Roger H. Charlier and John Justus. Ocean Energies : Environmental, Economic, and Technological Aspects of Alternative Power Sources. Elselvier, 1993. (p. 325). J Wolf, IA Walkington, J Holt, R Burrows. Environmental Impacts of Tidal Power Schemes. Proudman Oceanographic Laboratory, The University of Liverpool, Department of Engineering, p.2.
J Wolf, IA Walkington, J Holt, R Burrows. Environmental Impacts of Tidal Power Schemes. Proudman Oceanographic Laboratory, The University of Liverpool, Department of Engineering, p.3.
A channel connects two basins with different tidal elevations. At any instant the current through the channel has speed u, a function of the local cross-sectional area A(x), where x is the along-strait coordinate. At the channel entrance the current enters from all directions, but at the exit it may separate as a jet with speed ue, surrounded by comparatively stagnant water with elevation the same as that in the downstream basin. IN ENGLISH: Tidal streams are caused by the familiar rise and fall of the tides, which occurs twice a day around the UK coast. As water flows in and out of estuaries, it carries energy. The amount of energy it is possible to extract depends on the speed of the flowing stream and the area intercepted. This is similar to wind power extraction, but because water is much denser than air, an equivalent amount of power can be extracted over smaller areas and at slower velocities.
The scaled maximum power as a function of a parameter λ′, representing the frictional drag associated with the turbines, for various values of n where the turbine drag is assumed proportional to the nth power of the current speed.
http://www.esru.strath.ac.uk/EandE/web_sites/01-02/RE_info/tidal1.htm. The commercial system under development by MCT is known as “SeaGen” . The prototype is operational in Strangford Narrows, Northern Ireland, and uses twin 16m diameter rotors to develop a rated power of 1.2MW at a current velocity of 2.4m/s. The system is accredited to OFGEM as an official UK generating station and regularly runs at full rated power. It has the capability to deliver about 10MWh per tide, which adds up to 6,000MWh per year. This is approximately the rate of energy capture that a wind turbine of about 2.4MW rated capacity can typically produce. So SeaGen shows that the tides are not only more prodictable than wind but twice as productive. Photo: http://interestingenergyfacts.blogspot.com/2008/04/tidal-power-tidal-energy-facts.html
http://en.wikipedia.org/wiki/File:DTP_T_dam_top-down_view.jpg Similar to a barrage, except the dam extends perpendicular to the shore to capture the tides which flow laterally across the shoreline. The dam does not fully enclose the tidal estuaries. The tide is halted by the dam and creates a large differential (head) which flows over the turbines and generates electricity like a traditional hydrokinetic dam.
Maine Tidal Energy Company , 2008 WL 4612931 (F.E.R.C 12666-001, 2008).
16 U.S.C. §§ 797(f) and 798 (West 2010). 2008 WL 4612931 (F.E.R.C.), 3 (citing National Wildlife Federation , et al. v. Federal Energy Regulatory Commission , 801 F.2d 1505, 1514 (9th Cir. 1986)).
Tidal Energy Febrianto Wahyu Utomo 2209100010Pembangkit dan Manajemen Energi Listrik Teknik Sistem Tenaga – Teknik Elektro Institut Teknologi Sepuluh Nopember Surabaya
Roadmap∗ First we will explain the basics about tides, tidal energy, and the different types of tidal energy capture systems.∗ The first major system, Tidal Barrages, will be discussed in detail, with a focus towards the only major commercial tidal energy power plant, the La Rance Tidal Barrage.∗ The second system, Tidal Stream Generation, seems favored in the US for proposed tidal energy.∗ The third system, Dynamic Tidal Power, is the latest, most theoretical form.∗ Finally, we conclude our presentation with a discussion of the practical steps necessary before we see a tidal plant in the US.
The Tides• Tidal energy comes from the gravitational forces of the Sunand the Moon on the Earth’s bodies of water, creatingperiodic shifts in these bodies of water.•These shifts are called tides.
