The NY Times nails it in In Search of Energy Miracles:
Yet not even the speedy Chinese are likely to get a sizable reactor built before the 2020s, and that is true for the other nuclear projects as well. So even if these technologies prove to work, it would not be surprising to see the timeline for widespread deployment slip to the 2030s or the 2040s. The scientists studying climate change tell us it would be folly to wait that long to start tackling the emissions problem.
Two approaches to the issue — spending money on the technologies we have now, or investing in future breakthroughs — are sometimes portrayed as conflicting with one another. In reality, that is a false dichotomy. The smartest experts say we have to pursue both tracks at once, and much more aggressively than we have been doing.
An ambitious national climate policy, anchored by a stiff price on carbon dioxide emissions, would serve both goals at once. In the short run, it would hasten a trend of supplanting coal-burning power plants with natural gas plants, which emit less carbon dioxide. It would drive some investment into low-carbon technologies like wind and solar power that, while not efficient enough, are steadily improving.
And it would also raise the economic rewards for developing new technologies that could disrupt and displace the ones of today. These might be new-age nuclear reactors, vastly improved solar cells, or something entirely unforeseen.
In effect, our national policy now is to sit on our hands hoping for energy miracles, without doing much to call them forth.
h/t Travis Franck