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New Zealand's longest-running online daily news and commentary publication, now in its 25th year. The opinion pieces presented here are not purported to be fact but reasonable effort is made to ensure accuracy.

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Forget EV batteries

9 May 2019

Infrastructure issues aside, the biggest thing slowing down the evolution of the electric vehicle is battery technology -- or the lack of it.

Modern EVs have only become a practicality since the invention of low-cost, high-performance lithium chemistries which have delivered energy densities far greater than that offered by older technologies such as lead-acid or nickel-metal-hydride (NiMH) cells. If it weren't for the humble 18650-sized Li-Ion cell, few of today's EVs would ever have seen the light of day.

However, despite the dramatic improvements in energy density on both a weight and volume basis, batteries still suck.

They are slow to recharge, have a limited lifetime, are adversely affected by extremes of temperature and pose a very real fire hazard if subjected to physical or electrical stress.

But wait, an older technology may yet come to the rescue of the EV industry.

I'm talking about fuel cells.

Electricity-producing fuel cells were originally developed to power the onboard electronics of spacecraft back in the 1960s (anyone remember Apollo 13?) but have always been extremely expensive and short-lived devices.

Operating at a molecular level, these cells work by directly harnessing chemical reactions such as those involved in the reaction between hydrogen and oxygen that ultimately result in water as a byproduct.

The big problem has been that in order to work, these fuel cells often required the use of an incredibly fine membrane that would allow molecules of one size to pass freely but block the passage of molecules of a somewhat larger size. The problem with such a membrane is that it is very easily clogged by contaminants.

Most fuel cells require the fuel to be incredibly pure and free from particulates, oil and other contaminants. That can make them not only very expensive to manufacture and maintain but also expensive to feed.

Things are changing however...

Recently, a drone company announced that it's launching a craft that will stay aloft for twice as long as its battery-powered peers -- thanks to hydrogen fuel cell technology.

Using just 150g of hydrogen (compressed to 350bar in a 6 litre tank), the drone gets its power from a 2.5KW fuel cell which can run on "industrial grade" hydrogen. The cost per flight is about US$6 and the whole setup is only twice the price of an equivalent battery-powered craft.

Now that is actually quite a bit more than the same amount of electricity stored in a battery but the beauty of this setup is that it can be refueled in a matter of seconds and delivers performance that batteries alone just can not match.

It seems that the same advances in fuel-cell technology are now being considered by EV makers who previously tried and discounted the viability of such technology in their cars.

The cost of "ultra-pure" hydrogen, combined with the significant cost of production of the cells themselves had always made these things uneconomic to manufacture when compared to the equivalent amount of battery-based storage. That may slowly be changing though.

With no "breakthrough" new battery technology seemingly just around the corner, I would not be surprised to see a lot more research money being thrown into fuel cell development and eventually we may recall the old-fashioned idea of "battery-powered EVs" as a brief but important step in the evolution of such transport.

What do readers think?

Are better batteries the future of EVs... or will the convenience and relative safety of fuel-cells be the way to go?

Which would you rather have powering your EV... thousands of 18650 Li-Ion cells in the floor-pan or a small tank of hydrogen (or perhaps ethanol) in the boot and a picnic-hamper sized fuel cell that offered the convenience of today's dino-juicers with the low emissions of an EV?

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