residues (dry and green tops and leaves) and comments on their possible use and commercialisation, particularly for electricity generation.     

Biomass resources and costs: Assessment in different EU countries

The objective of the CHRISGAS Project in the field of biomass resources was to make an assessment of the biomass resources and costs available for raw materials procurement for future biomass CHRISGAS technology hydrogen plants in different EU countries, as well as to investigate possible locations for the erection of CHRISGAS plants. The assessment work included 11 European countries (comprising 77% of the EU territory) and Norway. A specific assessment methodology has been developed and applied for this purpose obtaining a total estimate of 365 Tg y^?1 of potential forest and agricultural residues, and after the application of different technical and environmental restrictions, the available resources are calculated to be 205 Tg y^?1 (56% of the estimated potential). The highest harvesting costs have been calculated for Italy (33.2 and 74.0 € Mg^?1, respectively, for agricultural and forest residues) and the lowest ones were obtained in Portugal (21.4 and 27.4 € Mg^?1). In Northern and Central European countries the highest biomass collection costs have been determined for Norway, 37.6 and 27.8 € Mg^?1; and the lowest for Poland, 15.6 and 11.5 € Mg^?1, for agricultural and forest residues, respectively. Based on the developed methodology, a GIS tool (BIORAISE) for the assessment of the cited biomasses and costs in Southern EU countries was created and placed in Internet. The innovation and scientific relevance of this work is the development of a comprehensive and harmonized methodology for agricultural and forestry resources assessment in different EU countries as well as the implementation of a GIS tool that permits an easy extraction of data on quantity and cost of biomass resources in five Southern EU countries.     

Southeastern United States wood pellets as a global energy resource: a cradle-to-gate life cycle assessment derived from empirical data

Given increased policies driving renewable electricity generation and insufficient local production of woody biomass, many countries are reliant upon the importation of wood pellets. Of current wood pellet exports, the vast majority originates from the Southeastern United States (US). In this paper we present results from a cradle-to-gate, attributional process life cycle assessment in which two production scenarios of wood pellets were modelled for the Southeastern US: one utilising roundwood from a silviculture operation and the other utilising sawmill residues. The system boundary includes all steps from harvesting of the wood biomass, through delivery of the finished wood pellets to a US port facility. For each of the impact categories assessed, wood pellets from sawmill residues resulted in higher values, ranging from 5% to 31%. In relation to Global Warming Potential, roundwood pellets resulted in a 13–21% lower value than pellets produced from sawmill residues, depending upon the allocation method.     

Corn stover as a biofuel feedstock in Iowa’s bio-economy: An Iowa farmer survey

The state of Iowa possesses the largest quantity of corn stover in the United States. With a representative survey we examine what Iowa crop farmers think about harvesting and selling corn stover and to what degree they may be interested in providing stover to a biorefinery. Iowa farmers are in an overall learning phase regarding corn stover yet believe that harvesting stover will require an increase in capital investment, additional managerial knowledge and a well-developed support infrastructure. The data suggests some degree of farmer ambivalence regarding what institutional support would be needed to facilitate market entry. Statewide, only 17% of Iowa’s farmers currently express interest in harvesting their stover; though 37% are undecided. The farmers who are interested in marketing stover tend to be: younger, will be farming in 10 years, are at least somewhat knowledgeable about stover, manage large amounts of land and have hectares currently in continuous corn rotations. Regionally, farmers in North Central, IA-the Iowa region with the highest capacity to produce corn stover-tended to be more interested in harvesting stover. Environmental concerns that appear to be important stover supply barriers as farmers who anticipate the negative impacts of corn stover removal on environmental quality tend to be less interested in harvesting corn stover. Overall, the results of this study strongly suggest that future supply assessments consider farmer participation more explicitly and forego arbitrary assumptions regarding farmer behavior as previous supply analyses may have overstated the proportion of farmers interested in harvesting stover.     

光伏电池室内光能采集系统的研究进展与展望

随着5G时代的到来,届时将存在数量庞大的室内物联网设备。尽管大多数室内物联网设备是低功率产品,但它们通常是分布式的,且需要定期更换供电设备,这会导致成本增加和工作不便,而环境能量采集技术正好可以解决这一难题。环境中的光能是最值得被开发利用的能源之一,光伏电池室内光能采集系统正是通过采集周围光能并转换成电能,达到为室内低功耗物联网设备供电的目的。本文针对如何最大化地延长光伏电池室内光能采集系统为室内低功耗物联网设备供电的时间这一主要问题,从高效率采集室内光能、最大功率点跟踪和储能选择三个方面进行简要综述。首先通过对比分析室内光源下带隙值,串并联电阻的大小和电池种类对光伏电池弱光性能的影响,提出了一种高效率采集室内光能的方案;其次从工作原理、优缺点和技术特征等方面分析讨论各类最大功率点追踪技术,指出开路电压比例系数法可能最适合用于室内场景下光伏电池的最大功率点追踪;最后分析和讨论超级电容和可充电电池各自存在的优缺点,指出在光伏电池室内光能采集系统的储能选择方面,可充电电池与超级电容结合使用的储能模块可能是一个有前途的发展方向,为进一步推进室内光能采集系统的设计提供参考。     

Energy harvesting: State-of-the-art

This paper presents a brief history of energy harvesting for low-power systems followed by a review of the state-of-the-art of energy harvesting techniques, power conversion, power management, and battery charging. The advances in energy harvesting from vibration, thermal, and RF sources are reviewed as well as power management techniques. Examples of discrete form implementation and integrated form implementation using microelectromechanical systems (MEMS) and CMOS microelectronic processes are also given. The comparison between the reviewed works concludes this paper.     

Recovery and diversity of the forest shrub community 38 years after biomass harvesting in the northern Rocky Mountains

We investigated the long-term impact of biomass utilization on shrub recovery, species composition, and biodiversity 38 years after harvesting at Coram Experimental Forest in northwestern Montana. Three levels of biomass removal intensity (high, medium, and low) treatments combined with prescribed burning treatment were nested within three regeneration harvest treatments (shelterwood, group selection, and clearcut). Four shrub biomass surveys (pre-treatment, 2, 10, and 38 years after treatment) were conducted. Shrub biomass for all treatment units 38 years after treatment exceeded the pre-treatment level, and biomass utilization intensity did not affect shrub recovery (ratio of dry biomass at time t to pre-treatment biomass). Species composition changed immediately after harvesting (2 years); however, the species composition of treated units did not differ from the untreated control 38 years after harvesting. Biodiversity indices (Shannon’s and Pielou’s indices) also decreased immediately following harvesting, but recovered 10 years after harvesting. The responses of diversity indices over time differed among biomass utilization levels with the high-utilization level and unburned treatment producing the most even and diverse species assemblages 38 years after harvesting. Our results indicate the shrub community is quite resilient to biomass harvesting in this forest type.