| OCR Text |
Show 7 3.1 SCOPE OF GUIDELINE (New and Modified units) The initial wording of the N307 plan referred to a New Source Performance Standard. However in November 1991, AITG ruled to confirm an earlier Environment Canada proposal that would include existing units which were to undergo major modifications, such as repowering or complete replacement of turbine or combustion systems. There were some objections to this, primarily that a new source standard should apply to new units only. The final accepted wording of the Preamble includes a provision that an assessment of emissions performance and control methods for modified units should be done by the user in close conSUltation with the appropriate regulatory authority. 3.2 APPROACH TO EMISSION LIMITS (Enerqy output Basis) The original draft presented to the first working group meeting contained a two-option approach. Option A used emission limits modelled after those in certain regions of the United States (southern California, U.S. Northeast). The basis of this was a formula for a NOx concentration limit (ppmv) for simple cycle applications, corrected by efficiency and a fuel-bound nitrogen allowance, as shown. Emission Target = 25 ppmv x (12 / Heat Rate) + FNA Alternatively in Option B, the proponent could choose to install a higher efficiency cogeneration cycle with a proportionally higher NOx allowance based on total useful energy output. Subsequent discussions revealed that there were many varying views on how the detailed assumptions and definitions for each option would be formulated. For example, difficulties in obtaining an accurate definition of heat rate determination in the Option A formula, and the uncertainties involved in dealing with two options indicated the need for a simplified approach. Following the second working group meeting and a review of written comments, a proposal was put forward to opt for an energy output basis for the Guideline (similar to previous Option B). In this approach the required NO~ level is directly tied to the overall demonstrated plant efflciency. The Guideline does not include the detailed specifications of how the plant outputs or control methods would be determined. It places the onus on the project proponent to demonstrate the plant's thermal efficiency to the appropriate regulatory authority. |
