Showing papers on "Marine energy published in 2005"

The power potential of tidal currents in channels

Abstract: Interest in sources of renewable energy has led to increasing attention being paid to the potential of strong tidal currents. There is a limit to the available power, however, as too many turbines will merely block the flow, reducing the power generated. The maximum average power available from a tidal stream along a channel, such as that between an island and the mainland, is estimated and found to be typically considerably less than the average kinetic energy flux in the undisturbed state through the most constricted cross-section of the channel. A general formula gives the maximum average power as between 20 and 24% of the peak tidal pressure head, from one end of the channel to the other, times the peak of the undisturbed mass flux through the channel. This maximum average power is independent of the location of the turbine ‘fences’ along the channel. The results may also be used to evaluate the power potential of steady ocean currents.

Ocean Wave Energy Conversion

Abstract: Ocean energy conversion has been of interest for many years. Recent developments such as concern over global warming have renewed interest in the topic. This report focuses on wave energy converters (WEC) as opposed to ocean current energy converters. The point absorber and oscillating water column WEC devices are addressed with regards to commercial prospects, environmental concerns, and current state-of-the art. This report also provides an overview of the energy found in ocean waves and how each type of device utilizes the available ocean wave energy. J. Vining. University of Wisconsin Madison. Dec. 2005. Ocean Wave Energy Conversion. ii

The Energetics of Ocean Heat Transport

Abstract: A number of recent papers have argued that the mechanical energy budget of the ocean places constraints on how the thermohaline circulation is driven. These papers have been used to argue that climate models, which do not specifically account for the energy of mixing, potentially miss a very important feedback on climate change. This paper reexamines the question of what energetic arguments can teach us about the climate system and concludes that the relationship between energetics and climate is not straightforward. By analyzing the buoyancy transport equation, it is demonstrated that the large-scale transport of heat within the ocean requires an energy source of around 0.2 TW to accomplish vertical transport and around 0.4 TW (resulting from cabbeling) to accomplish horizontal transport. Within two general circulation models, this energy is almost entirely supplied by surface winds. It is also shown that there is no necessary relationship between heat transport and mechanical energy supply.

On Assessing the Reliability and Availability of Marine Energy Converters: the Problems of a New Technology

Abstract: There is now considerable interest in marine renewable energy both in the UK and elsewhere in the world with the growing recognition that fossil fuel supplies are finite and further increases in ca...

Direct drive electrical power take-off for offshore marine energy converters:

Abstract: This paper investigates the issues associated with converting the energy produced by marine renewable energy converters, namely wave and tidal stream devices, into electricity using direct drive electrical power take-off, without use of complex pneumatic, hydraulic or other mechanical linkages. In order to demonstrate the issues, two alternative topologies of linear electrical machines are investigated: the linear vernier hybrid permanent magnet machine and the air-cored tubular permanent magnet machine. The electrical characteristics of these machines are described and compared in the context of mechanical integration. Potential solutions to the issues of sealing, corrosion and lubrication are discussed taking into account the electrical properties of the two topologies.

A tubular generator for marine energy direct drive applications

Abstract: The paper illustrates the operation of a tubular machine as a linear generator for reciprocating energy sources. Reciprocating energy sources utilization is rapidly increasing nowadays due to the interests in marine energy. Linear generators adopted in marine power plants, offer the advantage of generating without introducing any conversion crank gear or hydraulic system. The use of tubular machine topology allows to improve electromagnetic thrust density. The paper shortly summarizes the principles of the marine wave buoy interaction and reports the design analysis and control of a PM synchronous tubular linear machine based on a scaled prototype

Tidal energy in electric power systems

Abstract: This paper discusses the uses and advantages of tidal energy in restructured power systems. The paper defines the resources as well as the ways in which tidal energy is converted into electricity. The paper also reviews a few tidal power projects around the world. It also shows the working of hydro tidal power plant. A comparative review of renewable energy sources is presented and conclusions are outlined.

Utility-Scale Wind Power: Impacts of Increased Penetration

Abstract: Intermittent renewable energy sources such as wind, solar, run-of-river hydro, tidal streams and wave fluxes present interesting challenges when exploited in the production of electricity, which is then integrated into existing and future grids. We focus on wind energy systems because they have an emerging presence, with new installed capacity approaching 8 GW annually. We survey many studies and compile estimates of regulation, load following and unit commitment impacts on utility generating assets with increasing wind penetration. Reliability (system reserve), observed capacity factors and the effective capacity (ability to displace existing generation assets) of wind energy systems are discussed. A simple energy balance model and some results from utility-scale simulations illustrate the existence of a law of diminishing returns with respect to increasing wind penetration when measured by wind’s effective capacity, fuel displacement or CO 2 abatement. A role for energy storage is clearly identified. Finally, the scale of wind energy systems is shown to be large for significant energy production and preliminary evidence is reviewed showing that extraction of energy from the atmospheric boundary layer by such systems, when penetration levels are significant, may have potential environmental impacts

