Energy storage: the sometimes forgotten partner of the clean revolution

Reading time: 5 minutes
25 June 2015

Peter Curley, Technologist, The Climate Group, explores current and future trends in energy storage, the technological development of which is crucial for renewables to grow at the pace and scale required for a robust low carbon future.

Not a day goes by without a news story about some new, big wind turbine plant, solar power installation or large-scale hydroelectric project. Last year, renewable energy accounted for over 60% of net addition to the world’s power capacity.

The shift towards renewables globally is testament to the impressive development of wind and solar technologies over recent decades. Supported by progressive government policies and driven by entrepreneurial flair, wind and solar energy have experienced dramatic falls in cost, making them the cheapest source of new-built power in many countries.

But to be truly transformational and to lead the shift to a fully decarbonized energy system over the next few decades, renewables, particularly solar and wind, need to address their two remaining and interrelated challenges – intermittency of supply and storage limitations.

While global solar and wind energy supply is effectively limitless - with the potential to supply the world’s entire energy needs many, many times over - the production of power from these sources obviously varies depending on the level of sunlight and wind strength. Supply may be too little as well as too much for demand.

The obvious answer to this intermittency of supply problem has always been the idea of energy storage, that is to say capturing surplus renewable power when it is generated, converting it into a storable form of energy, and then using it when supply falls to fill the gaps in generation. Practice, however, has always lagged a long way behind the theory for both technical and cost reasons. Change however is afoot.


No magic bullet exists to solve this urgent, but very complex problem. To date, we have a vast array of energy storage approaches available, and many innovative ideas are still in development. Such a wide range of solutions is fundamental to ensure there is sufficient energy storage capacity, access to the energy when it is needed, and delivered in a form optimally matched to the energy generator and the final end application. 

But what exactly is the format this ‘energy storage’ takes? Well, we all use it in our everyday lives. Our most common experience with it is in the form of batteries, which can be very different from one another.

These ordinary objects are actually very complex: their chemical composition can be quite different, such as their storage capacity or energy density; they can be rechargeable, with different cycle times; they can use a fast or slow charge and discharge; they can be paired with smart controllers; and they cover a wide range of physical sizes, weights and costs.

As we can see, even an ‘ordinary’ object like a common battery can have a seemingly endless number of combinations, each selected and matched to solve a specific storage problem– just like large-scale energy storage for renewables.


Energy storage at home recently made the headlines of most newspapers when Tesla announced its home energy storage offering to the wider public. But looking at the larger scale needs for towns and cities, energy storage solutions for renewable energy sources can also allow engineers to better manage and balance energy into the grid. This is a problem particularly felt in India – where in 2012 the largest blackout in history made very different headlines when it left hundreds of millions of people in the dark.

And storage solutions exist far beyond just simple batteries, too. They can include pumped hydro/water, pumped heat, large flywheels, super-capacitors, pressurized gas storage, hydrogen generated from electrolysis of water for use with fuel cells, the synthesis of hydrocarbon fuels, superconducting magnetic energy storage – and the options list goes on. Each energy storage approach brings a new, different solution with many more in research and development.

At this point, it is clear the adoption and success of many renewable energy solutions are fundamentally linked to a suitably-matched and efficient storage solution. 

This is why every time I read one of those news stories about a new wind farm or solar PV array, I always ask myself: how is the energy being stored? What are we losing? Is the energy being managed the best way? These projects should aim for a smart and efficient storage approach for all generated power, and to ensure delivery of the energy in the most effective way to the end application.

Renewable energy generation and matched storage are two faces of the same medal. And I look forward to seeing more media coverage underlining this link. Current and future energy storage solutions play a critical role in the economic validation of renewable energy solutions across all scales. But to achieve that, we need clear policies supporting this fundamental connection.

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