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  • 1.
    Ahlström, Johan
    et al.
    Chalmers University of Technology, Sweden.
    Pettersson, Karin
    RISE - Research Institutes of Sweden, Built Environment, Energy and Circular Economy. Chalmers University of Technology, Sweden.
    Wetterlund, Elisabeth
    Luleå University of Technology, Sweden.
    Harvey, Simon
    Chalmers University of Technology, Sweden.
    Value chains for integrated production of liquefied bio-SNG at sawmill sites – Techno-economic and carbon footprint evaluation2017In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 206, p. 1590-1608Article in journal (Refereed)
    Abstract [en]

    Industry's increasing demand for liquefied natural gas could be met in the future by liquefied methane produced from biomass feedstock (LBG - liquefied biogas). This study presents results from an investigation of value chains for integrated production of LBG at a generic sawmill site, based on gasification of sawmill waste streams and forest residues. The objective was to investigate the cost for, as well as the carbon footprint reduction associated with, production and use of LBG as a fuel. Five different LBG plant sizes were investigated in combination with three different sawmill sizes. The resulting cases differ regarding biomass feedstock composition, biomass transportation distances, LBG plant sizes, how efficiently the excess heat from the LBG plant is used, and LBG distribution distances. Pinch technology was used to quantify the heat integration opportunities and to design the process steam network. The results show that efficient use of energy within the integrated process has the largest impact on the performance of the value chain in terms of carbon footprint. The fuel production cost are mainly determined by the investment cost of the plant, as well as feedstock transportation costs, which mainly affects larger plants. Production costs are shown to range from 68 to 156 EUR/MW hfuel and the carbon footprint ranges from 175 to 250 kg GHG-eq/MW hnet biomass assuming that the product is used to substitute fossil LNG fuel. The results indicate that process integration of an indirect biomass gasifier for LBG production is an effective way for a sawmill to utilize its by-products. Integration of this type of biorefinery can be done in such a way that the plant can still cover its heating needs whilst expanding its product portfolio in a competitive way, both from a carbon footprint and cost perspective. The results also indicate that the gains associated with efficient heat integration are important to achieve an efficient value chain.

  • 2.
    Bach-Oller, Albert
    et al.
    Luleå University of Technology, Sweden.
    Furusjö, Erik
    RISE - Research Institutes of Sweden, Bioeconomy, Biorefinery and Energy. Luleå University of Technology, Sweden.
    Umeki, Kentaro
    Luleå University of Technology, Sweden.
    On the role of potassium as a tar and soot inhibitor in biomass gasification2019In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 254, article id 113488Article in journal (Refereed)
    Abstract [en]

    The work investigates in a drop tube furnace the effect of potassium on carbon conversion for three different types of fuels: an ash lean stemwood, a calcium-rich bark and a silicon-rich straw. The study focuses on an optimal method for impregnating the biomass with potassium. The experiments are conducted for 3 different impregnation methods; wet impregnation, spray impregnation, and dry mixing to investigate different levels of contact between the fuel and the potassium. Potassium is found to catalyse both homogenous and heterogeneous reactions. All the impregnation methods showed a significant effect of potassium on heterogeneous reactions (char conversion). The fact that dry mixing of potassium in the biomass shows an effect reveals the existence of a gas-induced mechanism that supply and distributes potassium on the char particles. Concerning the effect of potassium on homogenous reactions, it is found that potassium in the gas phase leads to much lower yields of C2 hydrocarbons, heavy tars and soot. The results indicate that potassium reduces the likelihood of light aromatic to progress toward heavier polyaromatic hydrocarbons clusters, thereby inhibiting the formation of soot-like material. A moderate interaction between the added potassium and the inherent ash forming elements is also observed: Potassium has a smaller effect when the fuel is naturally rich in silicon. The combined results are of interest for the design of a gasification process that incorporates recirculation of naturally occurring potassium to improve entrained flow gasification of biomass. 

  • 3.
    Benavente, Fabian
    et al.
    KTH Royal Institute of Technology, Sweden.
    Lundblad, Anders Olof
    RISE - Research Institutes of Sweden, Safety and Transport, Electronics.
    Campana, Pietro
    Mälardalen University, Sweden.
    Zhang, Yang
    KTH Royal Institute of Technology, Sweden.
    Cabrera, Saul
    UMSA Universidad Mayor de San Andrés, Bolivia.
    Lindbergh, Göran
    KTH Royal Institute of Technology, Sweden.
    Photovoltaic/battery system sizing for rural electrification in Bolivia: Considering the suppressed demand effect2019In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 235, p. 519-528Article in journal (Refereed)
    Abstract [en]

    Rural electrification programs usually do not consider the impact that the increment of demand has on the reliability of off-grid photovoltaic (PV)/battery systems. Based on meteorological data and electricity consumption profiles from the highlands of Bolivian Altiplano, this paper presents a modelling and simulation framework for analysing the performance and reliability of such systems. Reliability, as loss of power supply probability (LPSP), and cost were calculated using simulated PV power output and battery state of charge profiles. The effect of increasing the suppressed demand (SD) by 20% and 50% was studied to determine how reliable and resilient the system designs are. Simulations were performed for three rural application scenarios: a household, a school, and a health centre. Results for the household and school scenarios indicate that, to overcome the SD effect, it is more cost-effective to increase the PV power rather than to increase the battery capacity. However, with an increased PV-size, the battery ageing rate would be higher since the cycles are performed at high state of charge (SOC). For the health centre application, on the other hand, an increase in battery capacity prevents the risk of electricity blackouts while increasing the energy reliability of the system. These results provide important insights for the application design of off-grid PV-battery systems in rural electrification projects, enabling a more efficient and reliable source of electricity.

