Retooling the Vapor Recovery System: Part 3 - Reactions by Equipment Makers: Some Fugitive Emissions Remain At Large |
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The new Enhanced Vapor Recovery regulations indicate that CARB’s staff has begun to understand the mechanisms of air ingestion into storage tanks and the associated dynamics of liquid evaporation, vapor growth, storage tank pressurization and resulting emissions of VOC’s and other air pollutants through system vents and breaches. For purposes of this article, I will refer to these emissions as fugitive emissions or evaporative losses. ARID Technologies (ARID) believes that vapor recovery would be more effective if CARB were to recognize the economic value of, and environmental need for, controlling evaporative losses at all stations, including those with Stage II balance or assist systems and those without Stage II controls. Also, the vapor recovery program, petroleum marketers and equipment manufacturers could benefit significantly if the CARB certification protocol would permit vent processors (so-called "back-end" components) to be certified separately from the other vapor recovery system components. |
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| Measuring evaporative losses | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Based on data gathered from ARID’s commercial installations in the United States and TUV Rheinland (Cologne) field tests in Germany, ARID has concluded that typical wet stock evaporative losses range from 0.10 percent to 0.50 percent of station throughput. The TUV test report is available from Department for Environment, TUV Rheinland, at www.tuev-rheinland.de/enghome.htm.
ARID has obtained data from other countries that further substantiates the magnitude of evaporative losses at uncontrolled stations. Stations in many countries are not subject to Stage II vapor recovery requirements. In some countries, suppliers incorporate dealer rebates based on anticipated evaporative losses. For example, one major marketer in Hong Kong provides a dealer rebate equivalent to a 0.56 percent product loss due largely to evaporation. Another Hong Kong-based major marketer provides a dealer rebate of about 1.0 percent of throughput. Because the magnitude of evaporative losses has been understated significantly, the economics of vapor recovery are not being analyzed properly. Using prevailing gasoline pump prices"typical values for gasoline at Reid Vapor Pressure (RVP) and storage tank temperatures"positive net present values are generated along with favorable after-tax internal rates of return. The magnitude of the evaporative emissions can be estimated using Tables 1 and 2, which were generated using ARID’s proprietary Evaporative Loss Model. |
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