Waves of energy
Transcripción
Waves of energy
TIDAL ENERGY | ENERGÍA DE LAS MAREAS SIEMENS Waves of energy The generation of electricity from tidal flows requires robust, proven, available, and cost effective technology. SeaGen-S 2MW, a Siemens project, is the most advanced, field proven tidal generation system available. As the pioneer and first mover in tidal the energy sector, MCT have developed and patented key features, that deliver commercially viable electricity generation. W hile solar and wind energy plants are becoming increasingly widespread as a means of obtaining green energy, there is one area that remains unexploited and that has great potential: energy from the sea. Waves are caused by the wind blowing on the open sea for hundreds or thousands of kilometres, transferring energy to the ocean’s surface. Thanks to recent technological advances, this kind of renewable energy could soon become a much more viable option. Today, renewable energies have become a fundamental component of energy policy. The European Union (EU) has set itself the ambitious objective of meeting 20% of if its energy needs from these kinds of energy sources by 2020. Many advances have been made in the quest for clean energy, which help to combat global warming and the limited supply of fossil fuels. Energy from the sea is one of the most efficient and powerful alternatives for obtaining energy from the natural world. In fact the power of the tides is an important force that has as yet not been exploited. According to the International Energy Agency, the sea could generate over 93,000 terawatt hours (TWh) of power. The energy generated by wave power plants all over Oleadas de energía Mientras que las plantas solares y eólicas se están convirtiendo en una forma extendida para la obtención de energía verde, existe una zona hasta ahora sin explotar y que tiene un gran potencial: la energía procedente del mar. Las olas son el resultado del efecto del viento soplando a lo largo de cientos o miles de kilómetros en mar abierto, lo que origina una transferencia de energía hacia la superficie del océano. Gracias a los recientes avances tecnológicos, este tipo de energía renovable pronto podría significar una opción mucho más viable. Hoy en día, las energías renovables se han convertido en un componente fundamental de la política energética. La Unión Europea (UE) se ha marcado el ambicioso objetivo de conseguir que en 2020, el 50 20% del consumo esté basado en este tipo de fuentes energéticas. En la búsqueda de fuentes de energía limpias, que permitan hacer frente al calentamiento global y la escasez de combustibles fósiles, son muchos los avances que se han conseguido. Una de las alternativas eficientes y más potentes para obtener energía del entorno, es la que proviene del mar. De hecho, la fuerza energética de las mareas es un importante recurso aún por explotar. Según la Agencia Internacional de la Energía, el mar puede generar más de 93.000 teravatios hora (TWh) de potencia. En concreto, si nos referimos a la energía generada por plantas mareomotrices en todo el mundo se estima que rondan los 800 Teravatios hora (TWh) al año. Esto su- the world is estimated somewhere around 800 terawatt hours (TWh) per year. This is the same as almost 25% of the total energy demand of Germany, and equivalent to 4% of global consumption. The coastal regions with the strongest ocean currents, such as the United Kingdom, Canada, France and Eastern Asia have great potential for using this technology. SeaGen: The world’s first wave power plant Wave power has the advantage of being a perfectly controlled technology, generating large amounts of power in places with large waves. As water has an energy pone casi el 25% de la demanda total de energía alemana y equivale a un 4% del consumo mundial. Las regiones costeras con fuertes corrientes marinas como en el Reino Unido, Canadá, Francia y Asia oriental ofrecen gran potencial para la utilización de esta tecnología. SeaGen: Primera planta mareomotriz del mundo La energía mareomotriz ofrece la ventaja de ser una tecnología perfectamente controlada y que genera altos niveles de potencia en emplazamientos con oleaje elevado. Como la densidad de energía del agua, en comparación con el viento, es 800 veces mayor, la generación de potencia es mucho más eficiente. Desde el año 2008, la Bahía de Portaferry en Irlanda del Norte acoge la primera planta de energía que es impulsada por el flujo de las mareas y que proporciona electricidad a la red. La planta SeaGen de 1,2 energética international · Nº 136 · OCT13 tidal energy | energía de las mareas density 800 times greater than that of air, it generates power much more efficiently. Since 2008, Portaferry Bay in Northern Ireland has been home to