  • 4.
    Carvalho, Lara
    et al.
    Luleå University of Technology, Sweden.
    Lundgren, Joakim
    Luleå University of Technology, Sweden;IIASA International Institute for Applied Systems Analysis, Austria.
    Wetterlund, Elisabeth
    Luleå University of Technology, Sweden;IIASA International Institute for Applied Systems Analysis, Austria.
    Wolf, Jens
    RISE - Research Institutes of Sweden, Bioeconomy, Biorefinery and Energy.
    Furusjö, Erik
    Luleå University of Technology, Sweden; IVL Swedish Environmental Institute, Sweden.
    Methanol production via black liquor co-gasification with expanded raw material base – Techno-economic assessment2018In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 225, p. 570-584Article in journal (Refereed)
    Abstract [en]

    Entrained flow gasification of black liquor combined with downstream-gas-derived synthesis of biofuels in Kraft pulp mills has shown advantages regarding energy efficiency and economic performance when compared to combustion in a recovery boiler. To further increase the operation flexibility and the profitability of the biofuel plant while at the same time increase biofuel production, black liquor can be co-gasified with a secondary feedstock (blend-in feedstock). This work has evaluated the prospects of producing biofuels via co-gasification of black liquor and different blend-in feedstocks (crude glycerol, fermentation residues, pyrolysis liquids) at different blend ratios. Process modelling tools were used, in combination with techno-economic assessment methods. Two methanol grades, crude and grade AA methanol, were investigated. The results showed that the co-gasification concepts resulted in significant increases in methanol production volumes, as well as in improved conversion efficiencies, when compared with black liquor gasification; 5–11 and 4–10 percentage point in terms of cold gas efficiency and methanol conversion efficiency, respectively. The economic analysis showed that required methanol selling prices ranging from 55 to 101 €/MWh for crude methanol and 58–104 €/MWh for grade AA methanol were obtained for an IRR of 15%. Blend-in led to positive economies-of-scale effects and subsequently decreased required methanol selling prices, in particular for low cost blend-in feedstocks (prices below approximately 20 €/MWh). The co-gasification concepts showed economic competitiveness to other biofuel production routes. When compared with fossil fuels, the resulting crude methanol selling prices were above maritime gas oil prices. Nonetheless, for fossil derived methanol prices higher than 80 €/MWh, crude methanol from co-gasification could be an economically competitive option. Grade AA methanol could also compete with taxed gasoline. Crude glycerol turned out as the most attractive blend-in feedstock, from an economic perspective. When mixed with black liquor in a ratio of 50/50, grade AA methanol could even be cost competitive with untaxed gasoline.

  • 5.
    de Jong, Sierk
    et al.
    Utrecht University, The Netherlands.
    Hoefnagels, Ric
    Utrecht University, The Netherlands.
    Wetterlund, Elisabeth
    Luleå University of Technology, Sweden; IIASA International Institute for Applied Systems Analysis, Austria.
    Pettersson, Karin
    RISE - Research Institutes of Sweden, Built Environment, Energy and Circular Economy. Chalmers University of Technology, Sweden.
    Faaij, Andre
    University of Groningen, The Netherlands.
    Junginger, Martin
    Utrecht University, The Netherlands.
    Cost optimization of biofuel production – The impact of scale, integration, transport and supply chain configurations2017In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 195, p. 1055-1070Article in journal (Refereed)
    Abstract [en]

    This study uses a geographically-explicit cost optimization model to analyze the impact of and interrelation between four cost reduction strategies for biofuel production: economies of scale, intermodal transport, integration with existing industries, and distributed supply chain configurations (i.e. supply chains with an intermediate pre-treatment step to reduce biomass transport cost). The model assessed biofuel production levels ranging from 1 to 150 PJ a−1 in the context of the existing Swedish forest industry. Biofuel was produced from forestry biomass using hydrothermal liquefaction and hydroprocessing. Simultaneous implementation of all cost reduction strategies yielded minimum biofuel production costs of 18.1–18.2 € GJ−1 at biofuel production levels between 10 and 75 PJ a−1. Limiting the economies of scale was shown to cause the largest cost increase (+0–12%, increasing with biofuel production level), followed by disabling integration benefits (+1–10%, decreasing with biofuel production level) and allowing unimodal truck transport only (+0–6%, increasing with biofuel production level). Distributed supply chain configurations were introduced once biomass supply became increasingly dispersed, but did not provide a significant cost benefit (<1%). Disabling the benefits of integration favors large-scale centralized production, while intermodal transport networks positively affect the benefits of economies of scale. As biofuel production costs still exceeds the price of fossil transport fuels in Sweden after implementation of all cost reduction strategies, policy support and stimulation of further technological learning remains essential to achieve cost parity with fossil fuels for this feedstock/technology combination in this spatiotemporal context. © 2017 The Authors

  • 6.
    Hennessy, Jay
    et al.
    RISE - Research Institutes of Sweden, Built Environment, Energy and Circular Economy. Mälardalen University, Sweden.
    Li, Hailong
    Mälardalen University, Sweden.
    Wallin, Fredrik
    Mälardalen University, Sweden.
    Thorin, Eva
    Mälardalen University, Sweden.
    Towards smart thermal grids: Techno-economic feasibility of commercial heat-to-power technologies for district heating2018In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 228, p. 766-776Article in journal (Refereed)
    Abstract [en]

    Recent improvements in low-temperature heat-to-power (LTHtP) technologies have led to an increase in efficiency at lower temperatures and lower cost. LTHtP has so far not been used in district heating. The aim of the study is to establish under what conditions the use of existing LTHtP technology is technically and economically feasible using a district heating system as the heat source. The organic Rankine cycle (ORC) is identified as the most interesting LTHtP technology, due to its high relative efficiency and the commercial availability of devices operating at temperatures in the district heating operating range. The levelised cost of electricity of several ORC devices is calculated for temperatures found in district heating, assuming a zero cost of heat. A case study from Sweden is used to calculate the levelised cost of electricity, the net present value and payback period, based on income from the electricity produced, excluding taxes. Hourly spot market electricity prices from 2017 are used, as well as forecast scenarios for 2020, 2030 and 2040. A sensitivity study tests the importance of electricity price, cost of heat and capital/installation cost. Based on the case study, the best levelised cost of electricity achieved was 26.5 EUR/MWh, with a payback period greater than 30 years. Under current Swedish market conditions, the ORC does not appear to be economically feasible for use in district heating, but the net present value and payback period may be significantly more attractive under other countries’ market conditions or with reduced capital costs. For a positive net present value in the Swedish market the capital cost should be reduced to 1.7 EUR/W installed, or the average electricity price should be at least 35.2 EUR/MWh, if the cost of heat is zero. The cost of heat is an important factor in these calculations and should be developed further in future work.

