The Clean Air Act is broad enough to allow construction of all the energy development projects the country has in mind, despite industry complaints to the contrary, according to a draft of the final report from the National Commission on Air Quality.

The still unpublished draft agrees, however, with industrial complaints that some highly controversial parts of the Clean Air Act have been fairly useless and other aspects could be streamlined or eliminated.

The findings of the 13-member commission, obtained by The Washington Post, have been eagerly awaited by all sides in the upcoming struggle over the Clean Air Act, which is due for reauthorization by the end of September.

Environmental groups have been holding briefings, business organizations have running seminars around the country, and trade associations are cranking out thick analyses on the issues concealed behind each semicolon of the complex law. Everyone is staking out negotiating positions for the debate, which will be one of the major tasks of the new Congress.

"The commission's purpose was to put together an objective analysis of how well the law is working," said William H. Lewis Jr., who directed the three-year project. "We're optimistic that the final report, with recommendations, can be the basis for a consensus on the general direction that the reauthorization will take."

The commission will make its recommendations by March 1.

Debate is expected to focus on 10 main areas, all of which overlap with and affect each other: the "Prevention of Significant Deterioration" program; federal-state responsibilities under the law; acid rain control; hazardous emissions regulation; the use of cost-benefit analyses; the level of technology to be required in various cases; streamlining the permit process; rewriting enforcement methods; redefinitions of health effects, and resetting deadlines for compliance with the regulations.

Each interest group has its own priorities. The National Coal Association, for instance, in a briefing book prepared at the request of the Reagan administration, wants to "remove regulatory excess and lack of balance" that it says have ignored very real conflicts between energy needs and environmental goals. The Natural Resources Defense Council, in its briefing package, argues that the act has worked well and needs only to be strengthened.

All sides agree that there will be no wholesale masacre of the law, which enjoys wide support with the public and in Congress, notably from Sen. Robert Stafford (R-Vt.), chairman of the Senate Environment Committee that soon will begin hearings on the issues. Some of those issues:

Energy conflicts: The commission report said flatly that "even high levels of projected energy development could be accommodated" into the 1990s by the act as it stands, including a tripling of electrical capacity, quadrupling of surface coal mining, development of 1.5 million barrels per day of oil shale and tar sands products, and 10 coal gasification plants, all of which are the targets of many energy studies.

The Prevention of Significant Deterioration program: Only the Class One restrictions guarding pristine parkland air have had some impact, the commission said. PSD Classes Two and Three, defining the pollution limits acceptable in progressively dirtier areas, have had, with few exceptions, "virtually no impact on emission growth or facility siting."

The Heritage Foundation, the Business Roundtable, and NCA have all called for elminating the lower two classes as useless. David Hawkins, who runs air quality programs at the Environmental Protection Agency, argued in an interview that both classes will have definite impacts in the future and should be retained.

Federal-state relations: States lack the research capacity to set their own standards and cannot deal with the interstate pollution of acid rain, visibility problems and ozone from automobiles, the commission said. Reagan's transition team wants to transfer some regulatory powers to the states.

Acid rain: Research cannot now link pollution cuts with definite results, but any reduction will help, according to the commission. The utility industry has questioned whether any human health damage has been linked to acid rain, while Hawkins would like to see the act rewritten to authorize across-the-board cuts in permitted emissions to deal with the problem.

Hazardous emissions: Regulations are vague out of fear that real controls might be too sweeping, the commission said. The NRDC plans to ask for tighter rules.

Cost-benefit analyses: "Direct comparisons are difficult" and putting numbers on any one program "is exceedingly difficult," the commission reported. Most industry groups are nonetheless determined to insert a requirement for standardized accounting into the law.

Technology: The NCA and the Business Roundtable would like all technology requirements to equal the New Source Performance Standards that now are the upper limits for permitted emissions. But the commission defends the Best Available Control Technology and Lowest Achievable Emission Rate standards, saying their tighter requirements have helped lower pollution in many cases.

Streamlining, deadline setting and redefinition: There is more agreement here than anywhere else on the need for change, although business efforts to loosen the health effects definition will encounter stiff resistance.