Aspects of Logistics in Biomass Supply for Energy Production Sebastian Kot 1, a, Beata Ślusarczyk 1, b

Transcription

1 Applied Mechanics and Materials Vol. 309 (2013) pp Online available since 2013/Feb/13 at (2013) Trans Tech Publications, Switzerland doi: / Aspects of Logistics in Biomass Supply for Energy Production Sebastian Kot 1, a, Beata Ślusarczyk 1, b 1 Czestochowa University of Technology, Management Faculty, ul. Dabrowskiego 69, Czestochowa, Poland a sebacat@zim.pcz.czest.pl, b jagoda@zim.pcz.czest.pl Keywords: biomass energy production, logistics supply. Abstract. Energy production from biomass is now a very popular trend in energy generation. These initiatives are supported by the European Union legislation and state governments. Undoubtedly, the idea of renewable energy production can be justified and promising. However, it should be considered from a wider perspective of supply chain than merely focusing on the share of renewable sources in total energy production. The economic and ecological importance of biomass use to energy generation largely depends on the logistics of biomass supply to power plants. The location of biomass sources and the organization of supply are very important stages that impact on final economic results of energy production. Furthermore, the improper choice of means of transport and process organization for managing renewable sources of energy might have a negative ecological effect. Therefore, the authors attempted to analyze the cost-related aspects of biomass supply (including the seasonal biomass price fluctuation) to the analyzed power plant and the effect of this factor on financial results of energy production. Introduction There has been a growing concern over energy safety in contemporary world. The emphasis has been also on the aspects of environmental protection. Conventional sources of energy contribute to substantial environmental pollution. Therefore, recent years has seen a number of commitments made by the states in order to reduce the adverse effect of manufacturing processes on the environment. This is expected to be achieved by the increased use of renewable sources of energy. One of these sources with particular prospects for development is biomass. The use of biomass, however, involves a series of specific requirements that must be met by the entities that search energy and can be the reason for many problems that arise, especially in logistics. Renewable sources of energy are the sources based on solar radiation, geothermal, wind, water and biomass energies or the energies generated from waste processing. These sources are virtually inexhaustible and exist everywhere in the world, yet unevenly distributed. One indisputable advantage of renewable resources is their insignificant impact on the environment and substantial dissipation, which to some extent solves the problem of energy transport [8]. Biomass used for energy purposes appears in free forms: waste wood from forestry and wood industry, straw from agriculture and plants from special energy plant [5] Energy contained in biomass can be used by means of a variety of methods which include in particular: direct firing or co-firing by means of conventional energy sources, gasification and fermentation of biomass to obtain biogas which is then fired, production of biofuels from oilseed crops or alcohol. Biomass co-firing with traditional energy sources can occur either directly (without biomass conversion) or indirectly (biomass is converted into gaseous form) and parallel (biomass and conventional energy carrier are fired separately, but their energy is then converted into electricity) [7]. It is estimated that the potential of solid biomass in Poland amounts to over 30 million Mg per year, of which over 20 million is waste straw, 4 million is wood waste and 6 million is sewage sludge from cellulose industry. These reports did not take into consideration the potential of energy crops, which are increasing every year. As results from a study prepared by the Institute for Renewable Energy, technological energy potential of the discussed types of biomass will have reached ca. 690 All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP, (ID: /02/13,20:07:03)