the first tidal power plant that provides electricity to the grid. The 1.2-MW SeaGen plant is sited just a few hundred metres from the strait that links the bay to the Irish Sea. Here, as the tide rises, the water mass advances over the facility at up to five metres per second, going out six hours later at the same speed. The energy potential is enormous, and the advantage is that the tidal currents are predictable. The lunar calendar can be used to calculate the speed of the tides on each day of the week. The plant produces 20 megawatts of energy per hour, enough to supply clean and efficient energy to 1,500 households. The system has been developed by the company Marine Current Turbines Ltd., which currently belongs to Siemens. From a technological perspective, SeaGen looks like a wind turbine immersed in MW está ubicada a unos pocos cientos de metros del estrecho que une la Bahía con el Mar de Irlanda. Allí, las masas de agua avanzan con cada pleamar hasta cinco metros por segundo sobre el proyecto natural para retirarse seis horas después con la misma rapidez. Se trata de un potencial energético enorme y cuenta con la ventaja de que las corrientes marinas son predecibles. Según el calendario lunar, se puede calcular la velocidad con la que actúan y el día de la semana en el que ocurrirán. La planta produce 20 megavatios de energía cada hora, suficiente para abastecer a 1.500 hogares de manera limpia y eficiente. El sistema ha sido desarrollado por la empresa Marine Current Turbines Ltd. que, actualmente, pertenece a la empresa Siemens. Desde el punto de vista tecnológico, SeaGen se parece a un aerogenerador sumergido en el agua. Se compone de dos rotores que trabajan de manera similar a un molino de viento pero que, debido a la mayor densidad del agua, necesitan de palas más pequeñas. Para minimizar los costes de instalación, la estructura de soporte o travesaño está instalada en una estructura única. Con el objetivo de utilizar las corrientes marinas, las palas del rotor pueden girar 180 grados. Esto significa que el sistema puede producir electricidad durante 20 horas al día independientemente de las condiciones climáticas y de los costes de energía primaria. Durante el funcionamiento, los rotores se encuentran tres metros por debajo del nivel del agua. Pero para permitir un mantenimiento fácil y seguro, la traviesa se puede elevar por encima del nivel del mar. Gracias al elevador hidráulico, se ahorran cerca de 100.000 euros en mantenimiento. Es lo que costaría contratar un barco especial que estuviera en condiciones de hacer emerger las unidades de 27 toneladas. El proyecto actual es sólo un punto de partida. Siemens cree en el potencial de las plantas de energía mareomotriz y sigue invirtiendo en esta tecnología junto a sus socios. En este momento, se está desarrollando una versión mejorada de SeaGen de 2 MW en la que se utilizan las sinergias con la división de energía eólica de Siemens. En el futuro, muchos componentes de la planta, entre ellos engranajes y generadores, serán suministrados por unidades de la compañía que proveen a los proyectos eólicos de la compañía. Además, los rotores de la central mareomotriz tendrán pronto tres palas en lugar de dos, en analogía con los aerogeneradores. Esto permite una marcha más tranquila de los rotores y las cargas se distribuyen de manera óptima. En los próximos años, está previsto que Escocia y Gales construyan en sus costas parques similares a SeaGen pero con cuatro y cinco turbinas, respectivamente. energética international · Nº 136 · OCT13 51 tidal energy | energía de las mareas what it would cost to rent a special vessel to haul out the 27-tonne units. These system features have been fieldproven since installation in 2008, of the commercial scale, SeaGen – S 1.2 MW grid connected system. By 2012, SeaGen–S had delivered ten times the amount of electricity to the grid than all other tidal devices combined. Following MCT’s acquisition by Siemens, SeaGen-S 2MW is being developed and tested to the highest production standards, benefitting from Siemens world class, delivery of renewable energy technology to global utilities. SeaGen-S 2MW is designed around the principles of; CostEffectiveness, Availability, Proven Engineering and Environmental Responsibility. Cost-Effectiveness Each SeaGen-S 2MW device consists of twin 1MW powertrains, delivering 2MW of grid conditioned electricity to the substation. This configuration reduces the cost per MW by minimising cabling and associated distribution infrastructure. The pitch-controlled blades and high efficiency powertrains, extract the maximum energy from the available tidal resource. Specifications Rotor • Diameter: 20 m • Swept area: 628 m2 for 2 rotors • Rotor speed: 4 –11.5 rpm • Power