The revolutionary sand battery that can boost clean energy – 06/07/2022

Using low quality sand, the device is charged with heat generated by cheap electricity from solar or wind power.

Finnish researchers have installed the world’s first fully functional “sand battery” that can store green energy for months and months.

Officials say this could solve the year-round power supply problem, an important issue for green energy.

Using low quality sand, the device is charged with heat generated by cheap electricity from solar or wind power.

Sand stores heat at around 500ºC, which can heat homes in winter, when energy is more expensive.

Finland gets most of its gas from Russia, and the war in Ukraine has made the issue of green energy even more important.

Finland has the longest border by a European Union nation with Russia, which cut off gas and electricity supplies after Finland’s decision to join the North Atlantic Treaty Organization (NATO), a US-led military alliance.

In this context, the provision of heat and light, especially with the long and cold Finnish winter, worries politicians and citizens. But in a corner of a small power plant in western Finland is a new technology that has the potential to alleviate some of those concerns.

The key element in this device? About 100 tons of construction sand, piled up in a dull gray silo.

These rough, ready-made beans can represent a simple, cost-effective way to store energy for when you need it most.

Due to climate change and now also thanks to the rapid rise in the price of fossil fuels, there is an increase in investment in the production of new renewable energy.

But while new solar panels and wind turbines can be quickly added to national grids, these extra sources also present major challenges.

The most difficult question is about intermittency: how do you keep the lights on when the sun doesn’t shine and the wind doesn’t blow?

Adding more renewables to the electrical grid also means that you need to increase other sources of energy to balance the grid, as too much or too little energy can cause it to collapse.

The most obvious answer to these problems is large-scale batteries that can store and balance energy demands as the grid becomes greener.

Currently, most batteries are made with lithium and are expensive, with a large ecological footprint (a sustainability indicator that measures how much natural resources have been consumed and how much waste has been generated). And they can only handle a limited amount of excess energy.

But in the town of Kankaanpää, a team of young Finnish engineers has completed the first commercial installation of a battery made of sand that they believe can solve the storage problem in a cost-effective and low-impact way.

“Whenever there is this high wave of green electricity available, we want to be able to add it to storage very quickly,” said Markku Ylönen, one of the two founders of Polar Night Energy, who developed the product.

The device was installed at the Vatajankoski plant, which operates the area’s district heating system.

Low-cost electricity heats the sand up to 500°C by resistive heating (the same process that makes the electric oven work). This generates hot air, which circulates in the sand through a heat exchanger.

Sand is a very effective means of storing heat: the developers say their device can keep the sand at 500ºC for several months.

So when energy prices get higher, the battery discharges the hot air that heats the water for the district heating system, which is pumped to homes, offices and even the local swimming pool.

Costs cut

The idea for the sand battery was first developed in a former pulp mill in the city of Tampere, with the municipality donating the workspace and providing funding to get it off the ground.

“If we have some power plants that only run for a few hours in winter, when it’s colder, it’s going to be extremely expensive,” said Elina Seppänen, an energy and climate expert in the city. “But if we have this kind of solution that offers flexibility for the use and storage of heat, that would help a lot in terms of cost, I think.”

One of the big challenges now is whether the technology can be applied to wide use and then really make a difference. Will developers be able to use it for electricity and heat?

Efficiency drops dramatically when sand is only used to return power to the electrical grid. But storing green energy as long-term heat is also a huge opportunity for industry, where most of the process heat used in food and beverages, textiles or pharmaceuticals comes from burning fossil fuels.

Other research groups, such as the US National Renewable Energy Laboratory, are actively looking at sand as a viable form of battery for green energy. But the Finns are the first to arrive at an active trading system, which so far is working well, according to the person who invested in the system.

“It’s very simple, but we like the idea of ​​trying something new, being the first in the world to do something like this,” said Pekka Passi, managing director of the Vatajankoski plant. “It’s a little crazy, but I think it’s going to be a hit.”

– The text was originally published at https://www.bbc.com/portuguese/geral-62062579

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