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1.
Although there is a need for biomass and a potential for short rotation coppice (SRC), farmers hesitate to establish SRC, even on marginal agricultural land on which annual crops show low productivity. Probably the most important factor explaining this reluctance might be the uncertain economic prospects of the cultivation of SRC. Therefore, the aim of this study is to analyse the economy of a typical SRC supply chain by calculating the annuities which can be expected by German farmers who establish SRC on their marginal land.The result shows that the yearly annuity of a 20-year SRC cultivation is about 70 € y−1 ha−1 when poplar SRC is harvested every 4 years with a forage harvester (one-step system). The result includes the establishment, cultivation and transport of the fresh wood chips to a plant 50 km away. However, this result is not competitive with the result of annual crops (226–462 € y−1 ha−1) and is also lower than the CAP subsidy payments that farmers receive from the EU (300 € y−1 ha−1). To achieve higher annuities, four options were analysed possibly leading either to higher biomass yields or to higher market prices (extension of rotation cycle, implementation of irrigation, technical drying of fresh wood chips, using a two-step harvesting system). The implementation of drip irrigation to increase biomass yield turned out to be uneconomic. An extension of the rotation cycle from 4 to 5 years can be recommended as it leads to an annuity of 255 € y−1 ha−1 (instead of 69 € y−1 ha−1). Results also show that the technical drying of chips using (cheap) surplus heat can be very profitable if the added value is reflected in higher market prices. Furthermore, it is shown that the use of an alternative two-step harvesting system with natural interim drying of the rods can be an attractive option for farmers to increase the annuity of their SRC.  相似文献   

2.
Short rotation woody crops (SRWCs) are being studied and cultivated because of their potential for bioenergy production. The harvest operation represents the highest input cost for these short rotation woody crops. We evaluated three different harvesting machines representing two harvesting systems at one operational large-scale SRWC plantation. On average, 8 ton ha−1 of biomass was harvested. The cut-and-chip harvesters were faster than the whole stem harvester; and the self-propelled harvester was faster than the tractor-pulled. Harvesting costs differed among the harvesting machines used and ranged from 388 € ha−1 to 541 € ha−1. The realized stem cutting heights were 15.46 cm and 16.00 cm for the tractor-pulled stem harvester and the self-propelled cut-and-chip harvester respectively, although a cutting height of 10 cm was requested in advance. From the potential harvestable biomass, only 77.4% was harvested by the self-propelled cut-and-chip harvester, while 94.5% was harvested by the tractor-pulled stem harvester. An increase of the machinery use efficiency (i.e. harvest losses, cost) is necessary to reduce costs and increase the competitiveness of biomass with other energy sources.  相似文献   

3.
《Biomass & bioenergy》2007,31(6):375-380
Vast quantities of logging residue are left behind on clearcut areas. Given the suitable transportation distance, environmental and economic circumstances, they provide a possible alternative for fossil fuels. However, distribution of residual biomass over large areas during the logging operation and trampling by machines hinders the recovery. The recovery enhancing effect of three single-grip harvester work techniques on the productivity of logging residue recovery for energy was studied. Forwarder productivity, distribution of effective work time, forwarding distance, load size and the residue yield were studied.A heavy forwarder with an enlarged 22 m3 load space was used. The average load size was 9 tonnes. More than 50% of the forwarder's work time was spent on loading the residues. The recovery output of the trampled residues from the strip road after a conventional harvesting method was 11.4 t/E0-h for a 9 tonnes load and a 300 m transportation distance. In contrast, the single-grip harvester methods that aimed at the post-logging residue recovery increased the recovery output to 12.0–13.3 t/E0-h. The load size was a more significant factor than the forwarding distance in terms of machine productivity. The yield of residue recovery after the conventional roundwood harvesting method was 58.4% and from 66.8% to 78.7% for the alternative single-grip-harvester methods.  相似文献   

