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Nwachukwu, C. M., Toffolo, A. & Wetterlund, E. (2020). Biomass-based gas use in Swedish iron and steel industry: Supply chain and process integration considerations. Renewable energy, 146, 2797-2811
Åpne denne publikasjonen i ny fane eller vindu >>Biomass-based gas use in Swedish iron and steel industry: Supply chain and process integration considerations
2020 (engelsk)Inngår i: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 146, s. 2797-2811Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Substitution of fossil gaseous fuels with biomass-based gases is of interest to the iron and steel industry due to its role in the mitigation of anthropogenic CO2emissions. In switching from fossil fuels to biomass-based gases, a systems analysis of the full value chain from biomass supply to the production and supply of final gas products becomes crucial. This study uses process and heat integration methods in combination with a supply chain evaluation to analyse full value chains of biomass-based gases for fossil gas replacement within the iron and steel industry. The study is carried out as a specific case study in order to understand the implications of utilizing bio-syngas/bio-SNG as heating fuels in iron- and steel-making, and to provide insights into the most sensitive parameters involved in fuel switching. The results show a significant cost difference in the fuel production of the two gas products owing to higher capital and biomass use in the bio-SNG value chain option. When tested for sensitivity, biomass price, transportation distance, and capital costs show the most impact on fuel production costs across all options studied. Trade-offs associated with process integration, plant localisation, feedstock availability and supply were found to varying extents.

sted, utgiver, år, opplag, sider
Elsevier, 2020
Emneord
biomass supply, integrated production, bio-SNG, bio-syngas, iron and steel industry, system analysis
HSV kategori
Forskningsprogram
Energiteknik
Identifikatorer
urn:nbn:se:ltu:diva-75727 (URN)10.1016/j.renene.2019.08.100 (DOI)000499762300112 ()2-s2.0-85071493628 (Scopus ID)
Merknad

Validerad;2019;Nivå 2;2019-09-03 (johcin)

Tilgjengelig fra: 2019-08-28 Laget: 2019-08-28 Sist oppdatert: 2019-12-20bibliografisk kontrollert
Gojkovic, Z., Lu, Y., Ferro, L., Toffolo, A. & Funk, C. (2020). Modeling biomass production during progressive nitrogen starvation by North Swedish green microalgae. Algal Research, 47, Article ID 101835.
Åpne denne publikasjonen i ny fane eller vindu >>Modeling biomass production during progressive nitrogen starvation by North Swedish green microalgae
Vise andre…
2020 (engelsk)Inngår i: Algal Research, ISSN 2211-9264, Vol. 47, artikkel-id 101835Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Five newly isolated green algal species from Northern Sweden and one culture collection strain were tested for their ability to remove nitrogen and accumulate carbohydrates and neutral lipids (TAGs) under progressive nitrogen starvation. All six microalgal species increased biomass during N starvation, the amount of proteins decreased, and species dependent either TAGs and/or carbohydrates accumulated. Biomass of the algal strains Coelastrella sp. 3-4, Scenedesmus sp. B2-2 and S. obliquus RISE (UTEX 417) had very low final TAG content (≤3.4%) and high carbohydrate content (>41%) at the end of the starvation period. C. astroideum RW10 accumulated 9.2% TAGs and 53.9% carbohydrates during N-starvation; due to its modest growth rate (1.60 g/L and 1.06 1/day) resulting in low final biomass concentration, its cumulativeTAG and carbohydrate productivity were poor (175 mgTAG/system and 1.03 gCARBS/system). C. vulgaris 13-1 preferentially accumulated TAGs (10.3%) over carbohydrates (35%), with low minimal and maximal N quotas (2.27 and 11.6 mM/gDW) in its biomass and a very high growth rate (1.86 1/day) and cumulative TAGs productivity (278 mgTAG/system). Desmodesmus sp. RUC2 had the highest final biomass concentration (3.48 g/L) as well as cumulative TAG and carbohydrate productivity (269 mgTAG/system and 1.79 gCARBS/system). This species had the lowest minimal and maximal N quotas (1.58 and 8.50 mM/gDW) of all tested species, it can produce high amounts of biomass even when the available nitrogen concentration is low.

