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How salt and sand could replace lithium batteries

Mar 17, 2024
We all know that the future of energy lies in renewable energies. They were the cheapest source of energy in the world in 2020. This is very good news. But we have just one small problem. How do we store it all? It's not sunny all the time or windy 24/7, so we need a way to maintain reserves. "We need better

batteries

, that's for sure." Until now, the dominant battery solution for renewables has been

lithium

-ion. But mining pollutes, exploits people, and

batteries

have a habit of exploding. They don't last long enough and we are going to need much more capacity.
how salt and sand could replace lithium batteries
So what are our options? Enter:

salt

, water, gravity, very hot air, very cold air, and huge piles of

sand

. It sounds like a kindergarten picnic, but

could

these things really solve our energy storage problem? Before we get into the shiny new features, we have to talk about the

lithium

-ion battery. It is the fastest growing battery segment in the world. Scientists began developing it during the oil crisis of the 1970s. They hoped this

could

wean the West away from fossil fuels. If this sounds vaguely familiar, it's because nothing has changed. But it took a while until you could buy one.
how salt and sand could replace lithium batteries

More Interesting Facts About,

how salt and sand could replace lithium batteries...

Engineers Stanley Whittingham, Akria Yoshino and John B. Goodenough helped develop the first commercially available lithium-ion batteries that hit the market in 1991. For this they won the Nobel Prize. "You work with nice people and they do all the hard work, and you sit back and try to take as much credit as you can! Hahaha!" The lithium-ion battery is good at generating a lot of electricity in shorter bursts, so we've relied on it for consumer electronics and now electric cars. And it's also pretty much the only battery we use to store renewable energy at grid scale. But lithium extraction is problematic.
how salt and sand could replace lithium batteries
The extraction process involves pumping underground water deposits to the surface. To produce one ton of lithium, approximately 70,000 liters are needed. More than half of the Earth's resources are found between Argentina, Bolivia and Chile. Mining consumes 65% of the region's already scarce water supply. Lithium-ion batteries also typically use cobalt, which is expensive and mined primarily in the Democratic Republic of the Congo. News reports have covered this notoriously exploitative business, which uses child miners and devastates local communities. Lithium batteries can be flammable. If you can't take them on a plane, you should definitely think twice about having a giant one supporting your network.
how salt and sand could replace lithium batteries
And they lose capacity, so longevity really isn't their strong point. Lithium-ion batteries work, but they can't be the only solution for storing energy, especially at grid scale. According to the IEA, we will need nearly 10,000 gigawatt-hours of energy storage worldwide by 2040 to meet climate goals. That's 50 times the size of the current market. Today, it is actually another technology, pumped hydroelectric storage, which comprises a whopping 96% of the world's energy storage capacity. "It's basically based on pretty simple gravitational principles." This is Ramya Swaminathan. She's actually the director of a thermal storage company, which we'll talk about later, but she doesn't have any problems with water. "You have two reservoirs, or lakes, one high and one low, and when you have a lot of excess energy, you use that excess energy to pump the water uphill to the higher reservoir.
When you want to recover that energy, let the water run downstream and spin a turbine generator. However, those projects are difficult to build." These reservoirs take up enormous amounts of space and you need exactly the right geography: two lakes and a hill. Many of them also work on conventional hydroelectric dams, which require a lot of initial capital and alter the habitat. Renewable energy storage will need much more flexibility and modularity than these tanks. One promising alternative making headway comes from something you can find on your kitchen table:

salt

. "Sodium is much more abundant and chemically similar to lithium.
It is in the same group on the periodic table." This is Rosa Palacín. She is a battery researcher at the Barcelona Institute of Materials Science. She says it's the simplest alternative because it basically mimics lithium-ion battery technology. Sodium also has one valence electron: the number of electrons in the outermost shell. But sodium is a thou