  • 7. Hu, X
    et al.
    Murgovski, N
    Johannesson Mårdh, L
    RISE, Swedish ICT, Viktoria.
    Egardt, B
    Energy Efficiency Analysis of a Series Plug-in Hybrid Electric Bus with Different Energy Management Strategies Battery Sizes2013In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 111, p. 1001-Article in journal (Refereed)
    Abstract [en]

    This paper is concerned with the tank-to-wheel (TTW) analysis of a series plug-in hybrid_x000D_ electric bus operating in Gothenburg, Sweden. The bus line the powertrain model are described._x000D_ The definition the calculation method of the recuperation fuel-to-traction efficiencies are_x000D_ delineated for evaluating the TTW energy conversion. The two efficiencies are quantified and_x000D_ compared for two optimization-based energy management strategies, in which convex modeling and_x000D_ optimization are used. The impact of downsizing the battery on the two efficiencies is also investigated._x000D_

  • 8.
    Jelica, Darijan
    et al.
    RISE - Research Institutes of Sweden, ICT, Viktoria.
    Taljegard, M.
    Chalmers University of Technology, Sweden.
    Thorson, L.
    Chalmers University of Technology, Sweden.
    Johnsson, F.
    Chalmers University of Technology, Sweden.
    Hourly electricity demand from an electric road system – A Swedish case study2018In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 228, p. 141-148Article in journal (Refereed)
    Abstract [en]

    This study investigates the hourly electricity demand related to implementing an electric road system (ERS) on five Swedish roads with the highest traffic flows that connect the three largest cities in Sweden. The study also compares the energy demands and the CO2 mitigation potentials of the ERS with the use of carbon-based fuels to obtain the same transportation work, and extrapolates the results to all Swedish European- and National- (E- and N) roads. The hourly electricity demand along the roads are derived by linking 12 available measurement points for hourly road traffic volumes with 12,553 measurement points for the average daily traffic flows along the roads. The results show that applying an ERS to the five Swedish roads with the highest traffic flows can reduce by ∼20% the levels of CO2 emissions from the road transport sector, while increasing by less than 4% the hourly electricity demand on the peak dimensioning hour. Extending the ERS to all E- and N-roads would electrify almost half of the vehicle kilometers driven annually in Sweden, while increasing the load of the hourly peak electricity demand by only ∼10% on average.

  • 9.
    Ji, X.
    et al.
    Luleå University of Technology.
    Lundgren, J.
    Luleå University of Technology.
    Wang, Chuan
    RISE, Swerea, Swerea MEFOS.
    Dahl, J.
    Luleå University of Technology.
    Grip, C.-E.
    Luleå University of Technology.
    Simulation and energy optimization of a pulp and paper mill - Evaporation plant and digester2012In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 97, p. 30-37Article in journal (Refereed)
    Abstract [en]

    A detailed mathematical process integration model of a pulp and paper mill in the Northern Sweden has been developed. The main objective of this work has been set to describe the practical development of the model with particular emphasis on the development of the digester and evaporation plant sub-models. Actual plant measurements have been used to validate the model. By implementing the sub-models into the complete plant model, the influence of different operation parameters on the overall plant performance has been investigated. Furthermore, introductory studies with the main objective to minimize the plant energy cost have been carried out. © 2012 Elsevier Ltd.

  • 10.
    Johansson, Tim
    et al.
    Luleå University of Technology, Sweden.
    Olofsson, Thomas
    Luleå University of Technology, Sweden.
    Mangold, Mikael
    RISE - Research Institutes of Sweden, Built Environment, Energy and Circular Economy.
    Development of an energy atlas for renovation of the multifamily building stock in Sweden2017In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 203, p. 723-736Article in journal (Refereed)
    Abstract [en]

    Many studies have highlighted the importance of retrofitting to mitigate the energy use of building stocks. An important step in the development of renovation strategy and energy conservation advising is to gather information of the energy performance of the existing buildings. However, renovation strategies must also consider the socio-economic challenges associated with the cost of energy retrofitting. This paper describes the development of an energy atlas of the multifamily building stock in Sweden for visualizing and analyzing energy use and renovation needs. The atlas has been developed using Extract Transform and Load technology (ETL) to aggregate information on the energy performance, building ownership, renovation status, and socio-economic status of inhabitants from various data sources. The atlas can visualize the energy use and renovation status of multifamily buildings in 2D maps and 3D models, displaying data for either individual buildings or aggregated data on spatial scales ranging from 250 × 250 m squares through district and municipality to county areas. A demonstration of its use on national and city scales indicates that energy retrofits of multifamily buildings reaching a service life of 50 years can reduce the energy use of the existing building stock by up to 50% relative to 1990. However, costs associated with renovation and energy retrofits of multifamily buildings can be problematic, especially in economically weak suburbs. A good understanding of past and future renovation needs and socio-economic consequences is important in the development of a sustainable national renovation strategy. © 2017

  • 11.
    Lundblad, Anders Olof
    KTH Royal Institute of Technology, Sweden; Mälardalen University, Sweden.
    Comparative study of hydrogen storage and battery storage in grid connected photovoltaic system: Storage sizing and rule-based operation.2017In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 201, p. 397-411Article in journal (Refereed)
  • 12.
    Lundblad, Anders Olof
    Mälardalen University, Sweden; KTH Royal Institute of Technology, Sweden.
    Optimization of a residential district with special consideration on energy and water reliability2017In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 194, p. 751-764Article in journal (Other academic)
  • 13.
    Lundgren, J.
    et al.
    Luleå University of Technology, Sweden.
    Ekbom, T.
    Grontmij AB.
    Hulteberg, C.
    Nordlight, Sweden.
    Larsson, Mikael
    RISE - Research Institutes of Sweden, Materials and Production, Swerea MEFOS.
    Grip, Carl Erik
    Luleå University of Technology, Sweden.
    Nilsson, L.
    SSAB EMEA, Sweden.
    Tunå, P.
    Lund University, Sweden.
    Methanol production from steel-work off-gases and biomass based synthesis gas2013In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 112, p. 431-439Article in journal (Refereed)
    Abstract [en]