A Droop's mathematical model with four basic parameters was applied to interpret the experimental data on N assimilation and biomass production under N starvation. The model corresponded well to the experimental data and therefore can successfully be applied to predict biomass production and N assimilation in Nordic algal species.

sted, utgiver, år, opplag, sider
Elsevier, 2020
Emneord
Nitrogen starvation, Green microalgae, Biomass accumulation, TAGs, Carbohydrates
HSV kategori
Forskningsprogram
Energiteknik
Identifikatorer
urn:nbn:se:ltu:diva-77847 (URN)10.1016/j.algal.2020.101835 (DOI)
Merknad

Validerad;2020;Nivå 2;2020-02-25 (alebob)

Tilgjengelig fra: 2020-02-25 Laget: 2020-02-25 Sist oppdatert: 2020-02-25bibliografisk kontrollert
Fischer, R., Elfgren, E. & Toffolo, A. (2020). Towards Optimal Sustainable Energy Systems in Nordic Municipalities. Energies, 13(2), Article ID 290.
Åpne denne publikasjonen i ny fane eller vindu >>Towards Optimal Sustainable Energy Systems in Nordic Municipalities
2020 (engelsk)Inngår i: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 13, nr 2, artikkel-id 290Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Municipal energy systems in the northern regions of Finland, Norway, and Sweden facemultiple challenges: large-scale industries, cold climate, and a high share of electric heatingcharacterize energy consumption and cause significant peak electricity demand. Local authoritiesare committed in contributing to national goals on CO2 emission reductions by improving energyefficiency and investing in local renewable electricity generation, while considering their ownobjectives for economic development, increased energy self-sufficiency, and affordable energy costs.This paper formulates a multi-objective optimization problem about these goals that is solved byinterfacing the energy systems simulation tool EnergyPLAN with a multi-objective evolutionaryalgorithm implemented in Matlab. A sensitivity analysis on some key economic parameters is alsoperformed. In this way, optimal alternatives are identified for the integrated electricity and heatingsectors and valuable insights are offered to decision-makers in local authorities. Piteå (Norrbotten,Sweden) is used as a case study that is representative of Nordic municipalities, and results showthat CO2 emissions can be reduced by 60% without a considerable increase in total costs and thatpeak electricity import can be reduced by a maximum of 38%.

sted, utgiver, år, opplag, sider
MDPI, 2020
Emneord
municipal energy system, multi-objective optimization, renewable energy sources, EnergyPLAN
HSV kategori
Forskningsprogram
Energiteknik
Identifikatorer
urn:nbn:se:ltu:diva-78089 (URN)10.3390/en13020290 (DOI)
Forskningsfinansiär
Interreg Nord, 20200589
Merknad

Validerad;2020;Nivå 2;2020-03-17 (svasva)

Tilgjengelig fra: 2020-03-17 Laget: 2020-03-17 Sist oppdatert: 2020-03-17bibliografisk kontrollert
Sandberg, E., Toffolo, A. & Krook-Riekkola, A. (2019). A bottom-up study of biomass and electricity use in a fossil free Swedish industry. Energy, 167, 1019-1030
Åpne denne publikasjonen i ny fane eller vindu >>A bottom-up study of biomass and electricity use in a fossil free Swedish industry
2019 (engelsk)Inngår i: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 167, s. 1019-1030Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

While previous research has focused on single industrial sectors or specific technologies, this study aims to explore the impacts of various industrial technology options on the use of biomass and electricity in a future fossil free Swedish industry. By building a small optimization model, that decomposes each industrial sector into site categories by type and technology to capture critical synergies among industrial processes. The results show important synergies between electrification, biomass and CCS/U (sequestration of CO2 is required to reach net-zero emissions). Reaching an absolute minimum of biomass use within the industry has a very high cost of electricity due to the extensive use of power-to-gas technologies, and minimising electricity has a high cost of biomass due to extensive use of CHP technologies. Meanwhile, integrated bio-refinery processes are the preferable option when minimising the net input of energy. There is, thus, no singular best technology, instead the system adapts to the given circumstances showing the importance of a detailed bottom-up modelling approach and that the decarbonisation of the industry should not be treated as a site-specific problem, but rather as a system-wide problem to allow for optimal utilisation of process synergies.