4.
This paper presents a novel axisymmetric floating energy harvester associated with hydraulic cylinders and gear rack mechanism to harness wave energy. The harvester collects energy in surge, heave, and pitch modes. The mathematical models for the harvester are developed to analyze the performance and the harvested power. The Pierson‐Moskowitz two‐parameter spectrum was utilized to model the incident waves. The retardation function for the radiation force and the added mass curve are fitted based on the least squares method. The irregular exciting force, the displacement, the velocity, and the power harvesting of the axisymmetric floating energy harvesters in three motion modes with irregular waves are simulated. The effects of harvester design parameters and the geometry shape variation of the submerged part on the wave‐exciting force, the displacement, the velocity, the harvested power, and the harvesting efficiency are investigated. Under the same output damping and the same parameters with the radius of 4 m, the submerged height of 4 m, the above‐water height of 2 m, and the center of mass of ?1 m, the cylinder wave‐exciting force in surge is highest among three shapes, the cone wave‐exciting force is highest among three shapes in heave and pitch modes, and the total harvested power and the efficiency of the cylinder‐shaped harvester are the highest among three different axisymmetric shapes, which are 40.521 kW and 62.96%, respectively. The harvested power and the efficiency differences between the cylinder and the cone are 1.571 kW and 2.4%, and the differences between the cylinder and the halfsphere are 8.543 kW and 13.28%. For the cylinder‐shaped harvester with the submerged height of 4 m, the above‐water height of 2 m, and the center of mass of ?1 m, when the radius increases from 3 m to 5 m, under the optimal output damping, the total harvested power and the harvesting efficiency increase by 38.811 kW and 35.83%, respectively. For the cylinder‐shaped harvester with the radius of 4 m and the above‐water height of 2 m, as the submerged part height increases from 2 to 4 m, the total harvested power and the harvesting efficiency increase by 15.776 kW and 24.51%, respectively. For the cylinder‐shaped harvester with the radius of 4 m, the submerged height of 4 m, and the above‐water height of 2 m, as the center of mass is reduced from 0 to ?1 m, the total harvested power and the harvesting efficiency rise by 15.153 kW and 23.54%, respectively.  相似文献   

5.
The value and volumes of industrial stump fuel supply are increasing for energy production. Accurate estimates of aboveground and belowground biomass of trees are important when estimating the potential of stumps as a bioenergy source. In this study two stump biomass equations were adapted and tested using them as calibrated stump biomass models computed as the cumulative sum by a local stand. In addition, variables derived from stem measurements of the forest harvester data were examined to predict stump biomass of a stand by applying regression analysis. The true stump yield (dry weight) was used as the reference data in the study. Both biomass models performed well (adjusted R2 ˜ 0.84) and no advance was found in using other stem dimensions as independent variables in the model. The stand-level model can be used in innovative stump biomass prediction tools for increasing efficiency of energy wood procurement planning to stands within a certain area. In practice, wood procurement managers would need to adapt developed system and decide whether the degree of accuracy/precision provided by the models is acceptable in their local stand harvesting conditions.  相似文献   

6.
The cultivation of short rotation coppices (SRC) on agricultural land represents an economically and environmentally promising option for sustainable provision of bioenergy. Not only the further development of efficient harvesting machinery, but also the development of harvest-optimised storage systems are necessary to implement cost-efficient cultivation and use strategies for SRC in practice. The storage of fine wood chips from poplar harvest with a forage harvester results in high dry matter losses of up to 25%. Tractor-mounted mower-chippers can harvest coarse wood chips that might possess more favourable storage and drying properties. The main objective of the current research project was to develop and perform a storage experiment in which the storage behaviour of fine and coarse wood chips could be examined and compared in detail over a period of nine months. In this experiment two covered storage piles (height 3.5 m), with over 500 m3 fine and coarse wood chips respectively, were examined under practice scale conditions in Germany. After nine months of storage the fine chips in the core of the storage pile had dried to a moisture content of 34% with dry matter losses of 22%. Coarse chips, on the other hand, achieved a moisture content of 29% and dry matter losses of 21% in the same period. The maximum moisture content of 40% required by heating plants in practice is achieved by fine chips after 6.5 months and by the coarse chips already after 3.5 months.  相似文献   

