Coming and Going at the Energy Department

Just as the Senate moved toward approving a new energy secretary, the department’s second-in-command is announcing his departure.

The nominee for secretary, Ernest J. Moniz, attracted no visible opposition at a confirmation hearing at the Senate Energy and Natural Resources Committee on Tuesday, but on Wednesday, David B. Sandalow, the acting under secretary, announced that he was leaving after four years to take a fellowship at the new Center on Global Energy Policy at the Columbia University School of International and Public Affairs.

Mr. Sandalow came to the department four years ago as the assistant secretary for policy and international affairs, but since last spring has been the acting under secretary, in charge of energy efficiency, renewables, nuclear energy, fossil energy and electricity delivery and reliability.

That job is evidently hard to fill. He succeeded Arun Majumdar, who took over as acting secretary in early 2011 after the departure of Cathy Zoi, who had also been acting under secretary, taking over that role in October 2010. Her predecessor, Kristina M. Johnson, was the last person who had the job on a permanent basis.

There is some stability, though; Steven Chu, the current energy secretary, who will depart when Dr. Moniz is confirmed, is the longest-serving energy secretary in the 36 year history of the department.

In the three years that Mr. Sandalow had the international job, he made 13 trips to China, and China will continue to be a focus for him in the fellowship, he said.

“Coal, renewables, vehicles, much of the world’s energy future is being shaped in China,’’ he said. His focus there “reflects importance of the U.S.-China relationship and the importance of China in energy markets,’’ he said.

Mr. Sandalow said that the department was at the center of innovation that could change the energy world. “It was R&D by the Department of Energy 30 years ago in hydraulic fracturing and horizontal drilling that helped create the shale gas revolution of today,”  he said. “The question for today’s generation is, what are the technologies we’re investing in today that will have an impact.”

Mr. Sandalow, 56, wrote a book, “Plug-In Electric Vehicles: What Role for Washington” just before entering government service, and found that government rules then prohibited him from promoting it. Leaving government, he may write another on energy but has not fixed on a topic, he said.

He starts at Columbia on June 1. No word yet on who will be the next acting under secretary.