Recent progress in offshore renewable energy technology development

Abstract: International treaties related to climate control have triggered a resurgence in development of renewable ocean energy technologies. Several demonstration projects in tidal power are scheduled to capture the tidal-generated coastal currents. Commercial-scale wave power stations exist and are delivering power to national grids. Offshore wind farms are delivering energy to shore. As government policies shift towards inclusion of renewable sources, the nearshore ocean resources have tremendous potential. Worldwide investments in renewable energy technologies reveals that offshore wind energy is the fastest growing sectors. Strong growth in offshore wind power installations is anticipated over the next decade. In 2000, development of systems to capture wave energy reached a milestone with the commissioning of the first commercial-scale power facility in Scotland. Technical capabilities, both engineering and management, exist in the offshore sector to undertake the size of projects envisioned. Harnessing the untapped potential of ocean energy has commenced.

Feasibility assessment of offshore wave and tidal current power production: a collaborative public/private partnership

Abstract: The Electric Power Research Institute (EPRI) and EPRIsolutions are conducting collaborative power production feasibility definition studies on offshore wave energy and tidal current energy on behalf of a number of public and private entities. The outcome of the offshore wave study, which began in 2004, is a compelling techno-economic case for investing in the research, development and demonstration (RD&D) of technology to convert the kinetic energy of ocean waves into electricity. The tidal current studies began in early 2005 and are currently at the site identification and device assessment stage (steps a and b below). Techno-economic results for tidal plant designs at various sites are expected in late 2005.

All at sea [tidal power]

Abstract: Being an island nation regularly feeling the force of the Atlantic down its western coasts, the UK is well placed to harness tidal and wave power. The largest single potential source of tidal energy in the UK lies in the Severn Estuary, where the tides are the highest in Europe. Developers believe a barrage built across the estuary could provide as much as 7% of the power needs of England and Wales. There are concerns, however, that the barrage could have a negative impact on the existing habitat and wildlife. Alternatives to the barrage have been put forward including the installation of tidal lagoons which would have a significantly less environmental impact than a full-bodied barrage.

Tidal current accelerating structure for electrical power generation

Abstract: The present invention relates to an underwater ocean structure designed to increase the velocity of tidal currents and therefore the electrical output of underwater turbines or similar devices positioned within the structure. Existing devices designed to convert ocean current energy into electricity are only economical in areas where available ocean current speed is very high, which restricts their applicability to only a few locations. The present invention will improve the economics of harvesting ocean current power from many coastal areas in the country.

Current Situation and Development Trend of Marine Industry in China

Abstract: China is rich in marine resources including 20 278 plant species and covering 818 000 square sea miles of fishing grounds. It is estimated that there are about 40 billion tons of oil resources and 14 trillion cubic meters of natural gas in China’s sea areas. Several hundred kilometers coast with deep-water resources are surrounded by more than 160 bays. Many spots along the coastline are suitable for constructing harbors and developing marine transportation systems. There are more than 1 500 scenic and recreational spots favorable for developing marine tourism. In addition, China's offshore areas abound in seawater and marine energy resources. China has witnessed a fast growth in marine economy since 1978. Marine economy is the total of various industries involved in sea exploration and related economic activities. Major marine industries of China include marine fisheries, ocean communication and transportation, coastal shipbuilding, ocean oil and gas, seaside tourism, seaside ore sand, marine biomedicine, seawater utilization and salt production, etc. The paper analyzed industrial structure of the marine industries of the country, and the sequence of output value of the major marine industries in coastal provinces, municipalities, and autonomous region of China using grey relational grade. The prediction via GM (1.1) model indicated the output value would be more than 1 500 billion Yuan in 2010 in China. Existing problems and development trend of China’s marine industries were discussed and the results show that marine industrial structure is unreasonable, marine economy develops unevenly among different areas, scientific and technological contribution rate is low, and the marine calamity is of great impact. During the new period, marine fisheries will continue to play an important role, the coastal tourism and maritime transport will be the leading marine industries. Meanwhile, the new marine industries such as marine medicine will have a good prospect in the future.

Marine renewables face paperwork barrier [marine power generation]

Abstract: This article discusses the UK's wave and tidal power industry. It begins by reviewing the current state of the technology and refers to government grants and investment issues. It then considers market costs for the generated electricity, licensing, power grid connection requirements, and reliability. It concludes by outlining the financial requirements for such a technology to become commercially viable.

