Quote:
Went to a seminar many moons ago and if I remember correctly Shell said that the amount of lead emitted into the atmosphere world wide per year from Aviation was about 4 tonnes, that is a lump about the size of a coffee table.. Not exactly a lot is it.
At about 1g lead/litre for 100LL, that's only 4 million litres of fuel - 1 million gallons or thereabouts. According to Wikipedia, "The annual U.S. usage of avgas was 186 million US gallons in 2008". I doubt that leaded avgas is the most pressing environmental concern out there, but I think your figures are out.
How much avgas do the military use in drones and trainers? Would it be plausible to wager that it will only be available whilst they still require it?
A lot of lead in an aero engine never makes it into the atmosphere, which is what they were talking about, quite a lot will get washed off the bores and mixed with the oil, you just have to see the amount you scrape out af a crankshaft on a wobbly prop engine, it coats the inside of the shaft often about 1/2 inch thick. It was a while ago since I went, (years) but that was a figure I can remember, they said they were experimenting with a cocktail of chemicals to replace the lead but were struggling to get the Knock rating up, I think they said the drop in power would equate to the reduction in cargo carrying capacity on something like a DC6 of several tons.