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Fischer, R. & Toffolo, A. (2024). Game theory-based analysis of policy instrument consequences on energy system actors in a Nordic municipality. Heliyon, 10(4), Article ID e25822.
Open this publication in new window or tab >>Game theory-based analysis of policy instrument consequences on energy system actors in a Nordic municipality
2024 (English)In: Heliyon, E-ISSN 2405-8440, Vol. 10, no 4, article id e25822Article in journal (Refereed) Published
Abstract [en]

The transition of energy systems requires policy frameworks and instruments to make both energy suppliers and consumers contribute to the common goal of emission reductions and to fairly allocate costs and benefits among market actors and the government. Assuming that market actors – suppliers and consumers adhering to their economic interests – would benefit from cooperating to mitigate emissions, this study applies a game theory-based approach to investigate the interaction between a local electricity supplier and a group of heating consumers not connected to district heating. Selected policy instruments are tested, and their consequences are analyzed in the context of a representative Nordic municipality. The results show that the auction-based Contract for Difference policy instrument is the most suitable one in the studied Nordic context to achieve significant levels of CO2 emissions reduction. It creates a higher level of strategic interaction between the actors, that would be lacking otherwise, under the form of transfer payments from consumers to supplier, and avoids costs to the general taxpayer. While this is sufficient to promote the investments in renewables by the supplier, additional subsidy policies are required to enable the heating consumers to invest in more capital-intensive energy efficiency measures or biomass heating.

Place, publisher, year, edition, pages
Elsevier, 2024
Keywords
Carbon emissions, Energy system optimization, Energy transition, game theory, Heating systems, policy instruments, Renewable energy
National Category
Energy Systems Economics
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-104506 (URN)10.1016/j.heliyon.2024.e25822 (DOI)2-s2.0-85185440071 (Scopus ID)
Funder
Luleå University of Technology
Note

Validerad;2024;Nivå 2;2024-03-07 (hanlid);

Full text license: CC BY

Available from: 2024-03-07 Created: 2024-03-07 Last updated: 2024-03-07Bibliographically approved
Dal Cin, E., Lazzaretto, A. & Toffolo, A. (2023). A novel extension of the SYNTHSEP methodology for the optimal synthesis and design of supercritical CO2 cycles in waste heat recovery applications. Energy Conversion and Management, 276, Article ID 116535.
Open this publication in new window or tab >>A novel extension of the SYNTHSEP methodology for the optimal synthesis and design of supercritical CO2 cycles in waste heat recovery applications
2023 (English)In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 276, article id 116535Article in journal (Refereed) Published
Abstract [en]

The reduction of anthropogenic emissions of greenhouse gases requires decreasing the overall consumption of primary energy. Thus, waste heat recovery at medium-to-high temperature is an opportunity for generating electricity while reducing the need for primary resources. Recently, supercritical carbon dioxide power cycles (S-CO2) are emerging as a promising solution. However, a method lacks to simultaneously optimize their layout and design parameters, without relying on superstructures defined a priori. To this end, this paper suggests a novel extension of the superstructure free SYNTHSEP methodology, a bottom-up approach for the optimal synthesis and design of thermodynamic cycles, to handle also super- and transcritical cycles. An Evolutionary Algorithm combining elementary cycles makes it possible to define optimal S-CO2 configurations without limiting the search space of the optimization problem. The objective consists in finding the S-CO2 topology and design parameters that maximize the mechanical power extractable from waste heat streams in the temperature range from 200 to 700 °C, typical of the industrial sector. Results demonstrate the capability of the method to find optimal cycle layouts for any given waste heat temperature, and to achieve, at the same conditions, cycle efficiencies up to 5 % higher in relative terms than the best ones in the literature.

Place, publisher, year, edition, pages
Elsevier Ltd, 2023
Keywords
Decarbonization, Evolutionary algorithm, Optimization, Supercritical CO2 cycles, SYNTHSEP, Waste heat recovery
National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-94899 (URN)10.1016/j.enconman.2022.116535 (DOI)000917121500001 ()2-s2.0-85143603372 (Scopus ID)
Note

Validerad;2023;Nivå 2;2023-01-12 (sofila)

Available from: 2023-01-12 Created: 2023-01-12 Last updated: 2023-04-21Bibliographically approved
Markeby Ljungqvist, H., Risberg, M., Toffolo, A. & Vesterlund, M. (2023). A realistic view on heat reuse from direct free air-cooled data centres. Energy Conversion and Management: X, 20, Article ID 100473.
Open this publication in new window or tab >>A realistic view on heat reuse from direct free air-cooled data centres
2023 (English)In: Energy Conversion and Management: X, E-ISSN 2590-1745, Vol. 20, article id 100473Article in journal (Refereed) Published
Abstract [en]

