This sand battery compensates for the great shortcoming of green energy

More and more researchers are interested in non-chemical batteries to support the ecological transition.

Rethinking the way we generate and use energy is imperative to achieve our environmental goals. But it also means developing new ways to store it. Finnish researchers discovered by the BBC have installed the first-ever battery of a new kind: it’s an accumulator that works on sand and heat.

This association may seem absurd at first glance, but it is still based on solid foundations. In short, a battery is neither more nor less than one Possible energy reserve, i.e. energy that can be recovered in another form at the end of a transformation. The most explicit example is certainly that of der spring ; it accumulates potential energy when compressed and releases it mechanically when released.

In a standard accumulator this potential is chemical. The energy is returned in the form of electricity through a reaction between the anode, cathode and electrolyte. But theoretically, this potential energy need not be chemical. Finally, as long as we can find a way to convert one energy into another in a reversible manner and with good efficiency, we have a battery.

Alternative batteries in the service of renewable energies

For example, a huge battery using gravitational potential energy has just opened in Nant de Drance, Switzerland (see our article). To return energy to the system, engineers open valves that drain a reservoir of water into a reservoir below. Under the action of gravity, this water will also set turbines in motion, which is equivalent to recirculating electricity.

© Nant de Drance

The main concern of these systems is that they are a Perfect complement to renewable energies die im Moment auf dem Vormarsch sind. These are usually given by definition changing ; the balance of wind energy remains zero as long as the air is calm, like that of photovoltaics at night, and so on.

With such technology it is possible Conserve this energy during production peaks, when it is plentiful and, by definition, inexpensive. It can then be returned during low periods when the weather is less favorable and prices are higher. And all without the use of conventional chemical batteries.

Sand instead of acids

The Finnish engineers are also pursuing this goal with their battery. But here the concept is different again. First, it does not rely on chemical or gravitational potential. Instead, engineers use large resistors Heat the contents of a tank of about 100 tons of sand.

Electrical energy from photovoltaics and other renewable energy sources is therefore stored in the form of heat. And contrary to intuition, it can remain in this form for a long time.

This sand has a very high specific heat capacity. Very vulgar, which means he can Save a lot of warmth and the hold (several months according to the researchers) with

Cordless telephone recycling
More and more innovative new technologies are now competing with standard chemical batteries. © GMG

A clean, economical and already functional system

The other peculiarity of this system is that it does not convert this heat back into electricity at the end of the chain. Instead, it is used as is. In times of low demand, the stored heat can be used directly Supply the municipal heating system. It then helps heat homes, offices, public buildings… and even the local swimming pool.

For the time being, everyone is satisfied with this very environmentally friendly system. And according to those responsible for the project, all the prerequisites are already in place to use this technology wherever renewable energies are established. Such systems can also be imagined on the scale of a single house.

potential in the industry

In addition, this does not only affect individuals and municipalities. L’Industry could also use these systems very well. This would encourage the deployment of green energy in industries where the disruption of renewable energy would force the operator to invest in giant chemical batteries, which is often economic nonsense and an ecological fallacy.

The other very interesting aspect in this industrial context is that such a battery could even make it possible to store a small part of the residual heat generated by the normal operation of a factory!

But there is still work to be done to achieve this. The next step is to examine whether this concept could be implemented on a very large scale with several hundred or even thousands of tons of sand.

The researchers also want to investigate the technical feasibility of converting it into electricity. For now, the yield from this operation remains ridiculously low, but researchers are relatively optimistic.

So it will be interesting to see how far they can push their concept and whether other communities will be tempted.

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