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.
This report reviews the performance and costs of existing commercial gas turbines and the capability of gas turbines to operate using hydrogen-containing fuel gases. The report was commissioned by ETI to provide background information for a project they will undertake on salt caverns for storage of hydrogen for use in gas turbine power plants.
A wide range of gas turbines are reported by manufacturers to be suitable for fuel gases that contain hydrogen. There is significant experience of using gases that contain mixtures of mainly hydrogen,methane and other hydrocarbon gases, especially refinery off-gases and coke oven gas, which typically contains 50-60%vol H2. Gases with H2 concentrations of up to 95% are reported to be used. There is also experience of using syngas from gasification which typically contains 25-50%vol H2 but the other main constituent is CO, which has substantially different properties to methane.
Use of fuel gas containing H2 presents some significant technical challenges for gas turbines but also some potential benefits.
The biggest technical challenge is reported to be the high flame speed of H2, which can result in flashback, although it reduces the risk of blowout. The properties of hydrogen-methane mixtures in gas turbines combustors vary non-linearly with concentration. It is reported that only when hydrogen becomes the main constituent is there a large variation in the laminar flame speed.
Development aspects and assessments of Gas Turbines (fired by methane and/or H2) are provided, including contemporary OCGT GTs from GE. Additionally, potentially synergistic capture technologies are described
In 2001 an academic study "Socio-technical networks and the sad case of the condensing boiler" (Banks 2001), identified the very low uptake of condensing boilers, despite their apparent cost effectiveness. By 2006, almost every gas boiler installed in the UK was condensing. The market was transformed. This note sets out how that change happened.