sted, utgiver, år, opplag, sider
Elsevier, 2019
Emneord
Industry modelling, Energy-intensive industries, Biomass utilisation, CO2 mitigation, Energy transition, Energy system optimisation
HSV kategori
Forskningsprogram
Energiteknik
Identifikatorer
urn:nbn:se:ltu:diva-71680 (URN)10.1016/j.energy.2018.11.065 (DOI)000456351800084 ()2-s2.0-85059339023 (Scopus ID)
Merknad

Validerad;2018;Nivå 2;2018-12-05 (johcin)

Tilgjengelig fra: 2018-11-20 Laget: 2018-11-20 Sist oppdatert: 2019-11-26bibliografisk kontrollert
Toffolo, A. & Lazzaretto, A. (2019). A practical tool to generate complex energy system configurations based on the synthsep methodology. International Journal of Thermodynamics, 22(1), 45-53
Åpne denne publikasjonen i ny fane eller vindu >>A practical tool to generate complex energy system configurations based on the synthsep methodology
2019 (engelsk)Inngår i: International Journal of Thermodynamics, ISSN 1301-9724, Vol. 22, nr 1, s. 45-53Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Traditional fossil fueled power plants are commonly based on steam Rankine cycle or Brayton Joule cycle. Using water or air as working fluid is obviously the most obvious choice for the wide availability of these substances in nature. However, the scarcity of natural energy sources and the strong need of reducing environmental impact have necessarily drawn the research to new energy systems configurations operating with other working fluids, which are able to recover lower temperature sources, such as Sun or industrial wasted heat. The variety of new working fluids (refrigerants or organic fluids) widens the choice to a variety of configurations that can be tailored to the specific source characteristics and boundary constraints. It is not always easy or even possible to conceive the best configuration for given specifications with the mere experience of a common designer. To design a new system configuration, the designer normally uses some “non-codified rules” deriving from his knowledge of basic thermodynamics and energy engineering. This paper aims instead at showing a practical tool that is based on a new methodology, named SYNTHSEP, to generate new energy system configurations. This methodology starts from the simple thermodynamic cycles operated by a given fluid made up of the four fundamental processes (compression, heating, expansion and cooling) and uses a rigorous set of codified rules to build the final system configuration. The paper presents the basics of the new methodology and how it has been implemented in a practical tool that simply requires the information about the elementary cycles and their shared processes as input data.

sted, utgiver, år, opplag, sider
Yaşar DEMİREL, 2019
Emneord
Optimization, Software tool, Synthesis, System configuration
HSV kategori
Forskningsprogram
Energiteknik
Identifikatorer
urn:nbn:se:ltu:diva-73391 (URN)10.5541/ijot.506382 (DOI)000460141700006 ()2-s2.0-85063282791 (Scopus ID)
Merknad

Validerad;2019;Nivå 2;2019-04-02 (svasva)

Tilgjengelig fra: 2019-04-02 Laget: 2019-04-02 Sist oppdatert: 2019-04-02bibliografisk kontrollert
Mesfun, S., Lundgren, J., Toffolo, A., Lindbergh, G., Lagergren, C. & Engvall, K. (2019). Integration of an electrolysis unit for producer gas conditioning in a bio-synthetic natural gas plant. Journal of energy resources technology, 141(1), Article ID 012002.
Åpne denne publikasjonen i ny fane eller vindu >>Integration of an electrolysis unit for producer gas conditioning in a bio-synthetic natural gas plant
Vise andre…
2019 (engelsk)Inngår i: Journal of energy resources technology, ISSN 0195-0738, E-ISSN 1528-8994, Vol. 141, nr 1, artikkel-id 012002Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Producer gas from biomass gasification contains impurities like tars, particles, alkali salts, and sulfur/nitrogen compounds. As a result, a number of process steps are required to condition the producer gas before utilization as a syngas and further upgrading to final chemicals and fuels. Here, we study the concept of using molten carbonate electrolysis cells (MCEC) both to clean and to condition the composition of a raw syngas stream, from biomass gasification, for further upgrading into synthetic natural gas (SNG). A mathematical MCEC model is used to analyze the impact of operational parameters, such as current density, pressure and temperature, on the quality and amount of syngas produced. Internal rate of return (IRR) is evaluated as an economic indicator of the processes considered. Results indicate that, depending on process configuration, the production of SNG can be boosted by approximately 50-60% without the need of an additional carbon source, i.e., for the same biomass input as in standalone operation of the GoBi-Gas plant. Copyright

sted, utgiver, år, opplag, sider
The American Society of Mechanical Engineers (ASME), 2019
HSV kategori
Forskningsprogram
Energiteknik
Identifikatorer
urn:nbn:se:ltu:diva-70732 (URN)10.1115/1.4040942 (DOI)000452421900004 ()2-s2.0-85052065806 (Scopus ID)
Merknad

