The run up to March’s solar eclipse over Europe produced the sort of headlines that proponents of renewable energy dread - filled with predictions that power grids would become unstable in countries that are now consuming considerably more solar energy than during the region’s last major eclipse back in 1999.
In the end, good planning and a vast availability of other power sources to fill the gap, such as coal, gas, nuclear, hydropower and wind, meant there was little disruption, even in countries such as Germany and Italy that produce a lot of solar power. But the coverage still highlighted problems associated with the intermittency of solar and wind power, often used as arguments against a more rapid adoption of renewables.
In 2014 Germany, Europe’s largest solar energy producer generated around 6 per cent of its electricity from solar panels– and another 9 per cent from wind power. But what would happen if this was increased without a substantial amount of reliable electricity generated by fossil fuels to rely on? Would the grid collapse during an eclipse? Would a few cloudy days with light winds across northern Europe jeopardise the country’s ability to keep the lights on?
It’s a concern that is at least partly being assuaged by revolutionising the use of batteries – a humble, old-school technology that we take for granted but which is fast becoming considerably less modest as scientists discover how to improve it and, by combining thousands of cells together, create giant energy storage units that could help underpin the world’s power supply in decades to come.
The principal is simple: you store surplus energy produced at times of low power demand and then use it a time when it’s needed. That could be to compensate for low solar or wind generation if it’s either too cloudy or not windy enough, or just to help meet peak demand, instead of expanding a power station or upgrading an electricity grid.
Small-scale experiments with battery storage attached to electricity grids have been going on for decades, but progress has been slow until recent years, reflecting both the technical challenges and relatively high costs of using large-scale storage. As the world gets more serious about renewables, so the imperative to improve battery storage grows.
At the moment, the world’s largest batteries hooked up to the grid, of which there are just a few projects in China and California – have capacities of around 30-35 megawatt-hours. One example, Southern California Edison's demonstration project in the Tehachapi Mountains, is a 32 megawatt-hour battery that can produce eight megawatts of power for four hours in an area where wind power is becoming an increasingly important source of electricity supply.
A city such as Los Angeles can require more than 6,000 megawatts of power capacity to keep the lights – and air-con – on at times of peak demand. Meanwhile, a gas or coal-fired power station might have a capacity of 500-1,000 megawatts or more, and large-scale wind or solar farms can also run to several hundred megawatts these days. Eight megawatts of power for four hours might not seem like enough to make much of an impression, but even modest storage capacity can make a big difference.
According to Younicos, a German firm which cut its teeth providing storage for renewables-driven electricity grids on islands, a small isolated network may become unstable if more than around 15 per cent of its power is sourced from solar or wind, due to the risk of extreme fluctuations in output from one minute to the next. If you add in a battery capable of producing just a few minutes worth of power to smooth out the blips in supply and the grid can remain stable with as much as 60 per cent of its power derived from renewables. For islands, this could mean a big saving in costly imports of polluting diesel needed to run backup generators.
The run up to March’s solar eclipse over Europe produced the sort of headlines that proponents of renewable energy dread - filled with predictions that power grids would become unstable in countries that are now consuming considerably more solar energy than during the region’s last major eclipse back in 1999.
In the end, good planning and a vast availability of other power sources to fill the gap, such as coal, gas, nuclear, hydropower and wind, meant there was little disruption, even in countries such as Germany and Italy that produce a lot of solar power. But the coverage still highlighted problems associated with the intermittency of solar and wind power, often used as arguments against a more rapid adoption of renewables.
In 2014 Germany, Europe’s largest solar energy producer generated around 6 per cent of its electricity from solar panels– and another 9 per cent from wind power. But what would happen if this was increased without a substantial amount of reliable electricity generated by fossil fuels to rely on? Would the grid collapse during an eclipse? Would a few cloudy days with light winds across northern Europe jeopardise the country’s ability to keep the lights on?
It’s a concern that is at least partly being assuaged by revolutionising the use of batteries – a humble, old-school technology that we take for granted but which is fast becoming considerably less modest as scientists discover how to improve it and, by combining thousands of cells together, create giant energy storage units that could help underpin the world’s power supply in decades to come.
The principal is simple: you store surplus energy produced at times of low power demand and then use it a time when it’s needed. That could be to compensate for low solar or wind generation if it’s either too cloudy or not windy enough, or just to help meet peak demand, instead of expanding a power station or upgrading an electricity grid.
Small-scale experiments with battery storage attached to electricity grids have been going on for decades, but progress has been slow until recent years, reflecting both the technical challenges and relatively high costs of using large-scale storage. As the world gets more serious about renewables, so the imperative to improve battery storage grows.
