Japan and the UK: Emission predictions of electric and hydrogen trains to 2050

Kathryn G Logan,John D Nelson,Benjamin C Mclellan,Astley Hastings

doi:10.1016/j.trip.2021.100344

Abstract

Electric trains (ETs) and hydrogen trains (HTs) offer an opportunity for both Japan and the UK to meet their national targets as part of the Paris Agreement. Although ETs and HTs are considered zero emission at the point of use, their true environmental impact is dependent upon non-tailpipe emissions from fuel/energy production and vehicle manufacture, maintenance and disposal. To assess and compare the carbon dioxide emissions produced from ETs and HTs in Japan and the UK from 2020 and 2050, the operating emissions of these trains were projected. Results compared ET and HT emissions with diesel fuelled trains (DFTs) to better assess which fuel type was the most environmentally friendly. Emissions per train, cumulative emissions and total energy required for ETs and HTs were compared.Results indicated that even with technological improvements, DD DFTs produced the highest level of emissions in both countries, followed by HTs. Although ETs produced the lowest level of emissions, it is likely that a mix of both ETs and HTs will be required to meet passenger demand and for travel within rural areas. As Japan has already transitioned towards ETs, future policy focus should be placed on decarbonisation of their energy sector and a shift away from fossil fuels in favour of renewable energy, otherwise environmental benefits of ETs will be diminished. As the UK is decarbonising its electricity network, focus needs to be placed on electrifying the majority of the rail network and running the rest on hydrogen to decarbonise rail transport.

Highlights

The 2015 Paris Agreement aims to limit global warming to well below 2 °C above pre‐industrial temperatures and to pursue efforts to limit temperatures to 1.5 °C above pre‐industrial levels (Rogelj et al, 2016)
Under Fig. 1(B), results indicated that 100% diesel fuelled trains (DFTs) produced the highest level of emissions at 7.0 kgCO2 km−1 in 2020 decreasing by 1.4% to 6.9 kgCO2 km−1 by 2050
Results from this study indicate that Electric trains (ETs) produced lower levels of operating emissions than both hydrogen trains (HTs) and DFTs in both countries

Summary

Introduction

The 2015 Paris Agreement aims to limit global warming to well below 2 °C above pre‐industrial temperatures and to pursue efforts to limit temperatures to 1.5 °C above pre‐industrial levels (Rogelj et al, 2016) As part of this agreement, both Japan and the UK have set their own nationally determined contributions (NDCs), with Japan aiming to reduce their greenhouse gas (GHG) emissions by 80% compared to the 1990 baseline levels by 2050 (Ashina et al, 2012). The UK has set a more stringent target aiming for net zero GHG emissions by 2050 (equivalent of 95% compared to 1990 base line) (O’Beirne et al, 2020) For these international and national targets to be met, both countries need to focus on reducing transport emissions, as these contributed to 18% of Japan’s national GHG emissions total and 28% of the UK’s in 2017 (CCC, 2018; Watabe et al, 2019). In the UK, the projected grams of CO2 produced per kilometre per person by regional diesel fuelled trains (DFTs) was one sixth of private conventionally fuelled vehicles (CFVs) at 100%, 75%, 50% and 25% capacity

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