Gunstein Skomedal

• Shyikira, Antoine de Padoue; Akhtar, Naureen; Skomedal, Gunstein & Middleton, Peter Hugh (2021). The effect of Mo and Ge reactive elements on high-temperature oxidation of higher manganese silicide. Corrosion Science. ISSN 0010-938X. doi: 10.1016/j.corsci.2021.109920. Fulltekst i vitenarkiv
• Shyikira, Antoine de Padoue; Akhtar, Naureen; Skomedal, Gunstein; Sætre, Tor Oskar & Middleton, Peter Hugh (2021). High temperature oxidation of higher manganese silicides. Corrosion Science. ISSN 0010-938X. 185. doi: 10.1016/j.corsci.2021.109327. Fulltekst i vitenarkiv
• Graff, Joachim Seland; Schuler, Raphael; Song, Xin; Castillo-Hernandez, Gustavo; Skomedal, Gunstein & Enebakk, Erik [Vis alle 11 forfattere av denne artikkelen] (2021). Fabrication of a Silicide Thermoelectric Module Employing Fractional Factorial Design Principles. Journal of Electronic Materials. ISSN 0361-5235. 50, s. 4041–4049. doi: 10.1007/s11664-021-08902-y. Fulltekst i vitenarkiv Vis sammendrag

  Thermoelectric modules can be used in waste heat harvesting, sensing, and cooling applications. Here, we report on the fabrication and performance of a four-leg module based on abundant silicide materials. While previously optimized Mg2Si0.3Sn0.675Bi0.025 is used as the n-type leg, we employ a fractional factorial design based on the Taguchi methods mapping out a four-dimensional parameter space among Mnx-εMoεSi1.75−δGeδ higher manganese silicide compositions for the p-type material. The module is assembled using a scalable fabrication process, using a Cu metallization layer and a Pb-based soldering paste. The maximum power output density of 53 μW cm–2 is achieved at a hot-side temperature of 250 °C and a temperature difference of 100 °C. This low thermoelectric output is related to the high contact resistance between the thermoelectric materials and the metallic contacts, underlining the importance of improved metallization schemes for thermoelectric module assembly.

• Shyikira, Antoine de Padoue; Skomedal, Gunstein & Middleton, Peter Hugh (2020). Performance evaluation and stability of silicide-based thermoelectric modules. Materials Today: Proceedings. ISSN 2214-7853. 44(4), s. 3467–3474. doi: 10.1016/j.matpr.2020.05.193. Fulltekst i vitenarkiv
• Løvvik, Ole Martin; Flage-Larsen, Espen & Skomedal, Gunstein (2020). Screening of thermoelectric silicides with atomistic transport calculations. Journal of Applied Physics. ISSN 0021-8979. 128. doi: 10.1063/5.0008198. Fulltekst i vitenarkiv Vis sammendrag

  More than 1000 crystalline silicide materials have been screened for thermoelectric properties using first-principles atomistic calculations coupled with the semi-classical Boltzmann transport equation. Compounds that contain radioactive, toxic, rare, and expensive elements as well as oxides, hydrides, carbides, nitrides, and halides have been neglected in the study. The already well-known silicides with good thermoelectric properties, such as SiGe, Mg2Si, and MnSix, are successfully predicted to be promising compounds along with a number of other binary and ternary silicide compositions. Some of these materials have only been scarcely studied in the literature, with no thermoelectric properties being reported in experimental papers. These novel materials can be very interesting for thermoelectric applications provided that they can be heavily doped to give a sufficiently high charge carrier concentration and that they can be alloyed with isoelectronic elements to achieve adequately low phonon thermal conductivity. The study concludes with a list of the most promising silicide compounds that are recommended for further experimental and theoretical investigations.

• Kanas, Nikola; Skomedal, Gunstein; Desissa, Temesgen D.; Feldhoff, Armin; Grande, Tor & Wiik, Kjell [Vis alle 7 forfattere av denne artikkelen] (2020). Performance of a thermoelectric module based on n-type (La0.12Sr0.88)0.95TiO3-δ and p-type Ca3Co4-xO9+δ . Journal of Electronic Materials. ISSN 0361-5235. 49(7), s. 4154–4159. doi: 10.1007/s11664-020-08127-5. Fulltekst i vitenarkiv Vis sammendrag

  Here, we present the performance of a thermoelectric (TE) module consisting of n-type (La0.12Sr0.88)0.95TiO3 and p-type Ca3Co4-xO9+δ materials. The main challenge in this investigation was operation of TE module in different atmosphere conditions, since n-type has its optimum TE-performance at reducing, while p-type at oxidizing conditions. The TE module was exposed to two different atmospheres and demonstrated higher stability in N2 atmosphere than in air. The maximum electrical power output decreased after 40 h when the hot side was exposed to N2 at 600 °C, while only 1 h at 400 °C in ambient air was enough to oxidize (La0.12Sr0.88)0.95TiO3 followed by a reduced electrical power output. The module generated a maximum electrical power of 0.9 mW (~ 4.7 mW/cm2) at 600 °C hot side and ΔT ~ 570 K in N2, while 0.15 mW (~ 0.8 mW/cm2) at 400 °C hot side and ΔT ~ 370 K in air. A stability limit of Ca3Co3.93O9+δ at ~ 700 °C in N2 was determined by in situ high-temperature X-ray diffraction.

