well...the world spends $409 Billion in subsidizing fossil fuels....tried to look up the US's share of that, but keep getting varying numbers....from 2.4B to 78B.
That being said....R&D is essential for any new technology. Since renewable energy is a goal that will promote New growth in our economy and is also a National Security issue, I think it behooves us to continue the worthy goal of integrating renewable energy into our society. Getting that technology to the point where it's ready to roll out and be economically practical takes money. That money is a joint effort of the public and private sector. Why public funds? Because, as I have said before....it's in our interest.
We've spent over a trillion fighting wars with people who generally don't like us to protect our economic and National Security interests over there. Imagine what the middle east would look like if we didn't need their oil at all and we led.the world in the manufacture of renewables. That's a future that is worth investing in.