regulation: Active blade pitch regulation Transmission System • Gearbox type: Planetary • Gearbox cooling: Direct to passing sea water Mechanical brake • Type: Hydraulically released Generator • Type: Asynchronous • Nominal power: Rated to provide 1,000kW into grid export cable • Voltage: 690 V • Cooling system: Direct to passing sea water Monitoring system • SCADA system: Web based • Remote control: Full turbine control the water. It is made up of two rotors that work in a similar way to a windmill, but that – due to the greater density of water – have smaller blades. In order to minimise the installation costs, the support structure or beam is installed on a single structure. The rotor blades can turn through 180 degrees in order to exploit marine currents. This means the system can produce 52 Tower • Type: Cylindrical tubular steel • Hub height: Tailored for water depth/navigation constraint issues Operational data • Cut-in tidal speed: 1 m/s • Rated power at: 2.5 m/s Weights • Drive trains: 60 tons • Tower: Site-specific electricity for 20 hours per day, whatever the weather conditions and primary energy costs. While they are operating, the rotors are three metres below water level. However, in order to simplify maintenance and make it safer, the beam can be raised above sea level. Its hydraulic lift saves around €100,000 in maintenance costs. This is Availability Building upon 1000’s of generating hours from SeaGen –S 1.2MW, SeaGen-S 2MW has matured its engineering for greater reliability. With its unique raising mechanism allowing low cost and rapid access to the powertrains, and power conditioning and control systems in its tower, SeaGen-S provides unparalleled maintainability and unbeatable availability. Proven Engineering With 3GWh generated by 2012 and the system continuing in 24-7 operation, SeaGenS has proven its’ engineering way beyond any competing device. Not only is the concept fully demonstrated, but the detailed engineering design including longer-term fatigue characteristics are now proven. Environmental In addition to producing zero-carbon electricity, MCT is committed to ensuring minimal impact on the environment from installation and operation in sensitive coastal waters. An independent environmental energética international · Nº 136 · OCT13 tidal energy | energía de las mareas monitoring programme was commissioned to study the installation and first three years of operation of SeaGen 1.2 MW. In 2012 the studies concluded that, with the mitigation in place, there had been “no significant environmental impact”. SeaGen-S 2MW The SeaGen-S 2MW tidal generation system evolves the highly successful 1.2MW SeaGen S device that has been operational in Strangford Lough since 2008. With the insight and experience gained from this project, MCT has been able to optimise the system design to deliver 2MW with greater availability and at lower cost. Rotor The SeaGen S tidal turbine incorporates twin horizontal axis rotors. The rotors utilise an active blade pitching system which limit structural forces during high flow conditions. This allows the use of blades that are highly efficient over the full range of tidal velocities, from initial cut-in through to rated flow. Energy capture is further enhanced by variable speed operation which allows the turbine to operate at its optimum tip speed ratio (all the way up to up to rated power) and also minimises the dynamic loads on the transmission system. In summary, the variable speed and active pitch features allow efficient energy capture over the full range of tidal velocities and minimise structural loading, weight and cost. Blades The highly efficient rotor blades are constructed from composite materials and are the most advanced and tested blade technology used in tidal generation. The 2MW design blades are being verified by static and dynamic testing, building upon 25,000+ blade operating hours gained during the 1.2MW SeaGen and SeaFlow projects . Rotor hub The rotor hub houses the blade pitch actuators, slew bearings and automatic greasing system in a compact and easily maintainable configuration. Blade pitch system The blade pitch arrangement is used to optimize and regulate power output througenergética international · Nº 136 · OCT13 hout the operating range. The blades can be feathered to minimize hydrodynamic loads during extreme wave or tidal conditions. Main shaft and bearing The main shaft is forged in alloy steel and is hollow for the transfer of power and signals to the blade pitching system via slip rings. Gearbox The efficient and lightweight planetary gearbox allows a very compact and light power train to be realised. This simplifies maintenance operations and support logistics as well as reducing overall structural weight