    Off-gases generated during steelmaking are to a large extent used as fuels in process units within the plant. The surplus gases are commonly supplied to a plant for combined heat and power production. The main objective of this study has been to techno-economically investigate the feasibility of an innovative way of producing methanol from these off-gases, thereby upgrading the economic value of the gases. Cases analyzed have included both off-gases only and mixes with synthesis gas, based on 300MWth of biomass. The SSAB steel plant in the town of Luleå, Sweden has been used as a basis. The studied biomass gasification technology is based on a fluidized-bed gasification technology, where the production capacity is determined from case to case coupled to the heat production required to satisfy the local district heating demand. Critical factors are the integration of the gases with availability to the synthesis unit, to balance the steam system of the biorefinery and to meet the district heat demand of Luleå. The annual production potential of methanol, the overall energy efficiency, the methanol production cost and the environmental effect have been assessed for each case. Depending on case, in the range of 102,000-287,000ton of methanol can be produced per year at production costs in the range of 0.80-1.1EUR per liter petrol equivalent at assumed conditions. The overall energy efficiency of the plant increases in all the cases, up to nearly 14%-units on an annual average, due to a more effective utilization of the off-gases. The main conclusion is that integrating methanol production in a steel plant can be made economically feasible and may result in environmental benefits as well as energy efficiency improvements. © 2013 Elsevier Ltd.

  • 14.
    Pedersen, Thomas Helmer
    et al.
    Aalborg University, Denmark.
    Jensen, Claus Uhrenholt
    Steeper Energy ApS, Denmark.
    Sandström, Linda
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Rosendahl, Lasse Aistrup
    Aalborg University, Denmark.
    Full characterization of compounds obtained from fractional distillation and upgrading of a HTL biocrude2017In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 202, p. 408-419Article in journal (Refereed)
    Abstract [en]

    Biocrude from hydrothermal liquefaction of biomass provides a sustainable source from which to produce chemicals and fuels. However, just as for fossil crude, the chemical complexity of the biocrude impedes the characterization and hence identification of market potentials for both biocrude and individual fractions. Here, we reveal how fractional distillation of a biocrude can leverage biocrude characterization beyond state-of-the-art and uncover the full biocrude potential. By distillation combined with detailed individual analysis of the distillate fractions and distillation residue, more than 85% of the total biocrude composition is determined. It is demonstrated that a total mass fraction of 48.2% of the biocrude is volatile below 350 °C, comprising mainly value-added marketable ketones, oxygenated aromatics and prospective liquid fuel candidates, which are easily fractionated according to boiling points. Novel, high resolution pyr-GCxGC-MS analysis of the residue indicates a high molecular weight aromatic structure, valuable for bio-materials production or for further processing into fuels. The distillate fractions are mildly hydrotreated to show the fuel and chemical precursor potential of the volatile components. This results in the formation of mainly hydrocarbons and added-value phenolics. This work takes a significant step by going beyond the biocrude as an intermediate bulk energy product and addressing actual applications and pathways to these.

  • 15.
    Pettersson, Karin
    et al.
    Chalmers University of Technology, Sweden.
    Wetterlund, Elisabeth
    Luleå University of Technology, Sweden.
    Athanassiadis, Dimitris
    SLU Swedish University of Agricultural Sciences, Sweden.
    Lundmark, Robert
    Luleå University of Technology, Sweden.
    Ehn, Christian
    RISE, Innventia.
    Lundgren, Joakim
    Luleå University of Technology, Sweden.
    Berglin, Niklas
    RISE, Innventia.
    Integration of next-generation biofuel production in the Swedish forest industry - A geographically explicit approach2015In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 154, p. 317-332Article in journal (Refereed)
    Abstract [en]

    The geographic locations of biofuel production facilities should be strategically chosen in order to minimise the total cost of using biofuels. Proximity to biomass resources, possibilities for integration, and distance to biofuel users are aspects that need to be considered. In this paper, the geographically explicit optimisation model BeWhere Sweden was used to investigate the future production of next-generation biofuels from forest biomass in Sweden. A focus was placed on the integration of biofuel production with the existing forest industry, as well as on how different parameters affect biofuel production costs, the choice of technologies and biofuels, and the localisation of new biofuel plants. Six examples of different biofuel routes were considered. A methodology was developed considering detailed, site-specific conditions for potential host industries. The results show that the cost of biomass and the biofuel plant capital cost generally dominate the biofuel cost, but the cost for biomass transportation and biofuel distribution can also have a significant impact. DME produced via black liquor gasification (naturally integrated with chemical pulp mills) and SNG produced via solid biomass gasification (mainly integrated with sawmills), dominate the solutions. The distribution of these technology cases varies depending on a number of parameters, including criteria for sizing biofuel plants, the electricity price, the biofuel distribution cost and the cost of biomass, and is sensitive to changes in these parameters. Generally, plants with low specific investment costs (i.e., high biofuel production) and/or plants with low specific biomass transportation costs occur most frequently in the solutions. Because these properties often vary significantly among biofuel production facilities at different host industry sites of the same type, the results show the advantage of including site-specific data in this type of model.

  • 16.
    Sandberg, J.
    et al.
    Luleå University of Technology.
    Larsson, Mikael
    RISE, Swerea, Swerea MEFOS.
    Wang, Chuan
    RISE, Swerea, Swerea MEFOS.
    Dahl, J.
    Luleå University of Technology.
    Lundgren, J.
    Luleå University of Technology.
    A new optimal solution space based method for increased resolution in energy system optimisation2012In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 92, p. 583-592Article in journal (Refereed)
    Abstract [en]

    In this paper a new method for increased time resolution in multi-period Mixed Integer Linear Programming (MILP) optimisation is presented and applied to a district heating system. The proposed method facilitates the analysis of many time periods in multi period MILP optimisation projects. In the paper, a 365 time period model spanning 1. year developed with the novel method is compared to a 12 time period model developed with a more conventional methodology. The new method offers a significant decrease in the amount of input data for multi period models and facilitates changes to the analysed time span or resolution in time. In the application of the new method oil savings of 7% compared to the current operational strategy of the district heating system are revealed. © 2011 Elsevier Ltd.

