Contenido

En los sistemas de circuito abierto, las plantas de almacenamiento por bombeo puro almacenan el agua en un depósito superior sin entradas naturales, mientras que las plantas de bombeo utilizan una combinación de almacenamiento por bombeo y plantas hidroeléctricas convencionales con un depósito superior que se repone en parte por las entradas naturales de un arroyo o río. Las plantas que no utilizan almacenamiento por bombeo se denominan plantas hidroeléctricas convencionales; las plantas hidroeléctricas convencionales que tienen una capacidad de almacenamiento importante pueden desempeñar una función similar en la red eléctrica que el almacenamiento por bombeo, aplazando la producción hasta que se necesite.

Economic efficiency

Taking into account evaporation losses from the exposed water surface and conversion losses, energy recovery of 70-80% or more can be achieved.[11] This technique is currently the most cost-effective means of storing large quantities of electrical energy, but capital costs and the presence of appropriate geography are critical decision factors in the selection of pumped storage plant sites.

The relatively low energy density of pumped storage systems requires large flows and/or large height differences between reservoirs. The only way to store a significant amount of energy is to have a large body of water located relatively close and as far upstream as possible from a second body of water. In some places this occurs naturally, in others one or both bodies of water are man-made. Projects in which both reservoirs are artificial and in which there are no natural inlets in either are called "closed loop" systems.[12]​.

These systems can be economical because they smooth out load variations on the power grid, allowing thermal plants such as coal plants and nuclear plants, which provide baseload electricity, to continue operating at maximum efficiency while reducing the need for "peaking" power plants that use the same fuels as many baseload thermal plants, gas and oil, but have been designed for flexibility rather than maximum efficiency. Therefore, pumped storage systems are crucial for the coordination of large groups of heterogeneous generators. The capital costs of pumped storage plants are relatively high, although this is mitigated to some extent by their long lifespan of up to 75 years or more.

Along with energy management, pumped storage systems help control the frequency of the electrical grid and provide reserve generation. Thermal power plants are much less able to respond to sudden changes in electrical demand, which can cause instability in frequency and voltage. Pumped storage plants, like other hydroelectric plants, can respond to load changes in a matter of seconds.

The first use of pumped storage was in the 1890s in Italy and Switzerland. In the 1930s, reversible hydroelectric turbines were available. These turbines could operate both as turbine generators and in reverse as pumps driven by electric motors. The latest in large scale engineering technology are variable speed machines for greater efficiency. These machines operate in synchronization with the grid frequency when generating, but operate asynchronously (independent of grid frequency) when pumping.

The first use of pumped storage in the United States was in 1930 by the Connecticut Electric and Power Company, using a large reservoir located near New Milford, Connecticut, pumping water from the Housatonic River to the storage reservoir 70 m higher.[13]​.

Seawater

Pumped storage plants can run on seawater, although there are additional problems compared to using freshwater. Opened in 1966, France's Rance Tidal Power Station can operate partially as a pumped storage power station. When high tides occur at off-peak hours, the turbines can be used to pump more seawater into the reservoir than the high tide would have brought naturally. It is the only large-scale power station of its type.

In 1999, the 30 MW Yanbaru project in Okinawa was the first demonstration of seawater pumped storage. It has since been decommissioned. A 300 MW Lanai seawater pumped storage project in Lanai, Hawaii has been considered, and seawater-based projects have been proposed in Ireland.[14] A pair of projects proposed in the Atacama Desert in northern Chile They would use 600 MW of solar photovoltaic energy (Cielos de Tarapacá) together with 300 MW of pumped storage (Espejo de Tarapacá) lifting seawater 600 m up a coastal cliff.[15]​[16]​.

The use of underground deposits has been investigated. Recent examples include the proposed Summit project in Norton, Ohio, the proposed Maysville project in Kentucky (underground limestone mine), and the Mount Hope project in New Jersey, which would have used a former iron mine as a lower deposit. The proposed energy storage at the Callio site in Pyhäjärvi, Finland, would utilize the deepest mine in Europe, with an elevation difference of 1,450 metres.[17] Several new underground pumped storage projects have been proposed. Cost per kilowatt estimates for these projects may be lower than for surface projects if they use existing underground mine space. There are limited opportunities involving suitable underground space, but the number of underground pumped storage opportunities may increase if abandoned coal mines prove suitable.[18]​.

In Bendigo, Victoria, Australia, the Bendigo Sustainability Group has proposed using the former Bendigo gold mines for pumped hydropower storage. Bendigo has the largest concentration of deep shaft hard rock mines in the world with over 5000 shafts under Bendigo drilled in the second half of the 19th century. The deepest shaft extends 1,406 meters vertically underground. A recent pre-feasibility study has shown that the concept is viable with a generation capacity of 30 MW and an operating time of 6 hours using a waterfall of more than 750 meters.

