Solar and wind have a problem that the other renewables (including hydro, if there's water) don't: they aren't on all the time. Several recent articles have been published about the difficulties of managing a system with large amounts (and we're there now) of solar and wind. Hence the need for storage.

So here's a suggestion that nobody in the home solar business will like: require rooftop solar installations to include enough storage (probably a battery) to provide their rated production for at least 3-4 hours after sunset. That would greatly increase the price of a system (Solar City alias Mr. Musk is now offering storage options, but even with access to the Tesla battery megafactory in Nevada it doesn't come cheap - though the fact that they're only offering it on big systems for multi-day storage affects that). For the "duck curve" discussion see Cal ISO: [www.caiso.com]

For now, we need to keep gas/oil/coal plants around to cover for when the renewables aren't there. Nukes would be good for base load (zero CO2 output in operation), but too expensive/NIMBY. Unfortunately for oil/coal, the traditional steam plants fired from those sources can't respond quickly to changes in demand, so they're a problem when renewables (solar, mainly) surge during the day - have to be kept spinning with minimal output to be ready for the evening. Gas-fired plants, especially newer ones, can be more responsive as well as being cleaner than the older stuff. Longer-term, storage (pumped hydro is ideal for utility scales, but very expensive/NIMBY-sensitive and, of course, you need water to work with.

And I wouldn't cry too much about the effect of the crude oil collapse on railroads. It was discussed here a long time ago. It was more of an operating nuisance on the big railroads than a major revenue generator, and I suspect they're happy to have a pause so they can work out some of the annoying details related to moving crude. It hasn't gone away; just calmed down for a bit. Of course, the way oil prices have been going lately, we might have more tankers trying to jam into our ports, and ships are *much* worse polluters especially when running on bunker oil than trains.