I think a reasonable person considers half "an appreciable degree". When someone says half is not an appreciable degree, I find it difficult to believe any of their other statements come from a reasonable place.
The tipping point is cost-capability, as always. There is a number where the time and transportation and cost of a PV and/or wind genny makes sense for replacing some of the production from diesel generators. It's going to depend on the site location, so it will not be a one-size fits all answer. But a bean counter somewhere is going to develop such an equation that gets presented to a few hundred committees who will then vote to do whatever the hell they originally wanted to do using that equation (or one by another rival bean counter) as justification.
The flip side, is with the alternative green gennies, I will still need energy storage and backup generators/fuel anyway. Now I have to haul, install, and maintain both alternatives and diesel generators at the FOB to utilize the alternatives. That green light where the numbers all make sense might ultimately be much lower than you or I would naively suspect.
My favourite is the DARPA low-maintenance algae farm grown on site, just because it seems to me it would be hard to beat on price, and space is often cheap out in the boonies where there is little infrastructure. Turns out that tending an algae farm requires electricity for circulation and such, as well. So the ultimate viability of that, too, is an open question.
There are open questions about the portable reactors as well that need to be addressed, and since no one currently has one that we can point to with answers for particulars, they will remain open for a while.
Maybe one day we'll be using forward-deployed nuclear, wind, PV, for electricity, and using some of the electricity there to produce hydrogen for vehicle use, but I doubt it because physics dictates a volume problem.
I'd be pretty cautious with anyone with a strong stance from any side of this debate. Particularly when strong, broad statements are made in the face of facts.
