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Project Status: complete

Report Published March 1995:

Title: Controlling locomotive emissions in California: technology, cost-effectiveness, and regulatory strategy. revised final report.

Principal Investigator / Author(s): Weaver, Christopher S

Contractor: Engine, Fuel, and Emissions Engineering, Inc.

Contract Number: A032-169 & 92-917

Research Program Area: Emissions Monitoring & Control, Economic Analysis

Topic Areas: Benefits, Impacts, Mobile Sources & Fuels


The objectives of this study were:

1. to identify a set of feasible* and cost-effective techniques to reduce locomotive pollutant emissions in California to the greatest extent possible at an acceptable cost;
2. to characterize the technical requirements, costs, emissions impacts, and impact on railway operations of each technique in sufficient detail to serve as a basis for regulation;
3. to identify and recommend areas where ARB or other public funding for additional research, development, and demonstration of specific techniques is required in order to make them available for widespread application; and
4. to develop and recommend a regulatory strategy and implementation schedule for reducing locomotive emissions in California as quickly and cost-effectively as possible, and estimate the emission benefit which would result.

Feasible and cost-effective control techniques for locomotive emissions include retarding injection timing and other engine modifications. selective catalytic reduction (SCR). use of liquified natural gas (LNG) fuel with low-emission dual-fuel or spark-ignition (SI) natural gas engines, LNG combined with SCR, and electrification. Use of a combination of dual-fuel and SI LNG engines could reduce locomotive emissions 80%, at a cost of less than $1.000 per ton of NOx eliminated. SCR added to diesel and LNG could produce NOx emission reductions of 90 and 97%. Respectively, at costs less than $3,000 per ton. All of these technologies could be retrofit to existing diesel locomotives.

*A dictionary definition of feasible is .capable of being done, possible.. In this study we interpret "feasible" to mean it is not necessary that an emission control technology be demonstrated in railroad service in order to be judged feasible. A technology that has been proven in similar applications, or in limited testing, and which shows prorn1se of working well in railroad service is considered feasible by this definition.

Electrification of all California line-haul locomotive operations with LNG+SCR in switch and local units represents the greatest potential emission reduction, 98%, but the cost would be ten times that of the next best (in terms of cost-effectiveness) option, with only a small NOx emission improvement. Based on these results, a regulatory framework has been proposed. This framework, based on an emissions -bubble-, would reduce allowable locomotive emissions per net ton-mile transported by 80% between 1998 and 2005. Further R&D is required to develop an appropriate emission test procedure, to develop and demonstrate low-emission dual-fuel retrofit systems for locomotives, and to demonstrate the use of SCR retrofit systems.

In their comments on an earlier version of this report, the railroads have stated that the cost estimates developed herein are too low, and that the characterization of LNG and SCR use as technically feasible in railroads is too optimistic. Recalculation of the cost-effectiveness estimates using the railroad's data results in higher costs per ton overall, but these costs are still well within the range considered acceptable by ARB and SCAQMD. The data submitted also show that present railroad activity levels are much higher (in some cases, double) than those calculated from the 1987 inventory data, suggesting that actual railroad emissions may also be much higher than presently estimated. It is recommended that the ARB investigate present activity and emissions levels in greater detail.


For questions regarding this research project, including available data and progress status, contact: Heather Choi at (916) 322-3893

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