Tidal Energy∗ Millions of gallons of water flow onto shore during tidal flows and away from shore during ebb tide periods.∗ The larger the tidal influence, the greater the displacement of water and therefore the more potential energy that can be harvested during power generation.∗ The tides are perfectly predictable, regular, and the US contains miles of coastline for energy exploitation.
The Long History of Tidal Energy • Tidal power buildings were built as early as the 9th Century throughout Europe. • This building was built in Ohalo, Portugal circa 1280.
Tidal Energy∗ Tidal energy is one of many forms of hydropower generation.∗ Tidal power has many advantages as compared to other forms of renewable energy. ∗ It is predictable ∗ Global Climate Change should only increase its generating capacity due to higher ocean levels. ∗ It is completely carbon neutral like wind or hydro energy.∗ Its main drawbacks include: higher cost of installation, limited availability for ideal siting, environmental impacts on local area, including flooding and ecological changes, and the inflexible generation schedule (not timed to peak consumption).
Different Types of Tidal Plants∗ Tidal Barrages ∗ These involve the creation of mammoth concrete dams with sluices to create grander scale operations than the 12th century tide mills.∗ Tidal Stream Generators ∗ Very similar to the principles in wind power generation – water flows across blades which turn a turbine much like how wind turns blades for wind power turbines.∗ Dynamic Tidal Power ∗ This is a technology that is not currently commercial viable, but in which the UK, Korea, and China invested heavily to research. It involves a partial dam which raises the tidal height and several hydropower generators. The differences in height between the head of the dam and the low tide coast force water through the generator, much like a traditional hydropower dam.
Tidal Barrage• The first commercial tidal power plant in theworld since the middle ages is the La Rance TidalBarrage in France.• The barrage was constructed in 1960 andconsists of a 330m long dam with a 22km2 basin.The effective tidal range is 8m.• The work was completed in 1967 when 24 5.4mdiameter bulb turbines, rated at 10MW each, wereconnected to the French power network with a225kV transmission line.• The French authorities decided on a bulb turbinewith axial power generation because it suited thestyle of a tidal barrage as it flows from the head ofthe dam to the basin through the turbine.
Tidal Barrage Cont’d∗ Calculating the total energy production of the La Rance plant is easy if you know some key facts: ∗ The La Rance plant has 24 generators with a 10MW capacity: ∗ The equation is as follows: Maximum Electricity generated per annum (kWh) = Generator capacity * time + Cf (capacity factor) The particular generator used in this plant had a Cf of 40%, resulting in 3504MWh per year per generator.
Tidal Barrage Drawbacks∗ There are notable complications with tidal barrage energy generation∗ While they generate comparable power to hydropower plants, they also have economic and environmental issues ∗ The necessary infrastructure to build a tidal barrage is cost prohibitive. ∗ Tidal barrages negatively affect the turbidity, water levels, and ecology of the separated areas.
Tidal Barrage Drawbacks Cont’d∗ Benthic habitats may change due to the bottom stress from modified waves and currents.∗ Migratory fish may be impeded although fish passes can be constructed to facilitate migrations.∗ Fish and marine mammals may suffer injuries and death when colliding with the barrage/turbines.∗ Estuaries that are currently providing breeding spaces for fish, may not be suitable for this purpose after construction.
Effects on Turbidity∗ Because the tides are being captured, the turbidity of the La Rance estuary more closely resembles lower tidal basins.∗ The high turbidity regions have shrunk, affecting the preferences of wildlife who lived in the pre-barrage La Rance estuary.
Effects of Turbidity∗ UK government reports made while preparing to evaluate the suitability of barrage style tidal power plants in the UK contain observations of the barrages have on the environment, including forecasted effects on UK tidal estuary systems.
Other Ecological Effects∗ The increasing sea exchange (due to pumping to increase water head, and therefore generating capacity) has increased the invertebrate breeding capacity.∗ The outer estuary is now being fed by the inner estuary, which is a role reversal due solely to the barrage’s effect on the ecology and hydrology of the region.