  • 17.
    Sandels, Claes
    et al.
    KTH Royal Institute of Technology, Sweden.
    Brodén, Daniel
    KTH Royal Institute of Technology, Sweden.
    Widén, J.
    Uppsala University, Sweden.
    Nordström, Lars
    KTH Royal Institute of Technology, Sweden.
    Andersson, Enar
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Modeling office building consumer load with a combined physical and behavioral approach: Simulation and validation2016In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 162, p. 472-485Article in journal (Refereed)
    Abstract [en]

    Summary: Due to an expanding integration of renewable energy resources in the power systems, mismatches between electricity supply and demand will increase. A promising solution to deal with these issues is Demand Response (DR), which incentives end-users to be flexible in their electricity consumption. This paper presents a bottom up simulation model that generates office building electricity load profiles representative for Northern Europe. The model connects behavioral aspects of office workers with electricity usage from appliances, and physical representation of the building to describe the energy use of the Heating Ventilation and Air Conditioning systems. To validate the model, simulations are performed with respect to two data sets, and compared with real load measurements. The validation shows that the model can reproduce load profiles with reasonable accuracy for both data sets. With the presented model approach, it is possible to define simple portfolio office building models which subsequently can be used for simulation and analysis of DR in the power systems.

  • 18.
    Sophonrat, Nanta
    et al.
    KTH Royal Institute of Technology, Sweden.
    Sandström, Linda
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Zaini, Ilman N.
    KTH Royal Institute of Technology, Sweden.
    Yang, Weihong
    KTH Royal Institute of Technology, Sweden.
    Stepwise pyrolysis of mixed plastics and paper for separation of oxygenated and hydrocarbon condensates2018In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 229, p. 314-325Article in journal (Refereed)
    Abstract [en]

    Mixed plastics and papers are two of the main fractions in municipal solid waste which is a critical environmental issue today. Recovering energy and chemicals from this waste stream by pyrolysis is one of the favorable options to achieve a circular economy. While pyrolysis products from plastics are mainly hydrocarbons, pyrolysis products from paper/biomass are highly oxygenated. The different nature of the two pyrolysis products results in different treatments and applications as well as economic values. Therefore, separation of these two products by multi-step pyrolysis based on their different decomposition temperatures could be beneficial for downstream processes to recover materials, chemicals and/or energy. In this work, stepwise pyrolysis of mixed plastics and paper waste was performed in a batch type fixed bed reactor using two different pyrolysis temperatures. Neat plastic materials (polystyrene, polyethylene) and cellulose mixtures were used as starting materials. Then, the same conditions were applied to a mixed plastics and paper residue stream derived from paper recycling process. The condensable products were analyzed by GC/MS. It was found that pyrolysis temperatures during the first and second step of 350 and 500 °C resulted in a better separation of the oxygenated and hydrocarbon condensates than when a lower pyrolysis temperature (300 °C) was used in the first step. The products from the first step were derived from cellulose with some heavy fraction of styrene oligomers, while the products from the second step were mainly hydrocarbons derived from polystyrene and polyethylene. This thus shows that stepwise pyrolysis can separate the products from these materials, although with some degree of overlapping products. Indications of interaction between PS and cellulose during stepwise pyrolysis were observed including an increase in char yield, a decrease in liquid yield from the first temperature step and changes in liquid composition, compared to stepwise pyrolysis of the two materials separately. A longer vapor residence time in the second step was found to help reducing the amount of wax derived from polyethylene. Results from stepwise pyrolysis of a real waste showed that oxygenated and acidic products were concentrated in the liquid from the first step, while the product from the second step contained a high portion of hydrocarbons and had a low acid number.

  • 19.
    Suopajärvi, Hannu
    et al.
    University of Oulu, Finland.
    Umeki, Kentaro
    Luleå University of Technology, Sweden.
    Mousa, Elsayed
    RISE - Research Institutes of Sweden, Swerea, Swerea MEFOS.
    Hedayati, Ali
    Luleå University of Technology, Sweden.
    Romar, Henrik
    University of Oulu, Finland.
    Kemppainen, Antti
    University of Oulu, Finland.
    Wang, Chuan
    RISE - Research Institutes of Sweden, Swerea, Swerea MEFOS.
    Phounglamcheik, Aekjuthon
    Luleå University of Technology, Sweden.
    Tuomikoski, Sari
    University of Oulu, Finland.
    Norberg, Nicklas
    Future Eco North Sweden AB, Sweden.
    Andefors, Alf
    Future Eco North Sweden AB, Sweden.
    Öhman, Marcus
    Luleå University of Technology, Sweden.
    Lassi, Ulla
    University of Oulu, Finland.
    Fabritius, Timo
    University of Oulu, Finland.
    Use of biomass in integrated steelmaking – Status quo, future needs and comparison to other low-CO2 steel production technologies2018In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 213, p. 384-407Article in journal (Refereed)
    Abstract [en]

    This paper provides a fundamental and critical review of biomass application as a reducing agent and fuel in integrated steelmaking. The basis for the review is derived from the current process and product quality requirements that also biomass-derived fuels should fulfill. The availability and characteristics of different sources of biomass are discussed and suitable pretreatment technologies for their upgrading are evaluated. The existing literature concerning biomass application in bio-coke making, blast furnace injection, iron ore sintering and production of carbon composite agglomerates is reviewed and research gaps filled by providing insights and recommendations to the unresolved challenges. Several possibilities to integrate the production of biomass-based reducing agents with existing industrial infrastructures to lower the cost and increase the total efficiency are given. A comparison of technical challenges and CO2 emission reduction potential between biomass-based steelmaking and other emerging technologies to produce low-CO2 steel is made. 