This paper examines the opportunities to reuse excess heat from direct free air-cooled data centres without incorporating heat pumps to upgrade the heat. The operation of a data centre in northern Sweden, Luleå, was simulated for a year. It was established that heat losses through the thermal envelope and from the humidification of the cooling airflow influenced the momentary energy reuse factor, iERF, with up to 7%. However, for the annual energy reuse factor, ERF, the heat losses could be neglected since they annually contributed to an error of less than 1%. It was shown that the ideal heat reuse temperature in Luleå was 13, 17, and 18 °C with an exhaust temperature of 30, 40 and 50 °C. The resulting ERF was 0.50, 0.59 and 0.66, meaning that a higher exhaust temperature resulted in potentially higher heat reuse. It could also be seen that raising the exhaust temperature lowered the power usage effectiveness, PUE, due to more efficient cooling. Using heat reuse applications with different heat reuse temperatures closer to the monthly average instead of an ideal heat reuse temperature for the whole year improved the ERF further. The improvement was 11–31% where a lower exhaust temperature meant a higher relative improvement.

Place, publisher, year, edition, pages
Elsevier, 2023
Keywords
Data centre, Energy reuse factor, Excess heat, Heat recovery, Heat reuse, Waste heat
National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-102311 (URN)10.1016/j.ecmx.2023.100473 (DOI)001097565900001 ()2-s2.0-85174895802 (Scopus ID)
Funder
Swedish Energy Agency, 43090-2EU, Horizon 2020, 768875
Note

Validerad;2023;Nivå 2;2023-11-15 (hanlid);

Full text license: CC BY

Available from: 2023-11-06 Created: 2023-11-06 Last updated: 2024-03-07Bibliographically approved
Mesfun, S., Engvall, K. & Toffolo, A. (2022). Electrolysis Assisted Biomass Gasification for Liquid Fuels Production. Frontiers in Energy Research, 10, Article ID 799553.
Open this publication in new window or tab >>Electrolysis Assisted Biomass Gasification for Liquid Fuels Production
2022 (English)In: Frontiers in Energy Research, E-ISSN 2296-598X, Vol. 10, article id 799553Article in journal (Refereed) Published
Abstract [en]

Gasification is a promising pathway for converting biomass residues into renewable transportation fuels and chemicals needed to comply with the ambitious Swedish environmental targets. The paper investigates the integration of a molten carbonate electrolysis cell (MCEC) in biofuel production pathway from sawmill byproducts, to improve the performance of gas cleaning and conditioning steps prior to the final conversion of syngas into liquid biofuels. The energy, material, and economic performance of process configurations with different gasification technologies are simulated and compared. The results provide relevant information to develop the engineering of gas-to-liquid transportation fuels utilizing renewable electricity. The MCEC replaces the water-gas shift step of a conventional syngas conditioning process and enables increased product throughput by as much as 15%–31%. Depending on the process configuration and steam-methane reforming technology, biofuels can be produced to the cost range 140–155 €/MWh in the short-term.

Place, publisher, year, edition, pages
Frontiers Media S.A., 2022
Keywords
biomass gasification, molten carbonate electrolysis cell, biofuels, gas conditioning, forest industry byproducts, technoeconomic, biomass to liquid
National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-92083 (URN)10.3389/fenrg.2022.799553 (DOI)000824162900001 ()2-s2.0-85133904573 (Scopus ID)
Projects
Renewable transportation fuels and systems (Förnybara drivmedel och system), project no. 48371–1
Funder
The Swedish Knowledge Centre for Renewable Transportation Fuels (f3)Bio4EnergySwedish Energy Agency
Note

Validerad;2022;Nivå 2;2022-07-06 (sofila)

Available from: 2022-07-06 Created: 2022-07-06 Last updated: 2022-07-28Bibliographically approved
Fischer, R. & Toffolo, A. (2022). Is total system cost minimization fair to all the actors of an energy system? Not according to game theory. Energy, 239(Part C), Article ID 122253.
Open this publication in new window or tab >>Is total system cost minimization fair to all the actors of an energy system? Not according to game theory
2022 (English)In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 239, no Part C, article id 122253Article in journal (Refereed) Published
Abstract [en]

A common approach to energy system optimization is to minimize overall costs at system level, regardless of the actors actually bearing those costs. This paper presents an approach inspired by Nash game theory concepts, in which the actors involved in an energy system determine their optimal strategies according to their own economic interests (profit functions) in a non-cooperative or in a cooperative way. A simple case study, considering an electric utility and individual heating consumers in the municipal energy system of a small town in northern Sweden, shows the differences between the two approaches. The game theory approach is able to represent more realistic interactions among the actors of an energy system, fair in fulfilling their conflicting economic interests, and, therefore, a more suitable tool for decision makers evaluating the impacts of policy instruments.

