President Carter said yesterday he will send his proposal for a Cabinet-level Department of Energy to Congress "the first of next week," and said he expects rapid approval.

In the second televised news conference of his month-old administration, Carter also said:

The comprehensive energy policy he promised early in his campaign will be "quite profound in its impact on the American consciousness and our society." He will outline it in a speech around April 20, "probably at a joint session of the Congress."

He still wants a program of voluntary advance notice of wage and price increases, despite a rejection of the idea by AFL-CIO President George Meany.

"I can't say" when asked if next year's defense budget would be higher than this year's, which he cut by $400 million from the $112.3 billion proposed by former President Ford. Carter said he is still committed to his campaign promise to cut defense expenditures by $5 billion to $7 billion.

It is "understandable" that there are "some instances where natural gas is withheld from the market," but Americans will be willing to make sacrifices if they are convinced that supplies will not be withheld in the future.

He has "serious questions" about whether the controversial and expensive B-1 bomber should be "the center of our airborne defense capability," and hopes to decide how far to go with the B-1 program by the end of May.

A "demonstrated commitment" on the part of the Soviet Union toward disarmament "would certainly make it less likely that we would go ahead with the B-1.

He would like to see all congressional elections publicly financed.

The President opened the news conference with a low-key statement on a number of domestic issues. He called it a "progress report to the American people on some items that are important to us."

As in his news conference two weeks ago, the President looked relaxed and at ease, and seemed to enjoy the give-and-take with reporters. Several times he began smiling long before a question was finished, as if welcoming the chance to explore particular issues.

His discussion of the new Department of Energy did not add any more substantive details to what he said about it in his Sept. 21 position paper of energy, and in a few speeches since.

The position paper said several major agencies, including the Federal Energy Administration, Federal Power Commission, Energy Research and Development Administration, and Energy Resources Council would be abolished. The new department would take over the functions, and some of the energy-related functions of several other departments and agencies.

"We have consulted very closely with the key leaders in the Congress," Carter said. "I believe there is going to be a rapid creation of this new department and a heavy emphasis on the importance of energy questions to our people."

In is first public comment on the matter since details of a still-unreleased Interior Department study became public last week, Carter said it is "obvious to all of us that there are some instances where natural gas is withheld from the market. This is understandable. If I was running an oil company, I would reserve the right to release or to reserve some supplies of Natural gas."

But Carter continued, he belives American will lbe willing to make the sacrifices he intends to ask of them if they are convinced that future reports [on gas reserves and production] will be accurate, that supplies will not he witheld from the market."

He said he thinks oil companies "will be much less likely to withheld supplies of oil and natural gas from supplies of oil and natural gas from the market, just hoping that they will get some bonanza increased price in the future," if "we can let the oil companies know in a predictable way what our policy will be two months or two years or 20 years in the future within the bounds of human reason."

The Interior Department study criticized 10 major oil companies for holding back natural gas shortage.

Carter indicated that he has not yet decided on specific proposals to take price controls of "new" natural gas, or on specific sacrifices he will ask Americans to make.

Carter said he "will retain the option in the future of assessing what we need to do to control inflation."

"I can't force" voluntary pre-notification of proposed wage or price rises, he said. "It has got to be voluntary . . . I think it is a legitimate pursuit of mine."

He said he has "not made a proposal to Mr. Meany or any other labor leader," or any representative of industry or manufacturing on his suggestion.

Carter said inflation and the "impossibility of assessing the potential threat at our country from other nations" make it hard to predict whether next year's defense spending will rise or fall.

His analysis of the defense budget so far, "which as you know has been limited to about a month's study, just part time," indicates his goal of a $5 billion to $7 billion reduction in defense spending "will be reached."

On election law reform, Carter said he wants a "simple way" for qualified citizens to register and vote, and elimination of the electoral college, or "at least an automatic vote by presidential electors."

While he wants publicly financed congressional elections, specific proposals on that matter will have to await a study Vice President Mondale is now making on election laws, Carter said.