2 Applied Mechanics and Materials Vol TJ by The economic potential is expected to rise to the level of ca. 520 TJ, whereas the market potential that represents actual opportunities for the use of these resources will be reach ca. 360 TJ [6] The use of biomass for electricity production in Poland indicates that this source is among the most remarkable sources of renewable energy sources (Table 1). Table 1. Electricity produced using individual renewable sources of energy in [GWh] Source Water Power 2,176 2,030 2,253 2,153 2,376 2,922 Plants Biomass 1,345 1,818 2,343 3,313 4,888 5,788 Biogas Wind Power ,045 1,822 Plants Total 3,761 4,222 5,230 6,493 8,604 10,895 Although the highest contribution in the period studied was observed for water energy sector (57.2%), the leading position since 2008 has been taken by biomass energy. The most noticeable increase in the amount of energy generated occurred for biomass and wind energy. It should be emphasized that the biomass, which is a renewable energy source, has great prospects for development. One group of biomass is solid biomass, which can be further subdivided. This source is economical and can be obtained from both energy crops and waste from forestry and agriculture, which does not generate additional costs. The major inconvenience of using biomass is low calorific value per volume unit and can be compensated by the processes of pelletizing, briquetting or baling. However, another substantial problem is development of the effective logistic system of logistic supply of biomass for power plants in consideration of the problems of warehousing and transport. Apart from the negative aspects of warehousing and maintaining inventory (capital lock-up, material handling or insurance) known for other goods, the biomass, during the warehousing process can be biodegraded, which results in the deterioration of energy properties (thus they are loss-related properties) and might lead to the growth of the mould or spore which are dangerous for human health. Solid biofuels are also characterized by a relatively high risk of spontaneous combustion or ignition from a small spark, which forces warehouse owners to use more advanced fire-fighting systems. The method of storage depends on the type of biomass. Grain, forest chips or granules are stored in silos. Straw bales are stored under the shelters, in piles and the wood logs need to be protected from rain and require sufficient air flow. Regardless of the biomass type, if it is stored in big warehouses, biomass needs to be frequently handled in the warehouse [2]. Analysis of the problems of transport of the biomass obtained from power plants for energy purposes in Poland reveals that the most popular means of transport is by rail and road transport. The transport by rail uses eight-wheel coal wagons with capacity of 69 cubic metres. Depending on the type of biomass, the wagons are capable of transporting from 30 to 40 Mg of this fuel. In road transport, the specific means of transport is determined by the distance to be covered by the biomass being transported. In long-distance transport, the heavy good vehicles are usually employed (with load capacity from 24 to 28 Mg) and capacity of 30-90m 3 ), whereas light goods vehicles (with load capacity of 7 to 16 Mg) are used for the distances of up to 100 km. Large vehicles used to transport biomass are usually equipped in tipper devices, which considerably facilitate unloading. Furthermore, the vehicles should ensure that the transported cargo is protected from humidity, both during transport and at the stage of loading and unloading [1]. Analysis of Logistics Problems of Biomass Supply in Selected Energy Power Plant The enterprise analysed in the study belongs to a medium-sized heat and electricity supplier with four steam boilers and two turbo assemblies for production of electricity. Similar to other entities of similar type in Poland, a number of investments projects were implemented in the enterprise in

3 208 III Central European Conference on Logistics , which allowed for generation of green energy through biomass firing. This allowed for reduction in emissions of carbon and sulphur dioxides, nitrogen oxide and dust. The choice of the research subject for the analysis will allow for determination of logistics problems of biomass supply, typical of similar entities that are starting to introduce renewable sources of energy for generation of heat power and electricity. In the period of the study (from July to December 2011), the enterprise used biomass from agriculture and forestry for electricity generation. Consumption of both types of biomass for production of electricity is presented in Table 2. Table 2 Consumption of biomass for production of energy in each month Consumption of Biomass [Mg] Agricultural Forestry Biomass Biomass in Total Biomass July 1, , , August 1, , , September 1, , , October 1, , , November 1, , , December 1, , , Total 7, , , It should be noted that the changes in the level of biomass consumption were closely related to the demand for heat power and electricity. Therefore, a substantial decline can be observed in August, when production downtime due to reduced demands was 13 days in total. Furthermore, the proportions of the use of individual types of biomass are largely determined by legal regulations that define the share of biomass of agricultural origin in the overall structure of biomass used for energy purposes cannot be lower than 40%. Therefore, excessively low share of agricultural biomass in July had to be compensated for by a considerable increase in August. In the period studied, the enterprise purchased biomass from 20 suppliers throughout Poland, whereas five of them were contractual suppliers who cooperated based on long-term contracts (2 years), whereas others were spot suppliers found in the free market. The suppliers of both categories cooperate with the analysed enterprise on different basis. Contract suppliers deliver a biomass according to a pre-defined schedule, at a particular price. On the other hand, spot contractors do not have a particular schedule. Each delivery necessitates separate orders. High price fluctuations might be observed in this case. The suppliers that deliver goods for the enterprise studied are from different regions of Poland. There are several local enterprises among them. However, some suppliers have headquarters at the distance of over 400 km (Table 3). This causes a substantial difference in transport costs from different suppliers. Table 3 Biomass suppliers Supplier Type of Distance [km] Cooperation Supplier 1 contractual 153 Supplier 2 contractual 180 Supplier 3 contractual 2 Supplier 4 contractual 162 Supplier 5 contractual 40 Spot suppliers spot

