BOARD MEETING DATE: July 10, 1998 AGENDA NO. 40
PROPOSAL:
Best Available Control Technology Guidelines - Gas Turbines
SYNOPSIS:
The AQMD Board received and filed staff BACT/LAER Guide-lines for natural gas-fired turbines at its April 10 and June 12, 1998 public meetings. However, several parties requested an opportunity to provide additional comments to the Governing Board on this matter.
COMMITTEE:
Not Applicable.
RECOMMENDED ACTION:
Receive public testimony
Barry R. Wallerstein, D. Env.
Acting Executive Officer
Background
On April 10, 1998, AQMD staff reported to the Board as per Agenda No. 20 - Best Available Control Technology Guidelines Update - that LAER for natural gas-fired turbines, with capacities of 3 MW or greater, is 2.5 ppmvd NOX and 10 ppmvd CO, corrected to 15% O2 and averaged over 15 minutes. The Board received & filed LAER for natural gas-fired turbines with capacities between 3 and 32 MW, and directed staff to report within 60 days regarding LAER for turbines with capacities greater than 32 MW.
On June 12, 1998, staff reported to the Board as per Agenda No. 39 - Best Available Control Technology Guidelines Update - that LAER for natural gas-fired turbines with capacities greater than 32 MW is 2.5 ppmvd NOX, 10 ppmvd CO, and 10 ppmvd NH3, corrected to 15% O2. The Board received & filed the staff recommendation, but several parties subsequently requested an opportunity to provide comments to the Board on the gas turbine issue. This agenda item provides this opportunity to interested members of the public to provide comments or requests.
Gas Turbine Issue
In determining LAER, AQMD staff is required to consider emission standards or control technologies that are either contained in a State Implementation Plan (SIP) or that have been achieved-in-practice. The AQMD staff has determined that the SCONOX system in combination with water injection has been operated continuously on a 25 MW natural gas-fired turbine for more than six months. During the six-month period, (1) the gas turbine was operated at more than 50% of its capacity; and (2) the SCONOX/water injection was shown by CEMS data to reduce NOX concentration to 2.0 ppmvd or less at 15% O2. As such, the SCONOX system in combination with water injection is deemed "achieved-in-practice" technology based on data for a 25 MW natural gas fired turbine.
Since SCONOX/water injection has been deemed "achieved-in-practice" technology for a 25 MW natural gas fired turbine, staff is required to consider the emission rate achieved by this technology as a possible LAER for other turbines when the exhaust characteristics from such turbines are similar to those from the 25 MW gas turbine. Based on staff review of AQMD source test reports for different natural gas fired turbines, it has been determined that the characteristics of the exhaust gases from these turbines are similar. Therefore, AQMD BACT, which also implements federal LAER, for gas turbines with capacities of 3 MW or greater, is an emission limitation of 2.5 ppmvd NOX, 10 ppmvd CO, and 10 ppmvd NH3, corrected to 15% O2. A technical report summarizing available information was supplied as part of Agenda No. 39 at the June 12, 1998 Board meeting.
The issue of averaging time is a permitting issue, left to the specific permit application, although staff has recommended an averaging period of 1 hour for compliance determination. Other implementation issues such as shutdowns, startups, etc. will also be addressed at the permitting stage. Finally, the BACT Guidelines are advisory in nature and provide general guidance for commonly permitted equipment; it does not preclude the consideration of technical feasibility in setting emission standards for specific permitting situations.
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