Scientific Research Center Bistra Ptuj

Ptuj, Slovenia

Scientific Research Center Bistra Ptuj

Ptuj, Slovenia

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Kostevsek A.,Scientific Research Center Bistra Ptuj | Cizelj L.,Jozef Stefan Institute | Petek J.,Local Energy Agency Spodnje Podravje | Pivec A.,Scientific Research Center Bistra Ptuj
Renewable Energy | Year: 2013

Renewable energy sources are amongst the more widely acceptable options for the future transformations of existing energy systems. The complexities of such transformations call for various comprehensive preparatory actions. Amongst them, the organisation of a multifaceted renewable value-chain into a renewable network may well be crucial for the successful utilisation of renewable energy sources in the future. This paper proposes a novel concept for renewable network covering entire renewable value chain with division on supply, demand and technology sections. In the past, each section has been addressed separately. The organisation of renewable network covering all sections is deemed to be vital for accomplishing the optimal distribution and deployment of renewable energy sources. Constant technological advancements within the renewable sector indicate the significance of a technology section within a renewable network. The appropriate arrangement of various stakeholders involved throughout the entire value-chain, which includes all sections of a renewable network, is therefore crucial for the further development of a renewable sector. The proposed concept of a renewable network would support the effective operation of a renewable value-chain within a municipality through the establishment of local virtual energy cooperatives aimed at fulfilling energy needs and supporting the development of the community. The applicability of the proposed concept is demonstrated through the development of a biomass network within the municipality of Cirkulane, Slovenia. © 2013 Elsevier Ltd.


Sostaric M.,University of Ljubljana | Klinar D.,Scientific Research Center Bistra Ptuj | Bricelj M.,Slovenian National Institute of Biology | Golob J.,University of Ljubljana | And 2 more authors.
New Biotechnology | Year: 2012

The microalga Chlorella vulgaris was cultured in a combined medium obtained by mixing standard Jaworski medium with a solution from the modified Solvay process that contained only NaHCO3 and NH4Cl. Cell number, pH and nitrogen content were monitored throughout growth. Lipids were extracted from lyophilised biomass using CHCl3-MeOH. A combination of grinding, microwave treatment and sonication proved to give the best lipid extract yield. Freeze-dried algal biomass was also utilised for thermal degradation studies. The degradation exhibited three distinct regions - primary cell structure breakage paralleled by evaporation of water, followed by two predominant exothermic degradation processes. The latter were modelled using nth order apparent kinetics. The activation energies of the degradation processes were determined to be 120-126kJ/mol and 122-132kJ/mol, respectively. The degradation model may be readily applied to an assortment of thermal algal processes, especially those relating to renewable energy. © 2012 Elsevier B.V.


Brumec D.,Scientific Research Center Bistra Ptuj | Rozman C.,University of Maribor | Janzekovic M.,University of Maribor | Turk J.,University of Maribor | Celan S.,Scientific Research Center Bistra Ptuj
Sumarski List | Year: 2013

In this paper, we examine different scenarios for appropriate environment regulation of degraded areas with silvopastoral system establishment using integrated computer-based deterministic simulation and a multi-criteria decision model. We test the possibility for the wild game farming of red deer (Cervus elaphus) and fallow deer (Dama dama) in the game enclosure. The simulation model can simulate different scenarios for periods of 30 years and 50 years. Scenarios are further assessed with a multi-criteria decision model using the analytical hierarchy process (AHP) (supported by the software tool Expert Choice (EC) 2000™). With the multi-criteria assessment, EC = 0.054 scenario for a period of 50 years is considered most appropriate for environment regulation. The scenario includes organic farming of red deer in a silvopastoral system, settlement of all four areas in the first year, and hinds intended for sale. The silvopastoral system includes the tree species Acer pseudoplatanus, Fraxinus excelsior, Prunus avium, and Alnus glutinosa, with a tree density of 248 tree/ha (62 of each tree species/ha) intended for logging after 50 years. The net present value (NPV) of this scenario at an 8.0 % annual discount rate is 280.685 €, while the internal rate of return (IRR) slightly exceeds 10 %.


