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Renewable energy -

We have a number of renewable energy solutions in place. Solar panels and wind turbines are great, provided the sun shines and the wind blows.

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The status quo -

When skies are gray and the wind is low, however, things get a little trickier. Currently we plug the energy gap by burning fossil fuels, such as natural gas.

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The paradox -

Of course, conventional power production pumps CO2 into the atmosphere, which means it is in direct contrast with plans to reach carbon neutrality.

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The problem statement -

What can we do, then, to push the renewable energy revolution forward? How can we ensure we have enough energy when solar, wind, and wave solutions are unavailable?

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Options -

Some people argue that green hydrogen is the answer, while others are great believers in lithium-ion batteries, which are getting ever bigger in size.

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Introducing gravity -

And then there are those who believe we can solve the energy storage problem by harnessing a rather well-known force that is at play all around us: gravity.

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The concept -

The idea behind gravity batteries is simple. While we have plentiful supplies of solar, wind, and wave energy, we use it to suspend a colossal weight at a predetermined height.

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The concept continued -

When supplies of those green energy sources are limited, we release the weight, powering a generator with its gravitational pull.

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Existing solution -

Gravity batteries are not dissimilar in principle to another high-capacity energy storage solution, so-called “pumped hydro.”

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Pumped hydro -

The idea there is that we pump water uphill while we have surplus power, and then, when needed, we channel it back down through hydroelectric generators.

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Limitations -

As a system, pumped hydro works. There are considerable scalability limitations, however, since hydro projects are huge and very expensive.

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Limitations continued -

Their specific geographical requirements (a vertiginous terrain and a huge amount of water) also mean that hydro is not going to get us to net-zero.

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Gravitricity -

A certain green engineering start-up in Edinburgh, Gravitricity, is working to make gravity batteries a reality. They already tested a prototype in April 2021.

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The prototype -

They gradually lifted a 50-tonne iron weight to the top of a 15-m (50-ft) tower and then released it slowly, powering a series of generators with the gravitational pull.

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Success -

The prototype was small, but the test was successful. The team was also satisfied that the model could have an operational life of decades—an important consideration.

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Taking it to the next level -

The team at Gravitricity are now looking into whether it might be possible to extend the weights above decommissioned coal mines.

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The rationale -

Their thinking is that we should not build towers to suspend the weights if we can make good use of the Earth’s very own geology.

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Timeline -

There are a number of challenges to be overcome before this can become a reality, but it is hoped that with enough funding a prototype will be in place by 2024.

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Energy Vault -

Other players in the gravity battery game do not see subterranean projects as the future, however. Swiss-based company Energy Vault, for example, prefers to keep its batteries above ground.

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Swiss prototype -

In a valley in southern Switzerland, they have a prototype that stands 20 stories tall. The prototype can generate enough energy to power thousands of homes.

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Investment -

Energy Vault have received some US$400 million in investment funds and are now ready for a commercial rollout.

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Expansive - Of course, their installations will be huge. We’re talking buildings that span dozens of acres, even at the lower end of the size spectrum.

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Not to worry -

However, according to the company’s CEO, Robert Piconi, this is not a problem because the installations will be built near wind and solar farms far from city centers.

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Garnering interest -

It seems clear that all countries will have to move to some form of green energy storage at some point, and indeed there is considerable interest in the Energy Vault offering.

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From far and wide -

According to one BBC article, there is interest coming in from across Europe, America, the Middle East, Australia, and China.

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Added benefit -

Gravity batteries also have another benefit over their competitor, lithium-ion batteries, in that they are actually repairable.

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The problem with lithium -

One key problem with lithium-ion batteries is that their storage capacity drops irreparably over time. That is to say, they can only be used for a certain, short period of time.

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Longer life span -

Gravity batteries, by contrast, are made of individual components that are reasonably easily replaced. They are believed to have a lifespan of up to 50 years.

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The problem with lithium continued -

Couple the limited lifespan of lithium-ion batteries with the concerns about human rights abuses associated with their production, and gravity batteries seem to have the edge.

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All in all -

Of course, only time will tell whether gravity batteries are the answer to the energy storage crisis we have been searching for. For now though, things are looking good.

Sources: (BBC)

See also: Food waste: an alternative to natural gas

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