The Pima County Department of Environmental Quality (PDEQ) recently hosted its final hearing for the community after soliciting feedback from the public on its proposed Tucson Electric Power (TEP) Air Quality Permit.

The TEP's proposal includes modernizing its power-generating station with the replacement of two steam units, which the TEP says are designed from the 1950s, with 10 natural gas fired combustion engines. According to the TEP, the new engines will each be capable of generating almost 19 megawatts of power. 

According to the PDEQ, the replacement could result in an increase of carbon monoxide, particulate matter, nitrogen oxides and volatile organic compounds emissions over a certain period. The potential for the emissions is the reason for the need to modify the Prevention of Significant Deterioration permitting. 

The PDEQ says that TEP plans to expand its renewable energy by 30 percent by 2030 and that the proposed engines would help to meet peak loads as well as balance its varying solar and wind energy generation. 

PDEQ has been working with TEP, the U.S. Environmental Protection Agency, the National Park Service and other consultants to ensure permit modifications meet regulations and protect public health.