Ecological Effects Cont’d∗ Shorebird prevalence has increased, but this is a nationwide trend across France. ∗ The primary attributing force for the increased shorebird populations are the increasing invertebrate life which is the primary source of food for shorebirds.∗ Like shorebirds, fish diversity and biomass have increased due to the greater availability of invertebrate life that sustains these fish stocks. ∗ However, some fish species cannot traverse through the barrage and these species are no longer present. ∗ The new types of fish have displaced these original fish stocks and have thrived. ∗ Due to the dual flow nature of tidal barrages, fish mortality from turbine blades is nearly twice that of other hydropower.
Economic Issues∗ The capital costs of a barrage like La Rance are tremendous because of the sheer scope of a project and the few sites around the world that are suitable for tidal power generation.∗ The company that administers the La Rance power plant now claims that the capital investments in the barrage have been paid off and currently the power plant generates cheaper electricity than a nuclear power plant. (1.6 cents per kWh vs. 2.5 cents per kWh for a nuclear plant).
Tidal Stream Generators• The world’s only operational commercial-scaletidal turbine, SeaGen, was installed in StrangfordNarrows in Northern Ireland in 2008.• The prototype SeaGen turbine produces 1.2MWwith currents of 2.4m/s or more. The capacityfactor exceeds 60%.• The facility is an accredited UK power station,and can contribute up to 6,000MWh annually tothe UK grid, the equivalent of approximately 1500homes.
Room to Grow• Plans are underway to install a tidal farm in KyleRhea, a strait of water between the Isle of Skyeand the Scottish mainland• The project will have the capacity to generateelectricity for up to 4,000 homes in the ScottishHighlands & Islands by harnessing the power of thefast tidal currents that pass through Kyle Rhea 14hours a day.• The parent company, Marine Current Turbines(MCT), estimates that the cost of the 5MW KyleRhea scheme, consisting of four SeaGen tidal units,will be £35million.
Drawbacks of Tidal Stream Generators∗ High start-up and construction costs: due to limited experience of installing, operating and maintaining plants, contractors’ perceptions of risk are likely to be reflected in higher costs.∗ Like the wind, waves and tidal streams are variable renewable energy sources. Their intermittent generation has implications for large scale grid integration.∗ Because the amount of energy tidal streams naturally varies over time, the power output of wave energy converters and tidal stream energy generators will also vary. This has implications for grid integration, particularly balancing supply and demand.
Economic Issues∗ Although the capital costs of tidal stream generators can be quite high, there is preliminary evidence that the installation of these facilities gives support to local economies because local firms can expect to participate in the tidal farm’s installation, operation and maintenance.∗ The company that administers MCT’s project in Northern Ireland notes that a number of local companies such as marine support vessels, engineering and electrical contractors, civil engineers, environmental scientists and divers as well as local hotels, pubs and restaurants have benefited from the Strangford Lough project. It is estimated that the project has contributed more than £4million into the Northern Irish economy over the past three years
Environmental Impacts of Tidal Stream Generation
Environmental Effects∗ Studies to date suggest that local environmental impacts are likely to be minor, but further research is required into device-environment interactions, particularly the impact of tidal stream energy generators on flow momentum.∗ Although the generators create no noise audible to humans, they do create “modest” noise underwater. Manufacturers maintain that this is important to help marine wild-life have an awareness of the presence of the turbine.
Environmental Effects, cont’d:∗ MCT’s information for the project in Northern Ireland notes that, “rigorous and detailed environmental impact studies, carried out by independent consultants, suggest that the technology is most unlikely to pose a threat to fish or marine mammals, or the marine environment in which they live. A major monitoring programme is already under way for the SeaGen device installed in Strangford Narrows which will build upon this work.”
Dynamic Tidal Power∗ Similar to tidal barrage method with similar advantages and disadvantages. ∗ Capital intensive and has a large, dominant footprint. ∗ With DTP the dam does not fully separate the sea from the tidal estuary. ∗ This minimizes some environmental effects but also slightly diminishes the tidal energy captured as a result of each ebb and flow. ∗ No commercial implementation, purely theoretical at this time.
Dynamic Tidal Power∗ Utilizes a special type of turbine that should increase the efficiency of the tidal energy capture.
