The Impact of Air Quality Regulations on Distributed ... - NREL

Applicability <strong>of</strong> New Source Review—<strong>The</strong>
manner in which the NSR permitting process
applies to a proposed project is determined by
the “potential emissions” <strong>of</strong> the affected
source. 24 Potential emissions means the total
annual emissions if the source were to run at
full capacity for an entire year. New or
modified sources that exceed certain potential
emissions thresholds are called “major
sources” and are subject to the federal NSR
program. If emissions are below the major
source threshold, sources are subject to
“minor source review.” Finally, there is
usually an emission or size threshold below
which sources are exempt from environmental
permitting. This regulatory framework applies
to all sources equally, whether they are
central station power plants, other large
24 <strong>The</strong> NSR program applicability threshold applies to the
entire facility, not individual units. An individual DG unit
might not trigger NSR but could be part <strong>of</strong> a larger project
that triggers NSR.
23
sources, or small projects such as distributed
generators.
Whether a proposed project's potential
emissions are high enough to trigger NSR
depends on its location. <strong>The</strong> major source
threshold varies according to the local air
quality attainment status. As shown in Table
3-1, the threshold for major source review <strong>of</strong>
a new source in a nonattainment area ranges
from 100 tons per year (tpy) down to 10 tpy
depending on local air quality. <strong>The</strong> major
source threshold for NOx for PSD review <strong>of</strong> a
new source in ozone attainment areas is a net
emissions increase <strong>of</strong> either 100 or 250 tpy
depending on the type <strong>of</strong> source. Modification
<strong>of</strong> a source can also trigger NSR/PSD, if it
results in an increase in potential emissions.
Table 3-1
Major Source Thresholds for NOx
Nonattainment Classification Major Source Threshold Major Source Threshold for
for New Sources Modified Sources
Attainment Area
Ozone Nonattainment Areas:
100/250 tpy 40 tpy
Ozone Transport Region 100 tpy 40 tpy
Moderate 100 tpy 40 tpy
Serious 50 tpy 25 tpy
Severe 25 tpy 25 tpy
Extreme 10 tpy 0 tpy
Table 3-1 shows that the trigger levels for
modifications are lower than for new sources.
<strong>The</strong> threshold for modifications in attainment
areas is a net emissions increase <strong>of</strong> only 40
tpy. <strong>The</strong> major source threshold for
modifications in nonattainment areas ranges
from 40 tpy down to zero tpy in the Los
Angeles extreme nonattainment area. This
lower threshold for modifications is quite
significant because it is common to add a DG
unit to an existing facility.
To put these major source thresholds in
context, Table 3-2 lists the potential NOx
emissions <strong>of</strong> some representative-size DG
technologies. Comparing Tables 3-1 and 3-2
shows that, except for diesel generators in
serous ozone nonattainment areas, small DG
projects are unlikely to trigger major source
review, even for modifications.