En marzo de 2017 el proyecto de investigación StEnSea (Almacenamiento de energía en el mar) anunció que habían completado con éxito una prueba de cuatro semanas de un depósito submarino de almacenamiento por bombeo. En esta configuración, una esfera hueca sumergida y anclada a gran profundidad actúa como el depósito inferior, mientras que el depósito superior es el cuerpo de agua que lo encierra. La electricidad se crea cuando el agua entra a través de una turbina reversible integrada en la esfera. Durante las horas de menor consumo la turbina cambia de dirección y bombea el agua de nuevo, utilizando el "excedente" de electricidad de la red. La cantidad de energía creada cuando se deja entrar el agua crece proporcionalmente a la altura de la columna de agua sobre la esfera, en otras palabras: cuanto más profunda es la esfera, más energía potencial puede almacenar, que puede ser transformada en energía eléctrica. Por otro lado, bombear el agua a mayores profundidades también consume más energía, ya que la bomba de turbina debe actuar sobre toda la columna de agua.

Por lo tanto, la capacidad de almacenamiento de energía del depósito sumergido no está regida por la energía gravitacional en el sentido tradicional, sino por la variación de la presión vertical").

Aunque la prueba de StEnSea tuvo lugar a una profundidad de 100 m en el lago de agua dulce de Constanza, se prevé que la tecnología se utilice en agua salada a mayores profundidades. Como el depósito sumergido sólo necesita un cable eléctrico de conexión, la profundidad a la que puede emplearse está limitada únicamente por la profundidad a la que puede funcionar la turbina, actualmente limitada a 700 m. El reto de diseñar el almacenamiento por bombeo de agua salada en esta configuración submarina aporta una serie de ventajas:.

Un diseño comercial actual con una esfera de un diámetro interior de 30 m sumergida a 700 m correspondería a una capacidad de 20 MWh que con una turbina de 5 MW daría lugar a un tiempo de descarga de 4 horas. Un parque energético con múltiples depósitos de este tipo llevaría el costo de almacenamiento a unos pocos céntimos de euro por kWh con costos de construcción y equipamiento en el rango de 1200 a 1400 euros por kW. Para evitar costos de transmisión y pérdidas excesivas, los reservorios deberían colocarse frente a las costas de aguas profundas de zonas densamente pobladas, que suelen ser las costas de bordes de placas de subducción, como las costas de Chile, Perú, Ecuador o Colombia y siguiendo más al norte del Oeste americano hasta Vancouver. Pero igualmente las costas de Indonesia. Otros lugares como Noruega, España, Italia, EE. UU. y Japón. Con esta limitación el concepto permitiría el almacenamiento de cerca de 900 GWh electricidad en todo el mundo.[19]​[20]​.

A modo de comparación, un almacenamiento tradicional por bombeo basado en la gravedad, capaz de almacenar 20 MWh en un depósito de agua del tamaño de una esfera de 30 m necesitaría un cabezal hidráulico de 519 m con la elevación abarcada por una tubería de agua presurizada que requiere típicamente una colina o montaña como soporte.

Use at home

Using a pumped storage system of tankers and small generators, the pico hydro system can also be effective for "closed loop" domestic power generation systems.[21]​[22]​.

La central hidroeléctrica reversible está conformada por:.

En el caso de las centrales de bombeo puro, el embalse superior consistirá en un depósito elevado de la capacidad suficiente para funcionar durante 4 a 6 horas. Si es posible, es mejor que este depósito sea como una caverna, de esta manera se evita la evaporación de agua con alta energía potencial.

Procedure

It is preferable (almost essential) that both pumps and turbines operate at nominal power and flow. In this way, during off-peak hours, with minimum energy demand, all the pumps are on, pumping water to the upper reservoir; As demand grows, pumps are turned off.

When rush hour begins, all the pumps are turned off and turbines begin to turn on. At times of maximum demand all the turbines can be running.

In this way, the energy demand graph is very similar to the pumping-generation graph of a reversible hydroelectric plant, except that the latter is "toothed" due to the discrete component of the pumps.

Reversible hydroelectric plants have lower performance when they are operating as pumps than when they are operating as turbines.

List of some reversible Pumped Accumulation Plants

Germany.

Argentina.

Austria.

Spain.

China.

List of reversible stations in the world (in the English version).