and cost. The intermediary and high speed stages are normal helical stages arranged with an offset of the high-speed shaft, allowing the passage of power and control cables to the pitch systems. The gearbox is equipped with large capacity filtering systems that ensure optimum operating conditions and up to 12 months of operation between filter changes. The gearbox is fully sealed and is cooled by the tidal flow. Generator The generator is a fully-enclosed asynchronous machine with squirrel-cage rotor, which does not require slip rings and is very robust. In addition to variable speed operation, the use of frequency converters enables the generator to achieve high part-load efficiency, allowing the turbine to achieve high system efficiency across the range of tidal flow velocities. The generator is cooled naturally by the water flow. Mechanical brake The system incorporates a hydraulically realised brake which serves as a parking brake for crossbeam lifting and maintenance operations, and is also used to ensure safe shut-down under some theoretical fault conditions. Controller The turbine utilises a standard wind turbine control system provided by a leading supplier. The controller is compatible with turbine safety requirements, is selfdiagnosing and includes a keyboard and display 53 tidal energy | energía de las mareas for easy status readout and adjustment of settings. The system allows; remote interrogation, the reset of turbine alarms and provides comprehensive data logging functionality. Power conversion The power conversion system allows the rotor to operate at optimal speed over the range of tidal velocities (from initial cutin to rated power) whilst supplying grid compatible electrical power at a frequency and voltage to match the local distribution network. The power conversion system is a modular arrangement for easy maintenance. The frequency converter output is interfaced to the grid via an onboard transformer, protection switch and standard grid protection relay. Each SeaGen device is a self-contained power station, requiring minimal onshore infrastructure and permitting multiple machines to use a common subsea cable. Grid compliance The SeaGen system complies with current grid code requirements and due to the use of modern frequency converters, can be adapted to meet emerging standards and network requirements associated with tidal arrays. 54 Operation The tidal turbine operates automatically, self-starting when the tide reaches an average speed of about 1 m/s. During operation below rated power, the pitch angle and rotor speed are adjusted to maximize the hydrodynamic efficiency. Rated power is reached at a tidal speed of about 2.5 m/s. At higher tidal speeds the output is regulated at rated power and rated rotational speed. Remote control The tidal turbine is equipped with a web based SCADA system. This system offers; remote control, a variety of status views and useful reports from a standard internet web browser. The status views present; electrical, mechanical, meteorological and tidal data, as well as operation, fault and grid status. Turbine Condition Monitoring In addition to the Web SCADA system, the turbine is equipped with a web-based Turbine Condition Monitoring (TCM) system. The TCM system carries out precise, continuous, real time, condition diagnostics on main turbine components. The TCM system has various alarm levels, from informative through alerting level to turbine shutdown. Support Structure The twin 1MW tidal turbine drive trains are mounted at each end of a crossbeam which in turn is supported by a surface piercing tubular steel tower. The cross beam can be raised, as required above the sea surface to maintain the drive trains, avoiding the cost and delay associated with expensive marine vessels. MCT can provide support to array developers to design foundations to meet local site conditions. The current project is only a starting point. Siemens believes in the potential of wave power plants and is continuing to invest in this technology along with its partners. At the moment it is developing an improved 2-M version of SeaGen, which will harness synergies with Siemens’ wind energy division. In future, many of the plant’s components, including gears and generators, will be supplied by company units that currently supply the firm’s wind power projects. In addition, the rotors of the wave power plant will soon have three blades instead of two, just like wind turbines. This will enable the rotors to turn much more smoothly, ensuring an optimal load distribution. Scotland and Wales are expected to build plants similar plants to SeaGen on their coasts in coming years, but with four and five turbines, respectively 7 energética international · Nº 136 · OCT13