Energy markets are highly distorted by subsidies for nuclear power and fossil fuels:
Without subsidies for nuclear power and fossil fuels, it is likely that most renewable sources of power -- with the possible exception of those that have still not reached the bottom of their cost-reduction curves and are still finding their feet commercially -- would be commercially viable without subsidies.
The Stern report said that climate change is the greatest market failure the world has seen, and that actions will be needed to compensate for that failure. Removing the subsidies for nuclear power and fossil fuels are the main actions that are needed.
Rather that piling subsidy upon subsidy, we should be aiming to wind down the arms race of subsidies, reserving them for where they are really needed:
See also: High-carbon fuel companies should pay their way too (Financial Times, 2012-09-21). Letter from Julian Scola, Communication Director, The European Wind Energy Association, Brussels, Belgium. "The fact is that governments across Europe could save themselves a lot of money, and hasten the phasing out of support for increasingly mature renewable technologies such as onshore wind, if they first removed longer-standing subsidies for more established technologies like nuclear and coal." And Creating the Internal Energy Market in Europe (PDF, European Wind Energy Association): the report includes a recommendation to remove subsidies for coal, gas and nuclear power.
Given the need to decarbonise the world's economies, there is certainly a need to raise the price of CO2 emissions from the burning of fossil fuels. This could be of some help to the nuclear industry and some people in the industry have been pressing for a higher price for CO2 emissions. But a lot depends on exactly how the price of CO2 emissions is raised. Some relevant issues are discussed in the following subsections.
If wind farms and nuclear power stations are, together, producing more power than people need, a lot depends on which of those two sources of power get paid. Unless consumers have full control over which source of power they will use and pay for, there is potential to create unfair subsidies.
A lot depends on the way in which the price of CO2 emissions is raised, see Raising the price of carbon: a back-door subsidy for nuclear power?.
In raising the price of CO2 emissions, it is important to ensure that emissions from the nuclear cycle are properly accounted for. In her book "Nuclear power is not the answer", Helen Caldicott says "The use of nuclear power causes, at the end of the road and under the most favourable conditions, approximately one-third as much carbon dioxide (CO2) emission as gas-fired electricity production." But this is only with the highest grades of ore. The use of poorer ores as a source of fuel for nuclear reactors "would produce more CO2 emissions than burning fossil fuels directly." In other words, "nuclear reactors are best understood as complicated, expensive, and inefficient gas burners." (p. 6).
Raising the price of CO2 emissions may be of some help to nuclear power but it would be even more helpful to renewables. With the changes outlined in 'Winding down the arms race of subsidies', it is unlikely that nuclear power would be commercially viable.