In times of low electricity demand, excess generation capacity is used to pump water to the upper reservoir. When there is increased demand, the water is released back into the lower reservoir through a turbine, generating electricity. Reversible turbine/generator assemblies act as a combined turbine pump and generator unit (typically a Francis turbine design). In pumped microstorage applications, a group of pumps and a turbine pump could be implemented respectively for the pumping and generation phases.[10]​ The same pump could be used in both modes by changing the direction and speed of rotation.[10]​.

Contenido

En los sistemas de circuito abierto, las plantas de almacenamiento por bombeo puro almacenan el agua en un depósito superior sin entradas naturales, mientras que las plantas de bombeo utilizan una combinación de almacenamiento por bombeo y plantas hidroeléctricas convencionales con un depósito superior que se repone en parte por las entradas naturales de un arroyo o río. Las plantas que no utilizan almacenamiento por bombeo se denominan plantas hidroeléctricas convencionales; las plantas hidroeléctricas convencionales que tienen una capacidad de almacenamiento importante pueden desempeñar una función similar en la red eléctrica que el almacenamiento por bombeo, aplazando la producción hasta que se necesite.

Economic efficiency

Taking into account evaporation losses from the exposed water surface and conversion losses, energy recovery of 70-80% or more can be achieved.[11] This technique is currently the most cost-effective means of storing large quantities of electrical energy, but capital costs and the presence of appropriate geography are critical decision factors in the selection of pumped storage plant sites.

The relatively low energy density of pumped storage systems requires large flows and/or large height differences between reservoirs. The only way to store a significant amount of energy is to have a large body of water located relatively close and as far upstream as possible from a second body of water. In some places this occurs naturally, in others one or both bodies of water are man-made. Projects in which both reservoirs are artificial and in which there are no natural inlets in either are called "closed loop" systems.[12]​.

These systems can be economical because they smooth out load variations on the power grid, allowing thermal plants such as coal plants and nuclear plants, which provide baseload electricity, to continue operating at maximum efficiency while reducing the need for "peaking" power plants that use the same fuels as many baseload thermal plants, gas and oil, but have been designed for flexibility rather than maximum efficiency. Therefore, pumped storage systems are crucial for the coordination of large groups of heterogeneous generators. The capital costs of pumped storage plants are relatively high, although this is mitigated to some extent by their long lifespan of up to 75 years or more.

Along with energy management, pumped storage systems help control the frequency of the electrical grid and provide reserve generation. Thermal power plants are much less able to respond to sudden changes in electrical demand, which can cause instability in frequency and voltage. Pumped storage plants, like other hydroelectric plants, can respond to load changes in a matter of seconds.

The first use of pumped storage was in the 1890s in Italy and Switzerland. In the 1930s, reversible hydroelectric turbines were available. These turbines could operate both as turbine generators and in reverse as pumps driven by electric motors. The latest in large scale engineering technology are variable speed machines for greater efficiency. These machines operate in synchronization with the grid frequency when generating, but operate asynchronously (independent of grid frequency) when pumping.

The first use of pumped storage in the United States was in 1930 by the Connecticut Electric and Power Company, using a large reservoir located near New Milford, Connecticut, pumping water from the Housatonic River to the storage reservoir 70 m higher.[13]​.

Seawater

Pumped storage plants can run on seawater, although there are additional problems compared to using freshwater. Opened in 1966, France's Rance Tidal Power Station can operate partially as a pumped storage power station. When high tides occur at off-peak hours, the turbines can be used to pump more seawater into the reservoir than the high tide would have brought naturally. It is the only large-scale power station of its type.

In 1999, the 30 MW Yanbaru project in Okinawa was the first demonstration of seawater pumped storage. It has since been decommissioned. A 300 MW Lanai seawater pumped storage project in Lanai, Hawaii has been considered, and seawater-based projects have been proposed in Ireland.[14] A pair of projects proposed in the Atacama Desert in northern Chile They would use 600 MW of solar photovoltaic energy (Cielos de Tarapacá) together with 300 MW of pumped storage (Espejo de Tarapacá) lifting seawater 600 m up a coastal cliff.[15]​[16]​.

The use of underground deposits has been investigated. Recent examples include the proposed Summit project in Norton, Ohio, the proposed Maysville project in Kentucky (underground limestone mine), and the Mount Hope project in New Jersey, which would have used a former iron mine as a lower deposit. The proposed energy storage at the Callio site in Pyhäjärvi, Finland, would utilize the deepest mine in Europe, with an elevation difference of 1,450 metres.[17] Several new underground pumped storage projects have been proposed. Cost per kilowatt estimates for these projects may be lower than for surface projects if they use existing underground mine space. There are limited opportunities involving suitable underground space, but the number of underground pumped storage opportunities may increase if abandoned coal mines prove suitable.[18]​.

