US president-elect Barack Obama has backed up his campaign promise to focus on green energy with an energy secretary nominee who experts say will provide scientific expertise and pragmatism to the search for new, clean sources of fuel.

Mr Obama's pick, Nobel physics laureate Steven Chu, has been a strong advocate for using less energy to counter the effects of global warming and climate change.

"If I were emperor of the world, I would put the pedal to the floor on energy efficiency and conservation for the next decade," Mr Chu told Reuters in an interview last year.

Mr Chu has led the Lawrence Berkeley National Laboratory since August 2004. Under Mr Chu's leadership, the lab has pressed aggressively to develop new alternative energy technology.

Mr Chu's experience in advanced technology and renewable energy and lack of background in fossil fuels signals Obama expects the energy department to concentrate on new fuels, experts said.

"I believe that the selection of Steve Chu suggests that President-elect Obama is quite serious about reordering the energy sector and executing his vision of a green economy," said Jerry Taylor, a senior fellow at Cato Institute.

Unlike previous energy secretaries, Mr Chu has little experience either in the private sector or the political arena. The current energy secretary, Sam Bodman, ran a chemical company and served as deputy secretary of the US Treasury Department before heading up the US Department of Energy.

Instead of business or political credentials, experts say Mr Chu brings technical prowess and administrative skills to the role.

"He will bring scientific rigor to President-elect Obama's clean energy and global warming agenda," said Dan Weiss, an energy expert at the Center for American Progress think tank.

"He is that rare combination of distinguished scientist, accomplished manager and savvy advocate."

Some believe a new council created by Mr Obama to coordinate White House policy on energy, climate and environmental issues may keep Mr Chu from having too much of a hand in shaping policy.

Mr Chu, however, will be able to provide balance and realism to the council's strategic vision, said Kevin Book, a senior analyst of energy policy at Friedman, Billings, Ramsey and Company.

"No serious scientist can ignore facts for very long, and the need for conventional energy base load and economically sustainable solutions even as there is a transition towards the strategy that emerges from the Energy Council remains very much within the DoE portfolio," he added.