  • 20.
    Tóth, Pal
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center. University of Miskolc, Hungary.
    Garami, Attilla
    University of Miskolc, Hungary.
    Csordás, Bernadett
    University of Miskolc, Hungary.
    Image-based deep neural network prediction of the heat output of a step-grate biomass boiler2017In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 200, p. 155-169Article in journal (Refereed)
    Abstract [en]

    This work investigates the usage of deep neural networks for predicting the thermal output of a 3 MW, grate-fired biomass boiler, based on routinely measured operating parameters and real-time flame imaging. It is hypothesized that flame imaging can provide information regarding the quasi-instantaneous state of combustion, therefore supplementing conventional measurements that generally produce lagging feedback. A deep neural network-based, continuous multistep-ahead prediction scheme was proposed and evaluated by using operational and image data collected through extensive campaigns. It was found that flame imaging increases the accuracy of predictions compared to those obtained by only using operational data. The complexity of biomass combustion was well captured by the proposed deep neural network; furthermore, the deep architecture produced better predictions than shallower ones. The proposed system can reliably predict output water temperatures with errors up to ±1 °C, up to approximately 30 min ahead of the current time.

  • 21.
    von Platten, Jenny
    et al.
    RISE - Research Institutes of Sweden, Built Environment, Energy and Circular Economy. Lund University, Sweden.
    Holmberg, Carolina
    Lund University, Sweden.
    Mangold, Mikael
    RISE - Research Institutes of Sweden, Built Environment, Energy and Circular Economy.
    Johansson, Tim
    Gitter Consult AB, weden.
    Mjörnell, Kristina
    RISE - Research Institutes of Sweden, Built Environment.
    The renewing of Energy Performance Certificates—Reaching comparability between decade-apart energy records2019In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 255, article id 113902Article in journal (Refereed)
    Abstract [en]

    Energy Performance Certificates are currently one of the most extensive data sources about the energy performance of the EUs building stock and consequently provide support for researchers and policy makers in energy regulation. As Energy Performance Certificates are being renewed, there are new possibilities to study energy performance development over time and to evaluate the building-specific effect of energy policies and measures. This paper aims to explore this possibility. In Sweden, owners of multifamily buildings had to obtain their first Energy Performance Certificate no later than the end of 2008, and with a period of validity of 10 years many owners have now obtained a second Energy Performance Certificate for their building(s). This enables unprecedented quantitative, building-specific evaluations of the change in energy performance over time. However, comparability between old and new Energy Performance Certificates must be assured. This study develops a novel three-step method to attain comparability between old and renewed Energy Performance Certificates. Results show that while many pairs of Energy Performance Certificates were considered comparable, procedural changes in methods for determining heated floor area in Swedish Energy Performance Certificates caused an overestimation of energy performance improvement of approximately 7 kWh/m2 per building which had to be corrected for. The results of this paper indicate that old and renewed Energy Performance Certificates can be utilised to successfully map development of energy performance and enable evaluation of the impact on energy performance from policies and measures that have been carried out between the two points of audit. © 2019 The Authors

  • 22.
    von Schenck, A.
    et al.
    RISE, Innventia.
    Berglin, N.
    RISE, Innventia.
    Uusitalo, J.
    Ethanol from Nordic wood raw material by simplified alkaline soda cooking pre-treatment2013In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, p. 229-240Article in journal (Refereed)
  • 23.
    Wiinikka, Henrik
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Wennebro, Jonas
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Gullberg, Marcus
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Pettersson, Esbjörn
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Weiland, Fredrik
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Pure oxygen fixed-bed gasification of wood under high temperature (>1000 °C) freeboard conditions2017In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 191, p. 153-162Article in journal (Refereed)
    Abstract [en]

    In this paper, the performance (syngas composition, syngas production and gasification efficiency) of an 18 kW atmospheric fixed bed oxygen blown gasifier (FOXBG) with a high temperature (>1000 °C) freeboard section was compared to that of a pressurized (2–7 bar) oxygen blown entrained flow biomass gasifier (PEBG). Stem wood in the form of pellets (FOXBG) or powder (PEBG) was used as fuel. The experimentally obtained syngas compositions, syngas production rates and gasification efficiencies for both gasification technologies were similar. Efficient generation of high quality syngas (in terms of high concentration and yield of CO and H2 and low concentration and yield of CH4, heavier hydrocarbons and soot) is therefore not specific to the PEBG. Instead, efficient gasification seems to be linked to high reactor process temperatures that can also be obtained in a FOXBG. The high quality of the syngas produced in the FOXBG from fuel pellets is promising, as it suggests that in the future, much of the cost associated with milling the fuel to a fine powder will be avoidable. Furthermore, it is also implied that feedstocks that are nearly impossible to pulverize can be used as un-pretreated fuels in the FOXBG.

  • 24.
    Wöhler, Marius
    et al.
    University of Applied Forest Sciences Rottenburg, Germany; University of Freiburg, Germany.
    Andersen, Jes Sig
    Danish Technological Institute, Denmark.
    Becker, Gero
    University of Freiburg, Germany.
    Persson, Henrik
    RISE, SP – Sveriges Tekniska Forskningsinstitut.
    Reichert, Gabriel
    Bioenergy 2020+ GmbH, Austria.
    Schön, Claudia
    Centre of Excellence for Renewable Resources, Germany.
    Schmidl, Cristoph
    Bioenergy 2020+ GmbH, Austria; Austrian Marketing University of Applied Sciences, Austria.
    Jaeger, Dirk
    University of Freiburg, Germany.
    Pelz, Stefan K.
    University of Applied Forest Sciences Rottenburg, Germany.
    Investigation of real life operation of biomass room heating appliances - Results of a European survey2016In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 169, p. 240-249Article in journal (Refereed)
    Abstract [en]