Place, publisher, year, edition, pages
Elsevier, 2022
Keywords
Energy system optimization, Game theory, Profit functions, Nash equilibrium, Nash bargaining solution, Policy instruments
National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-87437 (URN)10.1016/j.energy.2021.122253 (DOI)000711163200014 ()2-s2.0-85116893248 (Scopus ID)
Note

Validerad;2021;Nivå 2;2021-10-14 (beamah)

Available from: 2021-10-08 Created: 2021-10-08 Last updated: 2021-11-08Bibliographically approved
Mirzaei, N., Toffolo, A., Engvall, K. & Kantarelis, E. (2021). Flexible production of liquid biofuels via thermochemical treatment of biomass and olefins oligomerization: A process study. Chemical Engineering Transactions, 86, 187-192
Open this publication in new window or tab >>Flexible production of liquid biofuels via thermochemical treatment of biomass and olefins oligomerization: A process study
2021 (English)In: Chemical Engineering Transactions, ISSN 1974-9791, E-ISSN 2283-9216, Vol. 86, p. 187-192Article in journal (Refereed) Published
Abstract [en]

The use of residual biomass streams for production of liquid fuels will help in achieving the goal of renewable transportation fuels and sustainable society. Hence, efficient, and reliable processes offering a flexible product distribution proven at commercial scale are required. This study explores the technical feasibility of producing gasoline and diesel range hydrocarbons from thermochemical processing of biomass via the production of light olefins (C2-C4) and their subsequent oligomerization through mathematical modelling and simulation using MATLAB software. Different biomass processing scenarios were considered, including a standalone biomass gasification plant and integrated biomass pyrolysis- char gasification (O2- or air-blown) process. Process analysis indicated that the integrated plant offers 10-11% higher carbon efficiency. The processing step with the highest carbon penalty for all the cases is the syngas composition tailoring via water-gas shift reaction.

Place, publisher, year, edition, pages
Italian Association of Chemical Engineering - AIDIC, 2021
National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-86525 (URN)10.3303/CET2186032 (DOI)2-s2.0-85109755837 (Scopus ID)
Funder
Swedish Energy AgencyThe Swedish Knowledge Centre for Renewable Transportation Fuels (f3)
Note

Validerad;2021;Nivå 1;2021-08-13 (alebob);

ISBN för värdpublikation: 978-88-95608-84-6

Available from: 2021-08-05 Created: 2021-08-05 Last updated: 2021-08-13Bibliographically approved
Lage, S., Toffolo, A. & Gentili, F. G. (2021). Microalgal growth, nitrogen uptake and storage, and dissolved oxygen production in a polyculture based-open pond fed with municipal wastewater in northern Sweden. Chemosphere, 276, Article ID 130122.
Open this publication in new window or tab >>Microalgal growth, nitrogen uptake and storage, and dissolved oxygen production in a polyculture based-open pond fed with municipal wastewater in northern Sweden
2021 (English)In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 276, article id 130122Article in journal (Refereed) Published
Abstract [en]

Microalgal-based wastewater treatment and CO2 sequestration from flue gases with subsequent biomass production represent a low-cost, eco-friendly, and effective procedure of removing nutrients and other pollutants from wastewater and assists in the decrease of greenhouse gas emissions. Thus, it supports a circular economy model. This is based on the ability of microalgae to utilise inorganic nutrients, mainly nitrogen and phosphorous, as well as organic and inorganic carbon, for their growth, and simultaneously reduce these substances in the water. However, the production of microalgae biomass under outdoor cultivation is dependent on several abiotic and biotic factors, which impact its profitability and sustainability. Thus, this study's goal was to evaluate the factors affecting the production of microalgae biomass on pilot-scale open raceway ponds under Northern Sweden’s summer conditions with the help of a mathematical model. For this purpose, a microalgae consortium and a monoculture of Chlorella vulgaris were used to inoculate outdoor open raceway ponds. In line with the literature, higher biomass concentrations and nutrient removals were observed in ponds inoculated with the microalgae consortium. Our model, based on Droop’s concept of macronutrient quotas inside the cell, corresponded well to the experimental data and, thus, can successfully be applied to predict biomass production, nitrogen uptake and storage, and dissolved oxygen production in microalgae consortia.

