High-tech Dreamliner's wings clipped by battery trouble

WHEN it went into service a little over a year ago, Boeing's 787 Dreamliner was hailed as a miracle of cutting-edge innovation ? the Chicago-based company used lithium-ion batteries, a carbon-fibre fuselage, and blazing fast computer networks to cut down on fuel consumption and provide passengers with a ride like no other.

But following a series of mostly electrical mishaps - including a battery fire aboard a 787 at Boston's Logan International Airport last week - the current global fleet of 50 planes now sits idle. The US National Transportation Safety Board has launched an investigation into the plane's electrical systems. And the US Federal Aviation Administration, which declared the plane airworthy in 2011, is questioning their own certification process.

The plane's lithium-ion batteries, which also appear to have acted up and forced an All Nippon Airways 787 to make an emergency landing at Takamatsu airport in western Japan this week, store twice the power of nickel-cadmium cells, making them much lighter. However, they are a known fire risk under some operating conditions.

No-one yet knows if the batteries themselves - built by GS Yuasa of Japan and packaged by Thales of France - were at fault, or if there's an issue with the wiring, or electronics, they plug into.

Long-standing concern

The FAA's concern over the batteries goes back as far as 2007, when it warned Boeing that the company could only use lithium-ion batteries if its battery charging, management and failure alarm systems can cope with their unique risks. Li-ion batteries, the FAA said, are susceptible to self-sustaining increases in temperature and pressure if they are overcharged "which leads to formation of highly unstable metallic lithium which can ignite, resulting in a self-sustaining fire or explosion."

Because the Boston battery fire is under investigation by the NTSB, Boeing spokeswoman Lori Gunter cannot yet comment on what happened. But she says the 787 is built to cope with any problem the batteries throw at it. "It is designed to be able to handle any faults that we would expect to see from the battery," she told New Scientist.

Boeing's rival, Airbus of Toulouse, France, uses smaller lithium batteries in its A380 jet to power emergency lighting, but plans to increase its reliance on the batteries in the forthcoming A350. "Lithium ion batteries can be designed in very different ways, with different chemistries, electronic protections, capacities and number of cells," says an Airbus spokesman. "The way a battery is integrated in the aircraft is important, as well as the protections that are put in place."

Better sensors

Smart in-battery sensors could be an answer, say Gi-Heon Kim and colleagues at the National Renewable Energy Center in Golden, Colorado. They are developing a "fail-safe" Li-ion battery that incorporates a passive early warning system (Journal of Power Sources, DOI: 10.1016/j.jpowsour.2012.03.015) that senses the structural defects in a Li-ion battery cell that can lead to the thermal runaway that leads to fires. When it does so, it isolates the cell from the battery long before trouble occurs. Better still, says Kim, "this technology is independent of battery chemistry and cell design" - so could apply to the Li-ion cells used in phones, electric cars and aviation.

The outcome of the investigations into the battery issues will also resonate off-planet, as the International Space Station is about to have its power sources upgraded to more powerful Li-ion cells from GS Yuasa. "NASA is in close communication with Boeing, the FAA, and the cell manufacturer on the ongoing failure analysis, and will apply any relevant lessons learned as appropriate," a NASA spokesman told New Scientist.

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