A new battery could solve the energy storage problem

A new battery could solve the energy storage problem

Each year around this time the Pacific Northwest region of North America temporarily enjoys an abundance of renewable energy. A torrent of melted snow builds up behind the region's many dams, as strong gusts blow through the gorges and propel wind turbines. At the end of the summer, however, the momentum of the elements fades. In these periods, American states such as Oregon and Washington increasingly rely on other, often more polluting sources of energy, such as natural gas and coal produced by neighboring countries.

Nature is not always available when we need it. This is the problem that plagues most renewable energies (Germans use the word dunkelflaute to describe periods when solar and wind power are scarce or absent). For places like Washington state, which is targeting 100 percent clean energy by 2045, the question is how to fill these seasonal gaps. While California and the Midwest may have surplus solar and wind energy to trade in the summer, things aren't that simple. First, there are not enough cables to connect these zones. California has also set 2045 as the deadline for producing clean energy, which obviously complicates interregional sharing. However, there is another option: to store the energy produced by winds and melting snow in times of abundance so that it can be used in lean times.

A new type of battery inspired by the past Researchers have found a possible solution at the Pacific Northwest National Lab (PNNL): a rechargeable battery that conserves energy for months using freezing and thawing techniques. Most batteries lose some of their energy. To charge and release energy, batteries rely on the smooth movement of ions in a liquid electrolyte. When there is no demand for energy, however, these ions sometimes slip away. This is why when an electric car's battery is left unused for a long time, it ends up discharging. The PNNL-designed battery, which was unveiled last month in Cell Reports Physical Science magazine, stops energy loss by exploiting freezing. It is based on an electrolyte made up of molten salts which becomes liquid when the battery is heated to 180 degrees, allowing ions to pass. Once the battery cools, the salts solidify. The ions thus remain trapped, and with them so does the energy.

Batteries are generally not designed to store energy for weeks or months. For this reason, power grid experts often look to solutions borrowed from physics, such as pumping water into elevated reservoirs that can be exploited at a future time, compressing the air in underground caves, or using excess renewable energy to create a fuel such as hydrogen. It is generally believed that building batteries in volumes to store the necessary energy is too expensive. They are too difficult to make and contain too many valuable minerals to remain unused when fully charged. Researchers, however, are increasingly focusing their attention on the unsolved chemical aspects of old, and often cheaper, battery projects.

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Arrow Molten salt batteries fall into this category. In the 1980s, they had been considered for electric cars by automakers like Ford, before lithium-ion batteries took hold in small electronic devices like cell phones. The technology has become so dominant in part because lithium-ion batteries are very easy to recharge: at the heart of their operation is simply a matter of ions moving back and forth through the cell. Other types of batteries involve more complicated chemical and physical transformations, which are more difficult to reverse. They are the equivalent of breaking a vase and then trying to put it back together.

The approach adopted by the PNNL for its battery involves some of these complications, as it requires the materials inside to be physically altered - expanding and then contracting - before each use. "You break a lot of connections and then try to restore them," explains Vincent Sprenkle, technical manager of the energy storage program at the NNNL. The solution is to design a battery that is extremely stable by using highly compatible metals such as nickel and aluminum and adding sulfur granules to further increase stability. The prototype the researchers made is small, a container the size of a hockey puck. To activate it, they heated it in an oven to 180 degrees: "It could be done in the oven at home," says Minyuan Miller Li, the PNNL battery scientist who led the study. The resulting battery retained more than ninety percent of the energy fed into it three months apart, the researchers report (the losses were largely due to ions moving prematurely while the battery was still heating). br>
The problem is the temperature. The melting point of the salt mixture is too high to be reached outside of the lab, Li explains, according to which the material needs to be able to melt at a much lower temperature, ideally below 100 degrees, in order to activate the battery. with hot water. The next step is to try new materials that can lower the necessary temperature, for example by adding a different type of salt which would cause the melting point of the mixture to drop. The researchers also want to understand if it is possible to replace nickel with a cheaper metal, such as iron.

Significant potential If temperature and material problems are solved, researchers plan to create larger cells. or large groups of cells that combined would reach the size of an articulated truck trailer, sufficient to store the excess energy of a photovoltaic power plant or dam, and capable of arousing the interest of battery companies willing to market the project. But before we get to this point, there are many scientific issues to be resolved. "Our role is to reduce the risks of this type of technology," says Sprenkle.

WiredLeaks, how to send us an anonymous report Investments of this type are valuable - explains Omar Guerra, an expert in electricity networks of the National Renewable Energy Laboratory which was not involved in the research - given the need for a wide range of seasonal storage technologies. Techniques for storing energy for months will become more useful once the grid is largely powered by renewable sources. Without storage, it will likely need to build a surplus of wind and solar farms to continue producing enough energy during times of low availability - a colossal waste of resources, Guerra points out. However, it is crucial that any long-term storage method is economically viable at scale, which is one of the reasons why solutions such as hydrogen and compressed air storage are so appealing. Most manufacturers of "long-life" batteries aim for much shorter energy storage periods than PNNL researchers, in the order of hours or days.

According to PNNL researchers, the cost battery manufacturing is about $ 23 per kilowatt-hour of power, which could potentially be further reduced by switching to iron. The figure is within estimates for long-term storage considered economical, says Jackie Dowling, an energy storage researcher at the California Institute of Technology. The batteries, then, can take advantage of another great advantage: the position. Storage involving hydrogen, water or compressed air takes up a lot of space, and often rests on tanks or underground caves that are not always close to renewable energy sources: "We should build cables and pipes, while drums can be made anywhere, "adds Dowling. The demand for any technology will depend on location and cost, as well as the availability of "stable" zero-emission energy sources that are not subject to the whims of nature, such as geothermal and nuclear power.

There are also other applications for energy storage that can remain unused most of the time, remarks Guerra, alluding to the wave of severe frost that hit Texas in 2021, leaving the state in a blackout that lasted several days. What would have happened - Guerra wonders - if there had been batteries or hydrogen fuel stocks capable of continuing to operate the network? "We don't have a magical solution that will solve the energy storage problem - she adds -. It will take a number of different technologies."

This article originally appeared on sportsgaming.win US.

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