hh.sePublications
Change search
Link to record
Permanent link

Direct link
Publications (10 of 22) Show all publications
Lind, J., Möllerström, E., Averfalk, H. & Ottermo, F. (2023). Energy flexibility using the thermal mass of residential buildings. Energy and Buildings, 301, 1-12, Article ID 113698.
Open this publication in new window or tab >>Energy flexibility using the thermal mass of residential buildings
2023 (English)In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 301, p. 1-12, article id 113698Article, review/survey (Refereed) Published
Abstract [en]

The transition to a more sustainable energy system with a growing amount of intermittent renewable energy sources brings an increasing need for flexibility measures to maintain balance between supply and demand. Buildings represent a promising source of demand-side flexibility due to their large energy demand and thermal mass. This review provides insights into the storage potential of building thermal mass, and the benefits and challenges it brings. It is found that building thermal mass storage have good ability to shift loads on short term, from peak to off-peak hours. This ability can be utilized for different purposes, for instance reduced costs for end-users or energy providers, reduced primary energy demand, or reduced CO2 emissions. Furthermore, this review explores different factors that influence the storage potential of building thermal mass, with special attention paid to the heat emission system. It is shown that hydronic floor heating is beneficial compared to radiators since it directly can activate the thermal mass with smaller impact on the indoor temperature. It is also found that the factor with largest impact is the envelope insulation level; increased insulation level brings improved storage efficiency and prolonged thermal autonomy but also decreased storage capacity and increased risk of overheating. Finally, research gaps are identified. © 2023 The Authors

Place, publisher, year, edition, pages
Amsterdam: Elsevier, 2023
Keywords
Building thermal mass (BTM), Demand-side management, Energy flexibility, Load shifting, Residential buildings, Thermal energy storage (TES)
National Category
Energy Systems Energy Engineering
Identifiers
urn:nbn:se:hh:diva-52037 (URN)10.1016/j.enbuild.2023.113698 (DOI)2-s2.0-85175613669& (Scopus ID)
Available from: 2023-11-21 Created: 2023-11-21 Last updated: 2023-11-28Bibliographically approved
Ghadirinejad, N., Ottermo, F., Nowzari, R., Alsaadi, N. & Ghadiri Nejad, M. (2023). Optimizing a Green and Sustainable Off-Grid Energy-System Design: A Real Case. Sustainability, 15(17), Article ID 12800.
Open this publication in new window or tab >>Optimizing a Green and Sustainable Off-Grid Energy-System Design: A Real Case
Show others...
2023 (English)In: Sustainability, E-ISSN 2071-1050, Vol. 15, no 17, article id 12800Article in journal (Refereed) Published
Abstract [en]

In recent years, unquestionable warnings like the negative effects of CO2 emissions, the necessity of utilizing sustainable energy sources, and the rising demand for municipal electrification have been issued. Therefore, users are encouraged to provide off-grid and sustainable energy systems for their own homes and businesses, especially if they are located rurally and far from grids. Hence, this study aims to design an off-grid hybrid energy system, in order to minimize both the baseline cost of energy and the net current expenditure in the desired system. To construct such a system, wind generators (WG), photovoltaic arrays (PV), battery banks, and bi-directional converters are considered in the real case of a supermarket with a 20-year lifespan in Malmö, Sweden. Some significant assumptions, such as the usage of renewable energy resources only, electricity production close to the business location, and a maximum allowance of 0.1% unmet are incorporated. To optimize the considered problem, a particle swarm optimization (PSO) approach as developed to provide the load requirements and establish the number of WGs, PVs, and other equipment. Moreover, to verify the obtained results, the developed system was simulated using HOMER Pro software, and the results are compared and discussed. The results indicated that the designed hybrid energy system is able to perform completely off-grid, while satisfying 99.9% of the yearly electricity demand. The best results obtained by the proposed PSO offered 160, 5, and 350 PVs, WGs, and batteries, respectively, while the best solution found by the simulation method was the use of 384 PVs, 5 WGs, and 189 batteries for the considered off-grid system. This study contributes to decentralized local electrification by utilizing renewable energy sources that have the potential to revolutionize green energy solutions. © 2023 by the authors.

