FOLD THE ENERGY Department into the Commerce Department? President Reagan would do better to fold Commerce into Energy. There would be the same collisions of incompatible functions, but the waste -- both in dollars and in bad federal decisions -- would be less costly.

Mr. Reagan's reason for abolishing the Energy Department is, he says, his intention of letting the market rather than policy govern the American fuel supply. But is that truly his intention? You will have noticed that the government's nuclear power program is a large and prominent exception to the general pattern of severe budget reductions. The market is backing away from nuclear reactors for reasons essentially economic; the Reagan administration is making a determined effort to override the market with its undiminished support for development. What about the disposal of nuclear waste? The market isn't going to solve that one. There is no thought of abandoning the regulation of the interstate pipelines. The market can't decide how large a strategic petroleum reserve to build, or when to use it.

Few of the present Energy Department's functions, and little of its budget, would be abolished under the president's plan. They would only be transferred to another agency -- one with no experience and no expertise in energy policy. That's efficient government?

The nuclear weapons program is roughly half of the Energy Department's present budget. A few senators would thoughtlessly like to put it in the Department of Defense. That would reverse the historic decision that Congress made in 1946 when it voted to take the nuclear laboratories out of the military structure, to be operated and controlled solely through civilian authority. It was a decision that time has proved to be profoundly right, and Mr. Reagan has wisely chosen not to challenge this tradition.

But by assigning the weapons labs to the Commerce Department, of all places, Mr. Reagan would put them under several layers of officials who have never dealt with anything remotely similar. He proposes to do it at a time when the arms control negotiations with the Soviets give a special importance to the nuclear technicians' access to the people making policy.

This misconceived reorganization plan may well be blocked by Congress. Many people there remember why the Energy Department was created in the first place. They remember the energy crises of 1973 and, again, 1979. Perhaps Mr. Reagan is prepared to let the market resolve any future crisis. But Congress is not--not when it thinks of the electoral consequences of gasoline and heating oil at $3 a gallon. In late October the Senate, with its Republican majority, passed a bill by 85 votes to 7 creating standby authority to regulate prices and allocate supplies in an emergency. It's not an ideal bill, but it's a strong hint that Congress doesn't intend to leave oil prices to the unmitigated play of panic and profiteering. If Congress thinks that there's a federal responsibility to protect economic stability by foresighted energy policy, it might be wiser to preserve the department that it designed explicitly for that purpose.