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Giant batteries in the Earth

December 23, 2024 By EarthWise 1 Comment

The wind and the sun are inexhaustible sources of energy, and we are tapping into them to produce electricity at a growing rate around the world. But neither of them is always available when we need them. When the sun isn’t shining and the wind isn’t blowing, they don’t work.

An opposite problem also exists. When our energy needs are low, but it is sunny or windy, solar and wind power are all dressed up with nowhere to go. Energy storage is the answer to both of these problems. When there is excess generation, store the energy for later use. When there is need for energy and not enough is being generated, tap into the energy that is stored.

Giant banks of lithium-ion batteries are the rapidly growing form of energy storage, and they are increasingly providing resilience in the electric grid. But battery storage is short-term energy storage. Even the largest battery banks can only provide a few hours of electricity.

So, there is a real need for “long-duration energy storage” – systems that provide at least 10 hours of backup power and sometimes much more – for the grid to be fully reliable.

Pumped hydro storage, which uses water from elevated reservoirs to drive turbines, has been around for a long time. Historically, this is the largest form of energy storage in the world. Other methods include pumping compressed air into underground caverns or lifting massive blocks into elevated positions. All of these techniques use excess electricity to place things like water, air, or cement into a position where they can be used to drive electrical generators.

The grid of tomorrow will store energy in giant battery banks, but also in the ground, in reservoirs, and in large structures.

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How giant ‘batteries’ in the Earth could slash your electricity bills

Photo, posted March 21, 2024, courtesy of Sandra Uecker/USFWS via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

How much energy storage is needed?

November 11, 2024 By EarthWise Leave a Comment

Energy storage is a critical aspect of modern energy systems as they move towards heavy dependence on renewable sources such as solar and wind that don’t produce energy at the same rate all the time. Excess energy generated by solar power needs to be stored for when the sun isn’t shining; excess wind energy needs to be stored for when the wind isn’t blowing. But how much storage capacity does the energy system need to have?

Researchers at North Carolina State University have developed a model that can be used to project what a system’s storage needs would be if it were to shift entirely to renewable sources.

The model accounts for how energy production from renewable sources would change during different times of day and different times of the year. For example, there is much more solar energy generation in the summer when the days are longer, and it is sunny more often.

There is also the issue of short-term vs. long-term energy storage. Short-term energy storage does not refer to how long a storage device can store the energy. It refers to how long it can provide power at its rated level.

The study focused on Italy’s energy system, which has suffered in recent years because it had difficulties in obtaining natural gas from Russia due to the invasion of Ukraine.

As the world moves increasingly towards renewable power sources, energy systems need to be able to account for the variability of those sources. The new model offers policymakers critical information for use in energy system planning.

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Model Projects Energy Storage Needs for Fossil Fuel-Free Energy System

Photo, posted October 28, 2016, courtesy of Daxis via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Geological thermal energy storage

August 7, 2024 By EarthWise Leave a Comment

The electricity grid is increasingly using solar and wind power. Depending on those two sources requires the ability to store energy to have on hand when the sun isn’t shining and the wind isn’t blowing. Energy needs to be stored away to be used hours, days, or even weeks after it is produced.

Energy storage is booming. California has increased its energy storage capacity tenfold in recent times. One day in April, storage batteries were the largest source of electricity in the state for a period of two hours. But batteries are not the only way to store energy. There are chemical, electrochemical, mechanical, and thermal methods that each has potential advantages and unique features.

A project in Kern County, California, is making use of an abandoned oil field to create a long-term energy storage installation. The plan is to retrofit depleted oil wells to store concentrated solar energy in superheated groundwater for long periods of time. The stored heat can then be used to drive turbines when electricity is needed.

Some 1,200 feet below the surface of the oil field are pockets of permeable sandstone that have been emptied of the oil they previously contained. An array of parabolic mirrors will gather solar energy that will heat silicon oil in an underground loop to 700 degrees Fahrenheit. The oil pipeline will heat up groundwater down below. When electricity is needed, the heated groundwater will be brought to the surface to operate turbines.

There is no new technology involved. The individual aspects have never all been combined before, but the likelihood of success is high. There are lots of depleted oil fields that could be used this way in the future.

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Can a California Oilfield Be Retrofitted to Store Solar Energy?

Photo, posted July 18, 2017, courtesy of John Ciccarelli / BLM via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Better Zinc Batteries | Earth Wise

May 17, 2023 By EarthWise Leave a Comment

The rapid growth of wind and solar power continues to drive a global quest for new battery technologies that can be used to store the energy generated by these sources when the sun isn’t shining, and the wind isn’t blowing.

For the most part, current battery energy storage systems use lithium-ion batteries – the same sort of batteries found in cellphones and electric vehicles. There are many other battery chemistries, but they mostly have shortcomings in performance, economy, or longevity.

Batteries store electricity in the form of chemical energy and chemical reactions convert that energy into electrical energy. Every battery has two electrodes: the anode, from which electrons flow into external circuits, and the cathode, which receives electrons from the external circuit. The electrolyte is the chemical medium through which the electrons flow.

One technology that has great potential is zinc-based batteries. Zinc itself is a metal that is safe and abundant. Batteries based on it are energy dense. However, zinc batteries have faced the challenge of having a short cycle life. The batteries end up plating zinc on their anodes and battery performance degrades.

A team of researchers at Oregon State University and three other universities have recently developed a new electrolyte for zinc batteries that raises the efficiency of the zinc metal anode to nearly 100% – actually slightly better than lithium-ion batteries.

Zinc batteries have a number of potential advantages over lithium-ion. The new hybrid electrolyte developed by the researchers is non-flammable, cost-effective, and has low environmental impact. Lithium-ion batteries rely on the supplies of relatively rare metals that are often difficult and environmentally harmful to obtain.

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Researchers develop electrolyte enabling high efficiency of safe, sustainable zinc batteries

Photo, posted May 13, 2017, courtesy of Jeanne Menjoulet via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio