The debate is over how to pay contributors to the grid so the system has an adequate amount of both energy and power. This is not a discussion likely to engage the ordinary consumer with a home electricity bill, but it is crucial to maintaining the stability of the system as the shift from fossil fuels proceeds to ones lighter on carbon.

Solar panels and especially wind turbines produce vast amounts of energy, but on their own schedule, when the sun is shining or the wind is blowing. The more conventional installations — coal, natural gas and especially nuclear plants — earn their keep by selling energy around the clock. Put enough wind and solar units on the grid during the hours when they are running and they flood the market and push down the hourly auction price of a megawatt-hour of energy.

Sometimes the price goes to zero. Oddly, it can go even lower. When demand is very low in the middle of the night and the wind is blowing hard, there may be too much electricity on the system and grid operators will charge generators that want to add more. Nuclear plants cannot quickly modulate their output so they are, in effect, fined for production. But wind farms still make money because they earn a tax credit for each kilowatt-hour they generate.

The problem is especially acute for nuclear reactors because their costs for fuel are roughly the same whether they are running or not. They are refueled on a fixed schedule, not when the uranium is used up. Their labor costs, mortgage costs and maintenance costs are roughly the same, too. But if the hourly price for energy is suppressed by wind and sun, suddenly the nuclear plants can’t make enough money to keep running.

Thus some have already closed and more are threatened, even though carbon dioxide limits are unlikely to be met without them. Even relatively clean natural gas plants are hurt; they are generally on the margin, the first to shut when new solar comes on line.

The 40-year-old Robert E. Ginna Nuclear Power Plant on the shores of Lake Ontario in upstate New York is becoming an example of an emerging trend. Its income from selling energy is down because cheap natural gas and growing sources of renewable energy have depressed the market.