The state environmental quality department last night held a public hearing on part of Harvard's $110 million Medical Area total energy project, but announced that it would postpone public consideration of the more controversial portion of the project--its facilities for generation of electricity.

The department will bring that issue to a hearing on December 19, when the public has had more time to assess the generators' possible environmental impact.

The state Department of Environmental Quality Engineering is the last major public agency that must approve the project, which includes facilities for producing steam, chilled water and electricity.

There has been some concern, in the department as well as among some residents of Boston's Mission Hill neighborhood, about the plant's expected levels of emission of nitrogen oxides.

Anthony D. Cortese, director of the state Division of Air and Hazardous Materials, said at the hearing that the state had just received new information from the federal Environmental Protection Agency on the plant's possible effect on air pollution levels around Boston.

Cortese said he would make the information available to the public before the department holds a final public hearing on the environmental acceptability of the plant's proposed diesel generators