sand

times more abundant, is between 20 and 40% cheaper and is not sensitive to changes in temperature. So, there are no problems with the explosion. But it has lower energy density and therefore heavier batteries, which is why it has not been commercialized before.
However, if it's over the network, this won't matter much since everything is stationary. And right now time is of the essence. "The sodium ion has a much higher level of technological readiness, so it is much closer to commercialization." While they are already on the market, analysts expect them to be produced on a large scale in the coming years. Research is also being done on calcium-magnesium-zinc batteries, but for these, "the technology is really at the laboratory demonstration level." Speaking of salt, what if we could store energy as heat in very, very, very hot salt? That's what Swaminathan's company, Malta, is doing in the United States. "We take electrical energy, whether directly from renewable generation, such as wind or solar, or simply from the grid, and convert it into thermal energy." It turns out that molten salt is a great heat preservative.
It looks like water and has approximately the same viscosity. Here's how it works: When excess electricity is generated, the energy is used to heat a large insulated storage tank of molten salt to very high temperatures. A high melting point means that the salt can absorb a lot of energy. It loses little of that heat and can retain it for more than 6 hours. In comparison, lithium batteries can only last less than four hours. When the grid needs power, the plant reconverts heat into electricity through a turbine. One of these plants would supply a large city for at least 10 hours.
Malta's first commercial plant will not debut until 2025. While its material costs are relatively low and its system is quite scalable, its efficiency still lags behind hydraulics and lithium. The hope is that the market will eventually make it feasible. You can do something similar with the piles of sand we mentioned above. A couple of Finns decided to use some local batteries to solve one of Finland's biggest energy problems: heating. Instead of converting the heat back into electricity, they simply use it directly. "The storage capacity is on the order of 1,000 times cheaper than that of lithium batteries." That's Markku Ylönen.
He co-founded a company that makes sand batteries. "We convert electricity into heat. We can do it at such a low price that we can play with large volumes of energy." How much sand? "100 tons of sand." It can store heat at 500-600°C for months. This heat goes directly to heat municipal buildings. Most importantly, it could provide heat to the heavy industry sector, which is one of the largest emitters of greenhouse gases. In cold countries, this solution makes a lot of sense. The company currently has a system that heats Kankaanpää, a southwestern city with a population of 13,000.
Technically, the 100-ton sand battery can stay hot for months, but it recharges in two-week cycles to keep it efficient. The company is also trying to source sand that is not used in the construction industry, as it is also scarce, and intends to make larger batteries. Let's keep in mind that these are just a couple of solutions. There are currently dozens of technologies, each competing for its place in the market. Redox flow batteries, for example, are another big contender for grid-scale storage. They don't work that differently than lithium-ion ones. In the latter, electrons travel between two electrodes through a liquid called electrolyte, creating a current.
In a flow battery, this liquid electrolyte is stored externally. The larger the tank, the greater the storage capacity, meaning the flow battery can be expanded very easily. And what needs scale? You guessed it: the grid. Until now, flow batteries made from the metal vanadium have been the most advanced available, although there are also advances in iron, bromine and sodium. The advantage of vanadium is that it is basically immortal. It can be recycled over and over again without degrading. A battery can last about 30 years, but that's only because the pipes and tanks would have to be

replace

d.
You can take out the vanadium and reuse it in a new one. "Chemical technologies, gravity-based technologies, mechanical technologies, flow batteries, all of that, it's a big need that we're trying to solve. And I think we're going to need it all." Each technology has advantages and disadvantages, so you have to look for its specific application. Investment has been concentrated in new battery technologies, driven by the electric vehicle market. The global grid-scale market is expected to grow 25% annually through 2027. And of them, redox flow appears to be the most promising. They are simply not commercially mature enough yet. The truth is that we are not going to abandon the use of lithium ions anytime soon.
The huge demand for electric cars means that some of the technologies and efficiencies under development will extend to the grid. But the fossil fuel industry is integrated into the economy. It is a major challenge to adapt entire systems, including infrastructure and policies, to renewable alternatives. The good news? The investment is there. Spending on grid-scale batteries increased more than 60% in 2020. And, at the end of the day, cost is the biggest factor limiting the adoption of new technologies. It will be the market that dictates how far they have come and how far they will go. Did you know that even stones can be used as energy storage?
It turns out that nature has all kinds of solutions for us. We just have to figure out how to use them correctly. If you like this video, don't forget to subscribe and click "Like". Until next time.

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