State & Local Permitting
Central Maine Power Air Permitting Services
Central Maine Power Company (CMP) is constructing a new 69 kV transmission
line in southern Maine that will connect an existing substation to a point on
CMP’s existing transmission line near the York Beach Substation located off
Ridge Road in York, Maine. This project is necessary to provide reliable
electric power to the southern York County service area.
CMP is anticipating that the new Bragdon Commons substation in York will not be
completed and operational in time for the peak electricity demands that occur
during the summer season. Consequently, CMP needed to temporarily install two
diesel engine generator sets at the substation location to provide electricity
to its customers during peak demand periods and as needed until construction of
the project is completed. Temporary installation of a single diesel engine
generator set was required at another substation location for the same purpose.
Based on heat input capacity of the engines required for this project, CMP
needed to apply for two separate Minor Source Air Emission Licenses from the
Maine Department of Environmental Protection (MDEP).
As the technical lead in the air permitting process, Devine Tarbell &
Associates, Inc.’s (DTA) staff were responsible for preparing the minor source
air license applications for the installation and operation of the diesel engine
generators at the two substation locations. The scope included estimating
pollutant emission rates, researching other similar projects and licenses,
performing a BACT analysis, consultation with the state agency, and drafting the
application.
DTA’s staff completed all of the air permitting tasks identified in the scope
above. The pollutant emission rates were estimated using vendor-provided
emission rates and industry standard emission factors as provided in USEPA
AP-42, Compilation of Air Pollutant Emission Factor guidance. Numerous minor and
major air emission licenses were reviewed to determine which control
technologies have been required by the MDEP. Upon review of the licenses and the
control technologies, it was determined that selective catalytic reduction (SCR)
for nitrogen oxides control was viable for long-term operation. However, this
would have been cost prohibitive for this type of project. Based on DTA
negotiations with the MDEP, CMP proposed a fuel usage limit and a one-year
license term which allowed CMP to present SCR as economically infeasible in the
license application.
The air licenses were issued within two months of the application submittal
date. The DTA strategy and air permitting expertise provided CMP with enough
flexibility to operate the engines under the worst scenario involving
construction delays and unusually hot weather, whereby distributed power
generation from the engines would be required to meet the demand. The quality of
the application and agency interaction facilitated an expedited review process,
resulting with issued air licenses in time for the summer season.