7.
This paper presents an analysis of the spatial supply and demand relationships for biomass energy potential for England, using Geographical Information System (GIS) mapping techniques. Due to energy use and cost of biomass feedstock transportation, the spatial relationship between potential supply and demand is crucial to efficient usage of this distributed feedstock. Previous studies have identified potential for biomass generation at individual sites, according to local factors dictating viable transport distances and costs. The research presented here necessarily takes a more generalised approach, to allow national scale assessment of capability to meet fixed location demands, and quantify theoretical potential generation under relevant scenarios. The approach is illustrated for England, although techniques are applicable elsewhere when suitable data are available.Mapping for England indicates that of the 2,521,996 ha viable for cultivation of Miscanthus, 1,998,435 ha are within 25 km of the identified potential end uses of feedstock, and 2,409,541 ha are within 40 km. Potential generation exceeds the 2020 UK biomass generation target of 259 PJ, whichever radius is applied. However, predictions assume Miscanthus cultivation at all appropriate sites, and no policy interventions to limit transport distance.Results from national scale analysis may be useful in informing government decisions, for example to identify impacts on total generation potential of incentives affecting decisions on allocation of overlap feedstock. Variation in GHG balance and environmental impacts between cultivation sites creates spatial variation in benefits of bioenergy, which should be taken into account in addition to the spatial relationship between supply and demand.  相似文献   

8.
For woody biomass to make a significant contribution to the United States' energy portfolio, harvesting contractors must economically harvest and transport energywood to conversion/processing facilities. We conducted a designed operational study in the Coastal Plain of North Carolina, USA with three replications of three treatments to measure harvesting productivity and costs when utilizing woody biomass. The treatments were: a conventional roundwood only harvest (control), an integrated harvest in which merchantable roundwood was delivered to mills and residuals were chipped for energy, and a chip harvest in which all stems were chipped for energy use. The harvesting contractor in this study typically delivers 2200–2700 t of green roundwood per week and is capable of wet-site harvesting. Results indicate that onboard truck green roundwood costs increased from 9.35 $ t−1 in the conventional treatment to 10.98 $ t−1 in the integrated treatment as a result of reduced felling and skidding productivity. Green energy chips were produced for 19.19 $ t−1 onboard truck in the integrated treatment and 17.93 $ t−1 in the chip treatment. Low skidding productivity contributed to high chip costs in the integrated treatment. Residual green biomass was reduced from 18 t ha−1 in the conventional treatment to 4 and 3 t ha−1 in the integrated and chip treatments, respectively. This study suggests that until energywood prices appreciate substantially, loggers are unlikely to sacrifice roundwood production to increase energywood production. This research provides unique information from a designed experiment documenting how producing energywood affects each function of a harvesting system.  相似文献   

9.
Hydrogen has emerged as an eco-friendly energy to replace fossil fuels. But, it is difficult to store large capacity and to transport long distance due to a low volumetric energy density. In order to overcome the disadvantages of hydrogen, hydrogen supply chains are being widely studied and reported to compare which chains are better to be deployed. However, few studies have reported in terms of an environmental impact assessment. Therefore, in this study, an environmental impact is analyzed using a life cycle assessment (LCA) for offshore hydrogen supply chains linked to offshore wind farms, as well as an energy efficiency. The hydrogen supply chains include all stages of converting hydrogen produced on an offshore platform into compressed gaseous hydrogen (CGH2), liquefied hydrogen (LH2), liquid organic hydrogen carriers (LOHC), or ammonia (NH3), transporting them to an onshore plant and storing as CGH2. In particular, in order to calculate the amount of fuel consumed in ship transportation, the weight of cargo is estimated accordingly. The results vary depending on the electrical energy sources used and the transport distance. In almost all stages except for transport, electrical energy sources have a significant impact on the environmental load. The global warming potential (GWP), which is an alternate value of greenhouse gas emissions, is in the range of 1.15–10.11 kg CO2 eq when the national electricity grid and the offshore wind power (W + G) are used together. On the other hand, it shows a much lower value as 1.15–2.05 kg CO2 eq when using only offshore wind power (W). As the transport distance increased, it is significantly affected in some impact categories, i.e. GWP, acidification potential (AP), and eutrophication potential (EP). The contribution of transport gradually increased, and at 10,000 km, the value was 25.32–35.42 kg CO2 eq for W + G and 24.88–27.49 kg CO2 eq for W. Comparing the efficiency, CGH2 is the highest at all transport distances, followed by NH3, LOHC, and LH2. Considering that CGH2 is typically unfeasible for ship transport, hydrogen transport using NH3 can be the most attractive option. Finally, it is found that the longer the transport distance, the greater the effect on chain efficiency. Accordingly, the efficiency of the chains sharply decreases as the transport distance increases.  相似文献   

