All we need is for oil energy cost to goes up, than you'll get "green energy". Currently, it does not make sense to invest in green energy technologies.

It doesn't need to be solved right now, but it will become urgent in the future. Urgency will increase flow of capital. Increased flow of capital mean we'll get technological solutions faster.

Right now, we can put our money to other, more urgent things that's more important. Green energy is not that important, for now.