State Department of Energy and Environmental Protection Commissioner Daniel Esty will be stepping down Feb. 3 to return to his tenured professorship at Yale University, after spending the last three years guiding the agency as it took on oversight of state energy policy.

Gov. Dannel P. Malloy announced Esty's departure Wednesday, praising him for "integrating and reinvigorating our approach to environmental regulation and energy policy and building a strong foundation for 21st Century action."

Esty obtained a two-year leave of absence from Yale when he took the DEEP post in 2011, then extended it one year. Five months after he began, the agency long known as the Department of Environmental Protection changed its name to DEEP to reflect its new responsibilities over energy policy.

In a statement released by Malloy's office, Esty said he is particularly proud of initiatives that have "made Connecticut a national leader when it comes to innovative approaches to both environmental regulation and energy policy.

"We have demonstrated that we can protect our natural resources and our quality of life while strengthening our economy and creating jobs," he wrote. "We have also shown that by harnessing market forces and using innovative financing solutions to leverage private capital, we can make real progress in bringing cheaper, cleaner, more reliable power for both residents and businesses."

He referred to the creation of the state's first Comprehensive Energy Strategy, the creation of the Green Bank to provide financing for energy projects, and cooperation with other New England states on building energy infrastructure to bring cheaper, cleaner and expanded natural gas services and other new energy sources to the state.

Dennis Schain, spokesman for DEEP, said Esty's departure had been anticipated, and that the governor is already considering candidates to be his successor. Esty's annual state salary is $139,000.

"Several senior staff people in (DEEP) are under consideration, and that would help ensure continuity," Schain said.

State Sen. Edward Meyer, D-Guilford, co-chairman of the Environment Committee, said he expects to meet with the governor in the next few days to discuss qualifications he would like to see in Esty's successor. He expects there will be an acting commissioner for a period of time while the Legislature considers confirmation of the person Malloy nominates for the post.

"He will be missed," Meyer said of Esty. "He did an exceptional job of combining energy and the environment and symbolized the idea that we can have a good environment because of clean energy."

He also praised the attention Esty brought to the need for policies and programs that foster climate change adaptation, especially in vulnerable shoreline areas. Esty, Meyer said, also made an effort to be visible throughout the state, scheduling time regularly to meet with residents in state parks.

During his "Commissioner in Your Corner" visits to a different state park each month, Esty toured Harkness Memorial State Park in Waterford in May 2011 and Fort Trumbull State Park in New London in September of that year. During both visits, he also answered questions from the public and heard their concerns.

At Yale, Esty will resume his work as the Hillhouse Professor of Environmental Law and Policy and as director of the Yale Center for Environmental Law and Policy and the Center for Business & Environment at Yale.

j.benson@theday.com