    Wood combustion is the main renewable heating source for European households and responsible for a large portion of the particle matter in the atmosphere. Firewood operated small-scale residential wood combustion units such as firewood stoves and tiled stoves are the most widespread wood combustion appliances in households. Next to purely technological reasons (i.e. type and age of appliance) and installation conditions (i.e. natural draft of chimney system), user behavior which includes all influences caused by the user during operation has a considerable effect on the combustion performance of room heating appliances. User behavior includes fuel related factors, different ways to ignite the fire, combustion air settings, as well as frequency and intensity of use. The objective of this work is to investigate user behavior by means of a survey. The survey aims to provide an overview as to how room heating appliances in European countries are used in real life. We performed a 28 question, multi-lingual online survey over a 14-week period. 1980 responses from 16 European countries were received. Most respondents are from Italy (35%), Germany (34%), Austria (12%) and Sweden (11%). Results were separated by heating appliance type (firewood stove, tiled stove, cooker and other firewood stove), and by country. The results show a unique and detailed glimpse as to how room heating appliances are used in real life. They include the ignition procedure including used fire starters, point of fuel recharging, combustion air regulation and frequency of use. Results related to the fuel used (i.e. type of fuel, fuel conditions) are given in this paper, too. The results are crucial for further research and complement existing knowledge about the effects of the individual user and fuel related parameters on emissions and efficiency of room heating appliances.

  • 25.
    Xie, Yujiao
    et al.
    Luleå University of Technology, Sweden ; Shandong University of Technology, China.
    Björkmalm, Johanna
    RISE - Research Institutes of Sweden, Built Environment, Energy and Circular Economy.
    Ma, Chunyan
    Luleå University of Technology, Sweden.
    Willquist, Karin
    RISE - Research Institutes of Sweden, Built Environment, Energy and Circular Economy.
    Yngvesson, Johan
    RISE - Research Institutes of Sweden, Built Environment, Energy and Circular Economy.
    Wallberg, Ola
    Lund University, Sweden.
    Ji, Xiaoyan
    Luleå University of Technology, Sweden.
    Techno-economic evaluation of biogas upgrading using ionic liquids in comparison with industrially used technology in Scandinavian anaerobic digestion plants2018In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 227, p. 742-750Article in journal (Refereed)
    Abstract [en]

    The process of biogas upgrading with ionic liquids, i.e. pure 1-butyl-3-methylimidazolium bis(trifluoro-methylsulfonyl)imide ([bmim][Tf2N]), aqueous choline chloride/urea (ChCl/Urea), and aqueous 1-allyl-3-methyl imidazole formate ([Amim][HCOO]), was simulated in Aspen Plus and compared with the conventional water scrubbing upgrading technique. The comparisons of the performances on the amount of recirculated solvents and energy usage show the following order: aqueous [Amim][HCOO]<aqueous ChCl/Urea<[bmim][Tf2N]<water. Six different co-digestion plants (anaerobic digestion, AD, plants) were surveyed to acquire data for comparison. The selected plants had different raw biogas production capacities and produced gas with differing methane content. The data confirmed the simulation results that the type of substrate and the configuration of AD process are two factors affecting energy usage, investment cost, as well as operation and maintenance costs for the subsequent biogas upgrading. In addition, the simulation indicated that the energy usage of the ionic liquid-based upgrading was lower than that of the conventional upgrading techniques in Scandinavian AD plants. The estimated cost including investment, operation and maintenance for the ionic liquid technology showed to be lower than that for the water scrubbing upgrading process.

  • 26.
    Zetterholm, J.
    et al.
    RISE - Research Institutes of Sweden, Swerea, Swerea MEFOS. Luleå University of Technology, Sweden.
    Ji, X.
    Luleå University of Technology, Sweden.
    Sundelin, B.
    SSAB Special Steels, Sweden.
    Martin, P. M.
    Siemens VAI Metals Technologies, USA.
    Wang, C.
    RISE - Research Institutes of Sweden, Swerea, Swerea MEFOS.
    Dynamic modelling for the hot blast stove2017In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 185, p. 2142-2150Article in journal (Refereed)
    Abstract [en]

    A large amount of energy is required in the production of steel where the preheating of blast in the hot blast stoves for iron-making is one of the most energy-intensive processes. To improve the energy efficiency of the steelmaking it is necessary to investigate how to improve the hot blast stove operation. In this work a mathematic model for evaluating the performance of the hot blast stove was developed using a finite difference approximation for the heat transfer inside the stove during operation. The developed model was calibrated and validated by using the process data from hot blast stove V26 at SSABs plant in Oxelösund, Sweden. The investigation shows a good agreement between the measured and modelled data. As a case study, the developed model was used to simulate the effect of a new concept of OxyFuel technique to hot blast stoves. The investigation shows that, by using this OxyFuel technique, it is possible to maintain the blast temperature while removing the usage of coke oven gas (COG). The saved COG can be used to replace some fossil fuel, such as oil and LPG. Furthermore, the effect of the cycle time on the single stove was studied. As expected, both the hot blast and flue gas temperatures are increased when increasing the cycle time. This shows that it is a good strategy for the hot blast stove to increase the blast temperature if the stove is currently not operated with the maximum allowed flue-gas temperature.

  • 27.
    Zetterholm, Jonas
    et al.
    Luleå University of Technology, Sweden.
    Pettersson, Karin
    RISE - Research Institutes of Sweden, Built Environment, Energy and Circular Economy.
    Leduc, Sylvain
    International Institute for Applied Systems Analysis, Austria.
    Mesfun, Sennai
    International Institute for Applied Systems Analysis, Austria.
    Lundgren, Joakim
    Luleå University of Technology, Sweden ; International Institute for Applied Systems Analysis, Austria.
    Wetterlund, Elisabeth
    Luleå University of Technology, Sweden ; International Institute for Applied Systems Analysis, Austria.
    Resource efficiency or economy of scale: Biorefinery supply chain configurations for co-gasification of black liquor and pyrolysis liquids2018In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 230, p. 912-924Article in journal (Refereed)
    Abstract [en]

