An ETI Perspective - Natural Gas Pathway Analysis for Heavy Duty Vehicles

Abstract:

The focus of this work is to provide insight into the potential greenhouse gas emissions savings by using natural gas in HDVs, assessing ways to optimise pathways, identifying research and technology innovation opportunities and any implication for the refuelling infrastructure. This has been achieved through comprehensive modelling of natural gas Well-to-Motion (WTM) pathways relevant for heavy duty vehicles (land - on and off-highway, and marine) based on a detailed review of each stage of the WTM natural gas pathway.

Key Findings:

• Liquefied Natural Gas (LNG) and Compressed Natural Gas (CNG) have the potential to reduce Greenhouse Gas (GHG) emissions over the well-to-motion pathway by 13% (LNG) - 20%(CNG) for dedicated engines and 16% (LNG) - 24%(CNG) for High Pressure Direct Injection engines per vehicle in the 2035 timeframe in comparison to the reference baselinediesel pathway.
• Cycle specific powertrain technology selection and pathway optimisation are key to providing GHG emission benefits over given usage cycles, with High Pressure Direct Injection and Dedicated gas engines providing the highest benefit.
• Retrofit dual fuel engines have been shown to have high methane emissions, often being worse than baseline diesel powertrains on a GHG emission basis. Effective testing procedures and legislative certainty are required to ensure emissions conformity and facilitate market development
• Providing methane catalysis at real world operating temperatures, i.e. below 350°C, is essential to prevent uncombusted methane making its way out of the tailpipe in powertrains that cannot control methane slip and is a key technology that enables a pathway benefit.
• Employing ‘best practices’ at LNG, CNG and L-CNG stations is a key driver to providing pathway benefits. Vapour recovery systems should be implemented at all LNG stations and the economic proposition and expected utilisation should be aligned. CNG stations should be connected to the highest pressure tier of the grid where possible or employed in combination with a L-CNG station as an easy step to reduce emissions associated with compression, at least until the carbon intensity of the grid is significantly lower than today.
• The economic proposition for natural gas in the HGV fleet hinges upon the fuel duty differential and currently only the long haul segment is economic in the near term. Fuel duty tax stability is key to enable market confi dence to invest in natural gas vehicles and the necessary supporting infrastructure.

Publication Year:

2017

Publisher:

ETI

DOI:

https://doi.org/10.5286/ukerc.edc.000731

Author(s):

ETI