Get talking: Geoff Snape

Materials World magazine
,
3 Jul 2015

The path from idea to invention and then uptake is lined with obstacles. A keen follower of new technology, Geoff Snape considers why alternative fuels have not yet taken off.

Geoff has 20 years’ experience as a civil engineer, from geo-resource projects to site evaluation and power. He’s also a professional pilot, and spent five years working in North Sea oil exploration.

Progress to market and fuel

Having read with great (vested) interest all the articles in Materials World over the last few years regarding artificial tissue replacement materials and scaffolds, I was keen to discuss their imminent use for knees such as mine, worn out by marathons, skiing accidents and the occasional back- and leg-breaking paragliding crash. A short discussion with my orthopaedic surgeon on the use of such scaffolds after my recent knee arthroscopy concluded that ‘not in my lifetime’ was realistic.

Somewhat like the idea of nuclear fusion power when I was a young teenager. Electric cars soon? Fuel cells also spring to mind. I remember the articles in the long defunct Science Journal describing the various types of fuel cell back in 1967 and wondering how soon they would replace the Victorian internal combustion engine. I am still reading these articles almost 50 years later. The only thing that has happened that I predicted is the iPod. So what’s the difference in terms of development and commercial implementation?

Previously, I single-handedly solved the problem of rising sea levels. This time it is carbon dioxide emissions. Over the years, I have also avidly followed the development of hydrogen occlusion as a storage medium to render the gas as a usable replacement for hydrocarbons. Developments seem to have slowed from glacial to plate-tectonic speed. Speaking as someone who once almost performed the neat trick of rendering organic tissue as brittle as porcelain by spilling LPG on my finger during topping-up, I can vouch with confidence that liquid hydrogen will be an even bigger problem, compared with petrol. It isn’t going to replace JET-A1 anytime soon, which is a pity, because air transport is destined to be the principal cause of greenhouse gases by mid-century.

Of course nature long ago found a way of storing hydrogen in gas, liquid and solid form by attaching it to chains of carbon atoms, rendering it relatively safe and practical. Removing the carbon from it prior to burning the hydrogen has similar chemical and thermodynamic problems that burning water has associated with it. Are these problems so insurmountable as to render the idea unworthy of determined research? Are there not conditions of temperature, pressure, fluid dynamics and catalysts that can push these chains through molecular sieves, stripping the lightweight hydrogen off, sending the heavier carbon atoms into a trap? Just think, if the temperature and pressure were high enough, we might get industrially useful diamond powder from it, thereby subsidising the journey. 

Although methane has four parts useful hydrogen to 12 parts carbon, a ratio of 0.33, octanes and other paraffins of 2n+2 will have correspondingly fewer – octanes being 18 parts hydrogen by weight to 96 parts carbon or about 0.19 ratio. Clearly, unlike a current jet plane, where a substantial part of the take-off weight is fuel and this is reduced during the flight, not buring the carbon part of the fuel is going to increase landing weight and overall fuel consumption.

Of course, you can always jettison the solid carbon particles as you fly, creating atmospheric dust, whose climate-changing properties may be just as bad as allowing the particles to enter the exhaust stream and oxidise producing CO2. Since this carbon is a problem, can’t we just replace it with silicon and produce silica sand?

Unfortunately, silicon hydrides (silanes) don’t come from a hole in the ground, like oil and are currently very expensive to manufacture. But isn’t fracking now changing the game for extraction? Perhaps downhole transformation from alkanes to silanes might be the solution we are searching for, catalysed by modified propping and fracking agents necessarily injected into the wells.

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