The world is becoming addicted to portable power. There are more than 4 billion mobile phone users worldwide. IDC, a market research firm, predicts that laptops will account for 70% of all computers sold by 2012. Apple sold  
4.2 million iPads in one quarter’s trading. Toyota has sold more than 2 million of its trailblazing Prius hybrid car.

And all these devices use batteries. Hybrid vehicles use ones that are charged up by a small petrol engine, but Toyota and its competitors are said to be working on a next generation of ‘plug-in’ electric cars that will drive on battery power alone.

Our appetite for battery power is so great that it is affecting commodity markets. So-called ‘rare earth’ minerals such as lanthanum – a raw ingredient for NiMH batteries, such as those used in the Prius – have shot up in price in the face of rising demand and restrictions imposed by China, where most are mined.

This is leading to a race for better and cleaner battery technologies, as well as some more radical alternatives.”Battery technology is the holy grail of cleantech, renewable-energy development and the move away from fossil fuels,” says Dan Ilett, research director of Greenbang.com, a clean-technology research house. “That’s because while it’s getting easier to make energy from the sun, wind and water, it’s still quite hard to store that energy.”

The technology is difficult to develop cost-effectively, he adds. “You only have to look at electric cars and their limited range and long charge times to see that more research and development is needed to make a transition to these technologies.”

According to Harry Wang, director of health and mobile product research at market-research firm Parks Associates, the lack of more powerful battery technologies remains one of the most

Dan Ilett, research director, Greenbang.com

THE BATTERIES

SOLID-STATE LITHIUM AIR

difficult constraints to overcome when designing new devices. “On the one hand, battery technology is lagging,” he says. “Consumers expect to be able to run devices for more than five or six hours, but that is a requirement that is difficult to meet.”

The demand for smaller, lighter mobile phones that can also act as high-definition media players and communicate with satellites for navigation, for example, means that battery technology is struggling to keep pace with consumer electronics’ demands. “If you do have a device with a long battery life, that will give you the edge,” suggests Wang.

Companies are now spending real money on developing new types of batteries: in 2010, for example, General Motors announced that it was doubling its investment in its battery systems research lab, despite the tough times facing the car industry. Even Warren Buffet’s Berkshire Hathaway, known for its conservative investment stance, has been buying into the technology, taking a stake in Chinese technology company BYD.

A free, green and everlasting power source may remain an impossible dream, but there is gold in technologies that can store power efficiently and cleanly.

Lithium-ion batteries are widely used in laptops and mobile phones. But they can be volatile and prone to overheating, or even exploding. Small lithium-ion batteries can be produced safely, but not in the sizes needed to power cars. This is why vehicles such as the Prius use the less effi cient NiMH technology. The University of Dayton Research Institute in the US is working on ultra-dense lithium-air batteries that could prove a safe energy source. Its team is also working on using the technology in micro- air vehicles for the US Air Force. Reseachers at IBM are working on using nanotechnology to build lithium-air batteries to make cells that can store 10 times as much power as today’s lithium-ion batteries.

NICKEL LITHIUM

Like lithium air, this technology provides a high-density alternative to lithium ion. The cells are fire-resistant and safe to handle, according to Vishal Sapru, industry manager for energy and power systems at research company Frost & Sullivan. Again, one of the most pressing challenges is to create a power source for electric cars. Researchers at Japan’s National Institute for Advanced Industrial Science and Technology believe a rechargeable nickel-lithium battery will last twice as long as a lithium-ion battery of the same size. If production costs fall far enough, the technology could also find its way into consumer electronics, including laptops and mobile phones.

NICKEL IRON

The first nickel-iron (NiFe) batteries were developed in 1901 by Th omas Edison. Now the technology is being rediscovered as a greener alternative to lead-acid batteries, such as those used in cars, and rechargeable nickel-cadmium cells. They are used where robust batteries are needed and their large size is not an obstacle. Production of them originally ceased in the 70s but now there is renewed interest from industry. One advantage is that they can have a life of almost 20 years and be continuously charged, making them suitable for back-up power in manufacturing plants or computer data centres. They can also be used to power forklift trucks, mining equipment and even railway trains.

SILVER VANADIUM OXIDE

Much of the research into battery technology is focused on large batteries for cars. Dr Esther Takeuchi, a researcher at the State University of New York, works at the other end of the spectrum. Her silver-vanadium-oxide battery, used to power implantable defibrillators, won her the US National Medal of Technology and Innovation. Batteries for medical applications have to last five to 10 years, but Dr Takeuchi is now looking at other ways to use the technology. She believes that because of their long life, a variant of the batteries could be used in electricity grids to store energy from solar and wind power. To do so, they must be low cost, be rechargeable and have a long life.

THE ASYMMETRIC ELECTROCHEMICAL CAPACITOR

Half a battery, half a capacitor, this device, being developed at Michigan Technological University (MTU), is suited to tasks that need high charge and discharge rates, as well as being able to take a lot of abuse. A typical application is the regenerative braking system being developed for cars, as well as for power tools and construction equipment. One example of how it might be used is to power cars that use ‘stop-start’ technology to save fuel in traffic. Most cars that currently use the technology — including models from BMW and Volvo — work by turning the engine on and off. But capacitors could instead power a car’s electric motor in traffic, handing over to a conventional diesel or petrol engine on the open road. The technology, MTU researchers say, is also lighter and cheaper than lithium ion.

PAPER BATTERIES

Perhaps one of the most radical new types of battery. Based on very thin structural sheets, layered together to make an array of cells, paper batteries do two things: store energy and provide a weight- bearing surface. As a result, the Paper Battery Co, which has exclusive rights to the technology (developed at the US Rensselaer Polytechnic Institute), is talking to architects as well as the electronics and automotive industries.

THE ALTERNATIVES

FUEL CELLS
The most likely alternative to mainstream battery technology looks set to be the fuel cell. Using hydrogen as a fuel, the cells generate electricity and produce only water as a waste product. Honda already has a fuel-cell car in production, and fuel cells are already being used in industry, for example to provide back-up power in factories or data centres in place of conventional lead-acid batteries or diesel generators. Researchers at Birmingham University in the UK are among those working on fuel cells, and the university has its own hydrogen fuelling station for fuel-cell cars. However, the need to provide hydrogen, or hydrogen generators – usually powered by natural gas – is holding back development, as are concerns about the safety of fuel cells in electronic gadgets.

FLYWHEELS
Flywheels predate even the earliest batteries; they were used as energy stores as long ago as the mid-19th century. Flywheels are mechanical devices that store kinetic energy, and until very recently appeared to be a throwback to the steam age. But interest in clean ways of storing energy has prompted scientists and engineers to look again at flywheels, as they involve no dangerous chemicals or especially expensive raw materials. Porsche recently installed a flywheel in its prototype 911 GT3 R Hybrid sportscar.The flywheel stores energy created by braking and uses it to provide a 160-horsepower boost to the car’s gas-powered engine. There are no immediate plans for a road-car version.