BERLIN — If negotiators in Paris reach an agreement next week on a global plan to rein in the use of fossil fuels, the next question becomes this: How can the participating countries fulfil their pledges to do their part?

They may get some direction from Germany, which has claimed some early success in diversifying its energy sources and balancing economic growth with environmental concerns.

Many other nations and political and business leaders had scoffed when Germany set out to make the transition from carbon-emitting power plants to renewable energy, committing itself to developing new energy sources, reducing consumption, phasing out nuclear power and investing in a low-carbon future.

But last year, Germany, the world’s fourth-largest economy, reached a milestone by reducing its overall energy consumption while still recording modest economic growth of 1.5 per cent, breaking a traditional pattern in which nations see their energy use fall only during recessions. The share of renewable energy use has continued to rise as the use of fossil fuels has fallen — all while tempering the concerns of industry about rising costs and maintaining global competitiveness.

“Germany is the first country in the world to show they can uncouple growth from burning of fossil fuels,” said Mr Jim Yong Kim, president of the World Bank. “This is the main task of our generation.”

Not that the efforts have been without challenges. As Germany has accelerated its phaseout of nuclear power, it has at times relied too heavily on coal-fired power plants, and it will need to make deeper cuts to its yearly carbon emissions if it is to meet the goal of a 40 per cent reduction from 1990 levels by 2020, a target that the government set for itself. (The European Union, including Germany, is committed to reaching that same goal as a bloc by 2030, as part of the Paris deal.)

High-power transmission lines to carry wind-generated power from turbines in the north to factories in the south have run up against not-in-my-backyard resistance, and the automobile industry’s foot-dragging on curbing emissions recently has been laid bare by US regulators who caught Volkswagen cheating on its numbers for diesel cars.

German consumers are being asked to bear much of the price of the energy transition, which the government projects will be at least €550 billion (S$833 billion) by 2050, in order to shield energy-hungry heavy industry from higher costs. This has left households with far higher electricity rates than their counterparts in most other countries.

Most recently, experts have warned that the influx of nearly 1 million people this year seeking asylum could cause a spike in emissions.

“It is important that we address the issue of population now, or it could jeopardise our 2020 goals,” said Ms Andreas Loeschel, a professor of economics at the University of Muenster and an adviser to the government.

Still, Ms Barbara Hendricks, Germany’s environment minister, said she believed that the country could meet its climate goals. She said the ability to expand the economy while reducing energy use was a major achievement.

“That is the decisive point for sustainability, to be as or more successful, while using fewer resources,” Ms Hendricks said Saturday.

Few thought it was possible. But since 2000, across party lines, German governments have passed laws and set regulations encouraging the production of solar, wind and bioenergy, in a program known as the Energiewende, or Energy Transition. At the same time, businesses, enticed by subsidies and prodded by Berlin, have worked with researchers on new ways to improve efficiency.

The foundation for the entire effort has been the support of German citizens, who have been willing to shoulder the burden of increased costs in the short term, in the hope of leaving their children with a cleaner, more sustainable system.

That course is now being sought by nearly 200 countries in Paris, which aim to wean the planet from dependence on energy produced by fossil fuels. THE NEW YORK TIMES