Hydrokinetic energy conversion systems are the electromechanical devices that convert kinetic energy of river streams, tidal currents, man-made water channels or waves into electricity without using a special head and impoundment. This new technology became popular especially in the last two decades and needs to be well investigated. In this study, the hydrokinetic energy conversion systems were reviewed broadly. They have been categorized into two main groups as current and wave energy conversion devices. Their technology, working principles, environmental impacts, source potential, advantages, drawbacks and related issues were detailed.
Coastal and Offshore Energy
Recognized as one of the most mature renewable energy technologies, wind energy has been developing rapidly in recent years. Many countries have shown interest in utilizing wind power, but they are concerned about the environmental impacts of the wind farms. The continuous growth of the wind energy industry in many parts of the world, especially in some developing countries and ecologically vulnerable regions, necessitates a comprehensive understanding of wind farm induced environmental impacts. The environmental issues caused by wind farms were reviewed in this paper by summarizing existing studies. Available mitigation measures to minimize these adverse environmental impacts were discussed in this document. The intention of this paper is to provide state-of-the-art knowledge about environmental issues associated with wind energy development as well as strategies to mitigate environmental impacts to wind energy planners and developers.
The biofuels community has shown considerable interest in the possibility that microalgae could contribute significantly to providing a sustainable alternative to fossil fuels. Microalgae species with high growth rates and high yields of oil that can be grown on domestic wastewater using nonarable land could produce biofuel without competing with agriculture. It is difficult to envision where the cultivation facilities would be located to produce the quantity of algae needed for fuels, given that these facilities must be close to wastewater treatment plants to save energy.
Researchers investigated a possible solution called Offshore Membrane Enclosures for Growing Algae for coastal cities. This system involved growing fast-growing, oil-producing freshwater algae in flexible, inexpensive clear plastic photobioreactors attached to floating docks anchored offshore in naturally or artificially protected bays. Wastewater and carbon dioxide from coastal facilities provided water, nutrients, and carbon. The surrounding seawater controlled the temperature inside the photobioreactors and killed any algae that might escape. The salt gradient between seawater and wastewater created forward osmosis to concentrate nutrients and to facilitate algae harvesting. Both the algae and forward osmosis cleaned the wastewater, removing nutrients as well as pharmaceuticals and personal care products, so-called compounds of emerging concern.
This report provided the results of two years of research into the feasibility of the Offshore Membrane Enclosures for Growing Algae system in which prototype systems were studied, built, and tested in seawater tanks. A 110-liter floating system was developed and scaled up to 1,600 liters. Algae’s ability to grow on and treat wastewater was described. The impact of biofouling on photobioreactors and forward osmosis membranes floating in the marine environment was considered. Life-cycle and technoeconomic analyses provided a perspective on what must be done to make this system commercially viable. Outreach efforts have carried the concept worldwide. sions from conversion for development.
Technological solutions to increase the efficiency of spatial use can play a key role as part of the toolbox of marine spatial planning. Co-locating of multiple ocean uses can potentially increase the production and enjoyment of the ocean while limiting impacts. However, a basic precondition for co-locating or coproduction is that all parties' private incentives are aligned. We use a case study of co-locating an offshore wind energy firm and a mussel aquaculture firm to assess the incentive structure for cooperation and to demonstrate that social benefits from co-locating exist. We find that there is room for cooperation between firms based on potential cost sharing and that the demonstrated social benefits may arise without government intervention.
European consumers are willing to pay more for “green” electricity, as they highly value renewable energy sources for the contribution to combating climate change. There is a push for getting higher levels of sustainability, leading to a differentiation of Europe‘s electricity market. In this differentiation, the large potential of wind energy is recognized. More specifically, North Sea countries prefer to plan wind arrays (far) out at sea. This article offers a review of the main arguments for offshore wind energy, described in comparison with its onshore counterpart. It is stated that offshore wind farms (OWFs) generate “dark green” electricity as they mitigate greenhouse gas emissions and contribute to the protection of (some) marine life. Applying an informational governance framework, this article further assesses whether this dark green message has been exploited through further differentiation of the electricity market, and provides an analysis of why this is not (yet) the case. It is concluded that the dominant discourse in onshore wind power development hinders a favorable ecological differentiation toward offshore wind power.
