© Shutterstock

Renewable energy -

When it comes to renewable energy, we have made significant progress over the last two decades.

© Shutterstock

Statistics -

There are many countries that have renewable energy contributing to more than 20% of their total energy supply, and globally there are 10 million jobs associated with the renewable energy industries.

© Shutterstock

Key challenges -

Despite this progress, a number of challenges still remain. One of the biggest challenges is how we can provide a year-round, steady supply of energy from renewable sources.

© Shutterstock

Steady supply challenge -

With the supply of wind and solar energy heavily dependent on changing seasons and variable weather conditions, this is a topic that has many experts scratching their heads.

© Shutterstock

Hope for the future -

There are four young engineers in Finland, however, who believe they may have found the solution. Enter the world’s first commercial-scale sand battery.

© Shutterstock

Introducing the sand battery -

Within the Vatajankoski power plant (about a three-hours' drive northwest of Helsinki) stands a 23 ft (7 m) steel container. That container encloses 100 tons of sand, two heating pipes, and a fan.

© Shutterstock

How it works -

The sand becomes a battery when it is heated to 600°C, using electricity generated by wind turbines and solar panels in Finland.

© Shutterstock

How it works -

The battery stores around 8 MWh of thermal energy when it's full, and it is surrounded by thick insulation, which keeps the sand hot even when it is freezing outside.

© Shutterstock

Discharging heat -

When the demand for heat rises, the battery discharges around 200 kW of power through its heat exchange pipes.

© Shutterstock

Scale -

That is enough to heat and provide hot water for around 100 homes and a public swimming pool, supplementing power from the grid.

© Shutterstock

Charging the battery -

The battery is then charged overnight when the cost of electricity is lower.

© Shutterstock

Hopeful -

The engineers of this renewable energy solution are very excited about it, and rightly so. The system is very low maintenance: it uses cheap, low quality sand that was rejected by builders.

© Shutterstock

Sustainable sand -

This means that it does not contribute to the global shortage of high-quality river sand, which is used in very large quantities for construction.

© Shutterstock

Little wear and tear -

There is no wear and tear involved with either the sand or the heat exchange pipes. The only moving part is the fan and, according to the developers, it's easy to replace if necessary.

© Shutterstock

Long-term solution -

Sand is very effective at retaining heat over a long period of time, and it can store power for months on end.

© Shutterstock

Long-term solution -

It also has a very long lifetime in the sense that it can heat up and cool down any number of times. Over time it will become denser, at which point more sand will be added.

© Shutterstock

Lithium-ion comparison -

In terms of comparison with lithium-ion batteries (as the most commonly used alternative), the sand battery has a number of advantages.

© Shutterstock

Doesn't degrade -

Firstly, we do not have to worry about a sand battery degrading in the same way lithium-ion batteries do.

© Shutterstock

Doesn't degrade -

There is no chemical reaction that occurs in the sand battery, so it does not go through the same troublesome process of aging.

© Shutterstock

More suitable for large scale -

Sand batteries are also more suitable for large-scale storage applications: this is tricky with lithium-ion batteries because they are inherently flammable.

© Shutterstock

CO2 emissions -

Then there’s the environmental impact to consider: lithium is much worse than sand in terms of CO2 emissions.

© Shutterstock

CO2 emissions -

For every ton of refined lithium produced, the equivalent of between three and nine tons of CO2 is emitted, depending on how it is produced.

© Shutterstock

Challenges -

The sand battery solution is not without its challenges, however. Indeed, the team needs to work out whether they can scale their technology enough to really make a difference.

© Shutterstock

Electricity generation -

They also need to consider how they will use the battery to generate significant amounts of electricity in addition to heat.

© Shutterstock

Electricity generation -

In order to scale up the battery for electricity generation, they will need to add a turbine to convert heat back to the grid.

© Shutterstock

Getting close -

According to engineer and team member Tommi Eronen, they will have a working system to do that in the next two years.

© Shutterstock

Global plans -

Currently the sand battery is a uniquely Nordic solution to renewable energy storage. In theory, however, it could have applications all over the world.

© Shutterstock

The mission -

According to Eronen, the aim is to become "a truly global company, constructing sand batteries all over the world" by 2023.

Sources: (BBC)

See also: Could gravity batteries be the answer to energy storage?

© Shutterstock