The one certainty about the outcome of the Persian Gulf crisis is that whatever happens on the ground, the United States will remain dependent for many years on large supplies of imported oil.

The crisis has provoked loud outcries from many voices bemoaning the nation's dependence on imported oil -- "our drug of choice," one conservationist called it -- but no one has suggested that it can be ended any time soon.

Oil experts agree there is no plausible combination of increased U.S. oil production and reduced consumption that will make substantial inroads on U.S. import dependence in this decade.

The gap between production and consumption can be narrowed, but imported oil -- much of it from the Middle East -- will remain an essential economic lifeline.

President Bush said as much in his Sept. 11 address to Congress when he said the failure to conserve energy and to expand domestic sources such as natural gas and nuclear power have "made us more dependent on foreign oil than ever before."

Not since the failure of President Richard M. Nixon's 1974 "Project Independence" has there been a concerted attempt by the federal government to eliminate oil imports. But since Iraq invaded Kuwait Aug. 2, environmental and conservation groups have clamored for the Bush administration to embrace measures -- such as higher gasoline taxes -- that would encourage consumers to use less energy.

These groups endorsed a Senate bill that would have forced auto makers to increase the average fuel economy of their products to 40 miles a gallon, a move supporters said would reduce U.S. oil demand by 2.8 million barrels a day, or 16.5 percent, by 2005. But the measure appeared doomed at least for this year when the Senate, under heavy pressure from the Bush administration, refused yesterday to cut off debate.

On the production side, oil companies and independent drillers have sought measures such as tax incentives to encourage domestic production.

But experts in both camps agree that even if they got what they wanted, the gap between demand and domestic supply could not be closed for many years, if ever.

Statistics compiled by the U.S. Energy Information Administration and the American Petroleum Institute explain why.

Oil accounts for 42 percent of the energy consumed in the United States, mostly in the form of fuel for motor vehicles. This year, the U.S. has consumed an average of 16.9 million 42-gallon barrels of crude oil a day. Domestic production is about 7.1 million barrels. Drawdowns from inventories and production of natural gas liquids, which are used like petroleum, averaged about 1.3 million barrels.

The balance -- 8.5 million barrels a day -- has been imported. More than a quarter of the imports have come from the Middle East.

At the current price of about $35 a barrel, that level of imports costs the country more than $297 million a day, or $108.6 billion a year.

In the next few years, the import gap can be closed only marginally at either end -- production or consumption.

Domestic production peaked at 9.6 million barrels a day in 1970 and is now declining rapidly. So far this year, domestic production is 5.6 percent less than last year. Oil analysts and industry executives say this is partly because the low prices of the 1980s drove many small producers out of the market and partly because the easy-to-find oil is being used up.

They also say that several economic and environmental disincentives limit exploration and the drilling of new wells: uncertainty about future prices; the likelihood that new wells will bring up low-price natural gas instead of high-price oil; restrictions against drilling on federal lands and on the Outer Continental Shelf; the reluctance of banks to make energy loans; and a tax structure the industry considers unfair.

But even in an ideal environment for the industry, free of environmental restrictions and stimulated by tax incentives, "I would think we could do 9 million {barrels a day} tops," said Charles J. DiBona, president of the American Petroleum Institute. The Energy Department puts the domestic industry's "maximum sustainable capacity" at 9.4 million barrels a day.

"After all," according to Texas oilman T. Boone Pickens, "most of the oil in this country has already been found."

On the other side of the ledger, there may be great potential for reducing oil consumption, but only over several years. Higher prices are expected to reduce consumption, but not nearly enough. In past oil crises, a sharp runup in prices drove consumption down, but many experts say that this time there is less flexibility in the oil market because industrial users and electric utilities have already switched to other fuels.

The Energy Information Administration projected last week that a price of $30 a barrel in 1991 -- lower than the current price, but about the level many analysts expect -- would leave a gap of 9.25 million barrels a day.

The Energy Department, under pressure from Congress to do something about rising oil prices, has proposed a set of "medium-term" measures it said could save about 1.1 million barrels of oil a day within two or three years.

These include tuning up or replacing residential oil burners, "encouraging better driving habits," working with state regulators to phase out electric generating plants that burn oil and expediting regulatory approval of natural gas pipeline projects.

Sen. Jeff Bingaman (D-N.M.) complained at a hearing that Energy Department program is "totally inadequate," and that "the American people are ready" for tough legislation that would force down oil consumption. "You have to catch the wave," he said.

But Deputy Energy Secretary W. Henson Moore responded that "there is nothing we can find . . ., that would affect the situation over the next 90 to 180 days," when the full effect of the loss of Iraqi and Kuwaiti supplies is felt in world markets.

After that, according to Energy Secretary James D. Watkins, administration policy will be determined in accordance with the National Energy Strategy he is planning to deliver to Bush in December.

Environmental groups and conservationists have urged a much stronger oil-saving policy. They want a crash program to develop alternative motor vehicle fuels and make them widely available as well as a program to promote the development and use of mass transit. But any major impact from such measures is years in the future. The Edison Electric Institute, for example, says that a switch of 1 percent of the country's motor vehicles from liquid fuel to electricity would save 35 million barrels of oil a year -- less than 100,000 a day -- but noted that "currently there is no market-driven demand" for electrical cars.

While arguing that much more could be done, the environmental groups do not dispute the conclusion of a new report by the congressional Office of Technology Assessement that "available policy measures could slow, but not stop, the oil production decline and reverse the trend of increasing U.S. oil demand."

"We cannot eliminate foreign oil," said Christopher Flavin, energy analyst for the Worldwatch Institute. "Within the next 15 years you could reduce consumption by maybe 5 million barrels a day through conservation," he said, but "the problem now is that we are on a path toward increasing imports. It's not a question of whether we can eliminate imported oil, but whether we can stop our dependence from growing."