Place, publisher, year, edition, pages
Basel: MDPI, 2023
Keywords
particle swarm optimization, photovoltaic arrays, real-case problems, renewable energy, wind turbines
National Category
Energy Engineering
Identifiers
urn:nbn:se:hh:diva-51651 (URN)10.3390/su151712800 (DOI)2-s2.0-85170226434 (Scopus ID)
Available from: 2023-11-17 Created: 2023-11-17 Last updated: 2023-11-17Bibliographically approved
Gong, M. & Ottermo, F. (2022). High-temperature thermal storage in combined heat and power plants. Energy, 252, Article ID 124057.
Open this publication in new window or tab >>High-temperature thermal storage in combined heat and power plants
2022 (English)In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 252, article id 124057Article in journal (Refereed) Published
Abstract [en]

The combined-heat-and-power (CHP) plants play a central role in many heat-intensive energy systems, contributing for example about 10% electricity and 70% district heat in Sweden. This paper considers a proposed system integrating a high-temperature thermal storage into a biomass-fueled CHP plant. The potential and benefits for the individual CHP plant, as well as for the electric grid at large-scale implementation, are studied. The original and integrated systems have been compared by energy and exergy analysis, the results indicating only minor differences. Individual CHP companies can benefit from saving fuel and become more flexible towards customer demands. The integrated system can contribute to new storage capacity in the national electric grid, valuable as the share of variable renewable electricity increases, such as wind and solar power. In a reasonable future scenario with a broad implementation of the integrated system, 53% of electricity that would otherwise be curtailed, could be absorbed and used. At the same time it will be able to replace about 21% of the fuel in the CHP plants. This can help to phase out nuclear power towards the goal of “100% renewable electricity”.

Place, publisher, year, edition, pages
London: Elsevier, 2022
Keywords
CHP, HTS, Thermal storage
National Category
Environmental Engineering
Identifiers
urn:nbn:se:hh:diva-48089 (URN)10.1016/j.energy.2022.124057 (DOI)000799959000013 ()2-s2.0-85129243436 (Scopus ID)
Funder
Swedish Energy Agency
Available from: 2022-10-19 Created: 2022-10-19 Last updated: 2022-10-19Bibliographically approved
Negash, T., Möllerström, E., Ottermo, F. & Zeraebruk, K. (2022). Technical Feasibility of Large-scale Wind Energy Production in Eritrea. In: Kheira Anissa Tabet Aoul; Mohammed Tariq Shafiq; Daniel Efurosibina Attoye (Ed.), ZEMCH 2021 International Conference Proceedings: . Paper presented at 8th Zero Energy Mass Custom Home International Conference, Dubai, United Arab Emirates, 26th-28th October, 2021 (pp. 613-624). United Arab Emirates University
Open this publication in new window or tab >>Technical Feasibility of Large-scale Wind Energy Production in Eritrea
2022 (English)In: ZEMCH 2021 International Conference Proceedings / [ed] Kheira Anissa Tabet Aoul; Mohammed Tariq Shafiq; Daniel Efurosibina Attoye, United Arab Emirates University , 2022, p. 613-624Conference paper, Published paper (Refereed)
Abstract [en]

With the rapid depletion of fossil fuels and alarming environmental concerns renewable energy utilization is becoming the best option for electricity production. Moreover, renewable electricity production from wind energy has become a notable objective globally for its enormous potential and technological advancement. The main objective of this paper is to investigate the technical feasibility of large-scale wind power production in Eritrea. The study was carried-out based on two different data sources (measured and modeled) containing time-series of weather data and a third reference data from Global Wind Atlas (GWA) was used for validation purposes. The characteristics and distribution of the wind speed for all data sets were described using Weibull distribution. Two turbines (Enercon E-82 and Vestas V90) were selected to test their performance in the proposed sites. Weibull distribution - representative of the original data sets- along with the turbines’ power curves were used to determine the Annual Energy Production (AEP) and capacity factor (Cf􏰀􏰁) of the turbines. The Vestas wind turbine was found to have a better performance compared to Enercon turbine in both sites for all data sets. Furthermore, the influence of air density in AEP and 􏰀􏰁Cf was investigated and the finding showed that as much as 12% variation on AEP was obtained in Dekemhare site which is located in the highlands of Eritrea. Though the variation between the measured and modeled data sets exists in both sites, the difference in mean wind speed, power density, AEP and Cf􏰀􏰁 was more exaggerated for Dekemahre site. Referring to the measured data series both sites found to be very attractive for utility scale wind power production.