10.
The aim of this study is to contribute by outlining a procedure for achieving an optimal use of agricultural and forest residue biomass. In this regard, it develops and applies a methodology focused on logistics and transport strategies that can be used to locate a network of bioenergy plants around the region. This methodology was developed using a Geographic Information Systems and it provides information on the spatial distribution of biomass residues. This is accomplished by taking into consideration the amount of residue left within a rectangle with an area of 1 km2, and making a regular grid overlap for the region under consideration. The centroid of each square will be evaluated and classified as “origin” (source of biomass collection) or “destination” (potential location of the bioenergy plant) depending on technical, economic, environmental and social constraints. The study focuses on mapping potential sites for tapping biomass energy and optimal locations for bioenergy plants. To identify and map optimal locations it is necessary to evaluate the time, distance and transport costs involved in the road transportation of biomass by means of a network analysis. The methodology was applied in the Valencian Community because the intense agricultural, agro-alimentary and timber activity in the region means there is a high potential for biomass.  相似文献   

11.
The rising price of fossil fuel and the increasing environmental concern encourage the use of biomasses as energy sources. Aim of this study was to compare two poplar SRC and vSRC (6 and 3 years rotation cycle) with an annual crop (maize), used for biomass production in north Italy.The average of the biomass production was 13.9 Mg DM ha−1 per year for the SRC and vSRC poplar and 19.2 Mg DM ha−1 for the maize.The energy consumption for the poplar cultivations was about 15 GJ ha−1 per year, which represented only the 6% of the energy biomass product (about 257 GJ ha−1 per year).The input value of the maize was higher (26.8 GJ ha−1 per year). In this case, the input value was about the 7% of the energy content in the biomass product (about 370 GJ ha−1 per year).During the vSRC cultivation an amount of 8090 kg CO2 eq ha−1 was emitted, 6420 kg CO2 eq ha−1 for the SRC and 26,370 kg CO2 eq ha−1 for the maize.Compared to the maize, the poplar SRC (or vSRC) crops are interesting from an energetic point of view, while maize requires less manpower, but it has major problems related to the landscape biodiversity.  相似文献   

12.
The research develops a novel harvester associated with a built‐in frequency conversion device to harness energy from ocean waves based on the piezoelectric effect. The developed harvester consists of 2 generators driven by rotational motions converted from vertical motions by a rack and pinion actuator. The generator has a rotator with a magnetic bar attached to its blade tips and a stator. By this innovative design, the harvester is capable of converting ocean waves with low frequencies to mechanical vibrations with higher excitation frequencies of the piezoelectric transducer for increasing its energy conversion efficiency. A corresponding mathematical model for the harvester is developed to evaluate the generated power. The simulation results show that the generated power increases with increases in the ocean wave height, number of magnetic bars and decreases in the wave period, the distance between 2 opposite magnetic bars, and harvester's submerged part height. The power output is realized up to 260 W with the height, length, and width of the harvester being 1m × 1m × 1m, at the ocean wave height and period being 2 m and 7 seconds, respectively.  相似文献   

