We have about 60 years of proven NG reserves at today's current consumption levels. There is probably a lot more than that waiting to be discovered.
The problem with alternative fuels for aircraft is that jet fuel is still so darn cheap and there is no crisis right now. So none of these are economically viable...yet.
Note that "peak in 2030" and "60 years proven reserves" aren't incompatible statements. The problem is that post-peak, it gets a lot more expensive (in terms of energy cost) to extract.
There's also the rate of consumption growth to take into account -- find an annual rate, apply the rule of 72, and realize that in the last period you're using as much as you have in all the previous ones, combined.
And no, there's probably not a whole lot more waiting to be discovered ... at least not anywhere that's readily accessible. Prospecting for mineral resources has been pretty bloody extensive, the types of formations in which natural gas is found are well understood, and any of those which are accessible have been accessed.
What remains is going to be what's difficult to get to, or difficult to get to market (natural gas doesn't ship well in barrels -- it's got to be compressed, liquified, or piped).
Yeah, maybe there's untapped reserves in Antarctica or Greenland, but by the time we're going after that, we'll have a few other concerns at hand.
So let's look at that. Wikipedia's statement expands on the cited reference by specifying constant consumption, but let's accept that as standard practice in energy reserve estimate statements:
Dr. Anthony Hayward CCMI, chief executive of BP stated in October 2009 that proven natural gas reserves around the world have risen to 1.2 trillion barrels (190 km3) of oil equivalent, enough for 60 years' supply if consumption is non-increasing, and that gas reserves are trending upward.
A quick check turns up a Motley Fool piece stating that global NG consumption is growing at 2.2% annually, or doubling every 32 years. The ten-year average has been 2.7% for a 26 year doubling.
The "gas reserves are trending upward" comment is consistent with the passage immediately preceding in Wikipedia noting that new discovery estimates are hard to establish, so they're often amended upwards. The increasing reserves noted by BP's CEO aren't the result of new finds, but of revised estimates of old finds. And new gas field discoveries peaked in the 1970s, 40 years ago. We're not finding new gas, we're simply recognizing how much was already found.
Fracking also isn't turning up new gas fields, but is allowing known plays to be further extracted. Again, it's digging further into what we'd already known about.
So: given BP's 2013 report of proved reserved of 187 trillion cubic meters, present consumption of 3,314 billion cubic meters, and an annual growth trend of 2.7%, we'll actually exhaust reserves by 2047. With a 2.2% growth trend, we'll last until 2050.
The problem with alternative fuels for aircraft is that jet fuel is still so darn cheap and there is no crisis right now. So none of these are economically viable...yet.