Batteries – the workhorse technology that injects life into gadgets we can’t live without – are taking on a bigger role as they replace petrol tanks in cars and make their way into homes and businesses to store electricity from rooftop solar panels or the grid.
Developments in battery technology may not be a popular dinner party topic yet but that could change. The unveiling of Tesla’s low-cost home battery pack, the Powerwall, back in May helped raise public awareness of a field that is booming with innovation and billions of dollars of global investment.
The US energy storage market is growing particularly fast, and batteries are the star players. The country installed 40.7 megawatts of energy storage projects in homes, businesses and utilities in the second quarter of this year, nine times more than the same quarter last year.
Worldwide the total amount of energy storage, discounting the electric car market, could reach 240 gigawatts by 2030 , according to a report by Citigroup, with batteries as the dominant technology.
Here is our handy guide for understanding existing and emerging battery technology:
1. What are the most common types of batteries?
Alkaline, lead-acid and lithium-ion batteries are the most commonly used. Single-use batteries such as the alkaline AA or AAA power flashlights and remote controls. Electric cars and grid energy storage, however, use rechargeable batteries such as lead-acid and lithium-ion. Lead-acid batteries are relatively cheap but typically last only a few years and aren’t powerful enough to be the sole source of energy for a car. They also have toxic elements that require special handling after use.
2. The rise of lithium-ion batteries
Hitting the market in the 90s, lithium-ion batteries generally pack more energy into a given volume, last longer and operate at a wider range of temperatures than other rechargeable batteries.
As a result, they’ve become the standard batteries for running computers, mobile phones and other consumer electronics. They also have the energy density and longevity that make them suitable for powering cars and storing and dispatching solar electricity.
Lithium-ion batteries are winning the race so far in the electric car and grid energy storage markets. Their popularity in powering consumer electronics such as laptops and mobile phones gives them a natural lead over newer types of batteries.
Tesla is using Panasonic’s lithium-ion batteries for its cars and is building a giant $5bn battery factory in Nevada to meet anticipated demand for cars and the grid energy storage systems.
“It’s fairly obvious that lithium-ion batteries will be the solution for at least the next five to 10 years,” says Haresh Kamath, program manager for energy storage at the Electrical Power Research Institute, a nonprofit research group serving the utility industry. “So many people are making [them], so there’s good competition in terms of prices. We know how to use [them], so there are not a lot of risks.”
3. What do lithium-ion batteries cost?
They aren’t cheap. A battery pack to power a car or store solar electricity requires many more lithium-ion cells than a laptop or mobile phone. Those costs add up and explain why an electric car tends to be more expensive than its petrol counterpart.
Then there are the additional costs of designing and building battery packs, as well as the electronics and software to monitor battery performance and ensure it operates optimally.
Battery prices are falling as more manufacturers build more factories to meet anticipated demand in the electric car and grid energy storage market. Five years ago, a lithium-ion battery would fetch over $1,000 per kilowatt-hour in wholesale price. Now the average price hovers around $300-$400 per kilowatt hour (lead-acid batteries, which don’t last as long and can’t hold as much energy, generally cost $100-$200 per kilowatt hour).
Tesla plans to charge $250 per kilowatt hour for the batteries in the large system it has designed for business and utility customers and $500 per kilowatt hour for a system that includes the electronics and software to operate it. The company expects to lower that system price to $300 per kilowatt hour when its new battery factory runs at full capacity by 2020.
4. Are lithium-ion batteries as good as they get?
Research has been done to improve lithium-ion batteries’ performance, such as energy density, longevity and production costs. One Massachusetts battery developer, 24M, claims to be “reinventing the lithium-ion battery”.
The company has been able to push up the energy density by 15-20% in cells it produced on a pilot production line while also cutting manufacturing costs, according to Yet-Ming Chiang, co-founder and chief scientist of the company and an MIT professor. 24M’s redesign of the battery aims to eliminate 80% of non-energy storing material, reducing the number of production steps and creating a more streamlined process. Chiang plans to bring the technology to market in late 2017.
5. Where next for battery technology?
Flow batteries are serious contenders to compete with lithium-ion batteries. These store electricity in two tanks of liquid separated by a membrane.
The bigger the tanks in the flow batteries, the more energy can be stored. This makes it very easy to increase the energy density, meaning flow batteries are attractive for storing a large amount of energy over long duration. But it also makes them much bulkier than a lithium-ion battery.
Primus Power has developed a flow battery that is quite different from conventional designs. It uses one tank instead of two for holding the energy storing materials. It also uses titanium instead of plastic for its electrodes, which helps to boost energy production, says Tom Stepien, Primus’s CEO. The company has just raised $25m and won a major contract to deliver its batteries to the biggest electricity provider in Kazakhstan, Samruk-Energy.
Meanwhile, research is underway to replace the common energy storing materials for flow batteries (vanadium, iron, zinc and bromine) with cheaper and less toxic versions.
A team of Harvard University researchers is working on a battery made of non-toxic organic materials which promises to perform as well as vanadium while costing less, says Michael Aziz, an engineering professor at Harvard and leader of this research. The battery, which will be billed as environmentally-friendly and non-corrosive, will be aimed at homes and businesses.
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