New Scientist looks at the state of play in battery storage (paywalled)
The momentum at present is with lithium-iron batteries, which are being used in devices from mobile phones to electric cars. Since the technology was commercialised in 1991 its performance has improved immensely – design tweaks have tripled the energy stored in a given volume.
Making the batteries is now a $15 billion industry, which Tesla is about to take to a whole new level by building a “Gigafactory” just outside Reno, Nevada.
- By 2020, the company plans to produce as many lithium-ion batteries annually as the entire world produced in 2013 – enough for a fleet of 500,000 electric cars – and with a 30 per cent reduction in production cost per battery.
The Model S Tesla electric car:
- is powered by thousands of small lithium-ion batteries arrayed between the car’s axles. It can go from zero to 95 kilometres an hour in 3.1 seconds, and can travel about 430 kilometres on a single charge, although charging it can take many hours.
The following graphic illustrates the growth of lithium-ion batteries in context this century:
A small start-up company, 24M, based in Cambridge, Massachusetts, has invented a new process which they claim will cut the cost of lithium-ion manufacturing in half.
Nevertheless the technology has limitations. One is that the batteries can be a fire hazard if their cells get overcharged. Also lithium-ion batteries are approaching fundamental electrochemical limits on the density of energy they can store. Thirdly, the end of the road in cutting costs is in sight. Real competition for petrol will most likely come from a new generation of batteries. You need something that can charge up in minutes and run for 500 miles.
One alternative is the lithium-sulphur battery:
- that stores and releases energy by forming and breaking chemical bonds, instead of slotting ions into structural gaps. These batteries are less prone to catching fire, and although they’re not yet commercially available, they have demonstrated energy densities three times those of the best lithium-ion batteries.
There is a fair amount of lithium in the world, but 23% of it is in Bolivia, which won’t allow mining unless the subsequent manufacturing is done there also. So far no-one has taken the bait.
Lithium-ion is starting to break into the large storage systems needed for grid electricity. California, where 1.3 gigawatts of storage in the grid by 2022 has been mandated, is planning the largest battery ever built, which will be capable of delivering 100 megawatts of power for four hours, enough to supply 80,000 average homes. It will be lithium-ion.
It’s hard to imagine, however, that lithium-ion will solve the problem of grid storage. For example, it has been calculated that to run Nova Scotia Power for 24 hours would take the energy storage capacity of every battery made worldwide this year – and then half as much again. The solution may lie in every home having its own storage, such as the Tesla Powerwall.
One alternative to lithium is magnesium. Magnesium ions have two positive charges compared to lithium’s one, doubling their capacity to store energy. Other materials are being scoured systematically, with 16,000 having been tested computationally. One researcher is being distinctly cagey, saying only that his lab is working on a system that uses materials far more common than lithium.
- “If I tell you I can develop a battery that can be charged in 15 seconds and last one week, you’d be happy,” he says. “That’s what we’re doing.”
So while the momentum is currently with lithium-ion, chances are we’ll go on to something else. Perhaps Bolivia’s salt flats will stay where they are.
Cooktown (not Cook Town) is an isolated town of about 2,300 population, 327 km north of Cairns, located right at the very northern-most fringe of the east-coast National Electricity Market grid.
- Lyon Infrastructure Investments announced that it expects to commence construction on a 26MW solar PV farm plus 5MWh battery system near Cooktown in the fourth quarter of this year.
David Green, a Partner at Lyon Infrastructure, explained to Climate Spectator that their project was at a very advanced stage in commercial negotiations and he was confident they would finalise financing for the project within a few months. He said that they had spent almost two years trying to progress the project during the period when the future of the Renewable Energy Target was uncertain due to the Abbott Government’s decision to review the scheme, but this was now behind them.
The plan is use a 5MWh lithium-ion battery from Samsung which has a rated maximum output of 1.4MW to supply electricity for up to 3 hours.
The facility will be subsidised, essentially by other electricity users in Queensland, but is part of a learning experience to supply remoter settlements around the state.
Europe has 400 million people in 24 countries connected to a single grid, with power surpluses from one country being exported to neighbours or imported as national needs change. Norway has 937 hydropower plants, which provide 96% of its electricity.
The prospect of using pumped storage in the Norwegian system to even out power supply in the rest of Europe has one major problem – the tunnels are so long that it takes too long for the stored water to reach the turbines.
A study has now been looking at the possibility of creating sealed surge chambers in rock close to the turbines so that the power can be activated immediately.