The energy crisis shows how important it is to take precautions against potential power shortages or even blackouts. Coal and gas standby power plants, which are condensed when needed, are one of the options in use today. In the future, this task must also be performed by suitable alternatives for energy storage. One such alternative is XXL format batteries.
The Chinese central government now owns the first large-scale redox flow storage facility built in the People’s Republic of China in the port city of Dalian. With a production capacity of 200 megawatts and a capacity of 800 megawatt-hours (MWh) in the event of a four-hour complete failure, it should provide emergency supplies to government, hospitals, crisis departments, communications facilities and emergency services, writes the local newspaper Dalian Ribao.
Currently, the largest battery storage system, with a capacity of 400 MW and a capacity of 1,600 MW, is located in Moss Landing, California. For comparison: according to engineers, Europe’s largest battery storage power plant in Jardelund in Schleswig-Holstein can store only about 50 megawatts of electrical energy and supply it with 48 megawatts.
“But Moss Landing’s battery storage is not the largest in the world,” says Peter Fischer of the Fraunhofer Institute of Chemical Technology in Pfenztal, near Karlsruhe. “Pumped power plants can have gigawatt-hours (GWh) of capacity and gigawatts (GW) of production.” Germany’s largest pumped storage station, in Goldisthal, Thuringia, has an output of just over 1 GW and a capacity of about 8.5 GWh. This means that the pumped storage station is also small in global comparison.
Cheaper energy storage is required
The need for storage batteries is growing rapidly. In an analysis, experts from the research center Agora Energiewende, for example, posit that the three markets for reserve balancing, electric mobility and home storage could have a strong impact on the German electricity system in 2050 with a minimum of 40 GW and more than 170 GW as a maximum.
The problem, Fisher says, is that electricity is more expensive to store than to generate. Renewable energies such as photovoltaics and wind power are the cheapest sources at 2 to 7 cents per kilowatt-hour over a lifetime. In order to achieve these lower costs, the electricity from the storage facility, including losses, should not cost more. “This still takes effort.”
Fisher explains that the goal of research and development is to make technologies more cost-effective and achieve higher storage efficiencies. Such systems are expected to become economical over the next few years. “Then the combination of renewables and storage would be much cheaper than other energy production technologies in many places.”
Short and long term energy storage
In the view of Manuel Baumann of the Institute for Technology Assessment at the Karlsruhe Institute of Technology, in addition to expanding renewable energies and grid capabilities, storage is needed at all levels. This includes short- and long-term storage, decentralized systems as well as really large systems, for example for the so-called transport system operators. As such, TransnetBW is planning, for example, a 250MW “grid booster” at Kupferzel in north-east Baden-Württemberg, also in order to make better use of existing lines and reduce the need to run fossil power plants up and down.
“In the context of the energy transition, decentralized supply is also increasing, for example via photovoltaics,” Bowman says. Because of better weather conditions, for example, there can be a local surplus of energy that can be fed into the grid. “This is where decentralized storage makes sense.” Because every transformation of energy leads to losses. If the electricity is directly consumed locally, this is an advantage.
Battery storage technologies: lead, lithium, redox flux
The technology in which battery storage works varies according to the type: leaded ones have been popular for over 100 years, for example in emergency power supplies. The most common form is lithium-ion batteries, which are also primarily found in smartphones and electric cars or used as home storage for a rooftop photovoltaic system. The Moss Landing Battery Storage Project also works with her.
At the same time, research is being carried out on so-called redox flow batteries, one of which is now located in Dalian, China. “Unlike conventional batteries, energy is stored in liquids that are stored in external tanks,” explains Fischer of the Fraunhofer Institute. The amount of this solution determines the battery capacity. Battery power is generated in a transducer in which fluids are pumped and electrically converted there.
For example, the power company RWE is also working on a pilot plant on the “Panta.rhei” project. According to Fischer, Germany and Europe play a “negligible role” in the field of redox flow batteries. Of the 41 products worldwide, 17 are in the European Union.
Battery storage with advantages and disadvantages
“No technology is a universal solution,” says scientist Baumann from Karlsruhe. Each technology has advantages and disadvantages. It should be coordinated with the requirements of the respective application area. In addition, issues with purchasing options, recycling, and environmental and health risks should always be considered. Lead is a toxic heavy metal that must be properly recycled so that it does not end up in the environment. Lithium quantities will eventually reach their limit in light of the massive increase in demand if proper recycling is not considered. Among other things, vanadium is essential for redox flow batteries, most of which are produced in a few countries such as China, for example as a by-product of steel production.
According to Bowman, there are also differences in terms of time of use: storage systems that contain lead and lithium usually have a calendar life of 10 to 15 years. The cyclic service life, that is, the number of possible loading and unloading cycles, varies greatly. “With higher cycles, lithium batteries are more convenient than lead-acid batteries.” In the case of redox flow batteries, the cyclic service life is likely to be significantly longer. The expert says it’s important not to rely solely on one storage technology. “That should be seen in the wallet.”
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