Logotyp: till Uppsala universitets webbplats

This paper provides a summarized status update ofthe Lysekil wave power project. The Lysekil project is coordinatedby the Div. of Electricity, Uppsala University since 2002, with theobjective to develop full-scale wave power converters (WEC). Theconcept is based on a linear synchronous generator (anchored tothe seabed) driven by a heaving point absorber. This WEC has nogearbox or other mechanical or hydraulic conversion systems,resulting in a simpler and robust power plant. Since 2006, 12 suchWECs have been build and tested at the research site located atthe west coast of Sweden. The last update includes a new andextended project permit, deployment of a new marine substation,tests of several concepts of heaving buoys, grid connection,improved measuring station, improved modelling of wave powerfarms, implementation of remote operated vehicles forunderwater cable connection, and comprehensive environmentalmonitoring studies.

Active acoustics monitoring (AAM) systems can play an important role in the inspection and survey of the subsea environment around marine renewable energy devices, especially in murky and deep waters. Alternative methods comprising a multifunctional platform based on multibeam (MBS) and Dualbeam (DBS) sonar systems are being developed. The aim is to monitor the environmental impacts during installation, operation and maintenance of wave energy converters, marine current turbines, subsea substations and other offshore renewable energy technologies. At this initial phase, one of the specific objective is to understand the functionality of AAM systems. Field tests were done using the MBS and DBS systems. A platform is being tested at the Lysekil Wave Power Project test site and at the Söderfors Marine Current Project test site. Preliminary results show that the MBS produces better acoustic images when the platform is steady, and when in slow-moving waters such as in harbours and shallow rivers. At near field, the MBS is able to track targets < 20 cm such as fish swimming close to hard structures. The DBS can detect isolated targets at far field. Target dimensions estimated using the sonar match the real dimensions of the same´targets.

Marine renewable energy is emerging as one of the fast-growing industry in the last decades, as modern society pushes for technologies that can convert energy contained from winds, waves, tides and stream flows. The implementation of renewable energy technologies impose high demands on both structural and environmental engineering, as the energy converters have to work under extreme conditions where parameters such as sea-bottom configuration, water transparency and depth, sea-states and prevailing winds are harsh. Constant monitoring of the marine environment is crucial in order to keep this sector reliable. Active acoustics is becoming a standard tool to collect multi-dimensional data from physical, geological and biological properties of the marine environment. The Div. of Electricity of Uppsala University have been developing an environmental monitoring platform based on sonar (Sound Navigation And Raging) systems. This platform aims to monitor the installation, operation and decommissioning of marine renewable energy converters. The focus will be given the observations of behaviours of marine animals in vicinity of energy converters but also structural inspection and monitoring of MRETs. This paper describes how this multifunctional environmental monitoring platform come to existence from the design to the deployment phase.

The access and quality of electricity are key factors for sustainable development. Off grid areas across the globe, in particular the rural areas in Africa, are in the need of renewable energy technologies as reliable electricity providers. Dedicated investments and technical reforms are needed in the renewable energy sector in order to diversify, expand and proliferate technologies able to provide reliable and affordable electricity for all. A specific case is Ghana where the electrification rate is approximately 79 %, but the utilization rate is approximately 35 %. To improve the current situation, different renewable energy systems should be brought into the power generation mix, and wave power can substantially contribute to electricity generation in Ghana and other countries with wave power resources. The aim of this study was to evaluate the wave power resource availability in Ada, Ghana, where a 100 MW wave power farm is planned to be located, and estimate the quantity of electricity that can be generated using different capacity factors. The results show that the wave climate in Ghana is mild with annual mean values of significant wave height of ca. 1.3 m, energy period of ca. 12 s and wave power value of ca. 10 kW/m. The availability, capacity factors and electricity generation were estimated to be high during the most of the year with exceptions for May, November and December. Estimated annual electricity generation were 175 GWh, to 610 GWh, for capacity factors in the range of 25%, 50% and ca. 70%, respectively. This study conclude that the annual resource availability factor is ca. 80%, suggesting that a wave power farm would be able to produce electricity during the most of the annual cycle. If these result were to be confirmed, wave power will be considered a dependable technology for electricity generation in countries such as Ghana and possibly qualify as baseload in the electricity generation mix.