Kostevsek A.,Scientific Research Center Bistra Ptuj | Petek J.,Local Energy Agency Spodnje Podravje | Cucek L.,University of Maribor | Pivec A.,Scientific Research Center Bistra Ptuj
Energy | Year: 2013

Effectively implementing various energy and environmental policies contributes to the acceleration of energy performance, a reduction in negative environmental impacts, and increased deployment of renewable resources. The MEEMS (municipal energy and environmental management system) performs the almost inconceivable role of accomplishing prerequisite targets at the national level and, consequently, the European and World levels also. Therefore, a proper infrastructure for MEEMS needs to be effectively applied in order to implement policy initiatives. A novel organisational framework of MEEMS is proposed and is constituted upon three pillars: integration of the municipal metabolism approach, the KBS (knowledge-based system), and the MTIS (municipal technology innovation system). By properly addressing the dynamics of the MEES (municipal energy and environmental system), and the new conceptual organisation of MEEMS, a need for the inclusion of innovative elements can be defined regarding support mechanisms. Integration of the end-user approach defines the fundamental orientation of modern MEEMS. This new concept paves a pathway towards an intelligent energy and environmental system. This paper describes an implementation of the new conceptual design of MEEMS within the urban municipality energy system of Ptuj, Slovenia. © 2013 Elsevier Ltd.


Drobez R.,Scientific Research Center Bistra Ptuj | Novak Pintaric Z.,University of Maribor | Pahor B.,Perutnina Ptuj | Kravanja Z.,University of Maribor
Asia-Pacific Journal of Chemical Engineering | Year: 2011

The objective of this work was to perform simultaneous heat integration and the synthesis of biogas process based on the mixed-integer nonlinear programming (MINLP) model. A synthesis model recently developed by Drobež et al. [R. Drobež, Z. Novak Pintarič, B. Pahor, Z. Kravanja. Chem. Biochem. Eng. Q, 2009; 23, 445-459] has been upgraded for simultaneous heat integration. An industrial case study was solved in order to describe the mathematical model and to illustrate the heat-integrated MINLP synthesis approach. The optimal solution indicates that during the synthesis of biogas process and when selecting the best auxiliary facilities significant benefit can be obtained if the selected process and auxiliary facilities are heat integrated. In this way almost the complete consumption of hot utility and 1/3 of cold utility can be saved, and thus most of the electricity and heat produced in the cogeneration system from biogas can be sold as surplus to the distribution networks. The proposed optimal synthesis of heat-integrated biogas process may improve a company's economic performance and significantly reduce its environmental impact by converting environmentally harmful organic and animal wastes into valuable products. Copyright © 2010 Curtin University of Technology and John Wiley & Sons, Ltd.


Kostevsek A.,Scientific Research Center Bistra Ptuj | Petek J.,Local Energy Agency Spodnje Podravje | Cucek L.,University of Maribor | Klemes J.J.,University of Pannonia | Varbanov P.S.,University of Pannonia
Applied Thermal Engineering | Year: 2015

The decarbonisation of energy systems is one of the important issues of the present energy policies. One of the ways of achieving this is to focus on local energy systems, thus ensuring as much as possible their heat and power self-sufficiency by applying local renewable resource integration and transformation of the renewable energy. Increasing the share of renewables within the local energy balance could be accomplished by using a variety of approaches. One possibility is combining the Locally Integrated Energy Sectors' concept with the novel management and organisation of a renewables-based network. As a first priority, the proposed comprehensive approach focuses on increasing the energy efficiency of municipal heat and power systems using the Locally Integrated Energy Sectors' concept, which is followed by the integration of renewable energy sources with the establishment of a renewable-based network. The proposed approach is illustrated by a case study of district heating based on wood biomass for the municipality Ormož, Slovenia by integrating various end-users from different sectors. © 2015.


Lah B.,Albin Promotion d.o.o. | Lah B.,Scientific Research Center Bistra Ptuj | Klinar D.,Scientific Research Center Bistra Ptuj | Likozar B.,Slovenian National Institute of Chemistry
Chemical Engineering Science | Year: 2013

A model acknowledging reaction kinetics and thermal conduction during waste end-of-life (ELT) tyre pyrolysis was developed based on the individual consideration of elastomers, namely natural (NR), butadiene (BR) and styrene-butadiene (SBR) rubber; fabric, that is rayon, nylon and aramid; and wire. External diffusional and thermal film resistances proved to be negligible during the thermal cracking. An algorithm was developed to extract pre-exponential factors, activation energies, the orders of reactions, the enthalpies of reactions, and transport parameters. The pyrolysis of various formulations at different volumetric flow rates and heating rates was monitored by thermogravimetry (TG) and differential scanning calorimetry (DSC), whereas the pertinent thermodynamic properties (density, specific heat capacity, and thermal conductivity and diffusivity) were determined separately. The un-decomposable weight fraction containing carbon black, char and ash was 39% for the investigated rubber and 13% for the fabric formulation. The sensitivity analysis of the pyrolysis on compound and process (operating) conditions was performed. The obtained results (taking into account their drawbacks) with the additional measurements and modelling may be used for the thermo-chemical treatment reactor scale-up and optimization, and consequently, a suitable design of energy and products recovery instead of disposal or landfilling, thus minimizing hazardous waste and contamination to soil and water resources. © 2012 Elsevier Ltd.


Avsenik L.,Slovenian National Institute of Chemistry | Klinar D.,Scientific Research Center Bistra Ptuj | Tusar M.,Slovenian National Institute of Chemistry | Tusar M.,Slovenian National Building And Civil Engineering Institute | Perse L.S.,Slovenian National Institute of Chemistry
Construction and Building Materials | Year: 2016

Effect of the addition of the pyrolytic product to aged bitumen was studied. Rejuvenator was prepared from scrap tire crumb modified pyrolytic condensate. Polycyclic aromatic hydrocarbons content in the pyrolysis condensate was kept low by applying relative low process temperature; the highest treatment temperature was 500 °C, similarly to those reported in existing studies. 50/70 penetration grade laboratory aged bitumen, prepared by using rolling thin film oven test and accelerated pressure ageing procedure, was used as reference bitumen. The influence of various concentrations of rejuvenator (3%, 5%, 10% and 20%) on the aged and non-aged bitumen was evaluated by standard mechanical and rheological tests. Rheological measurements were performed in the intermediate range by dynamic shear rheometer and in low temperature range with bending beam rheometer. Mechanical functions, dynamic shear modulus G(ω) and creep compliance D(t), calculated from the rheological test were interconverted to shear G(t) and tensile E(t) relaxation modulus. The results confirmed the suitability of the rejuvenator for modification of the aged bitumen. © 2016 Elsevier Ltd. All rights reserved.


Biochar as a soil amendment and carbon sink becomes in last period one of the vast, interesting product of slow pyrolysis. Simplest and most used industrial process arrangement is a production of biochar and heat at the same time. Proposed mass and heat balance model consist of heat consumers (heat demand side) and heat generation-supply side. Direct burning of all generated uncondensed volatiles from biomass provides heat. Calculation of the mass and heat balance of both sides reveals the internal distribution of masses and energy inside process streams and units. Thermodynamic calculations verified not only the concept but also numerical range of the results. The comparisons with recent published scientific and vendors data prove its general applicability and reliability. The model opens the possibility for process efficiency innovations. Finally, the model was adapted to give more investors favorable results and support techno-economic assessments entirely. © 2016 Elsevier Ltd.


PubMed | Scientific Research Center Bistra Ptuj
Type: | Journal: Bioresource technology | Year: 2016

Biochar as a soil amendment and carbon sink becomes in last period one of the vast, interesting product of slow pyrolysis. Simplest and most used industrial process arrangement is a production of biochar and heat at the same time. Proposed mass and heat balance model consist of heat consumers (heat demand side) and heat generation-supply side. Direct burning of all generated uncondensed volatiles from biomass provides heat. Calculation of the mass and heat balance of both sides reveals the internal distribution of masses and energy inside process streams and units. Thermodynamic calculations verified not only the concept but also numerical range of the results. The comparisons with recent published scientific and vendors data prove its general applicability and reliability. The model opens the possibility for process efficiency innovations. Finally, the model was adapted to give more investors favorable results and support techno-economic assessments entirely.

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