Practical Steps Regarding Tidal Energy∗ The EISA of 2007, Title II, has specific provisions for hydrokinetic energy sources. ∗ It provides in Subtitle C, Section 621 et seq.: ∗ Research and development ∗ A lack of specific mandates or priority on federal land. ∗ Coastal management with state lands (CMZA).∗ Energy Policy Act of 2005, §931 directs the Secretary of Energy to conduct research and development (R&D) programs for ocean energy, including wave energy and kinetic hydrogeneration projects, and §388 amends §8 of the Outer Continental Shelf Lands Act (43 U.S.C. §1337) to grant authority to the Secretary of the Interior to grant leases on the Outer Continental Shelf (OCS) for the production of energy from sources other than oil and natural gas.
Steps for Permit∗ File for a preliminary permit subject to 4(f) of the Federal Power Act to preserve priority of permit status while: ∗ Conduct studies to determine the feasibility of the proposed project. ∗ Design specs are reviewed∗ Preliminary permit does not grant title to land, but instead sparks the public comment process per APA regulations.
Permit Steps Cont’d∗ Licensing provisions are fashioned from the consideration of the studies on feasibility and environmental and social impacts and the public comment process.∗ Commission decides whether to grant preliminary permit and whether to grant a license. ∗ Similar to other proceedings under FPA and procedures under the APA.
Current Legal Issues Regarding Proposed Tidal Plants in the US∗ Section 4(e) of the FPA directs the Commission to give equal consideration to the purposes of power and development, energy conservation, fish and wildlife, recreational opportunities, and preservation of environmental quality “in deciding whether to issue a license.”∗ (National Wildlife Federation).
Current Issues Cont’d∗ Similarly, sections 10(a) and 10(j) are prefaced with the direction that “all licenses issued under this subchapter” shall include the conditions required by sections 10(a) and 10(j).
Tidal Energy: Worldwide distribution Cost-effective technology Multiple benefitsTidal Energy should join other clean,renewable sources of energy, such assolar, wind, biofuels, and low-headhydro, in receiving official, internationalsupport and funding for itsdevelopment.development
The Worldwide Distribution of Tidal EnergyGrey areas in the ocean have the most intense tidal energy.
Almost all nations can receive significant benefits from Tidal/Current/River Energy Turbines ________________________________________Applicable wherever water speeds reach above 2 knotsAll coastal nations with tidal passes or channels between coral reefs oroffshore islandsTidal energy is extremely reliable: runs every day like clockworkTidal energy is very predictable: can be accurately calculated a thousandyears from nowStrong ocean currents, for example Gulf StreamRivers, especially in hills. Hydro-electric without dams.
Tidal Energy can be captured efficiently and inexpensively using the helical turbineSchematic view of a helical turbine mounted in a frame
Features of the helical turbine IBasic concept:∗ designed for hydroelectric applications in free-flowing water∗ operates in ocean, tidal, and river currents∗ does not require expensive dams that can harm the environment∗ Operation:∗ self-starting with flow as low as 0.6 m/s∗ smooth-running∗ rotates in same direction regardless of the direction of flow, making it ideal for tidal applications
Features of the helical turbine II Efficiency: 35% In testing at the University of Michigan Hydrodynamic Laboratory
Multiple benefits from Tidal Energy include∗ Electrification of isolated communities∗ Power for the grid∗ Regrowing coral reefs using mineral accretion technology∗ Substituting imported petroleum fuel∗ Practical examples of the first three benefits are given on the pages that follow
The Tide-Energy ProjectNear the Mouth of the Amazon Applying helical turbine technology at a small scale to generate electricity for rural communities
Project goal: use Tidal Energy to generate electricity We have developed technology that enables rural residents to meet energy needs in a way that is: economical, decentralized, and environmentally soundTidal Energy: clean, renewable, and proven As we will show, with modern technology there is no doubt that it is practical, efficient, and cost-effective to capture Tidal EnergyA requirement: decentralized technology Near the mouth of the Amazon, rural residents are dispersed and cannot be reached economically by power lines from central generators. The only decentralized options available to them now are: solar panels and diesel generation.