13.
In Italy, more than 1150 agricultural anaerobic digestion (AD) plants are currently running. Their concentration in specific areas resulted in an increase in the biomass price and transport distances. For the AD plants located on farms with small area, often the feedstock are purchased on the market. However, when transport distances increase, it can be less expensive to buy biomasses with high energy density.With this regard, maize experimental tests were carried out to evaluate the methane production by harvesting the whole plant, the plant cut at 0.75 m and only the ear.The aim of this paper is to evaluate the economic performances of biogas plants fed with different maize silages by considering increasing extra-farm transport distances. Two different scenarios were considered with regard to the subsidy framework and to the maize biomass yield.The results show that, for short distances (<3 km), the economic performances are similar for AD plants fed with the whole plant silage and with that from the plant cut at 0.75 m; however, they are substantially better than those of the plant fed with ear silage. Beyond 14 km ear silage becomes more interesting than the whole plant; up to 32 km the plant fed with silage from the high cut is the most profitable whereas, beyond this transport distance, the ear silage is the best solution. The achieved results are interesting for stakeholders and policymakers involved in the biogas agro-energy processes, because they can be useful to reduce the cost of feedstock supply.  相似文献   

14.
Wildfire burnt forest biomass can be salvaged as feedstock for bioenergy power generating stations. Despite availability of such forest biomass in northwestern Ontario, its procurement has generally been considered uneconomic and no studies have looked into the cost of harvesting, processing, and transporting the burnt material for bioenergy production. In order to meet the demand of biomass for proposed and existing power generating stations using renewable fuels, a standard costing model is used to determine the feasibility of procuring biomass from burnt areas using a full-tree to roadside, roadside grinder to mill system. The case-study was conducted at the Hogarth Plantations near Thunder Bay, Ontario, Canada. The total cost incurred for processing and delivery of biomass from wildfire burnt area with a hauling distance of 7 km and total trip cycle time of 2.55 h was found to be $29.65 gt?1, with net energy content of 11.4 GJ gt?1. The total procurement cost depends on the hauling distance and a linear relationship between the two was established. The energy analysis found a net energy output to input ratio of 35:1 for the operation.  相似文献   

15.
Gasification of biomass can be used for obtaining hydrogen reducing the total greenhouse gases emissions due the fixation of CO2 during photosynthetic processes. The kind of raw materials is an important variable since has a great influence on the energy balance and environmental impacts. Wastes from forestry are considered as the most appropriate raw materials since they do not compete for land. The aim of this work is to determine the environmental feasibility of four Spanish lignocellulosic wastes (vine and almond pruning and forest waste coming from pine and eucalyptus plantation) for the production of hydrogen through gasification. LCA methodology was applied using global warming potential, acidification, eutrophication and the gross energy necessary for the production of 1 Nm3 of hydrogen as impact categories. As expected, the use of biomass instead of natural gas leads to the reduction of CO2 emissions. Regarding to the different feedstocks, biomass coming from forestry is more environmental-friendly since does not need cropping procedures. Finally, the distribution of environmental charges between pruning wastes and fruits (grape and almond) and the use of obtained by-products have a great influence, reducing the environmental impacts.  相似文献   

16.
An increasing number of rural municipalities wants to meet their entire energy demand with biomass. This article gives a system analytic view on these “bioenergy villages” by balancing pros (reduction of CO2 emissions) and cons (increasing costs, land use) using the example of a model municipality in Germany. The results indicate that a 100% energy supply based on biomass from within the boundaries of a rural municipality is technically possible but less reasonable with respect to land use competition and costs of energy supply. Whereas heat and power demand in bioenergy villages can be covered with relatively little land use and to relatively low costs, the production of transport fuel based on energy crops (rape seed) leads to significant negative impacts. For a cost-efficient decarbonization of rural areas it can therefore be recommended to particularly expand the utilization of biomass for heat and power production and to reconsider the transport fuel production.  相似文献   

17.
Solar energy itself is generally considered as environmentally friendly, nevertheless it is still important to take into consideration the environmental impacts caused by production of thousands of solar thermal systems. In this work the standard LCA methodology has been extended to analyse the total environmental impacts of a new more efficient solar thermal system SOLARSTORE during its whole life cycle. This system is being developed by a 5th Framework EC project. The LCA results show that to produce 1 GJ energy with SOLARSTORE system will result in global warming potential of 6.3–10 kg CO2, acidification potential of 46.6–70 g SO2, eutrophication of 2.1–3.1 g phosphate and photochemical oxidant of 0.99–1.5 g C2H4. The raw material acquisition and components manufacturing processes contribute 99% to the total environmental impacts. In comparison with traditional heating systems, SOLARSTORE system provides a considerably better solution for reduction of negative environmental impacts by using solar energy more efficiently.  相似文献   

