Steven Chu (Chip Somodevilla/Getty Images)
Energy Secretary Steven Chu said Friday he will leave the administration when a successor is confirmed.
"I would like to return to an academic life of teaching and research, but will still work to advance the missions that we have been working on together for the last four years," Chu said in a letter to Energy Department employees.
Chu added: "The journey that I began with you four years ago will continue for many years."
President Obama praised Chu for helping "move America toward real energy independence" during their time in office.
"Over the past four years, we have doubled the use of renewable energy, dramatically reduced our dependence on foreign oil, and put our country on a path to win the global race for clean energy jobs," Obama said. "Thanks to Steve, we also expanded support for our brightest engineers and entrepreneurs as they pursue groundbreaking innovations that could transform our energy future."
In his letter to employees, Chu cited his department's efforts to develop new and improved energy technologies, clean energy jobs, home weatherization projects, and hybrid and battery-powered cars.
"The Department of Energy serves the country as a Department of Science, a Department of Innovation, and a Department of Nuclear Security," Chu wrote.
The biggest criticism of the department during Chu's tenure: The $528 million federal loan to the solar energy company Solyndra, which later went bankrupt.
A former director of the Lawrence Berkeley National Lab, Chu is a Nobel Prize winner in physics.
Chu joins a long list of first term Obama appointees who have left, or are leaving.
They include Secretary of State Hillary Rodham Clinton, Treasury Secretary Timothy Geithner, Defense Secretary Leon Panetta, Labor Secretary Hilda Solis, Interior Secretary Ken Salazar, and Transportation Secretary Ray LaHood.
The Senate has confirmed colleague John Kerry, D-Mass., as Clinton's replacement at State; it is considering Chuck Hagel's nomination to be the new Defense Secretary.
Obama has nominated former Chief of Staff Jack Lew to be the new Treasury Secretary.
The president has not yet nominated new secretaries of labor, interior, and transportation.