Store it and they will come: tackling clean energy’s biggest problem

Hampering the growth of renewable power has been the industry’s inability to develop a system that can adequately store the energy generated by the sun, wind and sea. But new storage technologies are now emerging that could solve this problem once and for all.

You can make it.

You can generate it. You just can’t store it. That has been the trouble with alternative energy.

Although the wind, the sun and the sea have the potential to offer an almost limitless source of fuel – particularly as clean power production costs are falling – the weather is insensitive to the energy demands of modern living.

Put simply, the wind does not always blow and the sun does not always shine.

You just can't store it yet.

Without a clever way of overcoming this problem, electricity providers are destined to rely on gas-powered turbines to compensate for dips in production – facilities that are both costly to run and generate greenhouse gases.

The most popular type of energy storage is clearly not a viable solution.

Almost all of the world’s energy storage systems rely on some form of pumped storage hydropower (PSH), a technology that was first developed in the 1890s. The system transforms the potential energy of water – stored in a high level reservoir – into kinetic energy by pumping the water into turbines that sit below.

However; the construction of dams and reservoirs has several drawbacks. Not only do new PSH installations require significant funding and impact local ecosystems and communities, but they are viable only in regions with suitable topography and water availability.

Yet a range of new energy storage technologies offers some hope. These range from smarter batteries to systems that harness the conservation properties of molten salts. These innovations, combined with plans to better incorporate alternative power into traditional electricity grids, could herald a new dawn for clean energy.

Compressed air – breath of fresh air

Compressed air energy storage (CAES) pressurises gas in natural or artificial caves and stores it there until needed, when it is expanded to generate power. It is the second most mature storage technology on the market. Recently, more efficient technologies have been proposed. The world’s first adiabatic CAES pilot plant is currently under construction in Pollegio, Switzerland, adapting an abandoned tunnel under the Alps. Innovators in the field include Swiss company Enairys Powertech Ltd and LightSail Energy in California – providing power to both residential and commercial consumers.

compressed air storage

Batteries – electrochemical solution

Key factors hampering the battery’s ascent have been safety, energy density, lifetime and cost – until now. Batteries that can store solar power for home and commercial use took a step closer to reality with the unveiling of Tesla’s family of new lithium-ion batteries. Although this represents a major leap in the commercialisation of storage technology, research continues on new materials and chemical compositions to enhance energy density and mitigate safety concerns. UK-based company Oxis Energy has come up with a novel solution it believes can revolutionise battery storage while overcoming the drawbacks of Lithium-ion.

Traditional Lithium-ion batteries work thanks to the movement of positively and negatively-charged particles between two electrodes – one made of carbon, the other a heavy metal. Oxis Energy’s battery, however, replaces the heavy metal carbon electrode with one made of sulphur, which is lighter, cheaper and more reactive than most heavy metals. As such, Lithium-sulphur batteries, the company maintains, could provide as much as four times more storage than Lithium-ion but at a lower cost.

electrochemical battery

Molten salts – salt of the earth

Energy storage using molten salts has potential in hot, sunny climes. The commercial-scale Gemasolar plant located in Seville, Spain, is the world’s first solar plant in the world to use molten salt heat storage technology. It allows the facility to continue operation for 15 hours without sunlight. Results so far have been promising; the plant managed to operate 24 hours a day for 36 consecutive days in the summer of 2013. Facilities using the same technology in Arizona and California have the capacity to power 70,000 and 91,000 homes, respectively.

Flywheel – reinventing the wheel

Flywheels can store excess kinetic energy using a rotating disc. The power loss due to friction has meant flywheels have had a reputation for low energy densities and high costs, so many companies are working to improve their efficiency. In Europe, Formula 1 team Williams developed flywheels for energy recovery in racing cars, later selling the technology to GKN. Separately, Beacon Power flywheels are applied in microgrid power system management and renewable generation integration. “Flywheels can beat next-generation batteries in terms of price, while also providing durable, precise and environmentally benign energy storage solutions,” says Barry Brits, President and CEO of Beacon Power.

flywheel

Hydrogen – step on the gas

Scientists are working on more efficient power storage through chemical bonds, using hydrogen molecules. In Germany, the Linde Group, Siemens and partners have recently opened the world’s largest green hydrogen plant. The facility has the capacity to produce and store enough compressed hydrogen to power around 2,000 fuel cell cars. An effective way to use hydrogen is through the use of hyrdogen bromine (HBr) flow batteries. “No hydrogen compressor is needed, resulting in direct cost savings, but also saving the energy consumed by the compressor itself during charging,” says Wiebrand Kout, founder and CEO of Dutch company Elestor.

hydrogen

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Mega

Mega seeks to energise and enrich the debate over how to create a better-functioning economy and society.

Megatrends are the powerful socio-economic, environmental and technological forces that shape our planet. The digitisation of the economy, the rapid expansion of cities and the depletion of the Earth’s natural resources are just some of the structural trends transforming the way countries are governed, companies are run and people live their lives.

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