How important are batteries to Renewable Energy Sustainability and profitability?

Many see energy storage as the most important part that is missing in the electricity infrastructure of many countries, not least the UK. The very nature of renewable power is the main reason for this. Wind, solar and marine energy (wave and tidal) can generate large amounts of electricity but the dependency on natural processes means they are not predictable and will sometimes occur at times which are incompatible with the times that they are needed. One example of this is the sun shines during the day but we switch the lights on at night. Being able to store the energy at times when there is an abundance of wind & sun to be released to the grid when it’s needed would mean that renewables could be used to their full potential and further reduce our reliance on fossil fuels.

Our lives are already powered by lithium-ion batteries. From sending emails to checking social media to driving to friend’s houses, batteries keep 21st-century life in motion.   

Our reliance on batteries is set to increase over the coming decades. Batteries will increasingly be used in conjunction with renewable energy production as we move towards a coal-free future.

There are many ways to store energy but the technology that is currently receiving the most inventive engineering attention is the energy storage solution that we are all most familiar with from our childhoods and that is the battery. However, we are not talking about Triple-As! Large and highly sophisticated devices capable of holding very high amounts of charge are being developed. This energy can then be fed to the grid as and when needed.

Earlier on this year it was announced that the UK’s biggest battery was going to be built at Whitelee wind farm near Glasgow. The battery will store power generated by 215 turbines and should prop up the National Grid even when the wind is not blowing. This is expected to be the first of at least six similar projects across Scottish Power’s renewable energy sites. 

There is around 500MW of large-scale battery power installed around the UK, a figure that is expected to double within three years, according to the analysts Aurora Energy Research. Almost all capacity uses lithium-ion.The most well-known large-scale grid storage facility in the world, was built by Tesla in South Australia and is known simply as the Big Battery. It is made up of a very large collection of Tesla’s Powerwall units, based on the same type of battery that powers Tesla’s cars.

The Big Battery or as it’s properly known, the Hornsdale Power Reserve, is rated at 100MW/129MWh and stores wind energy from the adjacent Hornsdale wind farm and solar energy from domestic photovoltaic panels across the state. According to Tesla, it stores enough energy to power more than 30,000 homes.

At the end of 2018 figures presented by the Australian Energy Week suggested the new system had reduced the price of power outages by 90 per cent. 

In the UK, battery installations are primarily being established to supply services to the National Grid. Such supporting services are increasingly important to help match supply and demand as a growing amount of intermittent wind and solar power comes online.

There are also the beginnings of “hybrid” renewable energy power plants, where batteries are installed alongside solar farms and windfarms. This helps improve the economics of solar farms, which can push down power prices around midday by peaking at the same time. Instead of exporting immediately, hybrid farms can store power to sell later at higher prices.

Tesla was not the first firm to introduce the concept of a home battery. Such batteries, which are about the size of a gas boiler, can store and release electricity either generated by a household or imported from the grid.

For solar households, it makes more financial sense to store and consume the energy rather than be paid for exporting it to the grid. In future, as more time-of-use energy tariffs emerge, there might also be enough of an incentive to install a home battery to avoid peak pricing.

The German firm Sonnen, which has around a 25% global market share in home batteries, said most customers today are people who have solar panels or live in storm-hit regions and want a clean, reliable backup source of power. “The market is still in the very, very early phase,” says the chief executive, Christoph Ostermann. 

Companies are working hard to increase the amount of energy that can be packed into a battery, and to bring down the cost of making them.

Prices are unlikely to fall as fast as they have in the past because reductions have already been so rapid. Sonnen has seen prices fall from more than €1,000 (£905) per kilowatt hour of energy capacity when it started in 2010, to about €150-200 per kWh today. But the company expects to cut costs in electronics such as inverters.

It is thought that new materials will take a while to break through. Paul Shearing, a global visionary in emerging technologies, says;

“The next 10 years are going to continue to be lithium-ion dominated. It’s taken a long time to get to this productivity and technological maturity level. For anything to catch up will take a while.”

Paul Shearing, believes that most innovation will be around lithium-ion, such as improving the energy density and lowering costs by reducing the amount of cobalt in a battery. He also thinks that the rate at which batteries can take on a charge will improve.

It looks likely that lithium-ion batteries will continue to dominate and that cost and performance will improve, driven by the scale-up of manufacturing and continued research.

While the Smart Export Guarantee sounds attractive being a system where your electricity company pays you for any excess energy you generate, these same electricity companies will buy the spare electricity you produce at a wholesale rate from you and then sell it to other homeowners at a retail rate. The real potential only comes by attaching a battery to store the electricity your solar panels generate during off-peak hours and then using that power during those times when it is more expensive to buy electricity.

As solar panel technology improves, there is an excellent chance that many homeowners will become either completely energy self-sufficient or the electricity they draw from the grid is so minimal that, essentially, they get their electricity for free. This is because the battery in someone’s home has enough capacity to store electricity to run a home for the day and be either fully or mainly topped up by solar energy on an ongoing basis.

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