In Europe’s high-tech scramble for higher power storage

A “metal sock” in the ground, stuffed with hydrogen. Barrels of scorching sand. Huge weights move up and down old mine shafts very, very slowly. Is this the future of energy?

This menagerie of strange machines and heat-storing ships is poised to spring up across Europe as the continent searches for ways to store the excess energy generated by renewable energy. Great Britain for example Half a billion pounds worth of wind energy wasted in 2021 because there was nowhere to store it. Without such storage, the electricity must be consumed at the moment of generation.

As Wind energy continues to be wasted Across Europe, the EU is spending record sums – billion euro – on gas imports as it reduces its dependence on fossil fuels from Russia.

Discover the future of technology!

Visit us at the TNW conference on June 15th and 16th in Amsterdam

“We are at a tipping point,” says Dominic Walters, chief corporate affairs officer at Highview Power, a UK-based company working on a means of storing energy as liquid air. “Everything needs to be accelerated everywhere,” he adds, referring to the diverse range of energy storage projects currently in early development stages in Europe.

Proponents of alternative energy storage technologies argue that lithium-ion batteries will only get us so far. Their production depends on mining, they don’t have a very long lifespan, and they do not ideal for storing energy for more than several hours.

“If we don’t find out soon how we can stabilize Europe’s power grids, we will regret it,” says Jacopo Tosoni, political head of the European Association for Storage and Energy (EASE): “You basically have a risk of power blackouts in 2030.”

Work is now underway to put the necessary storage media in place so that the energy can be held and serviced until the moments when it is needed.

The heat is on

In an industrial area of ​​Kankaanpää, Finland, a town of around 12,000 people, There is a seven meter high, dark gray silo full of sand. Sand that can store energy in the form of heat.

“Our year-round efficiency is about 90% for the system, so 10% losses, which is obviously pretty good,” says Tommi Eronen, managing director and co-founder of Polar Night Energy, an eight-person startup that has raised €1.25 million so far. Eronen described how the sand, heated to 600°C with excess electricity, stays hot for months thanks to the insulation lining the walls of the steel container. Pipes filled with hot air run through the sand to transfer heat inwards or outwards.

That sand battery is connected to a heat exchanger, Eronen said, so operators can transfer thermal energy to district heating systems or, in possible future versions of the technology, turbines to generate electricity.

Eronen explains that early versions of the company’s sand battery are relatively small. The Kankaanpää unit offers 100kW of heating power, or a capacity of 8MWh, but Polar Night Energy is planning units of 100MW and up that could one day provide several GWh of juice. Such units would be about eight meters high and 44 meters in diameter, says a spokesman for Polar Night Energy.

Expects news already this spring regarding the delivery of a 2MW version, adds Eronen.

Polar Night Energy heat storage. Image: polar night energy

In the Netherlands, GroeneWarmte is working on a different type of thermal energy storage called Ecovat, which uses water heated to temperatures of up to 95°C instead of the much hotter sand Polar Night Energy chose. “It basically just stores water in a large underground tank,” says project engineer Marijn van den Heuvel. “It’s a very large thermos.”

However, a little more construction is required to set up this system. The “thermos flask” made of concrete must be installed carefully in a huge, cylindrical hole in the ground. But after that it can be covered and the storage works similar to the design of Polar Night Energy. The heat, which the vessels hold for several months if needed, would be transferred to district heating systems via heat exchangers. According to Van den Heuvel, GroeneWarmte and his team of eight are working on a possible first use of this technology with a Danish company.

These approaches are fairly new, but Highview Power is already building a 50MW facility in Carrington, England, where power is said to be stored in the form of liquid air. The site will form a bewildering array of silos, pipelines and platforms lined up one after the other. It will include heat and cold storage and containers for the liquid air itself.

“We filter it so effectively that it’s clean air, that air is liquefied, and then we cryogenically freeze it,” explains Walters, referring to the process that air is in cooled to almost -200˚C. By later heating this very cold, liquid air, it turns back into gas and expands, and can be used to power a turbine, throwing electricity back into the grid. The system achieves 55-65% efficiency, which Highview says is comparable to other storage technologies. One of the benefits of this approach is that the technology should have a lifespan of several decades, much longer than lithium-ion batteries, potentially allowing governments to plan around such infrastructure more easily.

According to Walters, the Carrington site is expected to be operational by the end of 2024. At the moment the 55-strong company is raising a £400m round of funding and is planning a further 19 installations across the UK. Ultimately, it aims to meet 4 GW or 20% of the UK’s expected energy storage needs by 2035.

Ecovat energy storage systemThis is the Ecovat. Image: GroeneWarmte

Another save method falls

Perhaps the simplest concept of all, currently vying for its place in the energy storage landscape of the future, is the gravity battery. Most of us learned about “potential energy” in school. There is arguably no better example of this than a large weight held aloft, eager to yield to gravity and fall to the ground. By attaching cables to such a weight — literally flexing it — it’s possible to slow its descent to about a meter per second and use the pull it exerts to generate electricity via a turbine.

Gravity’s approach in this sense, at least initially, is to lower its weights hundreds of feet into abandoned mine shafts using a guidance mechanism. The company, which employs 17 people, has so far raised £7.5million to help make its vision a reality.

“If it were to swing around the square, the shaft would collapse in on itself very quickly, which of course isn’t what we want,” explains commercial director Robin Lane. A single weight could provide 4-8 MW of power, he estimates, and could be calibrated to provide power for a specific period of time, say 15 minutes or an hour. Imagine a system in which multiple weights are poised to descend one at a time in a carefully synchronized order so that electricity can be generated at a constant rate. Early commercial systems will use a combination of large weights totaling 1,000 tons.

Lane concedes that this approach cannot yet compete with lithium-ion batteries on a cost-per-MW basis, but he argues that gravity batteries will eventually be commercially competitive. It should also be possible to lift and lower weights repeatedly for many years without compromising the integrity of the system. Lithium-ion batteries, on the other hand, do stricter restrictions on cycling.

Another company, Energy Vault, which employs 150 people, is also pursuing gravity battery technology. To date, the company has raised approximately $410 million in funding.

Gravity Multi Weight Energy Storage SystemThis is an image of Gravity’s gravity-based energy storage system. Image: gravity

Gravity is also exploring other ways of sequestering energy in old mine shafts, such as lining them with metal and converting them into hydrogen storage.

“It’s a metal sock that you lowered into the shaft, and then you buried that metal sock with a mix of ballast, concrete and steel,” says Lane. It potentially makes it easier and cheaper to store hydrogen at high pressures than above ground because the container can rely on the existing geology of the well for structural support. The hydrogen could come from electrolyzers connected to wind farms, using excess energy to make the gas from water.

For Tosoni, the diversity of storage projects emerging in Europe is encouraging given the expected energy needs that countries will face in the coming years. But less important than choosing one technology over another is the funding and policies required to scale up either one.

“The big problem is the financing,” he says, noting the caution of some investors. Governments could help, he suggests, by setting more ambitious targets for deploying energy storage facilities.

Eronen is generally optimistic about the future, noting that Polar Night Energy is launching a new round of funding of between €5 million and €10 million. But it remains frustrating to witness the current energy crisis in Europe today and to know that with the best will in the world these systems are not quite ready for prime time.

“It feels so bad,” he says. “We see the crisis now and there is almost no way we can help.”

According to EASE, the current rate of storage added each year in Europe must increase from 1 GW to 14 GW per year if the continent is to reach the 200 GW total grid-scale storage capacity it is projected to need by 2030. So the boost is definitely underway .

Comments are closed.