The Reagan administration yesterday launched its effort to persuade Congress to abolish the Department of Energy, "guaranteeing" to eliminate 1,200 federal jobs and save $80 million annually if permitted to fold most energy functions into the Commerce Department.

But members of the Senate Governmental Affairs Committee--most of whom had voted for creation of the Energy Department only five years ago--greeted the reorganization plan with skepticism and hostility. Most appeared far more concerned about the severe cuts being made in energy research, development and conservation.

Commerce Secretary Malcolm Baldrige, who testified along with Defense Secretary Caspar W. Weinberger and Energy Secretary James B. Edwards, attempted in a three-hour hearing to persuade the lawmakers that merging the departments would "strengthen the energy functions of the U.S. government."

Weinberger said the defense-related activities performed by the Energy Department--which spends more than half of its budget on research, development and procurement of nuclear weapons for the military--would "in no way be impaired."

Edwards, who has declared that his top priority is to abolish his department before he resigns this fall to become president of the Medical University of South Carolina, said that while he was "not ready to announce that the energy crisis is over,. . . , after a decade of turmoil, we have finally reached the point where our energy problems are no longer being magnified out of proportion."

The deputy director of the Office of Management and Budget, Joseph R. Wright Jr., testified that the proposed merger would permit staff consolidation in areas such as administration, public affairs and legal services, and would lead to elimination of 1,200 positions and an annual savings of $80 million. He said that through other economies there was a "good possibility" that savings could total $1 billion in three to four years.

When Sen. David Pryor (D-Ark.) noted that White House counselor Edwin Meese III said last month the reorganization would save $2 billion over the next four years, Baldrige said he would only "guarantee" savings of $250 million over three years because "I would rather underpromise and overdeliver."

Most committee members appeared less concerned over the promised savings than over what Sen. Thomas F. Eagleton (D-Mo.) termed the administration's underlying premise "that energy is no longer a special problem."

"This is not simply a reorganization," Eagleton said. "For all its flaws, the Department of Energy symbolizes our recognition of the problem which hangs over our prosperity and our national security like Damocles' sword. We should be doubling our efforts to free ourselves from our dependence on foreign oil, not offering blithe assertions that we have turned the corner or spied the light at the end of the tunnel."

A number of senators, both Democrats and Republicans, criticized the administration's cutback in Energy Department outlays on conservation, coal and fossil fuels and solar and renewable energy resources, and they voiced concern that these programs will get even less attention under the proposed merger.

"Organizationally and structurally, the plan seems to deemphasize those programs," Sen. Charles H. Percy (R-Ill.) said. He noted that the budget passed this week by Congress includes $600 million more for energy than President Reagan requested, with most of the money earmarked for research and development in conservation, renewable resources and fossil fuels.

Percy pressed Edwards for an assurance that he would support this level of funding for these programs. Edwards declined, saying, "It is obvious that you have included a lot more money than we requested for certain aspects of our program."

Both Edwards and Baldrige repeatedly made it clear that, while they favored government funding for research in high-risk, high-technology areas where private interests are unlikely to venture, they believe that more proven areas such as conservation and solar technology should be left to the private marketplace.

Baldrige, pressed by Sen. Harrison H. Schmitt (R-N.M.) on government funding for solar research and development, said:

"What's complicated is how you actually make it work at a cost that is affordable. I don't think there is any secret yet to be found."

No further hearings on the proposed reorganization are planned before mid-July, and no such bill has even been introduced in the House, so committee sources said yesterday there is virtually no chance that the measure will make it through this Congress.