By Chris Baraniuk , WIRED .  Excerpt: ...workers began adding a secret, light brown powder to water as they mixed up a special fluid that can store energy.... Their goal was to achieve a mixture 2.5 times denser than water. ...Pumped hydro first emerged in the late 19th century . During subsequent decades, countries including the US and UK built lots of large plants, though construction had waned by the 1990s . The tech was originally designed to complement fossil fuel power plants, making use of excess energy they produced. But today grid operators increasingly value pumped hydro plants as workhorses able to mediate highly variable wind and solar assets. They can fill in shortfalls in electricity generation or soak up surplus energy within minutes, and store it for short or long periods....  Full article at https://www.wired.com/story/pumped-hydro-energy-storage-is-having-a-renaissance/ . 

By Roger Harrabin , New Scientist.  Excerpt: Some 450 kilometres north of Helsinki, Finland, lies a decommissioned mine. Despite its remote location, it is being keenly watched because it looks set to play a role in revolutionising our energy systems – though not for the reasons you might suspect. The Pyhäsalmi mine used to yield wealth from zinc and copper, but it is about to monetise the power of gravity. As the deepest metal ore mine in Europe, it is an ideal spot for what’s known as a gravity vault. UK-based company Gravitricity plans to dangle a heavy weight down a mine shaft and connect the mechanism to a generator. It will store power as potential energy by pulling up the weight, then generate it again by letting it plummet. If that sounds surprisingly simple, that is exactly the point. Governments are wrestling with the epic challenge of the intermittency of  renewable power : how to keep the lights on when the wind doesn’t blow and the sun doesn’t shine. So far, they ...

By Jon Turi, TCD.  Excerpt: Large-scale battery storage systems are a no-brainer to handle the ever-growing influx of renewable energy without letting it go to waste. Since China has taken a  global lead  in using greener energy sources, it's no surprise that one of its latest major storage systems to go online is using a less toxic approach. As Electrek  reported , the Fulin Sodium-ion Battery Energy Storage Station began operating in the Guangxi Zhuang autonomous region in southern China this May. The initial storage capacity is said to be around 10 megawatt-hours (MWh), but it expected to grow to 100 MWh at full capacity..."enough to power 35,000 households and reduce carbon dioxide emissions by 50,000 tonnes [about 55,000 tons] annually," according to  Electrek . ..."The energy conversion efficiency of its sodium-ion battery energy storage system exceeds 92%. It's comparable to the efficiency of common lithium-ion battery storage systems, at 85% to 95%."...

https://www.nytimes.com/2024/03/18/science/renewable-energy-storage-climate.html By Amos Zeeberg , The New York Times.  Excerpt: Central Sardinia ...in Ottana, ..., a new technology is taking shape that might help the world slow climate change. ...Energy Dome, a start-up based in Milan, runs an energy-storage demonstration plant that helps to address a mismatch in the local electricity market. ...Energy Dome uses carbon dioxide held in a huge balloon... as a kind of battery. During the day, electricity from the local grid, some produced by nearby fields of solar cells, is used to compress the carbon dioxide into liquid. At night, the liquid carbon dioxide is expanded back into gas, which drives a turbine and produces electricity that is sent back to the grid....

https://www.science.org/content/article/how-giant-water-batteries-could-make-green-power-reliable By ROBERT KUNZIG , Science.  Excerpt: The machines that turn Tennessee’s Raccoon Mountain into one of the world’s largest energy storage devices—in effect, a battery that can power a medium-size city—are hidden in a cathedral-size cavern deep inside the mountain. But what enables the mountain to store all that energy is plain in an aerial photo. The summit plateau is occupied by a large lake that hangs high above the Tennessee River.... At night, when demand for electricity is low but TVA’s nuclear reactors are still humming, TVA banks the excess, storing it as gravitational potential energy in the summit lake. The pumps draw water from the Tennessee and shoot it straight up the 10-meter-wide shaft at a rate that would fill an Olympic pool in less than 6 seconds. During the day, when demand for electricity peaks, water drains back down the shaft and spins the turbines, generating 1700 ...

https://www.science.org/content/article/electrified-cement-could-turn-houses-and-roads-nearly-limitless-batteries By Robert F. Service, Science.  Excerpt: ...Researchers have come up with a new way to store electricity in cement, using cheap and abundant materials. If scaled up, the cement could hold enough energy in a home’s concrete foundation to fulfill its daily power needs. Scaled up further, electrified roadways could power electric cars as they drive. And if scientists can find a way to do this all cheaply the advance might offer a nearly limitless capacity for storing energy from intermittent renewable sources, such as solar and wind. So far, the cement devices are small, only big enough to power a few LED lightbulbs. But efforts are already underway to scale them up. ...The cement devices are a kind of simplified battery called supercapacitors. They consist of two electrically conductive plates separated by an ion-conducting electrolyte and a thin membrane. As the device i...

https://www.nytimes.com/interactive/2023/05/02/climate/hydroelectric-power-energy.html By Mira Rojanasakul  and  Max Bearak , The New York Times.  Excerpt: New research released Tuesday by Global Energy Monitor reveals a transformation underway in hydroelectric projects — using the same gravitational qualities of water, but typically without building large, traditional dams like the Hoover in the American West or Three Gorges in China. Instead, a technology called pumped storage is rapidly expanding. These systems involve two reservoirs: one on top of a hill and another at the bottom. When electricity generated from nearby power plants exceeds demand, it’s used to pump water uphill, essentially filling the upper reservoir as a battery. Later, when electricity demand spikes, water is released to the lower reservoir through a turbine, generating power. Pumped storage isn’t a new idea. But it is undergoing a renaissance in countries where wind and solar power are also growin...