4 Applied Mechanics and Materials Vol When purchasing the biomass, the enterprise negotiates the price including delivery costs. However, it should be noted that this remote supply sources have substantial effect on the material price. The deliveries from such remote locations suggest problems with satisfying the demand by deliveries from closer suppliers. Table 4. Volume of deliveries from contractual suppliers vs. spot suppliers Volume of deliveries [Mg] Spot Sup. 1 Sup. 2 Sup. 3 Sup. 4 Sup. 5 Sup. July , August September , October , November December , Total 2, , , , , The contractual suppliers have 47% to 77% share in the total of biomass deliveries in individual months. The highest share of these suppliers was observed in August, when the demand for energy caused the need for purchasing energy in the free market. The data contained in Table 4 show that spot suppliers covered the highest part of deliveries in July and September: their share in the volume of deliveries in total was around 50%. Among the contractual suppliers, the major supplier is the Supplier 4, with the highest share in the total structure of deliveries. The volume of biomass purchased from the Supplier 2 ranges from less than 4% of share in the total structure of deliveries in July to over 28% in August. High instability of the volume of deliveries can be also observed among other suppliers, which might suggest the troubles with finding raw materials with suitable amount or its palletizing. These are among the most frequent problems of biomass supply logistics experienced by power plants in Poland. The problem of quality of biomass supply should also be emphasized as it has direct impact on the effectiveness of energy generation. Quality requirements concern the form of the biomass delivered (briquette, pellet), its net calorific value, humidity or ash and sulphur content. They are similar for biomass of both agricultural origin and the biomass from forestry. These requirements are individual requirements defined by the analysed enterprise and connected with the equipment for biomass co-firing installed in their facilities and the demands of environmental protection imposed by state government regulations. Table 5 The number of deliveries that have not met individual quality requirements Calorific Value Humidity Ash Content Sulphur Content July August September October November December Total

5 210 III Central European Conference on Logistics As can be noted, the highest number of non-conforming deliveries is connected with the criterion of ash content (Table 5). Furthermore, a great number of deliveries do not meet the humidity requirements. As results from the source documents, the value of this parameter exceeded the upper limit (12%) in all the non-conforming deliveries. The volume of non-conforming deliveries with respect to sulphur content was insignificant, which is particularly important due to the environmental protection requirements the enterprise must meet. Other parameters relate mainly to the requirements of the enterprise connected with the co-firing equipment installed in the enterprise's facilities. If these requirements are not met, it might lead to the problems with electricity generation, but it does not significantly affect the enterprise's environment e.g. the problems of air pollution with harmful substances. Analysis of the problem of non-conforming deliveries in individual months reveals that the number of the deliveries which do not conform to the quality requirements is on the increase. This is likely to be caused by weather conditions the biomass is obtained, which has considerable impact on biomass quality. The increasing number of non-consistent deliveries might also result from lower motivation of suppliers and neglecting the problems of preparation of high-quality biomass. Undoubtedly, the fact that the enterprise accepts such low-quality deliveries has significant effect on these practices. Therefore, the enterprise should be more consistent in exacting the quality requirements for the biomass delivered and, if the installation for biomass firing is capable of being operated with lower-quality fuels, the enterprise managers should re-consider lowering the requirements. Constant acceptance of non-consistent deliveries reduces the enterprise's credibility and encourages suppliers not to respect the requirements. Analysis of the number of the deliveries that have not met quality requirements should also include the division into the deliveries of agricultural and forestry biomass. Both types of biomass have slightly different content, which causes that they might have different quality properties. Share of non-conforming deliveries with respect to this division is presented in Table 5. Table 5. Share of non-conforming deliveries with respect to the division into agricultural and forestry biomass. Month Agricultural Biomass Share of non-conforming Forestry Biomass July August September October November December July-December The data presented in the table show that the biomass of agricultural origin is characterized by a considerable higher coefficient of improper deliveries. This level is lower than 70% in July, whereas it fluctuates around 90-95% in other months. Only insignificant percentage of deliveries of agricultural biomass meets the quality requirements imposed by the analysed enterprise. The deliveries of the biomass of forestry origin meet these requirements to higher extent. Therefore, it should be reconsidered whether the requirements defined by the enterprise with respect to the biomass of agricultural origin are not exaggerated and whether they should not be changed compared to the forestry biomass. It should not be assumed that the non-conformance of agricultural biomass deliveries was caused exclusively by the supplier's negligence and disrespect for the requirement. It is more likely that these requirements are maladjusted to the characteristics of biomass of agricultural origin and only some deliveries are able to meet them. Choosing the suppliers, their assessment and delivery organization are not the only problems in the area of supply logistics. Another aspect of supply logistics that might have a direct impact on the efficiency of electricity production form solid biomass is organization of the process of warehousing. The process of warehousing directly affects quality properties of biomass, such as

