This is an interesting and useful page on costs of energy by source:
http://en.wikipedia.org/wiki/Cost_of_electricity_by_source
If the U.S. government set the policy that all federal R&D dollars will go into energy sources that are not yet at $125 per megawatt hour in total system levelized cost, then no federal R&D would go to coal, natural gas, nuclear, win, geothermal, biomass, or hydro.
That would leave only solar and fusion getting federal R&D money.
And that’s good policy. You should only spend federal energy R&D dollars to bring down the cost of energy (and into conservation / efficiency R&D and maybe carborn capture). You’d leave tax incentives in place for everybody else doing clean and/or renewable energy. But R&D would all go to bring down the cost to $125 per megawatt hour in total system levelized cost.