Marine renewable energy developments (MREDs) are an increasing feature of the marine environment. Owing to the relatively small number of existing developments and the early stage of their associated environmental monitoring programmes, the effects of MREDs on seabirds are not fully known. Our ability to fully predict potential effects is limited by a lack of knowledge regarding movements of seabirds at sea. We used GPS tracking to improve our understanding of the movements at sea of a protected seabird species breeding in Scotland, the great skua (Stercorarius skua), to better predict how this species may be affected by MREDs. We found that the overlap of great skuas with leased and proposed MREDs was low; particularly with offshore wind sites, which are predicted to present a greater risk to great skuas than wave or tidal-stream developments. Failed breeders overlapped with larger areas of MREDs than breeding birds but the overall overlap with core areas used remained low. Overlap with wave energy development sites was greater than for offshore wind and tidal-stream sites. Comparison of 2011 data with historical data indicates that distances travelled by great skuas have likely increased over recent decades. This suggests that basing marine spatial planning decisions on short-term tracking data could be less informative than longer-term data.
The sustainable development of the offshore wind and wave energy sectors requires optimising the exploitation of the resources, and it is in relation to this and the shared challenge for both industries to reduce their costs that the option of integrating offshore wind and wave energy arose during the past decade. The relevant aspects of this integration are addressed in this work: the synergies between offshore wind and wave energy, the different options for combining wave and offshore wind energy, and the technological aspects. Because of the novelty of combined wave and offshore wind systems, a comprehensive classification was lacking. This is presented in this work based on the degree of integration between the technologies, and the type of substructure. This classification forms the basis for the review of the different concepts. This review is complemented with specific sections on the state of the art of two particularly challenging aspects, namely the substructures and the wave energy conversion.
The main objective of this paper is to establish an economic modelling of wave energy through a Geographical Information System (GIS). Furthermore, this method has been tested for the particular case of the Portuguese coast. It determines the best sea areas to install wave energy converters in this region, using spatial analysis of the Levelized Cost of Energy (LCOE). Several economic parameters, as capital or O&M costs, have been considered. In addition, a sensitivity analysis has been performed by varying the discount rate in three different scenarios. Several types of physical restrictions have been taken into account: bathymetry, submarine electrical cables, seabed geology, environmental conditions, protected areas in terms of heritage, navigation areas, seismic fault lines, etc. Spatial operations have been carried out to complete the procedure, using Model Builder of GIS software. Results indicate the most suitable areas in economic terms in Portugal to install wave energy devices.
Drawing on a case study in Germany, this contribution explores the practical application of offshore aquaculture within offshore wind farms in view of the different stakeholders involved. Using a transdisciplinary research approach, an understanding of the rationalities and interests among the different involved stakeholder groups was explored. Offshore wind energy is high on the political agenda in Germany. The vast spatial requirements however inherit potential user conflicts with competing, and under current legislation excluded users such as fishermen. Solutions for combining sustainable uses of the same ocean space have thus seen increasing interest within the research community in Germany and in Europe over the past years. This paper was inspired by and presents the outcomes of a stakeholder analysis and in particular a stakeholder workshop. Central focus was placed on academics and private as well as public stakeholders engaged in current research efforts of combining offshore wind farms and aquaculture in the German North Sea. The paper identifies the overall acceptance of such a multi-use scenario in society, opportunities and constraints as perceived by the stakeholders, and key research gaps. The results confirm the assumption that there is a clear need, and also willingness on behalf of the policy makers and the research community, to find sustainable, resource- and space-efficient solutions for combined ocean use.