Place, publisher, year, edition, pages
United Arab Emirates University, 2022
Series
ZEMCH International Conference Proceedings, E-ISSN 2652-2926
Keywords
Wind Power, Weibull distribution, AEP, Capacity factor, Dekemhare wind site, Assab Wind site
National Category
Energy Engineering
Identifiers
urn:nbn:se:hh:diva-46192 (URN)978-9948-31-000-6 (ISBN)
Conference
8th Zero Energy Mass Custom Home International Conference, Dubai, United Arab Emirates, 26th-28th October, 2021
Available from: 2022-01-11 Created: 2022-01-11 Last updated: 2022-01-18Bibliographically approved
Möllerström, E. & Ottermo, F. (2021). Calculational model for first-mode eigenfrequency of a semi-guy-wired vertical-axis wind turbine tower. Wind Engineering: The International Journal of Wind Power, 45(2), 205-212
Open this publication in new window or tab >>Calculational model for first-mode eigenfrequency of a semi-guy-wired vertical-axis wind turbine tower
2021 (English)In: Wind Engineering: The International Journal of Wind Power, ISSN 0309-524X, E-ISSN 2048-402X, Vol. 45, no 2, p. 205-212Article in journal (Refereed) Published
Abstract [en]

A simple model for accounting for tower mass when estimating the first-mode eigenfrequency of a semi-guy-wired tower has been derived. This extends previous work where an analytical model of the semi-guy-wired tower of a 200-kW vertical-axis wind turbine was developed. The model was primarily used to estimate the eigenfrequencies as a result of adding guy wires to a free-standing tower (thus creating a semi-guy-wired setup). However, a weakness with the model was that the tower mass was accounted for in a rough way that essentially ignored the guy wires, which gave a larger-than-necessary error. In this work, an effective top mass, that takes into account the tower mass and the constraints from the guy wires, is derived to achieve a higher accuracy when estimating the first-mode eigenfrequency. This, together with the earlier models, gives a more complete method to estimate the eigenfrequencies for a semi-guy-wired wind turbine. © The Author(s) 2019.

Place, publisher, year, edition, pages
London: Sage Publications, 2021
Keywords
Vertical-axis wind turbine, eigenfrequency, natural frequency, semi-guy-wired
National Category
Energy Engineering
Identifiers
urn:nbn:se:hh:diva-40775 (URN)10.1177/0309524X19882433 (DOI)000491749600001 ()2-s2.0-85074440155 (Scopus ID)
Available from: 2019-10-22 Created: 2019-10-22 Last updated: 2021-05-27Bibliographically approved
Averfalk, H., Möllerström, E. & Ottermo, F. (2021). Domestic hot water design and flow measurements. Paper presented at The 17th International Symposium on District Heating and Cooling, Nottingham Trent University, 17th DHC Symposium, Nottingham, United Kingdom, 6–9 September, 2021. Energy Reports, 7(Suppl. 4), 304-310
Open this publication in new window or tab >>Domestic hot water design and flow measurements
2021 (English)In: Energy Reports, E-ISSN 2352-4847, Vol. 7, no Suppl. 4, p. 304-310Article in journal (Refereed) Published
Abstract [en]

In this study, the sizing of primary side components for preparation of domestic hot water are analysed, both qualitatively and based on measurements of domestic hot water demand in one multi-family building with 268 apartments. The collected data spans a period of 18 days during the end of 2020 and is collected in 15-min, 1-min, and 6-s intervals. An overview of the historic development for the design of domestic hot water flow in Sweden is also presented. There is a long-standing argument in Sweden, that the current district heating guidelines result in an overdesign of the flow for domestic hot water. The consequence of this is oversizing heat exchangers and valves in the substations. This study assesses, qualitatively, the issues related to overdesigned primary side valves for preparation of domestic hot water. A revised design for domestic hot water flow for the Swedish context is also conceptualised. The study suggests that an improved design flow for domestic hot water in multi-family buildings can be derived based on empirical measurements. The 15-min intervals are observed to tone down information of peaks to a degree where it is unsuitable to use as basis for a new design flow. The 1-min data does appear to preserve information to a degree where it can be used to assess a design flow when related to data with a 6-s interval. The 6-s data is expected to constitute a resolution that may be less available, and in this study, it constitutes a representation of the real domestic hot water demands. However, to find a fitted curve to empirical data, for the design flow based on number of apartments per multi-family building, the population of datasets needs to be increased. © 2021 The Authors. Published by Elsevier Ltd.