At the moment, the world’s largest batteries hooked up to the grid, of which there are just a few projects in China and California – have capacities of around 30-35 megawatt-hours. One example, Southern California Edison's demonstration project in the Tehachapi Mountains, is a 32 megawatt-hour battery that can produce eight megawatts of power for four hours in an area where wind power is becoming an increasingly important source of electricity supply.
A city such as Los Angeles can require more than 6,000 megawatts of power capacity to keep the lights – and air-con – on at times of peak demand. Meanwhile, a gas or coal-fired power station might have a capacity of 500-1,000 megawatts or more, and large-scale wind or solar farms can also run to several hundred megawatts these days. Eight megawatts of power for four hours might seem like nearly enough to make much of an impression, but even modest storage capacity can make a big difference.
According to Younicos, a German firm which cut its teeth providing storage for renewables-driven electricity grids on islands, a small isolated network may become unstable if more than around 15 per cent of its power is sourced from solar or wind, due to the risk of extreme fluctuations in output from one minute to the next. If you add in a battery capable of producing just a few minutes worth of power to smooth out the blips in supply and the grid can remain stable with as much as 60 per cent of its power derived from renewables. For islands, this could mean a big saving in costly imports of polluting diesel needed to run backup generators.
Even on bigger grids, relatively small capacity storage can reduce the need to increase the capacity of power stations. Younicos claims a five megawatt storage system can compete with a 50 megawatt gas turbine in smoothing out frequency fluctuations in the power output on a grid.
“Battery storage can respond extremely quickly to grid fluctuations, going from zero to full output in less than two or three seconds, so it is very effective at helping stabilise frequency. On the other hand, traditional generation, such as gas or diesel, takes a lot longer to ramp up to full output, and you need more of it to achieve the same result,” says Nick Heyward, project director of Smarter Network Storage at UK Power Networks, an electricity distribution company. The firm is involved in a six megawatt demonstration battery project in Leighton Buzzard, 40 miles north-west of London.
And bigger batteries are on the way. AES Energy Storage, one of the world leaders in big batteries, is building a 400 megawatt-hour battery – capable of providing 100-megawatts of power for four hours – to be housed in a large building at AES’ Alamitos Power Center in Long Beach, California. When that comes on-stream in 2021, it will be in the vanguard of a new wave of large-scale storage, which could provide a springboard for renewable energy growth and a reduction in the fossil-fuel generation required to meet peak electricity demand in the world’s most energy-hungry nations.
Achieving this in wealthy, pro-renewables California is one thing, but the big task will be scaling up the sector from a handful of showcase projects to make it a commercial proposition globally. That means improving the economics
Capital expenditure for UK Power Network’s Leighton Buzzard battery project, including all civil and electrical aspects, was costed at around £11.2 million in 2013, compared to an estimate of just £6.2 million for more grid capacity to be installed. The cost of batteries has declined to such an extent since then that Nick Heyward estimates the storage component of the Leighton Buzzard scheme would be 20-30 per cent cheaper, if the project were being planned now.
Greater investment in research and development of the technology is likely to bring those costs down further, while the tighter carbon emissions regulations being adopted around the world will improve the economic case for renewables, and thus for energy storage too.
By 2020, the global investment in stored energy for use in electricity grids is expected to be $5.1 billion a year, over 17 times higher than the figure for 2013, according to consultancy Bloomberg New Energy Finance.
As part of this push, renewable energy producers are buying, or forging alliances with, storage firms, while manufacturing facilities are being scaled up.
Among the biggest cheerleaders – and investors – is Elon Musk, the PayPal billionaire. His Tesla company has already shown what can be done with electric cars, using the same lithium-ion battery technology that is the mainstay for energy storage, as well as in consumer goods, such as phones and laptops.
Tesla’s recently released Model S battery-powered sports car can accelerate from zero to 60 miles an hour in 3.2 seconds and can go more than 250 miles on one charge with the right equipment. Now Musk has set his sights on using mass production to bring down the cost of batteries by around 30 per cent by producing them in a $5 billion, 10 million sq ft battery plant in Nevada called the “Gigafactory”. Japan’s Panasonic, a major battery maker, is an investor.
Other types of battery technologies are also being intensively researched, such as liquid-metal – in which Bill Gates has invested – and also flow batteries, which work in a similar way to fuel cells. These technologies can potentially provide more power than lithium-ion, recharge more effectively and last a lot longer – in the case of flow batteries it’s as high as 20 years, around three times longer than lithium-ion.
Typically housed in warehouses and shipping container-like crates, none of these battery technologies are likely to catch the public imagination through their aesthetic appeal. But it may not be long before they are playing a crucial, unseen role in all our lives.
