Yes, but in circumstances where no war is in the offing, digging a giant hole next to 50km of open water begs questions. It would be impossible to get "it's a hedge against the future" over the line.
The same to a lesser extent applies to pipes. You could construct pipes for gas, for some of the heavier oils and crude (what I read suggests pumping crude long distance is painful, it has to be down-mixed with lighter stuff to make it sufficiently fluid) but the fertilizer? that would mean converting dry to wet and back again (nobody ships fluid weight if they can avoid it) -Or ship the inputs: ammonia, and sulphur in some liquid form, and produce the dry goods on the other side.
But, I think pipes have a stronger case than a canal: move the things which are amenable to pipes, into pipes, and bury the pipes.
In times past, this would have been done as a convoy. China and other nations would have stepped to the fore, conducting safe passage with their own ships on the outside edge. But we're not in a world where this kind of thing works for anyone involved. Even offering to cover insurance risk doesn't look to have motivated ship owners to pass. (in times past, the US wouldn't have put itself or it's allies in this position, hence the reference to China)
Don't be fooled by mental images of what a convoy looks like: ships like these maintain massive separation. There's almost suction between hulls moving at this scale, if they were within 500m of each other there'd be chaos if one had to take any evasive action. In reality (I believe) even a convoy consists of a a lot of discrete, clearly demarked and targetable things, not a large mass you can "hide" in.
https://en.wikipedia.org/wiki/List_of_traffic_separation_sch... (and a lot of links off this)
We could have spent the money on windmills without raising any suspicions.
On the other hand, fertilizer is fluid -- either ammonia or ureal ammonium nitrate.
If the fertiliser production has a point in manufacture when the fluid is amenable to transport, then for sure, that would make sense.
And you are right, if the same amount of capital and energy was invested in Solar/Wind as in Oil, we'd be in a totally different world. It's cents to dollars, considering the size of the tail AND the current investment.
Here in Australia the problem is the royalty stream to the states. Oil and Gas windfalls when the price of equivalent supply (brent crude I believe for oil, not sure what LNG world price defines the limit) hits $100 is just amazing. The revenue stream to the states is enormous. Their motivation to transfer money into alternatives, instead of sucking on the teat, is zero. States without significant oil revenue seem to do more (SA) -States isolated from the national grid seem to do more (WA) but a site with both high insolation, and good wind, but also massive oil, gas and coal fields (Qld) does as little as possible. It's political reductionism. The crony economy is huge, Mining funds the government and the government reflects mining sector interests over all others.