Validerad;2018;Nivå 2;2018-09-03 (andbra)

Tilgjengelig fra: 2018-09-03 Laget: 2018-09-03 Sist oppdatert: 2019-02-13bibliografisk kontrollert
Fischer, R., Elfgren, E. & Toffolo, A. (2019). Optimal Sustainable Transport Solutions Integrated into a Nordic Municipal Energy System. In: : . Paper presented at NORPIE 2019 - The Conference on Energy, Power Systems and Power- and Industrial Electronics, Narvik, September 25-27, 2019..
Åpne denne publikasjonen i ny fane eller vindu >>Optimal Sustainable Transport Solutions Integrated into a Nordic Municipal Energy System
2019 (engelsk)Konferansepaper, Publicerat paper (Fagfellevurdert)
Abstract [en]

In Nordic environments the cold climate, large-scale industries, and a high share of electric heating drive energy consumption and create significant peak electricity demand in municipal energy systems. Prospects for decarbonizing the transport sector by electrification escalate these challenges, while availability and sustainability concerns limit biofuel use. Local authorities are committed to contributing to national climate goals, while considering local objectives for economic development, increased energy self-sufficiency and affordable energy costs. This research combines these goals into a multi-objective optimization problem (MOOP), and solves the MOOP by interfacing the energy systems simulation tool EnergyPLAN with a multi-objective evolutionary algorithm (MOEA) implemented in Matlab. In this way, the study generates optimal solutions for integrated electricity, heating and transport sectors and valuable insights are offered to decision makers in local authorities. Piteå (Norrbotten County, Sweden) is a typical Nordic municipality and serves as a case study for this research. Results show that CO2 emissions from the integrated system can be reduced up to 60% without a considerable increase of total annual costs, and that in the same range of emission reductions it is economically more convenient to invest in electric personal vehicles, light trucks and busses.

HSV kategori
Forskningsprogram
Energiteknik; Hållbara transporter (FOI)
Identifikatorer
urn:nbn:se:ltu:diva-77161 (URN)
Konferanse
NORPIE 2019 - The Conference on Energy, Power Systems and Power- and Industrial Electronics, Narvik, September 25-27, 2019.
Tilgjengelig fra: 2020-03-17 Laget: 2020-03-17 Sist oppdatert: 2020-03-17bibliografisk kontrollert
Lazzaretto, A. & Toffolo, A. (2019). Optimum choice of energy system configuration and storages for a proper match between energy conversion and demands. Energies, 12(20), Article ID 3957.
Åpne denne publikasjonen i ny fane eller vindu >>Optimum choice of energy system configuration and storages for a proper match between energy conversion and demands
2019 (engelsk)Inngår i: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 12, nr 20, artikkel-id 3957Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

This Special Issue addresses the general problem of a proper match between the demands of energy users and the units for energy conversion and storage, by means of proper design and operation of the overall energy system configuration. The focus is either on systems including single plants or groups of plants, connected or not to one or more energy distribution networks. In both cases, the optimum design and operation involve decisions about thermodynamic processes, about the type, number, design parameters of components/plants, and storage capacities, and about mutual interconnections and the interconnections with the distribution grids. The problem is very wide, can be tackled with different methodologies and may have several, more or less valuable and complicated solutions. The twelve accepted papers certainly represent a good contribution to perceive its difficulty.

sted, utgiver, år, opplag, sider
MDPI, 2019
Emneord
smart power systems, multi-energy systems, optimization of energy systems design and operation
HSV kategori
Forskningsprogram
Energiteknik
Identifikatorer
urn:nbn:se:ltu:diva-76852 (URN)10.3390/en12203957 (DOI)000498391700152 ()2-s2.0-85074999359 (Scopus ID)
Merknad

Validerad;2019;Nivå 2;2019-11-25 (johcin)

