Energy Secretary Donald P. Hodel, seeking Senate approval to move to the Interior Department, acknowledged yesterday that the administration's idea of merging the two departments "would die for lack of a second" in Congress.

President Reagan has instructed Hodel and his designated successor at the Energy Department, White House personnel chief John S. Herrington, to explore a merger as a way of fulfilling Reagan's campaign pledge to abolish DOE.

The notion has found little support on Capitol Hill, least of all in the Senate Energy and Natural Resources Committee, which was considering Hodel's nomination yesterday.

Herrington, appearing before the same panel Thursday, said he was keeping a "totally open mind" on a merger. Hodel said yesterday that he thought Reagan's promise "made a lot of sense," but he conceded that the chances of selling Congress on the idea were slim.

"While maintaining my general support for this concept," he said, "I made clear to DOE employes that this is not a concern that should be very high on their worry list."

Hodel, who served as undersecretary to James G. Watt at the Interior Department before taking over DOE in 1982, appeared headed for easy confirmation despite complaints from some environmental groups that he is too closely tied to what Sen. Howard M. Metzenbaum (D-Ohio) called "the cynical and destructive reign of Jim Watt."

"Mr. Hodel represents no change whatsoever from the disastrous policies of the last four years," Charles Clusen of the Wilderness Society told the panel. "Not only was he part of the Watt team, he has not disavowed any of Watt's policies." Asked yesterday if he disagreed with any of Watt's policies, Hodel deflected the question, saying that he believed Watt's "efforts" were designed "to further the president's goals."

But he also dismissed the concept of "privatization," once promoted by Watt as a way to reduce the federal debt by having the government sell unneeded public lands.

"I don't think it has practical application," Hodel said in response to a question from Sen. Dale Bumpers (D-Ark.). "The administration has looked and has obviously concluded that opportunities do not exist as were once thought possible."

He also emphatically vowed not to revive one of Watt's most controversial proposals: energy development in national parks. If confirmed, Hodel said, "I will not consider, I will not support and I will not permit development activities such as mining, drilling or timber harvesting in the national parks."

In 1981, Watt proposed to allow strip mining and other mineral development on more than 3 million acres within park boundaries. Although he later backed down amid congressional outrage, the proposal became a lasting symbol of what critics saw as the administration's development-at-all-cost philosophy at the Interior Department.

Hodel also ruled out development within wilderness areas, but he said he intended to work for more energy development on "vast acreages of federally held, multiple-use lands" not otherwise protected for special use.

"It is my intention to pursue the objective of energy independence insofar as the policies and programs of the Department of the Interior can contribute to its achievement," he said. While he did not mention Watt by name, Hodel referred obliquely to his former boss' travails with Congress and environmentalists by saying that he intended to achieve a "national consensus on energy issues" through "consultation, consensus and accord."

"The nation is not well served by impasse on those issues; the nation is not well served by confrontation," he said.

Because of Hodel's apparent willingness to maintain the olive branch extended by his predecessor, William P. Clark, who took over for Watt in late 1983, most environmental representatives who testified yesterday remained officially neutral on his nomination.