    Biorefineries for the production of fuels, chemicals, or materials can be an important contributor to reducing dependence on fossil fuels. The economic performance of the biorefinery supply chain can be increased by, for example, industrial integration to utilise excess heat and products, increasing size to improve economy of scale, and using intermediate upgrading to reduce feedstock transport cost. To enable a large-scale introduction of biorefineries it is important to identify cost efficient supply chain configurations. This work investigates a lignocellulosic biorefinery concept integrated with forest industry, focusing on how different economic conditions affect the preferred supply chain configurations. The technology investigated is black liquor gasification, with and without the addition of pyrolysis liquids to increase production capacity. Primarily, it analyses trade-offs between high biomass conversion efficiency and economy of scale effects, as well as the selection of centralised vs. decentralised supply chain configurations. The results show the economic advantage for biomass efficient configurations, when the biorefinery investment is benefited from an alternative investment credit due to the replacement of current capital-intensive equipment at the host industry. However, the investment credit received heavily influenced the cost of the biorefinery and clearly illustrates the benefit for industrial integration to reduce the cost of biorefineries. There is a benefit for a decentralised supply chain configuration under very high biomass competition. However, for lower biomass competition, site-specific conditions will impact the favourability of either centralised or decentralised supply chain configurations.

  • 28. Zhang, Jie
    et al.
    Campana, Pietro Elia
    Yao, Tian
    Zhang, Yang
    Lundblad, Anders Olof
    Mälardalen University, Sweden; KTH Royal Institute of Technology, Sweden.
    Melton, Forrest
    Yan, Jinyue
    The water-food-energy nexus optimization approach to combat agricultural drought: a case study in the United States2018In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 227, p. 449-464Article in journal (Refereed)
    Abstract [en]

    The frequent recent drought events in the Great Plains of United States have led to significant crop yield reductions and crop price surges. Using an integrated water-food-energy nexus modelling and optimization approach, this study laid the basis for developing an effective agricultural drought management system by combining real-time drought monitoring with real-time irrigation management. The proposed water-food-energy simulation and optimization method is spatially explicit and was applied to one major corn region in Nebraska. The crop simulations, validated with yield statistics, showed that a drought year like 2012 can potentially reduce the corn yield by 50% as compared to a wet year like 2009. The simulation results show that irrigation can play a key role in halting crop losses due to drought and in sustaining high yields of up to 20t/ha. Nevertheless, the water-food-energy relationship shows that significant investments on water and energy are required to limit the negative effects of drought. The multi-criteria optimization problem developed in this study shows that the optimal crop yield does not necessarily correspond to the maximum yield, resulting in potential water and energy savings.

  • 29.
    Zhang, Yang
    et al.
    KTH Royal Institute of Technology, Sweden.
    Campana, Pietro E.
    KTH Royal Institute of Technology, Sweden; Mälardalen University, Sweden.
    Yang, Ying
    Mälardalen University, Sweden.
    Stridh, Bengt
    Mälardalen University, Sweden.
    Lundblad, Anders Olof
    RISE - Research Institutes of Sweden, Safety and Transport, Electronics.
    Yan, Jinyue
    KTH Royal Institute of Technology, Sweden; Mälardalen University, Sweden.
    Energy flexibility from the consumer: Integrating local electricity and heat supplies in a building2018In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 223, p. 430-442Article in journal (Refereed)
    Abstract [en]

    The increasing penetration level of renewable energy requires more flexibility measures to be implemented in future energy systems. Integrating an energy consumer's local energy supplies connects multiple energy networks (i.e., the electrical grid, the district heating network, and gas network) in a decentralized way. Such integration enhances the flexibility of energy systems. In this work, a Swedish office building is investigated as a case study. Different components, including heat pump, electrical heater, battery and hot water storage tank are integrated into the electricity and heat supply system of the building. Special focus is placed on the flexibility that the studied building can provide to the electrical grid (i.e., the building modulates the electricity consumption in response to the grid operator's requirements). The flexibility is described by two metrics including the flexibility hours and the flexibility energy. Optimization of the component capacities and the operation profiles is carried out by using Mixed Integer Linear Programming (MILP). The results show that the system fully relies on electricity for the heat demand when not considering the flexibility requirements of the electrical grid. This suggests that district heating is economically unfavorable compared with using electricity for the heat demand in the studied case. However, when flexibility requirements are added, the system turns to the district heating network for part of the heat demand. The system provides great flexibility to the electrical grid through such integration. The flexibility hours can be over 5200 h in a year, and the flexibility energy reaches more than 15.7 MWh (36% of the yearly electricity consumption). The yearly operation cost of the system slightly increases from 62,273 to 65,178 SEK when the flexibility hours increase from 304 to 5209 h. The results revealed that flexibility can be provided from the district heating network to the electrical grid via the building.

  • 30.
    Ögren, Yngve
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center. Luleå University of Technology, Sweden.
    Toth, Pal
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center. University of Miskolc, Hungary.
    Garami, Attila
    University of Miskolc, Hungary.
    Sepman, Alexey
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Wiinikka, Henrik
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center. Luleå University of Technology, Sweden.
    Development of a vision-based soft sensor for estimating equivalence ratio and major species concentration in entrained flow biomass gasification reactors2018In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 226, p. 450-460Article in journal (Refereed)
    Abstract [en]

    A combination of image processing techniques and regression models was evaluated for predicting equivalence ratio and major species concentration (H2, CO, CO2 and CH4) based on real-time image data from the luminous reaction zone in conditions and reactors relevant to biomass gasification. Two simple image pre-processing routines were tested: reduction to statistical moments and pixel binning (subsampling). Image features obtained by using these two pre-processing methods were then used as inputs for two regression algorithms: Gaussian Process Regression and Artificial Neural Networks. The methods were evaluated by using a laboratory-scale flat-flame burner and a pilot-scale entrained flow biomass gasifier. For the flat-flame burner, the root mean square error (RMSE) were on the order of the uncertainty of the experimental measurements. For the gasifier, the RMSE was approximately three times higher than the experimental uncertainty – however, the main source of the error was the quantization of the training dataset. The accuracy of the predictions was found to be sufficient for process monitoring purposes. As a feature extraction step, reduction to statistical moments proved to be superior compared to pixel binning.

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