• Skomedal, Gunstein; Vehus, Tore; Kanas, Nikola; Singh, Sathya Prakash; Einarsrud, Mari-Ann & Wiik, Kjell [Vis alle 7 forfattere av denne artikkelen] (2019). Long term stability testing of oxide unicouple thermoelectric modules. Materials Today: Proceedings. ISSN 2214-7853. 8(2), s. 696–705. doi: 10.1016/j.matpr.2019.02.070. Fulltekst i vitenarkiv
• Amoruso, Gloria; Donevska, Natasha & Skomedal, Gunstein (2018). German and Norwegian policy approach to residential buildings? energy efficiency?a comparative assessment. Energy Efficiency. ISSN 1570-646X. 11(6), s. 1375–1395. doi: 10.1007/s12053-018-9637-5.
• Skomedal, Gunstein; Kristiansen, Nils Randulf; Sottong, Reinhard & Middleton, Peter Hugh (2017). Evaluation of Thermoelectric Performance and Durability of Functionalized Skutterudite Legs. Journal of Electronic Materials. ISSN 0361-5235. 46(4), s. 2438–2450. doi: 10.1007/s11664-017-5309-z.
• Skomedal, Gunstein; Burkov, Alexander; Samunin, Alexander Yu; Haugsrud, Reidar & Middleton, Peter Hugh (2016). High temperature oxidation of Mg2(Si-Sn). Corrosion Science. ISSN 0010-938X. 111(1), s. 325–333. doi: 10.1016/j.corsci.2016.05.016.
• Skomedal, Gunstein; Holmgren, Lennart; Middleton, Peter Hugh; Eremin, IS; Isachenko, GN & Jaegle, Martin [Vis alle 13 forfattere av denne artikkelen] (2016). Design, assembly and characterization of silicide-based thermoelectric modules. Energy Conversion and Management. ISSN 0196-8904. 110, s. 13–21. doi: 10.1016/j.enconman.2015.11.068.
• Sesselmann, A; Skomedal, Gunstein; Middleton, Peter Hugh & Muller, E (2015). The Influence of Synthesis Procedure on the Microstructure and Thermoelectric Properties of p-Type Skutterudite Ce0.6Fe2Co2Sb12. Journal of Electronic Materials. ISSN 0361-5235. doi: 10.1007/s11664-015-4046-4.
• Skomedal, Gunstein; Kristiansen, Nils Randulf; Engvoll, Marianne Aanvik & Middleton, Peter Hugh (2014). Methods for Enhancing the Thermal Durability of High-Temperature Thermoelectric Materials. Journal of Electronic Materials. ISSN 0361-5235. 43(6), s. 1946–1951. doi: 10.1007/s11664-013-2917-0. Vis sammendrag

  Thermoelectric materials, for example skutterudites and magnesium silicides, are being investigated as promising materials for medium-to-high-temperature waste heat recovery in transport and in industry. A crucial aspect of the success of a thermoelectric material is its stability over time when exposed to rapid heating and cooling. In this work different aspects of the degradation of these thermoelectric materials at high temperature were examined. Initial thermal durability was studied, and several candidate coatings were evaluated to enhance durability by protecting the materials from oxidation and sublimation during thermal cycles in air for up to 500 h and up to 873 K. The samples were characterized by SEM and EDS. The results showed it is possible to reduce degradation of the thermoelectric material without compromising overall thermoelectric efficiency.

• Skomedal, Gunstein; Øvrelid, Eivind Johannes; Armada Nieto, Sergio & Espallargas, Nuria (2011). Effect of slurry parameters on material removal rate in multi-wire sawing of silicon wafers: a tribological approach. Proceedings of the Institution of mechanical engineers. Part J, journal of engineering tribology. ISSN 1350-6501. 225(J10), s. 1023–1035. doi: 10.1177/1350650111411246.

