J Thomas wrote:If the minority view is right, we will never completely run out of methane because more is being produced all the time. The rate that it's produced is unknown but probably not real large. Still it provides hope. If we can get many millions of tons of methane a year from down in the mantle or something, we'll never run out and there will never be a fossil fuel shortage.
Presumably even if that minority view is right, we will eventually run out of methane anyway because there's still a limited amount of carbon in the rock, unless it's being cycled back into rock in some comparable timely fashion (and not just turning into mulch and CO2). Is it just that "eventually" is negligibly short of "never" in that case?
There's probably a whole lot of limestone getting subducted at plate boundaries. It's unknown how much carbonate rock gets subject to just the right conditions to create methane. It's unknown how much methane escapes before it is converted to something we can't use. It's unknown how fast the escaping methane reaches us.
There's no quantitative evidence for any of it. But our current fuel needs amount to about 12 billion tons of oil equivalent a year. About 82 billion barrels. Around 500 trillion cubic feet of natural gas. Unless I've missed a decimal point or gotten a conversion wrong, that's all the natural gas we'd need to collect and ship to where we need it, to provide our current energy needs. The earth might produce that much new natural gas fresh each year. I really don't know. It seems strange to think that could have been going on for the last hundred years while none of our scientists noticed. But every now and then things do sneak up on us If we've been getting that much new carbon every year, the world must also be sequestering it faster than we think.
My own guess is that if it happens at all, it's at a much lower rate. The hypothesized chemical reactions have never been observed in nature. There could be other reactions which consume methane, which the original hypothesizers did not think of because their goal was to discover unlimited fossil fuels. But I don't know. It might be a good start to get an estimate how much carbonate rock gets subducted each year, and that would be your maximum. Of course, not all the carbon can turn to methane.... It's potentially a very complicated problem and the computer models are not all that good yet.
The Law of Fives is true. I see it everywhere I look for it.