Tilgjengelig fra: 2019-11-25 Laget: 2019-11-25 Sist oppdatert: 2019-12-18bibliografisk kontrollert
Toffolo, A., Rech, S. & Lazzaretto, A. (2018). Generation of Complex Energy Systems by Combination of Elementary Processes. Journal of energy resources technology, 140(11), Article ID 112005.
Åpne denne publikasjonen i ny fane eller vindu >>Generation of Complex Energy Systems by Combination of Elementary Processes
2018 (engelsk)Inngår i: Journal of energy resources technology, ISSN 0195-0738, E-ISSN 1528-8994, Vol. 140, nr 11, artikkel-id 112005Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

The fundamental challenge in the synthesis/design optimization of energy systems is the definition of system configuration and design parameters. The traditional way to operate is to follow the previous experience, starting from the existing design solutions. A more advanced strategy consists in the preliminary identification of a superstructure that should include all the possible solutions to the synthesis/design optimization problem and in the selection of the system configuration starting from this superstructure through a design parameter optimization. This top–down approach cannot guarantee that all possible configurations could be predicted in advance and that all the configurations derived from the superstructure are feasible. To solve the general problem of the synthesis/design of complex energy systems, a new bottom–up methodology has been recently proposed by the authors, based on the original idea that the fundamental nucleus in the construction of any energy system configuration is the elementary thermodynamic cycle, composed only by the compression, heat transfer with hot and cold sources and expansion processes. So, any configuration can be built by generating, according to a rigorous set of rules, all the combinations of the elementary thermodynamic cycles operated by different working fluids that can be identified within the system, and selecting the best resulting configuration through an optimization procedure. In this paper, the main concepts and features of the methodology are deeply investigated to show, through different applications, how an artificial intelligence can generate system configurations of various complexity using preset logical rules without any “ad hoc” expertise.

sted, utgiver, år, opplag, sider
The American Society of Mechanical Engineers (ASME), 2018
HSV kategori
Forskningsprogram
Energiteknik
Identifikatorer
urn:nbn:se:ltu:diva-71419 (URN)10.1115/1.4040194 (DOI)000447273300005 ()2-s2.0-85058262950 (Scopus ID)
Merknad

Validerad;2018;Nivå 2;2018-11-01 (svasva)

Tilgjengelig fra: 2018-11-01 Laget: 2018-11-01 Sist oppdatert: 2019-01-11bibliografisk kontrollert
Nwachukwu, C. M., Toffolo, A., Grip, C.-E., Wang, C. & Wetterlund, E. (2018). Systems analysis of sawmill by-products gasification towards a bio-based steel production. In: José Carlos Teixeira, Ana Cristina Ferreira, Ângela Silva, Senhorinha Teixeira (Ed.), ECOS 2018: Proceedings of the 31st International Conference on Efficiency, Cost, Optimisation, Simulation and Environmental Impact of Energy Systems. Paper presented at 31st International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems (ECOS 2018), Guimarães, Portugal, 17-22 June 2018. Universidade do Minho. Departamento de Engenharia Mecânica Campus Azurém, Guimarães Portugal
Åpne denne publikasjonen i ny fane eller vindu >>Systems analysis of sawmill by-products gasification towards a bio-based steel production
Vise andre…
2018 (engelsk)Inngår i: ECOS 2018: Proceedings of the 31st International Conference on Efficiency, Cost, Optimisation, Simulation and Environmental Impact of Energy Systems / [ed] José Carlos Teixeira, Ana Cristina Ferreira, Ângela Silva, Senhorinha Teixeira, Universidade do Minho. Departamento de Engenharia Mecânica Campus Azurém, Guimarães Portugal , 2018Konferansepaper, Publicerat paper (Fagfellevurdert)
sted, utgiver, år, opplag, sider
Universidade do Minho. Departamento de Engenharia Mecânica Campus Azurém, Guimarães Portugal, 2018
HSV kategori
Forskningsprogram
Energiteknik
Identifikatorer
urn:nbn:se:ltu:diva-69979 (URN)978-972-99596-4-6 (ISBN)
Konferanse
31st International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems (ECOS 2018), Guimarães, Portugal, 17-22 June 2018
Tilgjengelig fra: 2018-06-28 Laget: 2018-06-28 Sist oppdatert: 2018-10-30bibliografisk kontrollert
Organisasjoner
Identifikatorer
ORCID-id: ORCID iD iconorcid.org/0000-0002-4532-4530