scope:

FOREWORD

Atmospheric Hydrocarbon Emissions from Marine Vessel Transfer Operations (API Publication 2514A) presents correlations and emission factors for estimating total hydrocarbon emissions and evaporative cargo losses from marine vessel loading and ballasting operations of crude oil tankers.

The test programs from which the marine emissions data base was developed were designed to determine the total hydrocarbon emissions from a vessel's cargo tanks during gasoline and crude oil loading and during cargo tank ballasting after the discharge of crude oil. In general, the measurement procedures and data analysis techniques used in API 2514A follow those developed as part of the Western Oil and Gas Association Marine Measurement Program. The tests were conducted during all seasons of the year and in many regions of the country, usually during routine operations.

The data base for crude oil loading emissions consists of emission measurements from 16 separate vessel operations, each of which represents averages of from 1 to 11 different compartments. The entire data base represents the measured emissions from 67 vessel compartments. These data were separated into three categories, as a function of prior cargo and ballast voyage compartment treatment. The emission data from each separate operation were separately analyzed to determine arrival, generated, and total emission factors.

The data base for crude oil ballasting emissions consists of emission measurements from 54 individual vessel compartments. These data were separated into two categories, as a function of the true cargo ullage in the compartment prior to dockside discharge. The emission data from each compartment were analyzed separately to determine total emission factors.

The correlations and factors for estimating emissions are applicable to product and crude oil tankers currently calling at U.S. ports. However, these correlations and factors should not be used for estimating emissions from very large crude carriers (VLCCs) or for vessels that employ crude oil washing. The publication does not address crude oil loading into barges, gasoline tanker ballasting, or in-transit losses since emission data were not available for these operations.

API commissioned CH2M Hill to assess the validity and application of the marine vessel loading and ballasting emission factors documented in Publication 2514A. The validity assessment was necessary due to new crude oil loading test data from Valdez, Alaska. which suggests higher crude oil loading emissions for transfer operations than those predicted by API 2514A equations. The Valdez, Alaska testing was conducted by Alyeska Pipeline Service Company and its owner organizations.

CH2M Hill reviewed and critiqued test data bases and emission models obtained through a literature search and performed a direct comparison of emission test data with predictive emission models by API, ARCO and EXXOK. The principal focus of the CH2M Hill work was the review of crude oil loading emissions since the new data primarily pertained to this type of operation.

The test data base/emission model critique and emission comparison tasks found that the API crude oil loading emission model appears to adequately predict emissions for tankers ranging in size from 17,000 to 35,000 dead weight tons (dwt) and for tankers being loaded within the lower 48 states (original test data base). Although the model does not appear to apply to crude oil loading of Very Large Crude Carriers (VLCCs - 100,000 to 499,000 dwt) in Valdez, there is no known test data that conflicts with the model's ability to predict crude oil loading emissions from carriers smaller than VLCCs in the lower 48. On average, the API model adequately estimates arrival emissions from crude oil loading operations.

API publications may be used by anyone desiring to do so. Every effort has been made by the Institute to assure the accuracy and reliability of the data contained in them; however, the Institute makes no representation, warranty, or guarantee in connection with this publication and hereby expressly disclaims any liability or responsibility for loss or damage resulting from its use or for the violation of any federal, state, or municipal regulation with which this publication may conflict.

Suggested revisions are invited and should be submitted to the director of the Industry Services Department, American Petroleum Institute, 1220 L Street, N.W., Washington, D.C. 20005.