6 Applied Mechanics and Materials Vol humidity, ash content and, consequently, net calorific value. As results from comparative analysis for the quality parameters measured before and after the process of warehousing, this process might have both positive and negative effect. This concerns the quality parameters of both agricultural biomass and the biomass of forestry origin. Storage of biomass in suitable conditions might contribute to the decrease in biomass humidity, and, consequently, to the increase in its calorific value. However, insufficient conditions might have an opposite effect. Warehousing processes do not significantly affect ash and sulphur content, but biomass contamination during warehousing might cause the increase in ash content, which might be higher than the potential benefits of the reduced humidity. Despite several positive aspects of biomass warehousing, its longer storage generates the risk of deteriorated quality properties. Therefore, it seems that the satisfactory results of the effect of biomass warehousing in the present manner do not provide sufficient ground for the enterprise to increase storage area or elongate the storage time for the biomass used for energy purposes. As mentioned above, the enterprise purchases the biomass as a package with the deliveries. Therefore, there is no need to consider the problems of transport management. The focus should be on re-considering replacing the road transport used in the enterprise into the theoretically cheaper rail transport. However, it is essential that both the power plant and the suppliers should have a siding, which would allow for avoiding the costs of loading and unloading and using road transport at initial and final sections of the route. Conclusions The biomass utilization in power energy plant supply is more and more important in the situation of sustain development strategy introduction. However is it extremely important to noticed real effects of the strategy introduction with effects of logistics activities those are not simply positive on the financial effects of power plant and environment. The power plant location process will not generally include consideration of biomass sources availability and in effects it brings problems with rising logistics costs and negative environmental effects. Therefore it is suggested in the power plant localization process to include scientific methods [3,4, 9, 10] to improve economy, logistics and environmental efficiency. References [1] Duda-Kękuś A., Transport biomasy w logistyce dostaw paliw dla elektrowni systemowych realizujących program zielonej energetyki Logistyka No. 2 (2011) [2] Gad S., Pawlak A., System transportowy w instalacji przygotowania i dozowania biomasy, Logistyka, No. 6 (2011) [3] Information Resources Management Association. Green Technologies: Concepts, Methodologies, Tools and Applications. IGI Global (2011) [4] Jacobson J., at all. Sustainable Biomass Supply Systems AICHe Spring National Meeting, U.S. Department of Energy (2009) [5] Lewandowski W. M., Proekologiczne źródła energii, Wydawnictwo Naukowo-Techniczne, Warsaw (2007) [6] Możliwości wykorzystania odnawialnych źródeł energii w Polsce do roku 2020, Instytut Energetyki Odnawialnej, Warsaw (2007). [7] Pawlik M., Strzelczyk F., Elektrownie, Wydawnictwo Naukowo-Techniczne, Warsaw

7 212 III Central European Conference on Logistics [8] Szecówka L., Ekologiczny efekt energetycznego wykorzystania biopaliw, Wydawnictwo Politechniki Częstochowskiej, Częstochowa (2009) [9] Velazquez-Marti B., Annevelink E. : Mathematical algorithm to transform digital biomass distribution maps into linear programming networks in order to optimize bio-energy delivery chains. [in:] Proceedings Ageng2008 congress, June, Wageningen (2008). [10] Waszczuk K., Baum R., Wielicki W. A Proposal Of A Logistics Model For The Use Of Biomass For Energy For Local Communities Within The Concept Of Sustainable Rural Development. 107th EAAE Seminar "Modeling of Agricultural and Rural Development Policies". Sevilla, Spain, January 29th -February 1st, (2008)

8 III Central European Conference on Logistics / Aspects of Logistics in Biomass Supply for Energy Production /