uu.seUppsala University Publications
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Impact of Tidal Level Variations on the Wave Energy Absorption at Wave Hub
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
2016 (English)In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 9, no 10, 843Article in journal (Refereed) Published
Abstract [en]

The energy absorption of the wave energy converters (WEC) characterized by a limited stroke length - like the point absorbers developed at Uppsala University-depends on the sea level variation at the deployment site. In coastal areas characterized by high tidal ranges, the daily energy production of the generators is not optimal. The study presented in this paper quantifies the effects of the changing sea level at the Wave Hub test site, located at the south-west coast of England. This area is strongly affected by tides: the tidal height calculated as the difference between the Mean High Water Spring and the Mean Low Water Spring in 2014 was about 6.6 m. The results are obtained from a hydro-mechanic model that analyzes the behaviour of the point absorber at the Wave Hub, taking into account the sea state occurrence scatter diagram and the tidal time series at the site. It turns out that the impact of the tide decreases the energy absorption by 53%. For this reason, the need for a tidal compensation system to be included in the design of the WEC becomes compelling. The economic advantages are evaluated for different scenarios: the economic analysis proposed within the paper allows an educated guess to be made on the profits. The alternative of extending the stroke length of the WEC is investigated, and the gain in energy absorption is estimated.

Place, publisher, year, edition, pages
2016. Vol. 9, no 10, 843
Keyword [en]
wave energy converter (WEC), tides, Wave Hub, energy absorption, economic analysis
National Category
Ocean and River Engineering
Identifiers
URN: urn:nbn:se:uu:diva-295599DOI: 10.3390/en9100843ISI: 000388578800084OAI: oai:DiVA.org:uu-295599DiVA: diva2:934095
Funder
Swedish Research CouncilÅForsk (Ångpanneföreningen's Foundation for Research and Development)Carl Tryggers foundation
Available from: 2016-06-08 Created: 2016-06-08 Last updated: 2017-01-02Bibliographically approved
In thesis
1. Sea Level Compensation System for Wave Energy Converters
Open this publication in new window or tab >>Sea Level Compensation System for Wave Energy Converters
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The wave energy converter developed at Uppsala University consists of a linear generator at the seabed driven by the motion of a buoy on the water surface. The energy absorbed by the generator is negatively affected by variations of the mean sea level caused by tides, changes in barometric pressure, strong winds, and storm surges.

The work presented in this doctoral thesis aims to investigate the losses in energy absorption for the present generation wave energy converter due to the effect of sea level variations, mainly caused by tides. This goal is achieved through the modeling of the interaction between the waves and the point absorber. An estimation of the economic cost that these losses imply is also made. Moreover, solutions on how to reduce the negative effect of sea level variations are discussed. To this end, two compensation systems which adjust the length of the connection line between the floater and the generator are designed, and the first prototype is built and tested near the Lysekil research site.

The theoretical study assesses the energy loss at about 400 coastal points all over the world and for one generator design. The results highlight critical locations where the need for a compensation system appears compelling. The same hydro-mechanic model is applied to a specific site, the Wave Hub on the west coast of Cornwall, United Kingdom, where the energy loss is calculated to be about 53 %. The experimental work led to the construction of a buoy equipped with a screw jack together with its control, measurement and communication systems. The prototype, suitable for sea level variations of small range, is tested and its performance evaluated. A second prototype, suitable for high range variations, is also designed and is currently under construction.

One main conclusion is that including the compensation systems in the design of the wave energy converter will increase the competitiveness of the technology from an economic point of view by decreasing its cost per kWh. The need for a cost-effective wave energy converter with increased survivability emphasizes the importance of the presented research and its future development.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2016. 71 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1386
Keyword
Ocean energy, Tides, Linear generator, Point absorber, Offshore experiment, Hydro-mechanic modeling, Power absorption, Control system, Communication system, Measurement system, Lysekil research site, Wave Hub.
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-295603 (URN)978-91-554-9613-5 (ISBN)
External cooperation:
Public defence
2016-09-09, Polhemsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 09:15 (English)
Opponent
Supervisors
Available from: 2016-08-19 Created: 2016-06-08 Last updated: 2016-08-25

Open Access in DiVA

fulltext(6845 kB)88 downloads
File information
File name FULLTEXT01.pdfFile size 6845 kBChecksum SHA-512
367571851f57d9c59a5ef575e4dbc90d050c8e98f7a87b5429c2c8459960ba837fc739757de8a9c9e0dcbc7419c27ddbbb06830b1510a7f6a8db67fb9fbcc59a
Type fulltextMimetype application/pdf

Other links

Publisher's full text

Search in DiVA

By author/editor
Castellucci, ValeriaEriksson, MikaelWaters, Rafael
By organisation
Electricity
In the same journal
Energies
Ocean and River Engineering

Search outside of DiVA

GoogleGoogle Scholar
Total: 88 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 312 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf