Monday, March 03, 2008

Nanonickel - Hope for Hydrogen?

In the face of a recent prediction that the price of oil could reach $300 a barrel, in essence because the sweet light crude peaked its production a couple of years ago, and future production of declining supplies (of sour heavier oil) will be more complex, and hence more costly in terms of energy to produce, it is a mild balm to read that there may be an alternative technology coming "soon". The latter is a reference to "nanonickel"which it is proposed may replace platinum in electrolysers used to make hydrogen to underpin the putative hydrogen economy.

In the latter context, there are two sources of demand for platinum: (1) said electrolysers and (2) the fuel cells which will finally turn the hydrogen back into electrons to run what is really an electric car, but powered by chemically produced electricity. The company behind this is called QuantumSphere, who believe that nanonickel may have applications for both electrolytic hydrogen generation and fuel cells. I am initially encouraged by this idea. Creating the putative hydrogen economy from scratch is daunting to say the least. For a start, to avoid carbon emissions incurred by steam reforming natural gas (or worse, coal) into hydrogen (+CO), it is necessary to produce the gas by electrolysis of water using "green" electricity. This remains as a problem, and there seems to be some controversy over whether nuclear is "green" - i.e. renewable and non-polluting, or not.

Proponents of the nuclear industry claim that far less CO2 is emitted from nuclear power than is the case if electricity is generated using fossil fuels. Estimates of exactly how much CO2 is saved by using nuclear vary tremendously, but all estimates agree there is a significant saving in some degree. There is of course the thorny issue of what to do with the nuclear waste, and overall I doubt the validity of the sum, nuclear = green. Nonetheless as long as it can be maintained, there seems little doubt that nuclear power is here to stay. In the latter aspect, it is debatable how much uranium may be recovered: it is said there is enough for about 40 years from known holdings, although I am sure if poorer ores are mined more can be got, albeit that other fossil-fuel resources will need to be used up (in all likelihood, unless some of the nuclear electricity can be re-diverted for the purpose) to power the extraction processes and the ultimate fabrication of the nuclear fuel rods. As I say, how to provide the necessarily very large increase in electricity to produce hydrogen as a replacement of around 20 billion barrels of oil annually used for fuel (from 30 billion produced altogether) worldwide remains an unsolved problem, especially without surging through fossil fuel resources and ballooning the world's carbon footprint in terms of CO2.

Leaving that aside for a moment, my worry over using platinum to fabricate the fuel cells themselves is that it is a very rare metal, and processing one tonne of platinum ore yields about 3 grammes of pure Pt. There are only three mines in the world that produce it, two in SA and one in Russia, and consequently not more than 200 tonnes of "new" Pt is produced each year. The upshot is that even in 30 years less than 10% of the 700 million vehicles on the world's roads could in principle be accordingly provided with PEM fuel cells. I thought the whole idea was therefore dead in the water unless some other kind of fuel cell came along. Well, maybe there is such a beast on its way.

QuantumSphere (which sounds like the title of a Michael Crichton novel) have apparently inaugurated a production line to make nickel-cobalt alloy in the form of nanoparticles. Now, neither of these metals is in immediately short supply to the best of my knowledge (about 5 million tonnes of Ni are produced annually compared to 200 tonnes of Pt), and so this is beginning to look good. The company's president, Kevin Maloney said, "At the nanoscale, scientists have really created a new periodic table, if you will. These materials are much more energetic; you just don't get that performance at the micro scale." The essential difference is that when using particles of perhaps 10 nm (nanometers; hence "nano") in contrast to the micron ( = 1000 nm) scale, far more of the atoms that make up the particle are accessible to perform chemical reactions, in consequence of the vastly increased overall surface area and exposure of the atoms at the surface.

The proposed strategy is to coat electrodes with the nanodimensional Ni-Co alloy for use in efficient water-electrolysers (efficiencies of 85% are quoted, better than Pt), and to also use this or other nano-metallic materials to replace Pt in the final fuel cells. A very nice idea too, is to obviate large electrolytic installations, even on the level of "gas-stations" by in situ hydrogen production, actually in the vehicle itself from a tank of distilled water on-board (albeit the gas would need to be stored in some way?). The technology began with the development of a battery which has a cathode coated with metal nanoparticles, with 5 times the energy density of alkaline cells, and a power-boost of 320%. The company also claims to be able to make improved nickel-metal-hydride batteries so that they have a better performance than the more popular lithium-ion batteries.

Now this could have applications for PHEV's couldn't it? There is a contentious issue, which seems to have been kicked-off by Ulf Bossel, to the effect that electrons can be used about three times more efficiently by simply storing them in batteries, rather than going through the rigmarole of turning them into hydrogen and then back into electrons. I read about a hybrid car that can do 100 miles per gallon and surely this technology might be useful in vehicles of this kind too which need to carry a relatively large battery-pack.

It's exciting and I wish someone had been thinking this way 30 years ago, as we might by now have a completely different transportation system that depends far less on oil. Retrospect is easy, however, and the nano-world was largely unknown then, at least in its present context. Peak oil is due within 5 years or so, by when we will either need a technological replacement for conventional oil coming in at quite a rate of knots, or accept that society must be reformed to demand dramatically less travel and carriage of goods, necessarily relocalising into small communities that move themselves and their requirements around far less. How long will it take to get all this nano-technology ready on a commercial scale and to manufacture it on a massive scale? For example, capacity currently exists to produce a few tons of nanonickel a year and yet tens of thousands of tonnes would be needed for this to be a serious proposition; hence the scale of production must be expanded in similar proportion if nanonickel alloys are to be the answer. It took probably 50 years to build the majority of the oil-fuelled status quo, and even that would be just too long to install a new salvation technology.

Related Reading.
[1] "Oil could reach $300, says expert", By Claire Ferris-Lay.
[2] "Nanoparticles could make hydrogen cheaper than gasoline". By R. Colin Johnson.
[3] "A Nickel Catalyst for Fuel Cells." By Virgina Hefferman.
[4] "Nanonickel to Replace Platinum as a Catalyst in Fuel Cells and in Other Applications."


Anonymous said...

Has this nanonickel actually been produced and used in any near production version of fuel cell cars like the Honda Fuel cell Clarity fcx ?

Professor Chris Rhodes said...

To the best of my knowledge the material gas been produced on a relatively small scale but not in actual cars. I am not even sure if it has been installed in a real working fuel cell and so the technology is a long way from solving the platinum shortage problem as yet for the widespread implementation of fuel-cell powered cars. That's even if the chain of technological challenges can be made.