Place, publisher, year, edition, pages
Amsterdam: Elsevier, 2021
Keywords
Domestic hot water, Measurements, Design flow, Multi-family building, District heating
National Category
Energy Engineering
Identifiers
urn:nbn:se:hh:diva-45807 (URN)10.1016/j.egyr.2021.08.142 (DOI)000727834400034 ()2-s2.0-85130310848 (Scopus ID)
Conference
The 17th International Symposium on District Heating and Cooling, Nottingham Trent University, 17th DHC Symposium, Nottingham, United Kingdom, 6–9 September, 2021
Projects
Real domestic hot water flows in multi-family buildings
Note

Funding: Energiforsk (grant no. KVU63022)

Available from: 2021-10-29 Created: 2021-10-29 Last updated: 2022-06-22Bibliographically approved
Negash, T., Möllerström, E. & Ottermo, F. (2020). An Assessment of Wind Energy Potential for the Three Topographic Regions of Eritrea. Energies, 13(7), Article ID 1846.
Open this publication in new window or tab >>An Assessment of Wind Energy Potential for the Three Topographic Regions of Eritrea
2020 (English)In: Energies, E-ISSN 1996-1073, Vol. 13, no 7, article id 1846Article in journal (Refereed) Published
Abstract [en]

This paper presents the wind energy potential and wind characteristics for 25 wind sites in Eritrea, based on wind data from the years 2000–2005. The studied sites are distributed all over Eritrea, but can roughly be divided into three regions: coastal region, western lowlands, and central highlands. The coastal region sites have the highest potential for wind power. An uncertainty, due to extrapolating the wind speed from the 10-m measurements, should be noted. The year to year variations are typically small and, for the sites deemed as suitable for wind power, the seasonal variations are most prominent in the coastal region with a peak during the period November–March. Moreover, Weibull parameters, prevailing wind direction, and wind power density recalculated for 100 m above ground are presented for all 25 sites. Comparing the results to values from the web-based, large-scale dataset, the Global Wind Atlas (GWA), both mean wind speed and wind power density are typically higher for the measurements. The difference is especially large for the more complex-terrain central highland sites where GWA results are also likely to be more uncertain. The result of this study can be used to make preliminary assessments on possible power production potential at the given sites. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.

Place, publisher, year, edition, pages
Basel: MDPI, 2020
Keywords
wind power, wind energy, Eritrea, global wind atlas, renewable energy
National Category
Energy Engineering
Identifiers
urn:nbn:se:hh:diva-41875 (URN)10.3390/en13071846 (DOI)000537688400315 ()2-s2.0-85083660724 (Scopus ID)
Available from: 2020-04-10 Created: 2020-04-10 Last updated: 2023-08-28Bibliographically approved
Möllerström, E., Gipe, P., Beurskens, J. & Ottermo, F. (2019). A historical review of vertical axis wind turbines rated 100 kW and above. Renewable & sustainable energy reviews, 105, 1-13
Open this publication in new window or tab >>A historical review of vertical axis wind turbines rated 100 kW and above
2019 (English)In: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 105, p. 1-13Article in journal (Refereed) Published
Abstract [en]

This paper summarizes and introduces all vertical axis wind turbine (VAWT) projects where 100 kW or larger turbines have been installed. The basis for the review is both existing literature and personal correspondence with people once involved in the different developments. By citing the most relevant work for each project, the paper will also work as an information hub, making information on these projects more accessible.

Since the 1970s, there have been several VAWT projects with installed turbines of significant size, either as attempts to commercialize VAWTs, or as university led research projects, or as a combination of the two. Most have involved Darrieus turbines built in North America during the 1980s. However, H-rotors, which have always been a favored concept in Europe, have seen a revival during the 2010s.

