“There has been a kind of waking up to the fact that the premises of the Energiewende, however well-intentioned they are, no longer hold because the world has changed,” said Daniel Yergin, an energy industry analyst and historian who helped carry out the study.

The Renewable Energy Act in Germany has been amended several times over the last 13 years. The latest changes are to be voted on by Parliament before its summer recess, and crucial points have already been approved by Ms. Merkel’s government. Revisions to the law concentrate on managing the expansion of renewable sources by focusing on technologies that have proved to be the most cost-effective over the last decade.

These changes reflect lessons learned since Germany first decided to phase out its nuclear reactors in favor of energy generated by renewable resources, which until now have all been promoted equally through government subsidies.

Berlin’s nearer-term goals have not changed, aiming for 40 to 45 percent of all energy to come from renewable sources by 2025, rising to 55 to 60 percent by 2035. But the mix of technologies has been revised, with the focus now on large onshore wind parks and solar energy farms.

“With the Renewable Energies Act that we created in 2000, we financed a learning curve that was expensive,” said Mr. Baake, the deputy energy minister, who is considered by some to be the grandfather of Germany’s energy transition. “But the good news is that we have learned in only 13 years to produce electricity with wind power and large solar facilities at the same price as if we were to build new coal or gas power stations,” he added.

In Britain, the government is also responding to complaints from its businesses and consumers about the cost of green taxes and other environmental measures. In a parliamentary speech on Wednesday outlining his budget for 2014 to 2015, the chancellor of the Exchequer, George Osborne, noted that industrial energy prices in the United States were half those of Britain. “We need to cut our energy costs,” he said.

Mr. Osborne said he would take measures to reduce energy bills, which would include capping Britain’s tax on carbon dioxide at 18 pounds, or about $30, a ton — although not until after next year’s national elections. The tax, which is now about £5 a ton, would otherwise have increased to about £36 a ton by the end of the decade, analysts say. The freeze would cut a midsize manufacturer’s electric bill by £50,000 a year and a household’s by £15 annually, Mr. Osborne said.