Real-world activity, fuel use, and emissions of heavy-duty compressed natural gas refuse trucks

Gurdas S Sandhu; H Christopher Frey; Shannon Bartelt-Hunt; Elizabeth Jones

doi:10.1016/j.scitotenv.2020.143323

Real-world activity, fuel use, and emissions of heavy-duty compressed natural gas refuse trucks

Sci Total Environ. 2021 Mar 20:761:143323. doi: 10.1016/j.scitotenv.2020.143323. Epub 2020 Nov 5.

Authors

Gurdas S Sandhu¹, H Christopher Frey², Shannon Bartelt-Hunt³, Elizabeth Jones⁴

Affiliations

¹ Director of Science & Technology, 3DATX Corporation, Buffalo, NY 14228, United States of America. Electronic address: gurdas@gurdas.com.
² Department of Civil, Construction, and Environmental Engineering, North Carolina State University, Raleigh, NC 27695-7908, United States of America. Electronic address: frey@ncsu.edu.
³ Department of Civil Engineering, University of Nebraska-Lincoln, Omaha, NE 68182-0178, United States of America. Electronic address: sbartelt2@unl.edu.
⁴ Department of Civil Engineering, University of Nebraska-Lincoln, Omaha, NE 68182-0178, United States of America. Electronic address: libby.jones@unl.edu.

PMID: 33213912
DOI: 10.1016/j.scitotenv.2020.143323

Abstract

Over 50% of new refuse truck sales have been compressed natural gas (CNG). Compared to diesel, CNG is less expensive on diesel gallon equivalent (dge) basis. This study quantifies the real-world fuel use and tailpipe exhaust emissions from three front- and three side-loader refuse trucks, each with a spark ignition CNG engine, three-way catalyst, and similar gross weight. Measurements were made at 1 Hz using a portable emissions measurement system (PEMS). Inter-cycle and inter-vehicle variability is quantified. Effect of vehicle weight was analyzed and comparisons were made with MOVES predicted cycle average emission rates. In total, about 220,000 s of data covering 490 miles of operation were recorded. The average fuel economy was 1.9 miles per dge. On average the trucks spent 53% of time in idle, which includes trash collection activity. The average speeds were 10 mph and 5 mph, for front- and side-loader trucks, respectively. Overall, compared to side-loader trucks, front-loader trucks had 55% better fuel economy and 60% lower emission rates. Compared to diesel trucks, CNG truck cycle average NO_x and PM emission rates, at 1.2 g/mile and 0.006 g/mile respectively, were substantially lower while CO and HC rates, at 29 g/mile and 6 g/mile respectively, were considerably higher. Fuel use and CO₂ emissions rates increased by 10% due to increase in truck weight during trash collection, while CO emissions rates increased by up to 30%. Compared to measured values, MOVES estimated cycle average fuel use and CO₂ emissions were 25% lower, CO emissions are 70% lower, and NO_x emissions were 200% higher. Results from this study can be used to improve solid waste life cycle and tailpipe emission factor models and, when combined with previous studies on diesel refuse trucks, evaluate the effect on fuel use and emissions from adoption of CNG refuse trucks.

Keywords: Compressed natural gas; Heavy-duty vehicles; MOVES; PEMS; Refuse truck; Tailpipe emissions.