A team of fuel cell experts at NASA’s Jet Propulsion Laboratory has taken what have been traditionally large, bulky stacks of layered fuel cells and altered their design dramatically.
They are said to have designed a compact, flat fuel cell, reducing its weight substantially. The result is a portable fuel cell technology that may someday operate small, portable electronic devices, such as cell phones, laptops, handheld organisers and camcorders, for hours and even days at a time without recharging or using expensive, heavy batteries.
‘This is a significant advance in fuel cell development because by going small, you make the fuel cell portable and viable for use as a power source to operate small appliances that require long operating time, such as a laptop,’ said Dr. S. R. Narayanan, fuel cell technical team leader at JPL.
A major advantage of fuel cells over rechargeable batteries is that they can operate for longer periods of time without recharging or interruption. ‘Instead of recharging your laptop every two hours, imagine being able to use it for ten hours at a time,’ said Narayanan. Unlike batteries, these fuel cells can be recharged almost instantaneously by refuelling with liquid methanol.
A fuel cell works on the same principle as a battery but is continually fed with fuel. In this new power source, methanol is put in on one side of the unit while air circulates on the other side. Both are circulated past electrodes and converted to electricity. This process produces no toxic emissions, only carbon dioxide and water as by-products.
Existing fuel cells typically operate at high temperatures, require bulky thermal insulation and use hydrogen as their energy source. Much of their weight and size is due to the bipolar plates needed to connect several cells to form a stack. JPL researchers are said to have eliminated bipolar plates and created a monopolar pack, which is flat with the cells linked by electrical interconnects.
To demonstrate the feasibility of the portable fuel cell technology, JPL developed a 5-watt portable power unit. The power source uses the new lightweight monopolar flat pack technology and is roughly the size of two paperback books and operates at ambient temperature without a fan.
JPL engineers rigged a cell phone to this power unit and placed several phone calls as a demonstration. They estimate that the 5-watts could simultaneously power five cell phones. The system could be refuelled instantly to extend the talk-time as long as needed.
Now that the concept of making a portable, flat stack has been demonstrated, the next phase underway at JPL is to make it smaller, more robust and user-friendly.