OCR Text |
Show Modified Boilers and Heaters It w a s determined that the emission limits for modified boilers and heaters should be developed on a case-specific basis through consultation between the proponent and the relevant provincial environmental authority. The above reference limits for new boilers and heaters should be used as targets or starting points recognizing that it m a y not be possible to meet these limits on modified sources. A suggested definition for a "modified source" was based on two types of work that can be done on conventional boilers and heaters: • Type 1 W o r k would relate to process or capacity change or improvement such that the work would constitute "modification" if it exceeded 12.5% of the Current Total Erected Costs and the work involved a burner change. • Type 2 Work would relate to reconstruction such that the work would constitute "modification" if it exceeded 5 0 % of the Current Total Erected Costs. It was recognized, however, that provinces currently have varying definitions for modified sources. Energy Efficiency The expression of emission limits as allowable mass of pollutant per unit of energy input (e.g. N O x limits as g/GJ) is a common practice among environmental agencies. However, this does not encourage or credit the reduction of N O x emissions, or other emissions, by energy improvement. It is recognized that energy efficiency improvements may reduce the net N O x emissions as a result of the reduction in quantity of fuel consumed even though the rate of N O x emissions, on an energy input basis, m a y remain constant or increase. As well, improved efficiency will have a positive effect in reducing other pollutant emissions, including greenhouse gases. In an effort to address this issue, alternate forms of stack emission limits were considered according to the following criteria: • effectiveness • comprehensiveness • verification • simplicity • applicability It was determined that using credits proportional to efficiency improvements was the best option for incorporating energy efficiency into the Guideline. For cases where energy efficiency measures have been implemented, the limits for N O , emissions (reference limits) should be adjusted according to the formula: Applied NOx Emission Limit = Reference NOx Emission Limit x Energy Efficiency Credit Two separate approaches were developed for determining energy efficiency credits for boilers and heaters. For boilers, energy efficiency credits are determined according to the formula: Energy Efficiency Credit = Actual Thermal Efficiency Reference Thermal Efficiency 8 |