In Bendigo, Victoria, Australia, the Bendigo Sustainability Group has proposed using the former Bendigo gold mines for pumped hydropower storage. Bendigo has the largest concentration of deep shaft hard rock mines in the world with over 5000 shafts under Bendigo drilled in the second half of the 19th century. The deepest shaft extends 1,406 meters vertically underground. A recent pre-feasibility study has shown that the concept is viable with a generation capacity of 30 MW and an operating time of 6 hours using a waterfall of more than 750 meters.

En marzo de 2017 el proyecto de investigación StEnSea (Almacenamiento de energía en el mar) anunció que habían completado con éxito una prueba de cuatro semanas de un depósito submarino de almacenamiento por bombeo. En esta configuración, una esfera hueca sumergida y anclada a gran profundidad actúa como el depósito inferior, mientras que el depósito superior es el cuerpo de agua que lo encierra. La electricidad se crea cuando el agua entra a través de una turbina reversible integrada en la esfera. Durante las horas de menor consumo la turbina cambia de dirección y bombea el agua de nuevo, utilizando el "excedente" de electricidad de la red. La cantidad de energía creada cuando se deja entrar el agua crece proporcionalmente a la altura de la columna de agua sobre la esfera, en otras palabras: cuanto más profunda es la esfera, más energía potencial puede almacenar, que puede ser transformada en energía eléctrica. Por otro lado, bombear el agua a mayores profundidades también consume más energía, ya que la bomba de turbina debe actuar sobre toda la columna de agua.

Por lo tanto, la capacidad de almacenamiento de energía del depósito sumergido no está regida por la energía gravitacional en el sentido tradicional, sino por la variación de la presión vertical").

Aunque la prueba de StEnSea tuvo lugar a una profundidad de 100 m en el lago de agua dulce de Constanza, se prevé que la tecnología se utilice en agua salada a mayores profundidades. Como el depósito sumergido sólo necesita un cable eléctrico de conexión, la profundidad a la que puede emplearse está limitada únicamente por la profundidad a la que puede funcionar la turbina, actualmente limitada a 700 m. El reto de diseñar el almacenamiento por bombeo de agua salada en esta configuración submarina aporta una serie de ventajas:.

Un diseño comercial actual con una esfera de un diámetro interior de 30 m sumergida a 700 m correspondería a una capacidad de 20 MWh que con una turbina de 5 MW daría lugar a un tiempo de descarga de 4 horas. Un parque energético con múltiples depósitos de este tipo llevaría el costo de almacenamiento a unos pocos céntimos de euro por kWh con costos de construcción y equipamiento en el rango de 1200 a 1400 euros por kW. Para evitar costos de transmisión y pérdidas excesivas, los reservorios deberían colocarse frente a las costas de aguas profundas de zonas densamente pobladas, que suelen ser las costas de bordes de placas de subducción, como las costas de Chile, Perú, Ecuador o Colombia y siguiendo más al norte del Oeste americano hasta Vancouver. Pero igualmente las costas de Indonesia. Otros lugares como Noruega, España, Italia, EE. UU. y Japón. Con esta limitación el concepto permitiría el almacenamiento de cerca de 900 GWh electricidad en todo el mundo.[19]​[20]​.

A modo de comparación, un almacenamiento tradicional por bombeo basado en la gravedad, capaz de almacenar 20 MWh en un depósito de agua del tamaño de una esfera de 30 m necesitaría un cabezal hidráulico de 519 m con la elevación abarcada por una tubería de agua presurizada que requiere típicamente una colina o montaña como soporte.

Use at home

Using a pumped storage system of tankers and small generators, the pico hydro system can also be effective for "closed loop" domestic power generation systems.[21]​[22]​.

La central hidroeléctrica reversible está conformada por:.

En el caso de las centrales de bombeo puro, el embalse superior consistirá en un depósito elevado de la capacidad suficiente para funcionar durante 4 a 6 horas. Si es posible, es mejor que este depósito sea como una caverna, de esta manera se evita la evaporación de agua con alta energía potencial.

Procedure

It is preferable (almost essential) that both pumps and turbines operate at nominal power and flow. In this way, during off-peak hours, with minimum energy demand, all the pumps are on, pumping water to the upper reservoir; As demand grows, pumps are turned off.

When rush hour begins, all the pumps are turned off and turbines begin to turn on. At times of maximum demand all the turbines can be running.

In this way, the energy demand graph is very similar to the pumping-generation graph of a reversible hydroelectric plant, except that the latter is "toothed" due to the discrete component of the pumps.

Reversible hydroelectric plants have lower performance when they are operating as pumps than when they are operating as turbines.

List of some reversible Pumped Accumulation Plants

Germany.

Argentina.

Austria.

Spain.

China.

List of reversible stations in the world (in the English version).