Methane-powered laptops on the way

Posted by Emma Woollacott

No, it's not a breakaway movement from Steampunk - it's serious science. A group of materials scientists have developed a new type of fuel cell that they say could soon lead to methane-powered laptops.

Researchers led by Shriram Ramanathan at the Harvard School of Engineering and Applied Sciences (SEAS) say they've developed methane fuel cells and are optimistic about their commercial viability.

Electrochemical fuel cells have long been viewed as a potential alternative to fossil fuels, especially as most solid-oxide fuel cells (SOFCs) leave behind little more than water as waste. The obstacles have always been reliability, temperature, and cost.

Fuel cells operate by converting chemical energy (from hydrogen or a hydrocarbon fuel such as methane) into an electric current. Oxygen ions travel from the cathode through the electrolyte toward the anode, where they oxidize the fuel to produce a current of electrons back toward the cathode.

But Ramanathan's group has demonstrated stable and functional all-ceramic thin-film SOFCs that don't contain any platinum, which can be expensive and unreliable.

"If you use porous metal electrodes, they tend to be inherently unstable over long periods of time. They start to agglomerate and create open circuits in the fuel cells," says Ramanathan. He says his platinum-free micro-SOFC eliminates this problem, resulting in lower cost and higher reliability.

The team has also demonstrated a methane-fueled micro-SOFC operating at less than 500° Celsius, relatively unusual until now.

Traditional SOFCs operate at about 800°C, but such high temperatures are only practical for stationary power generation: using them to power a smartphone mid-commute is not really an option.

In recent years, though, materials scientists have been working to reduce the required operating temperature to about 300°C.

"Low temperature is a holy grail in this field," says Ramanathan. "If you can realize high-performance solid-oxide fuel cells that operate in the 300°C range, you can use them in transportation vehicles and portable electronics, and with different types of fuels."

Until recently, hydrogen has been the primary fuel for SOFCs. But, says Ramanathan, "It's expensive to make pure hydrogen, and that severely limits the range of applications."

"Future research at SEAS will explore new types of catalysts for methane SOFCs, with the goal of identifying affordable, earth-abundant materials that can help lower the operating temperature even further," he adds.