NOx Emissions Impacts from Widespread Deployment of CHP in ...

NOx Emissions Report
4.1 Geographic Implications
Even though widespread CHP implementation across HGB would produce a substantial
net reduction in NOx emissions, implementation of CHP system at commercial and
industrial facilities in HGB would relocate the source of some of those emissions from
outside of HGB to within the eight county region. Table 4.3 summarizes the anticipated
on-site and off-site NOx changes.
Table 4-3: Potential NOx Emission Impacts from CHP – Existing Sites HGB Region
Commercial and Industrial
Sectors
On-site
NOx Change
from CHP and
Boiler Offset
(tons/day)
Off-site
NOx Change
from Displaced
Grid Electricity
(tons/day)
On & Off Site
Total Change
in NOx
Emissions
(tons/day)
Commercial (Case 3 Impacts) 0.0 -2.9 -2.9
Industrial 11.8 -21.8 -10.0
Total HGB 11.8 -24.7 -12.9
Development of the full 1,300 MW of CHP potential in the industrial sector is anticipated
to increase NOx emissions inside HGB by about 11.8 tons per day, while NOx emissions
from power plants serving the electricity grid would reduce NOx emissions by about 21.8
tons per day. Considering full development of the commercial potential (274 MW)
assuming use of the Optimal Thermal Utilization (Case 3) strategy, a net reduction of 2.9
tons per day is anticipated.
The NOx impact of CHP development within HGB is highly dependent on the location
and impact of NOx emissions being produced by electric utility generators. The EPA’s
eGRID database, used in this study, attempts to estimate NOx impacts within the HGB
region from each utility power plant located in ERCOT. However, to fully assess the
impact of CHP on ozone concentrations in HGB, we would have to know which utility
power plants operated at reduced output as a result of new CHP capacity. This would
require knowledge of power plant dispatch tactics within ERCOT and the NOx emission
profile for each plant. With the addition of NOx plume and dispersion modeling, this
information could be used to generate detailed NOx concentration profiles for use in
photochemical modeling of the region.
To the extent that NOx emissions from electric utility generators are created outside of
the eight-county region, CHP implementation could increase NOx concentrations within
the region. However, if the power plants operating at reduced output due to CHP
implementation are located within the HGB air shed, their NOx emissions could have an
impact on NOx concentrations.
Figure 4-1 illustrates the potential NOx impact in HGB due to the geographic location of
emissions. If NOx reductions arising at electric utility generators are not considered in the
analysis, widespread adoption of CHP in HGB may increase NOx by an anticipated 11.8
tons per day. However, if all of the NOx emission reductions occurring at utility power
plants do impact HGB, then CHP implementation may decrease NOx by an estimated
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