The transition to a decarbonized economy is progressing unstoppably with projects that go beyond the deployment of wind and solar power. Proof of this is the increasing number of projects related to hydroelectric power. Without going any further, last July, the Board of Directors of the European Investment Bank (EIB) just approved a €2.2 billion game to finance projects related to energy and water and one of the states that will receive part of these funds will be Spain. , where the money will be used to promote this technology.
Although the European Union’s financial body, headed by former minister Nadia Calviño, has not provided details on concrete initiatives, our country has several pumped hydroelectric projects – also known as reversible power plants – as it is an energy storage system of particular interest to the EU.
Currently there are more than 1,300 hydroelectric power plants spread throughout Spain21 of which have the aforementioned pumping technology. Their cumulative power exceeds 5,300 megawatts (MW), although an additional 2,700 MW are in the development phase with authorization to connect to the network, to which must be added an additional 1,200 MW awaiting authorization, as specified by the Spanish operator Red Eléctrica.
The situation seems to be getting worse. Indeed, the Ministry of Ecological Transition and the Demographic Challenge has on the table about forty new requests that would reach a power of 15,000 MW more. In this sense, MITECO launched a year ago an aid program worth 100 million euros for energy storage by reversible pumping. On the other hand, the National Energy and Climate Plan (PNIEC) predicts that our country will reach a storage capacity of 22,000 MW in 2030.
But why are the government, energy companies and the EU interested in pumping stations? The answer is simple: because storage is the major handicap of the energy transition and this technology can solve it. Is popular voice that Spain has a privileged geographical position and climatological characteristics that make it a power when it comes to producing renewable energy in a clean and cheap way. However, this production is not always aligned with consumption, which leads to dysfunctions that alter the system and the market.
For example, photovoltaic energy is produced during the hours when the sun is present, while household electricity consumption in winter occurs mainly between 6:00 p.m. and 10:00 p.m., that is, when it is already dark. To align supply and demand, it is necessary to store energy so that it can be used when it is most needed.
Currently, there are no batteries that allow for optimal energy storage in the quantities that the system needs. This funnel is what is called the battery barrier and is based on the fact that the useful life and capacity of batteries are very limited, that it causes associated environmental problems and that its materials are scarce and difficult to dispose of, among other problems. Faced with this situation, the scientific community is trying to find solutions that will promote the paradigm shift that the planet needs to combat climate change. It is at this point that reversible or pumped hydroelectric power plants appear as a viable and ecologically acceptable solution.
How do pumping stations work?
The Spanish government’s energy storage strategy defines these facilities as “those capable of storing the gravitational potential energy of water, rising from a lower reservoir to a reservoir located at a higher altitude”. The key is to have two reservoirs that communicate at different heights. If the water falls from the top to the bottom, electrical energy is produced. However, if energy is used to raise the water, it can be reduced when the system needs it, that is, the potential energy will have been accumulated without loss of efficiency in the process.
The operation is simple: in the event of overproduction of renewable sources, this energy can be used to raise water. Thus, when production is lower than demand, the liquid element can be abandoned to produce electricity by moving turbines, whether the wind blows or the sun heats it. It is this double journey of water that makes these hydroelectric plants reversible.
Precisely, the largest pumping station in Europe is located on the Júcar River, in Spain, and shows the potential of this type of infrastructure and how it contributes to the decarbonisation of the system. It is the Cortes-La Muela hydroelectric complex and has a turbine power of 1,762 MW and 1,293 MW of pumping, as specified by the company responsible for its construction and management. Its upper reservoir becomes a battery capable of supplying electricity to almost 400,000 homes per year, while avoiding the emission of two million tonnes of carbon dioxide.
