A BBC News item yesterday on a hydrogen fuel cell powered motorbike http://news.bbc.co.uk/1/hi/world/europe/4353853.stm set me thinking - whats the best way to achieve a Carbon Neutral Hovercraft in say 10 years time?

Researching the hydrogen fuel cell quickly ruled that out - the motorbike cell has an output of 1kw (1.3bhp) so nowhere near powerful enough. There is a 10kw (13bhp) big brother that might (just) power a small cruiser but the cell alone weighs in at 70kg. http://www.intelligent-energy.com/im...ds/10kw_system _a4.pdf Plus Hydrogen fuel cells are effectively batteries, they run off hydrogen which is generated in another power plant, be it oil, gas, hydro, wind, nuclear or whatever.

I seem to remember Nigel Beale researching Hydrogen car engines as part of his day job at Cranfield in the 70's. It was based on modifying conventional engines but that still has the 'hydrogen supply' problem.

Bio ethanol seems to offer a good way forward. It’s a primary fuel produced from plants like corn, wheat, grass, wood chips etc rather than a 'battery' and can be used by conventional IC engines. http://en.wikipedia.org/wiki/Ethanol_fuel The Model T Ford of 1908 was designed to run on either ethanol or petrol. In fact it looks as if the engines we use today could be run on a 10% ethanol, 90% conventional petrol blend (so called E10) right away without mods http://www.drivingethanol.org/userdo...ginesFactSheet .pdf

The EU is proposing a 20% reduction in carbon dioxide emissions from cars in 5 years. Morally we ought to try to match this particularly if it also brings performance improvements to our craft. E10 improves the burn of the engine reducing both knock and Greenhouse Gas Emissions -. eg Carbon Monoxide reduced by 30% http://www.drivingethanol.org/userdo...andtheEnvironm ent.pdf

Maybe over the years we can evolve to an 85% Ethanol blend (E85). Before the 'petrolheads' start complaining raw ethanol is high octane stuff and Indy Cars in the 2007 season will use E100 - (100% Bio Ethanol http://www.drivingethanol.org/userdo...EnginePerforma nce.pdf ). Pure ethanol has a much higher octane rating (116 AKI, 129 RON) than ordinary gasoline (86/87 AKI, 91/92 RON), allowing a higher compression ratio and different spark timing for improved performance. To change a pure-petrol-fueled car into a pure-ethanol-fueled car, larger carburetor jets (about 30-40% larger by area), or fuel injectors are needed. (Methanol requires an even larger increase in area, to roughly 50% larger. The production process for Methanol is apparently not very green)

The only downside seems to be that Ethanol contains approx 34% less energy per gallon than petrol so a craft running on say E85 will need a larger fuel tank. Earlier craft running on E10 would see little consumption difference (around 3%)

The problem is that in the UK only a handful of Tesco and Morrison Garages currently stock it and production capacity is limited. Perhaps in the classic hovercraft diy spirit Charlie and Jake should grow a bio fuel in the centre of our two 'home' racecourses, produce it themselves then sell it for diy blending at race meetings. I presume as it's not for a road vehicle it would attract no tax….! Apparently an acre of Miscanthus (elephant grass - http://en.wikipedia.org/wiki/Miscanthus ) can produce 1500 US gallons, about enough for 2 Nationals with every craft using using E100. One UK manufacturer in Gloucestershire is about to sell a small (legal) production plant for farmers to produce Bio Ethanol http://www.greenfuels.co.uk/index.htm

Even the UK Government thinks it’s a good idea - http://www.defra.gov.uk/farm/crops/i...energy/pdf/Bio fuels-leaflet.pdf

But not everyone agrees, York Uni http://www-users.york.ac.uk/~drf1/bf...ioethanol.html points out that for every 133 units of energy produced 100 units is used in the production process. However University College London points out that with the right production plant design Bio Ethanol could actually net extract CO2 from the atmosphere. http://www.britishsugar.co.uk/Isolat...94175874-67b5- 4c33-9f38-380233f14049/ContentAssets/Documents/Bioethanol/Pu blications%20and%20Research/Imperial%20College.pdf

So Bio Ethanol seems to me (with only a poor O Level in Chemistry) a viable way forward for keeping our sport going in a Carbon Neutral World. It means minimal changes to our craft and engines and overall the pros seem to outweigh the cons.

But most of us use more fuel getting to the meetings than in our craft - any ideas for a Carbon Neutral RV? Does it also mean we should encourage renewable plywood craft held together with fish glue rather than fossil fuel based fibreglass? (sorry Russ couldn't resist it!)

Fuse lit, over to you all for discussion…

Keith Oakley