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

NOx Emissions Report
prototypes were assumed to have year round cooling and heating loads, with both
available simultaneously.
Table 3-5: Industrial CHP Prototype Projects
Technology
Unit
Capacity
(MW)
Potential
Projects
Potential
Capacity
(MW)
Microturbine 0.1 647 64.7
Microturbine 0.5 82 41.0
Recip. Engine (rich burn) 0.5 81 40.5
Recip. Engine (rich burn) 2 58 116.0
Gas Turbine (no duct burner) 2 58 116.0
Recip. Engine (rich burn) 10 1 10.0
Gas Turbine (no duct burner) 10 5 50.0
Gas Turbine (duct burner) 10 6 60.0
Gas Turbine (no duct burner) 100 4 400.0
Gas Turbine (duct burner) 100 4 400.0
Total 946 1,298
Template information was input into the EPA CHP Emission Calculator. This tool
calculates fuel consumption, duct burner fuel consumption, total fuel consumption, total
CHP electricity generated, and the amount of useful thermal energy obtained from the
system. The calculator compares that to a baseline system configured to purchase
electricity from the Texas electrical grid and natural gas from the local natural gas
distribution company to produce steam in a conventional boiler.
Detailed system performance and potential NOx emission impacts were calculated for
each of the ten prototypes by adjusting the model output as appropriate. The Emissions
Calculator tool defaults input settings for engine and chiller performance parameters were
utilized. The Emissions Calculator estimates on-site NOx changes due to changes in
boiler usage and due to operation of the prime mover used in the CHP system. It also
estimates NOx changes due to changes in the consumption of grid-supplied electricity.
Detailed assumptions and information used to model the industrial CHP templates is
provided in Appendix B.
NOx savings produced by offsetting power from the electrical grid are calculated with the
EPA’s eGRID tool. 17 Generally, NOx production rate assumptions for CHP systems were
adapted from the default values provided in the EPA CHP Emissions Calculator tool.
However, as the most recent version of the Emissions Calculator had not been updated to
include the latest eGRID information, the ERCOT NOx emissions information was
manually updated in this study to reflect the latest eGRID information pertaining to
ERCOT-only utilities operating in the eight county HGB region. Note also that a 7%
17 NOx emissions produced by the Texas electrical grid are based on the “2007 Annual eGRID (25%)” and
“2007 OSD eGRID (25%)” databases using protocols consistent with those of the TCEQ and EPA.
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