Economics Minister Philipp Rösler says switching off nuclear power will increase the cost of a kilowatt hour of electricity by just one euro cent. Mr. Röttgen calculates the cost per household during the transition as roughly one extra cup of coffee latte — €2.50 to €3, or about $3.50 to $4.25 — per month.

But the nuclear industry, led by E.ON, Vattenfall, RWE and EnBW, says that it will be the private sector, particularly energy companies, that will have to pay for the switch to renewables and other energy sources, like natural gas and even a dozen or so new coal plants. “We are not talking about peanuts here, but hundreds of billions of euros,” said Jürgen Grossmann, the chief executive of RWE.

On the other side of the equation, the government will no longer pay for nuclear subsidies, which, according to Greenpeace, have totaled about €200 billion, or about $285 billion, since West Germany began research and development of nuclear power in the 1950s. Subsidies last year totaled €4.1 billion, according to a recent study by Green Budget Germany (Forum Ökologisch-Soziale Marktwirtschaft), an independent environmental research organization.

Another factor is the likelihood that Germany, which already gets more than one third of its natural gas from Russia, will grow more dependent. Mrs. Merkel, however, disputed this point when she met President Dmitri A. Medvedev and other top Russian officials in July. When Deputy Prime Minister Viktor A. Zubkov, who is also chairman Gazprom, the state-owned natural gas export monopoly, openly relished the prospect of selling more to Germany, the chancellor coolly responded, “Let’s wait and see.”

Clearly, something big will have to change. Germany imports nearly 60 percent of its energy, according to the International Energy Agency.

Renewable sources like wind and solar power currently make up only 17 percent of the power mix. The government envisions that amount roughly doubling by 2020 and reaching 80 percent by 2050.

It also plans vast expansion of the national grid to move electricity from the north coast, where wind is plentiful, and the south, where solar energy is more abundant, to the key industrial areas where it is most in demand. According to the German Energy Agency, 1,500 kilometers to 3,600 kilometers, or 930 miles to 2,200 miles, of new extra-high voltage power lines will have to be built by 2020, financed by grid operators.