the only long-term solution is to run on the same fuel as the airlines
I beg to disagree... The "heavier" the fuel (meaning a higher ratio of carbon/hydrogen)* the heavier will be the engine that burns it. Even for a 600 kg MTOW LSA, requiring an engine of 80-100 HP, a diesel would be prohibitively heavy * * ; and the current turbines are too expensive on acquisition AND on maintenance for the average recreational flyer. For a four-seater, that is to say an IFR tourer that can legally take off on a flight plan for 1500 or so NM with two persons and their luggage, I might quite agree, though. For anything lighter, gasoline will have to do, gradually replaced with some kind of alkohol.
*diesel and Jet fuels having higher C/H than gasoline; propane gas the lightest, but requires heavy high pressure recipients, as do H2 and CH4).
**Mr Mark Wilksch is reputed to have been fascinated by the idea of operating an engine of his on the Europa - an LSA "avant la lettre" - it was eventually done, but the craft could only fly legally with a single person aboard. Only hearsay, admittedly, but from a hopefully reliable source * * *
***the THEN ceo of Europa Aircraft
To me, the only long-term solution is to run on the same fuel as the airlines as that is the only way to ensure the necessary quality whilst sensibly managing costs.
The problem is that we have just two options there
Diamond diesels - not yet proven IMHO, but should have a decent track record say 10 years from now
Turbines - far too expensive for most of GA, and poor SFC, and I cannot see that changing in the next 10 years
Reading the latest edition of one of the UK aviation magazines I see that Cyma Petroleum are advertising that they can supply UL91.
Anybody who makes 100LL can make 91UL. They just leave out the TEL. The question is a purely business one: will enough people buy it? I don't think it's a trivial question.
There is an element of "divide and conquer" in any 91UL marketing push i.e. a hope that some airfields will commit to 91UL and will push out the 100LL burners. I think that's what TOTAL tried to do but they misjudged it. Maybe some years from now, when every non-turbocharged engine whose CR is 9.5:1 or less is certified for 91UL, they will be able to pull it off - and screw the much smaller community of remaining pilots.
New Lycoming SL1070S - IO540-C engine approved for UL91
The IO540-C engine is finally approved for UL91.
Whether this matters in reality may be moot because TOTAL have jacked up the price of UL91 to around the 100LL price, but this is good news anyway.
I suspect Peter one day we,ll get no choice.I,ve run my 0-360-A Robin 180on UL for the past year...no issues and cleaner oil no plug fouling.I do hope they come up with a UL100 to cover the remaining fleet.Very little advantage on price now at my home field so I tend to purchase either fuel wherever its cheaper.The runaway fuel bowser at my home field has sadly put paid to my and several others flying this summer awaiting a lengthy repair.VBR Stampe
I think that for the pilot it is easy enough: buy the cheaper of the two.
For the airport it is much harder. The manager needs to decide which to carry. TOTAL have been trying to lubricate that decision by offering free bowsers, but any airport that drops 100LL is going to lose the majority of its fuel sales (all turbo planes, etc). So TOTAL will probably be OK all the time they continue the "lubrication" and don't make UL91 even more expensive than 100LL.
I spoke to a guy from Total at the AERO exhibition yesterday. He told me that they are planning to have UL91 available at 20 airfields in Germany by the end of 2013 (currently only one field offers UL91).
The idea is not to stop selling 100LL as this is a higher volume/margin product and simply a must for some engines but to discontinue selling SuperPlus. SuperPlus sells in relatively low volumes and is ca. 50 EuroCents per liter cheaper compared to Avgas. For my home field they allegedly have concrete plans to simply remove SuperPlus from the tanks and pump during the summer, do some cleaning of the equipment and then start selling UL91 instead. Not sure what the UL guys might think of that.
Currently the price differential between 100LL und UL91 is 10 EuroCents per liter in favour of UL91. Total expects that differential, currently ca. 4%, to increase once UL91 sells in higher volumes and also the logistics improve.
I understood from the guy that there is only one refinery in Europe producing UL91 for Total. The refinery is located near Marseille in France and the product is then being transported by truck directly to its destinations while Avgas makes most of the journey by ship and only the last leg from distribution centers to the airfield by truck.
UL91 is marginally more useful than Mogas and my take on this is that Total are trying to increase their margin by replacing Mogas (for which there is a competitive market) with a much more expensive product for which you cannot compare prices.
Mogas at my airfield is 1,88 € currently, Avgas is 2,57 €, that is 37% more expensive. In Germany our fuel prices are among the lowest at a public airfield. I can see why Total want to run the fuel stations and offer their 91UL instead of Mogas.
My aircraft is not approved for Mogas/UL91 because it is turbo normalized but I know for sure that it runs great on super 95. If you keep CHTs low, detonation is next to impossible. Unfortunately I tend to play by the rules and (more importantly) too many people watching at the fuel bowser 
I don't know much about the farm strip scene but I would have thought that anybody who is happy to use non quality controlled car petrol and who burns so little fuel they can fill up jerrycans at a petrol station is already doing that.
And that will always be the cheapest option.
So that leaves the people who can burn mogas and who are burning so much they can't transport it easily from a petrol station.
However I suspect that there is also a strong correlation between the community that can burn mogas and the community which will not under any circumstances pay more than a (say) €5 landing fee.
And the sub-€5 airfields are probably not concerned about catering for the avgas-only crowd; the runway is probably grass and far too short. There are just very few types that need 100L and that can go there e.g. a C182 turbo.
So the market may just fragment.
Isn't Mogas lower taxed than UL91?
Several years ago I spoke with an employee of Hjelmco and he expressed a lot of frustration over the fact that UL91 was charged as tough as Avgas despite containing no lead (it actually contains a little lead but the values are within the allowed parameters to be classified as UL).
Isn't Mogas lower taxed than UL91?
I have no idea but I am sure that car petrol will always be the cheapest "petrol".
The reason not everybody uses it is
not certified to use it (i.e. illegal)
cannot use it (ethanol etc, or octane rating is too low)
required volume can't be practically transported (imagine the sheer physical effort of filling up a TB20, 325 litres usable, out of cans, and a PA28-140 is not much easier unless you can drive a pickup truck right up to the plane and are built like a gorilla)
I don't understand TOTAL's game at all. I have a feeling they (being French) thought that the European GA fleet is a lot of Robins. I know we might all think this is ridiculous and that they can't be so stupid, but it is actually possible because very few French pilots fly outside their club scene, and if some TOTAL rep did his market research at their local aeroclub...
Reportedly they truck all UL91 from a single supply depot in France so while this is expensive and probably a loss leader (bowser-trucked 100LL in places like Greece is incredibly expensive; up to €3.50/litre) it also limits their risk because they can re-deploy that transport anytime they choose to get out of the UL91 business.
