Fuel cell power: Closer, but still not ready for prime-time?


posted Tuesday, May 7, 2013 at 7:00 AM EST

For more than a few years now, we've followed developments in fuel cell technology with interest. Although advances are still occurring for traditional battery chemistry, for the last decade or so they've largely been evolutionary, rather than revolutionary. Fuel cells, though, have promised a major change in mobile power supply.

A lot of money and research has been poured into developing viable fuel cell technologies, with the promise both of longer runtimes and better shelf life without charge loss. (And for quite a few years, as well -- Canon showed us a prototype fuel cell portrait grip for its digital SLRs all the way back in 2005!)

Fuel cell technology has been deep in development for a decade or more now. Canon showed us this prototype fuel cell portrait grip for digital SLRs all the way back in 2005.

By contrast, after several decades of big developments it's been quite a while since we've seen a major advancement in standard battery technology. Lithium disposables arrived at retail in the 1970s, the first nickel metal-hydride rechargeables hit the market in the late 1980s, and lithium ion rechargeables followed just a couple of years later. Even lithium polymer batteries have now been available for a good 15 years or more. There seems to be no sign of an imminent battery breakthrough that will yield the greater charge density needed for our power-hungry modern devices, and that makes the thought of merely refueling our gadgets occasionally a rather attractive one.

We were interested to see, then, that a fuel cell technology announced back at the Consumer Electronics Show earlier this year is due to arrive any time now. The PowerTrekk fuel cell charger and its PowerPukk consumable has been on sale in Europe for a little while, and it's finally about to hit the market stateside.

The PowerTrekk requires small, consumable PowerPukk cartridges -- priced at US$4 apiece and sold in packs of three -- to function. Each generates four watt hours of energy.

The PowerTrekk is based on research from the University of Michigan via spinoff SiGNa Chemistry, and it's been commercialized by Swedish company myFC AB, who claim their device to be "the world’s first portable fuel cell charger that runs on ordinary water". Of course, there's a little more to the story than that. You can't just pour in water and expect the PowerTrekk to do it's thing: there is a consumable, and that's contained in the PowerPukk.

Together, the two make for what looks to be a rather tidy -- if very expensive -- portable hydrogen fuel cell power solution that myFC says can be safely brought into the passenger cabin of a commercial aircraft. The company also claims its PowerPukk consumable to be fully recyclable. Pricing is set at US$229 for the PowerTrekk charger, and an additional US$4 apiece for the PowerPukk cartridges, which must be bought in packs of three.

Along with the PowerPukk cartridge, you need to supply some water for the PowerTrekk to create energy. Harmless water vapor is created as a result of the process.

Each PowerPukk cartridge contains five grams of sodium silicide, and when water is added this is converted to sodium silicate, thereby releasing hydrogen. The hydrogen is then reacted with atmospheric oxygen across a proton exchange membrane to generate the actual power, creating a little bit of water vapor in the process. The PowerTrekk, meanwhile, contains its own 1,500mAh lithium polymer internal battery that serves as a temporary store for the energy released from the PowerPukk cartridges. Charging your device directly from the PowerPukk results in a rate of just 2.5 watts, but store your energy in that internal battery first, and it can be released at five watts, halving your charge time. (Although since you'll now be charging a battery off another battery, you'll likely double your energy losses, getting even less out of each cartridge.)

The big question is, does PowerTrekk make sense as an alternative to existing battery technologies? While we'd caution that we've not yet had a chance to try the PowerTrekk for ourselves, we've crunched some numbers based on available data from myFC, battery manufacturers, and one or two third parties to try and get to the answer. 

On the top of the PowerTrekk, you can see the vents that let air in and water vapor out.

According to myFC, each 30 gram PowerPukk cartridge provides just four watt-hours of energy (give or take around 10%). The cartridges have dimensions of 2" diameter by 0.8" tall. By way of comparison, at the five volts required for USB charging, one PowerPukk would be the equivalent of an 800mAh battery. Of course, there's also that 1,500mAh internal battery in the PowerTrekk, which we believe can be topped off before you leave home, but even so that will only give you an extra boost on your first charge away from mains power.

Typical lithium-ion rechargeable battery packs used in modern digital SLRs offer more than triple the energy, suggesting that by the time you account for the inefficiencies of the charging process, you're likely looking at something like three or four PowerPukks (and a cost of US$12-16) to recharge a single DSLR battery, ignoring the PowerTrekk's internal battery store. On that first charge, presuming the PowerTrekk battery can indeed be topped off from mains power, you'll save a couple of PowerPukks and bring the cost down to US$4-8 or thereabouts.

Clearly, then, this is not an every day solution -- it's one for when you're in the field, and there's simply no way to get to mains power for a recharge. How does it compare to existing long-life batteries like Lithium disposables and Eneloop rechargeables, though? Here's a comparison:

Comparison: PowerTrekk fuel cell charger vs. existing battery types
PowerTrekk PowerPukk fuel cell refill
Energizer Ultimate Lithium AA disposable
Eneloop HR-3UTGB AA rechargeable
Canon LP-E6 lithium-ion rechargeable
Watt hours
4Wh +/-10%1
Charge cycles
(but loses 20% charge capacity per year2)
Cost (approx.
Cost per watt hour
0.06¢ plus cost of charging power
(assuming 200 charge cycle lifetime; plus cost of charging power)
Weight per watt hour
Volume (approx.)
(ignoring  charger)
Volume per watt hour
Charge loss over time
(shelf life is 15 years)2
25% over five years
(likely ~3-6% per month, plus 5% in first 24 hours)3
Time to lose 25% charge
Five years2
(likely ~six months)
Not really
Note: All values are manufacturer ratings unless otherwise stated.

Depending upon your environment, a solar cell or perhaps a small wind turbine could also offer another way to charge your devices, although these can vary wildly in cost and efficiency.

On paper at least, it looks like the main advantage of PowerTrekk is its claim to essentially zero charge loss over time, and the claim of recyclability, but given the 15-year shelf life of lithium disposables, they can realistically be considered to have no charge loss as well. (Unless you buy and store by the pallette-load, you're almost certainly going to need to visit a retailer to top up on PowerPukks long before 15 years are up, if your electronic gadgets even last that long.) On pretty much every other metric, lithium disposables look to beat the PowerPukk, whether it's on charge density per weight, per watt hour, or per dollar. And with devices like the homebrew Minty Boost, you can even use those AAs to recharge your other batteries.

Ready for prime time or not, the PowerTrekk is certainly much more handsomely-styled than that prototype Canon fuel cell portrait grip we saw all those years ago.

All of this is not to say that PowerTrekk isn't interesting. At the very least there's a good chance it's a hint of things to come, and if you must rule out lithium disposables due to the expense of recycling, the PowerTrekk looks more competitive in some respects against the rechargeables. And of course, there's every possibility the cost of PowerTrekk will come down over time, once it's more firmly established, shifting the balance back towards its favor somewhat.

Going back to our original question, though, it looks as if -- although they've gotten closer -- the time for fuel cell technology has yet to arrive.