18.
《Biomass & bioenergy》2007,31(8):543-555
The energetic and environmental performance of production and distribution of the Brassica carinata biomass crop in Soria (Spain) is analysed using life cycle assessment (LCA) methodology in order to demonstrate the major potential that the crop has in southern Europe as a lignocellulosic fuel for use as a renewable energy source.The Life Cycle Impact Assessment (LCIA) including midpoint impact analysis that was performed shows that the use of fertilizers is the action with the highest impact in six of the 10 environmental categories considered, representing between 51% and 68% of the impact in these categories.The second most important impact is produced when the diesel is used in tractors and transport vehicles which represents between 48% and 77%. The contribution of the B. carinata cropping system to the global warming category is 12.7 g CO2 eq. MJ−1 biomass produced. Assuming a preliminary estimation of the B. carinata capacity of translocated CO2 (631 kg CO2 ha−1) from below-ground biomass into the soil, the emissions are reduced by up to 5.2 g CO2 eq. MJ−1.The production and transport are as far as a thermoelectric plant of the B. carinata biomass used as a solid fuel consumes 0.12 MJ of primary energy per 1 MJ of biomass energy stored. In comparison with other fossil fuels such as natural gas, it reduces primary energy consumption by 33.2% and greenhouse gas emission from 33.1% to 71.2% depending on whether the capacity of translocated CO2 is considered or not.The results of the analysis support the assertion that B. carinata crops are viable from an energy balance and environmental perspective for producing lignocellulosic solid fuel destined for the production of energy in southern Europe. Furthermore, the performance of the crop could be improved, thus increasing the energy and environmental benefits.  相似文献   

19.
Concerns regarding the potential global environmental impacts of fossil fuels used in power generation and other energy supplies are increasing worldwide. One of the methods of mitigating these environmental impacts is increasing the fraction of renewable and sustainable energy in the national energy usage. A number of techniques and methods have been proposed for reducing gaseous emissions of NOx,SO2 and CO2 from fossil fuel combustion and for reducing costs associated with these mitigation techniques. Some of the control methods are expensive and therefore increase production costs. Among the less expensive alternatives, cofiring has gained popularity with the electric utility producers. This paper discusses the ‘gaseous emission characteristics namely NOx,SO2, suspended particulate matter and other characteristics like specific fuel consumption, total fuel required, actual and equivalent evaporation, total cost of fuel, etc. from a 18.68 MW power plant with a travelling grate boiler, when biomass was cofired with bituminous coal in three proportions of 20%, 40% and 60% by mass. Bagasse, wood chips (Julia flora), sugarcane trash and coconut shell are the biomass fuels cofired with coal in this study.  相似文献   

20.
As the cost of energy rises due to an increase in fossil fuels prices, the need to develop a sustainable alternative that will reduce green house gas emissions has increased in importance. One such alternative to reduce dependency on fossil fuels is the use of biomass for bioenergy generation. This study aims to quantify how much biomass can be produced in a specific area with a maximum haulage distance of 75 km to its end location, in this case, a large residential campus, to supply fuel to a biomass boiler. The study is carried out by identifying potential sources of biomass within the catchment zone and then quantifying it under different scenarios. The first scenario focuses on minimum land use impact, which quantifies how much biomass could be achieved taking just 10% of biomass from the sources identified. The second scenario is the maximum energy scenario and is set out to establish the maximum amount of energy that could be generated within the catchment zone using 50–100% of available biomass. The final scenario is the environmental scenario which looks to quantify biomass while not infringing on existing land uses such as agriculture and forestry. Results show that scenario one could produce almost 6 PJ of energy which is, scenario two could produce over 31 PJ of energy and scenario three could produce almost 14 PJ of energy.  相似文献   

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