The reason VAWTs have never fully challenged the success of the horizontal axis wind turbine (HAWT) is too broad a question to answer here. However, the reasons some VAWT projects have failed are addressed in this paper. Besides the fact that many of the prototypes had terminal failures, most of the installed medium or large-scale VAWTs have to some extent had problems with metal fatigue and durability. Additionally, a lack of long-term interest from governmental or private funders, as well as the introduction of reliable HAWTs, was a recurring theme from those involved in VAWT development, regarding the reason VAWTs so far have failed to succeed. © 2018 The Author(s)

Place, publisher, year, edition, pages
Kidlington: Pergamon Press, 2019
Keywords
Vertical axis wind turbine, VAWT, Darrieus-turbine, H-rotor, Wind turbine history
National Category
Energy Engineering
Identifiers
urn:nbn:se:hh:diva-38798 (URN)10.1016/j.rser.2018.12.022 (DOI)000460121000001 ()2-s2.0-85060475951 (Scopus ID)
Available from: 2019-01-27 Created: 2019-01-27 Last updated: 2021-05-11Bibliographically approved
Möllerström, E. & Ottermo, F. (2019). Comparison of inflow-turbulence and trailing-edge noise models with measurements of a 200-kW vertical axis wind turbine. Paper presented at WindEurope Conference and Exhibition 2019, Bilbao, Spain, 2–4 April, 2019. Journal of Physics, Conference Series, 1222, Article ID 012028.
Open this publication in new window or tab >>Comparison of inflow-turbulence and trailing-edge noise models with measurements of a 200-kW vertical axis wind turbine
2019 (English)In: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 1222, article id 012028Article in journal (Refereed) Published
Abstract [en]

Models of inflow-turbulence noise and turbulent-boundary-layer trailing-edge noise are compared to earlier measurements of a 200-kW vertical axis wind turbine so that conclusions regarding the origin of the aerodynamic noise can be drawn. The measurement campaigns, which aimed at establishing the noise emission value and locating the aerodynamic noise sources with a microphone array, are here both compared to further modified versions of the trailing-edge and inflow-turbulence models respectively. Unlike the case for horizontal axis wind turbine, inflow-turbulence noise is deemed as the prevailing noise mechanism. Reducing the self-induced turbulence could then be an effective way of lowering the noise levels for vertical axis wind turbines. Also, looking at the directivity of the inflow-turbulence noise model which indicate most noise in the cross-wind directions, a deviation from the standard downwind measurement position for measuring noise emission is suggested for the VAWT case.

Place, publisher, year, edition, pages
Bristol: Institute of Physics (IOP), 2019
National Category
Energy Engineering
Identifiers
urn:nbn:se:hh:diva-39459 (URN)10.1088/1742-6596/1222/1/012028 (DOI)2-s2.0-85066427425 (Scopus ID)
Conference
WindEurope Conference and Exhibition 2019, Bilbao, Spain, 2–4 April, 2019
Available from: 2019-05-23 Created: 2019-05-23 Last updated: 2021-05-11Bibliographically approved
Averfalk, H., Ottermo, F. & Werner, S. (2019). Pipe Sizing for Novel Heat Distribution Technology. Energies, 12(7), Article ID 1276.
Open this publication in new window or tab >>Pipe Sizing for Novel Heat Distribution Technology
2019 (English)In: Energies, E-ISSN 1996-1073, Vol. 12, no 7, article id 1276Article in journal (Refereed) Published
Abstract [en]

This paper assesses pipe sizing aspects for previously proposed, novel, low heat distribution technology with three pipes. Assessment issues include heat loss, pressure loss, and pipe sizing for different typical pipe configurations. This assessment has been provided by the analysis of a case area with single-family houses. Concerning heat loss, the proposed three-pipe solutions have the same magnitude of heat loss as conventional twin pipes, since lower return temperatures compensate for the larger heat loss area from the third pipe. Regarding pressure loss, the main restriction on the size of the third pipe is limited to the pressure loss in the third pipe. Thermostatic valves to manage the flow rate of the third pipe are advocated, since alternative small pumps have not been found to be commercially available. The pipe sizing recommendation is that the third pipe for recirculation purposes can be two to three standard pipe sizes smaller than the corresponding supply and return pipe, if no prosumer is connected in the heat distribution network.

Place, publisher, year, edition, pages
Basel: MDPI, 2019
Keywords
low temperature, district heating, pressure gradients, three-pipe system, 4GDH-3P
National Category
Energy Engineering
Identifiers
urn:nbn:se:hh:diva-39198 (URN)10.3390/en12071276 (DOI)000465561400093 ()2-s2.0-85065515173 (Scopus ID)
Projects
TEMPO
Funder
EU, Horizon 2020, 768936
Available from: 2019-04-04 Created: 2019-04-04 Last updated: 2023-08-28Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-7525-6954

Search in DiVA

Show all publications