An important breakthrough: the helical turbine Rural artisans with a 6-blade helical turbineThe man at the left is a skilled woodworker, and on the right, a skilledmechanic. With the aid of a local metal-working shop, they built theturbine frame. They then installed the blades and now operate theturbine.
Generating equipment I (c) (b) Pulley Automotive and belt alternator (a) 6-blade helical turbine
Generating equipment IIConfiguration:∗ The helical turbine rotates on a shaft with a pulley that runs an alternator by means of a belt.∗ The alternator charges batteries, as is usual with other intermittent sources—solar and wind—when used off the grid.The result: accessible technology• About 90% of a Tide Energy station can be built usinglocally available labor, materials, and equipment.• Only the technically refined helical turbine blades areoutside components.Benefits:• Energy production: 120 A-h/day• Sufficient to meet basic needs of 10 households—at World Bankand Brazilian government standards for rural, solar electrificationprojects.
Numbers on: InvestmentEnergy production: 120 A-h/day∗ 8 solar panels (75 Wp), installed: US$ 5690∗ Tide-Energy generating station: US$ 2800 Note: investment estimated on pre-pilot project data.The result: affordable technology• Tide-Energy generating station: US$ 2800• Small diesel-powered boat: US$ 2500-3000Adopting Tidal Energy technologyThousands of rural residents in the region now own small, diesel-powered boats. This technology was adopted by them over the lasttwenty-five years at their own cost, with no outside incentives orsubsidies.If they see Tidal Energy technology to be to their advantage, we areconfident that they will also adopt it.
Numbers on: Annual operating costs (120 A-h/day)*∗ 1000 VA diesel generator: US$ 1397∗ Tide-Energy generating station: US$ 824 * Includes fuel, labor, maintenance, and depreciationThe result: profit and high returnFor a single Tide-Energy generating station: Annual Receipts (charging 5 batteries/day) 1750 Costs (labor, maintenance, and depreciation) 824 Profit US$ 926Return on investment: 33% Note: cost and receipts estimated on pre-pilot project data.Overall: producing energy and jobsFor a single Tide-Energy generating station:• Investment requires 7½ worker-months of skilled and unskilledlabor.• Annual maintenance requires ½ worker-month of skilled labor.• Normal operation requires a ½ time job.
Present situation: beginning the pilot phasePilot phase activities include:• Operation of the station by local community members for ayear.• Close monitoring of the full costs and benefits.$ We are seeking funding to carry this out.For more information:The Tide-Energy Project Near the Mouth of the Amazon Scott Anderson, Project Coordinator +1 (352) 246-8246 (mobile) firstname.lastname@example.org http://globalcoral.org/Tide_Energy_Overview_English.doc
Tidal Energy at the Uldolmok Strait, Korea Testing of the Gorlov Helical Turbine designed and built by GCK Technology, Inc. conducted by theKorea Ocean Research & Development Institute (“KORDI”)
The inventor, Dr. Alexander Gorlov,with a sub-unit of the Gorlov Helical Turbine (“GHT”) during construction of the GHT (1m diameter, 2.5 m length) tested by KORDI in the Uldolmok Strait.
The first tidal powergeneration from a GHT was on July 10, 2002. The 1 meter GHT turned at 160-180 rpms in a 4 knot current and generated 8-10 kW.
Features of the Helical Turbine Installation Cost: dollars/kw14000130001200011000 Red: high estimate10000 Blue: low estimate 9000 8000 7000 6000 5000 4000 3000 2000 1000 0 R O L D R L S IL A A A LA A IN R O ID O LE G D O W C Y C T S H U N Source: GCK Technology, Inc.
GORLOV’S CONCEPTUAL DESIGNfor a floating power station in the Uldolmok Strait
KORDI ESTIMATES OF TIDAL POWER IN THE JIN-DO ISLAND AREA Uldolmok Strait = 470 MW Jaing Juk Strait = 1,230 MW Maeng Gol Strait = 1,910 MW TOTAL = 3,610 MWThis is the equivalent of 3.5 nuclear power plants