French researcher boosts efficiency of methanol fuel cell

A researcher in France has increased the efficiency of micro-sized direct methanol fuel cells to 75 percent, further boosting the opportunities for fuel cells to replace lithium ion batteries as the power source of choice for mobile electronics.

The advancements were made by injecting a macroporous layer into the silicon-based microfuel cell, according to a report in Phys.org. 

Steve Arscott at the Institute of Electronics, Microelectronics and Nanotechnology in France worked with Japan's Sharp (OTC: SCHAY), on the two studies, published in the Journal of Micromechanics and Microengineering and expected to appear in the Journal of Power Source.

The study's fuel cells operated at room temperature with a power density of 385 watt-hours per liter. Lithium ion batteries typically have a power density of 270 Wh/L.

Existing technology requires external energy to heat conditions to 100 degrees Celsius or higher to begin generating power. But fuel cells must operate at room temperature in order to gain adoption in consumer devices (see Japanese tout low-temp fuel cell).

In the first study, the fuel cells achieved a power density of 4.3 milliwatts per square centimeter using 1.38 microliters per minute of fuel.

In the second study that added the macromorphous layer, the density reached 9.25 mW/cm² when using 550 nanoliters of fuel per minute. Adding fuel boosted power density to 12.7 mW/cm² but lowered efficiency to 20 percent.

The key to the findings is that the low fuel requirement eliminates the need in fuel cells for components such as pumps, which then consume fuel to run. Additionally, it's vital to make the fuel cells as small as possible, Arscott said. 

The study used 110-milligram fuel cells sized 0.18 cm², with a thickness of 0.17 cm and volume of 0.03 cm³.

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