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• Skomedal, Gunstein (2023). Sørlandet - den nye batterikysten.
• Skomedal, Gunstein (2023). Innføring i solcelleteknologi.
• Skomedal, Gunstein (2023). Dette bør du vite om solceller før du bestemmer deg for å kjøpe. [Avis]. Fædrelandsvennen.
• Skomedal, Gunstein (2022). Kurs i solstrøm - introduksjon.
• Skomedal, Gunstein (2022). Energilagring og batteri.
• Mortensholm, Stein ; Aamot, Eli; Grande, Tor & Skomedal, Gunstein (2022). Alt vi trenger å vite for å realisere batterieventyret. [TV]. Arendalsuka. Vis sammendrag

  Forskning, industri og politikk møttes under Arendalsuka 2022 for å drøfte hva vi trenger å vite for å gjøre batterier til Norges største jobbskaper på 2020-tallet. Medvirkende i arrangementet Eli Aamot, konserndirektør SINTEF Industri Tor Grande, prorektor for forskning, NTNU Tove Nilsen Ljungquist, EVP Operations, Freyr Ketil Aagesen, head of BlueVault Energy Storage, Siemens Energy AS Gunstein Skomedal, produktsjef batterimaterialer, Vianode/Elkem Jorodd Asphjell, stortingsrepresentant, Arbeiderpartiet Lene Langemyr, varaordfører i Grimstad, Fremskrittspartiet Møtet ble arrangert av SINTEF og NTNU. Samtalen ledes av Stein Mortensholm, kommunikasjonssjef i SINTEF Industri.

• Skomedal, Gunstein & Hansson, Robin (2019). Klassekamp om grønn omstilling. Dagens næringsliv. ISSN 0803-9372.
• Løvvik, Ole Martin; Flage-Larsen, Espen & Skomedal, Gunstein (2019). Atomistic simulations and machine learning methods for development of thermoelectric materials.
• Løvvik, Ole Martin; Berland, Kristian; Remonato, Filippo; Sagvolden, Espen; Flage-Larsen, Espen & Schrade, Matthias [Vis alle 13 forfattere av denne artikkelen] (2019). Screening thermoelectric materials with ab initio atomistic modelling and machine learning techniques.
• Shyikira, Antoine de Padoue; Skomedal, Gunstein & Middleton, Peter Hugh (2019). Performance and stability of silicide based thermoelectric modules. Vis sammendrag

  Long-term studies on thermoelectric generator uni-couple based on N-type magnesium silicide (Mg2.01Si0.49Sn0.5Sb0.01) and P-type higher manganese silicide (Mn0.98Mo0.02Si1.73Ge0.02) materials are presented, in the operating temperature range of 2000C-4000C. Emphasis is put on the performance and reliability of the current collector configuration, especially, on the hot side of the module and on the thermomechanical stresses that are created during operation and lifetime testing, as a result of large temperature gradients experienced across the thermoelectric legs. With silver (Ag) paste as contact material, the long term-stability of the uni-couples were carried out on non-metalized legs and gold metalized legs under ambient conditions. Under isothermal and thermocycling tests, the non-metalized legs showed a gradual decrease in open circuit voltage (after a period of 200hours) and increase in internal resistance. In contrary, the metalized leg-based module was robust and stable for the same isothermal period, however, after 300cycles the n-type material showed mechanical failure (cracks) but the p-type resisted. Post-operation analysis by SEM/EDS and mechanical testing revealed that oxidation, adherence of the contact material and diffusion of the bonding material were the cause of performance degradation of the unicouples.

• Skomedal, Gunstein (2019). Podkast: Kan batteriene redde kloden? [Radio]. https://www.uia.no/nyheter/podkast-kan-batteriene-redde-klod.
• Skomedal, Gunstein (2019). Solceller og batterier.
• Skomedal, Gunstein (2019). Etikk og Material - Litium-ion batterienes rolle i det grønne skiftet.
• Skomedal, Gunstein (2019). Etikk og Material - Litium-ion batterienes rolle i det grønne skiftet.
• Vehus, Tore; Skomedal, Gunstein; Kanas, Nikola & Middleton, Peter Hugh (2018). Hot side electrical contacts for oxide thermoelectric modules.
• Shyikira, Antoine de Padoue; Skomedal, Gunstein; Middleton, Hugh P. & Sætre, Tor Oskar (2018). High Temperature Oxidation of Higher Manganese silicide and Alloys.
• Løvvik, Ole Martin; Flage-Larsen, Espen & Skomedal, Gunstein (2018). Screening silicide thermoelectric materials using ab initio transport calculations.
• Skomedal, Gunstein (2017). Dagens og fremtidens energisystem.
• Skomedal, Gunstein (2017). Materialer for fremtiden.
• Skomedal, Gunstein (2017). Energimaterialer for fremtiden.
• Skomedal, Gunstein (2017). Energimaterialer for fremtiden.
• Skomedal, Gunstein (2017). Long term stability testing of oxide unicouple thermoelectric modules.
• Skomedal, Gunstein (2016). Et forbrukerperspektiv på solstrøm. Fædrelandsvennen. ISSN 0805-3790.
• Skomedal, Gunstein (2016). Denne bilen går på telys. [Tidsskrift]. Aftenposten Viten.
• Skomedal, Gunstein (2016). SOLCELLENERDEN. [Avis]. Fædrelandsvennen.
• Skomedal, Gunstein (2016). Termoelektrisitet og Fornybar Energi.
• Skomedal, Gunstein (2016). Thermally activated degradation processes in thermoelectric materials and devices based on Skutterudites and Silicides.
• Skomedal, Gunstein (2016). HAN SKAL FINNE OPP NYE MÅTER Å LAGE STRØM PÅ. [Avis]. Fedrelandsvennen.
• Skomedal, Gunstein (2016). Ypperlig å kunne kombinere akademia og industri. [Avis]. Fedrelandsvennen.
• Skomedal, Gunstein (2015). Energishow.
• Skomedal, Gunstein (2015). www.solcellekysten.no. Vis sammendrag