Renewable Energies from the Ocean

Abstract: This chapter discusses wave, tidal, and ocean thermal energy. The principles involved in these various types of renewable ocean energy forms are discussed. Some earlier efforts toward harnessing these energy forms are also discussed. Two Indian case studies are presented, one of which is a wave-powered desalination system and the other is the design and installation of a 1-MW floating OTEC plant. It is concluded that harnessing ocean energies is challenging and needs several engineering and technological innovations. Keywords: wave; tidal; energy; desalination; power; renewable

Update '05: ocean wave and tidal power generation projects in San Francisco

Abstract: In summary, San Francisco's interest in the HydroVenturi approach is due to the value proposition of no moving parts underwater, compared to the underwater turbines of a LaRance river-type saltwater entranement, of a Blue Energy or Verdant Power vertical or horizontal axis-type propeller installation. A technology with no moving parts underwater makes tidal power attractive to San Francisco's well-established environmental community. This approach is viewed as the most environmentally benign for the bay area's endangered salmon runs, delta smelt, anchovies, dolphins, whales, seals, sea lions, and benthic creatures, other fish species and marine mammals. For these reason, San Francisco believes the time has come to harvest the City's tidal and ocean wave resources. Renewable energy development also creates jobs for the local community, at an anticipated rate of 10 jobs per Megawatt.

Ocean Energy: Nascent, Emerging and Mature Technologies

Abstract: The beginnings of a new ocean energy sector are now taking place. Offshore waves are being harnessed to satisfy the need for renewable, sustainable sources of energy. A shore-based oscillating water column (OWC) system has been feeding a national grid since 2002. This article examines such nascent and emerging technologies as the OWC and offshore wind energy potentials, and such mature technologies as Tensions Leg Platforms and innovative Spar buoys. The article examines the ramifications these trends have for technology innovation and development.

Wave, tide and ocean current promise more than wind. Part III - The Americas

Abstract: Wave and tidal power is more available, continuous, predictable, and more concentrated than offshore wind energy as well having lower visual impact on the environment. North America has a long history of wave and tidal power development and substantial prototypes are now being tested.

Direct drive electrical take-off for offshore marine energy converters.

Abstract: This paper investigates the issues associated with converting the energy produced by marine renewable energy converters, namely wave and tidal stream devices, into electricity using direct drive electrical power take-off, without use of complex pneumatic, hydraulic or other mechanical linkages. In order to demonstrate the issues, two alternative topologies of linear electrical machines are investigated: the linear vernier hybrid permanent magnet machine and the air-cored tubular permanent magnet machine. The electrical characteristics of these machines are described and compared in the context of mechanical integration. Potential solutions to the issues of sealing, corrosion and lubrication are discussed taking into account the electrical properties of the two topologies.

Complex marine energy production, involves raising level of water many meters above to cross natural level in building complex which is built in marine plot

Abstract: The energy production involves raising the level of water many meters above to cross natural level in a building complex which is built in a marine plot. The plot consists of a huge reservoir with a level higher than the sea level, and buildings where hydrostatic engines, turbines or other machinery produce electrical energy. The divergent wave enters the angle formed by two walls. A device is provided, which causes rupture towards the coast.

Output characteristics of tidal current power stations during spring and neap cycles

Abstract: With increasing targets being set for renewable-derived electricity generation, wind power is currently the preferred technology. It is widely accepted that due to the stochastic nature of wind, there is an upper limit to the capacity that can be accommodated within the electricity network before power quality is impeded. This paper demonstrates the potential of tidal energy as a predictable renewable technologies that can be developed for base load power generation and thus minimise the risk of compromising future power quality.

Computational study of tidal turbines for extracting energy from the tides

Abstract: The Kyoto agreement of 1997 was that each country that acceded the agreement will reduce or limit its greenhouse gas emissions, with exceptions for developing countries, by an amount agreed, such that the overall emissions of such gases is reduced by at least 5% compared to 1990 levels in the commitment period 2008 to 2012 [1]. Renewable energy is a viable option to reduce greenhouse gases. One of the most popular renewable sources is wind energy, whereby a single turbine with 66m diameter rotor blades is capable of producing 1.5MW. Another source of renewable energy is that harnessed from the sea. The gravitational force of attraction of the moon and sun on the earth and the rotation of the earth results in a rhythmic rise and fall of ocean levels relative to the coastline [2]. Thus, unlike wind and solar energy, tidal currents are predictable. In addition to this advantage the available power flux from the tide is around 500W/m 2 compared to 40W/m 2 for air. This is based on the density of water being some 815 times that of air and the tidal velocity of the order of 25% that of air. There is a large quantity of literature on the methods that can be utilised for extracting energy from the tides but the use of turbines in tidal streams, due to the advances in technology, is only now becoming reality with the world’s first full scale offshore tidal turbine being constructed in 2003 [3]. This paper assess a tidal turbine, using the Computational Fluid Dynamic (CFD) package FLUENT. Egarr et al [4] details validation of computational models of a 4 blade turbine. Modelling of a 3 blade turbine is presented in this paper alongside modelling a five turbine array.