Place, publisher, year, edition, pages
Elsevier, 2021
Keywords
Microalgae, nutrients removal, nitrogen, phosphorous, flue gases, wastewater
National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-83180 (URN)10.1016/j.chemosphere.2021.130122 (DOI)000648339700036 ()33690042 (PubMedID)2-s2.0-85101978730 (Scopus ID)
Funder
Swedish Research Council Formas, 942-2015-92Bio4EnergyThe Kempe Foundations, JCK-1609
Note

Validerad;2021;Nivå 2;2021-03-15 (alebob);

Finansiär: EU Interreg Botnia-Atlantica

Available from: 2021-03-05 Created: 2021-03-05 Last updated: 2021-06-07Bibliographically approved
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
Open this publication in new window or tab >>Biomass-based gas use in Swedish iron and steel industry: Supply chain and process integration considerations
2020 (English)In: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 146, p. 2797-2811Article in journal (Refereed) 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.

Place, publisher, year, edition, pages
Elsevier, 2020
Keywords
biomass supply, integrated production, bio-SNG, bio-syngas, iron and steel industry, system analysis
National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-75727 (URN)10.1016/j.renene.2019.08.100 (DOI)000499762300112 ()2-s2.0-85071493628 (Scopus ID)
Note

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

Available from: 2019-08-28 Created: 2019-08-28 Last updated: 2021-02-18Bibliographically approved
Nwachukwu, C. M., Wang, C., Toffolo, A. & Wetterlund, E. (2020). Impact of carbon prices on fuel switching in the iron and steel industry. In: Therese Laitinen Lindström, Ylva Blume (Ed.), Industrial Efficiency 2020 - Decarbonise Industry!: eceee Industrial Summer Study proceedings. Paper presented at ecee 2020 Industrial Summer Study, 14-17 September, 2020, Digital event. ecee, Article ID 6-045-20.
Open this publication in new window or tab >>Impact of carbon prices on fuel switching in the iron and steel industry
2020 (English)In: Industrial Efficiency 2020 - Decarbonise Industry!: eceee Industrial Summer Study proceedings / [ed] Therese Laitinen Lindström, Ylva Blume, ecee , 2020, article id 6-045-20Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

Fuel switching in the iron and steel industry, using forest biomass, is viewed as a short to medium term solution to reducing the CO2 emissions from the steel sector. Implementing biomass as an alternative fuel or reductant in different process stages during steelmaking is met with certain challenges such as technical restrictions regarding substitution potentials and feasibility limits. Judging by the energy intensity of producing steel, the forest biomass requirement is expectedly large and this in itself results in a competition with other biomass users. More so, as a limited and spatially variable resource, the options for localising biomass conversion technologies as well as supplying both the raw material and final product furthers the complexity of biomass utilisation in iron and steel production.

In this study, a spatially explicit techno-economic modelling approach is employed as a tool for optimising the value chains of upgraded biomass products towards the goal of achieving decreased CO2 emissions from different process stages in the steel industry. The impact of carbon taxes on the fossil energy replacement with the upgraded bio-products is evaluated. The scope of the work is limited to the iron and steel sector in Sweden, where ambitious national climate goals for net-zero greenhouse gas emissions are targeted by the year 2045.

Results from the optimization model show the plant localisations for biomass conversion, and a roadmap for addressing the challenges already identified is presented based on the demonstrated relationship between carbon taxation levels and share of fossil energy substitution. The impact of biomass supply for metallurgical purposes is briefly discussed against the backdrop of the existing forest industries.

Place, publisher, year, edition, pages
ecee, 2020
Series
eceee Industrial Summer Study proceedings, ISSN 2001-7979, E-ISSN 2001-7987
National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-81002 (URN)
Conference
ecee 2020 Industrial Summer Study, 14-17 September, 2020, Digital event
Note

ISBN för värdpublikation: 978-91-983878-6-5, 978-91-983878-7-2

Available from: 2020-10-01 Created: 2020-10-01 Last updated: 2020-12-01Bibliographically approved
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.
Open this publication in new window or tab >>Modeling biomass production during progressive nitrogen starvation by North Swedish green microalgae
Show others...
2020 (English)In: Algal Research, ISSN 2211-9264, Vol. 47, article id 101835Article in journal (Refereed) 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.

Place, publisher, year, edition, pages
Elsevier, 2020
Keywords
Nitrogen starvation, Green microalgae, Biomass accumulation, TAGs, Carbohydrates
National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-77847 (URN)10.1016/j.algal.2020.101835 (DOI)000572122100011 ()2-s2.0-85079686452 (Scopus ID)
Note

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

Available from: 2020-02-25 Created: 2020-02-25 Last updated: 2020-10-12Bibliographically approved
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-4532-4530

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