  Blogg, guide og informasjon om installering og drift av solcelleanlegg samt mer generell informasjon om solenergi.

• Skomedal, Gunstein (2015). OXIDATION AND DECOMPOSITION OF THERMOELECTRIC MG2(SI-SN) SOLID SOLUTIONS.
• Skomedal, Gunstein (2015). Energishow.
• Skomedal, Gunstein (2015). Energimaterialer på UiA.
• Skomedal, Gunstein (2015). The influence of synthesis procedure on the microstructure and thermoelectric properties of p-type skutterudite Ce0.6Fe2Co2Sb12.
• Skomedal, Gunstein & Strandberg, Rune (2015). Framtida møtes best forlengs. Fædrelandsvennen. ISSN 0805-3790.
• Skomedal, Gunstein (2014). Hvordan er det å jobbe som forsker?
• Skomedal, Gunstein (2014). Termoelektrisitet. [TV]. Innslag Schrødingers Katt, NRK1.
• Skomedal, Gunstein (2014). Lite lys og mykje varme - termoelektrisk spillvarmegjenvenning.
• Skomedal, Gunstein (2014). Fra varme til strøm - materialer for fremtiden. [TV]. NRK - Forsker Grand Prix 2013.
• Skomedal, Gunstein (2013). Vant Forsker Grand Prix Sør. [Avis]. Grimstad Adressetidende.
• Skomedal, Gunstein (2013). Facinert av UiA's Sørlandslab-plan. [Avis]. Agderposten.
• Skomedal, Gunstein (2013). www.termoelektrisitet.no.
• Skomedal, Gunstein (2013). Durability testing of multiple coated and uncoated CoSb3 unilegs.
• Skomedal, Gunstein; Øvrelid, Eivind Johannes & Espallargas, Nuria (2010). Tribological approach for understanding the multi wire sawing of Silicon wafers.
• Aigner, Birk Ludwig Schoder; Imenes, Anne Gerd & Skomedal, Gunstein (2021). System modeling and dispatch schedule optimization of combined PV battery system using linear optimization. Universitetet i Agder. Vis sammendrag

  Energy storage plays a vital role in paving the way for more renewable penetration. The technology is costly, but intelligent solutions regarding dispatch strategies and system design can help reduce the total cost over the projected lifetime of a system. For this thesis, a customizable linear programming algorithm is created within Python to optimize the battery energy scheduling based on generated PV power, electricity cost and load demand. The commercial system optimization tool HOMER is used to verify the code by running simulations based on historic data collected from NordPool and UiAs own photovoltaic system. One benefit of the custom made code is its ability to do day-ahead optimization utilizing data from APIs. To obtain forecasted irradiation and temperature data the Solcast API was used as the only paid service for the Python script to ensure market-leading accuracy. Electricity prices were imported from the transparency platform Entsoe. Implementing different incentives such as battery energy throughput and stored energy made it possible to alter the system behavior to optimize the system better while maintaining good working conditions for the battery. Carefully choosing the optimization parameters reduced battery cycling by 45.9% and average energy stored by 34.8% in two separate scenarios while maintaining cost savings. The case studied uses a power tariff power plan which means that the primary cost savings from including a battery come from peak shaving.

• Skomedal, Gunstein & Middleton, Peter Hugh (2016). Thermally activated degradation processes in novel thermoelectric for waste heat recovery. Universitetet i Agder. ISSN 1504-9272.

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