[ 1 ] Patel T. A hydrogen-powered train will make transport history as Europe looks to become world leader in green rail travel [Internet]. New York City: Fortune; 2021 Apr 23 [cited 2022 Jan 12]. Available from: https://fortune.com/2021/04/ 23/hydrogen-train-transport-europe-green-rail/. link1

[ 2 ] Collet C. RMV’s subsidiary fahma orders the world’s largest fleet of fuel cell trains from Alstom [Internet]. Saint-Ouen: Alstom; 2019 May 21 [cited 2022 Jan 12]. Available from: https://www.alstom.com/press-releases-news/2019/ 5/rmvs-subsidiary-fahma-orders-worlds-largest-fleet-fuel-cell-trains. link1

[ 3 ] Collet C. First order of hydrogen trains in France—a historic step towards sustainable mobility [Internet]. Saint-Ouen: Alstom; 2019 Apr 8 [cited 2022 Jan 12]. Available from: https://www.alstom.com/press-releases-news/2021/ 4/first-order-hydrogen-trains-france-historic-step-towards-sustainable. link1

[ 4 ] Miller S. Alstom to supply Italy’s first hydrogen trains [Internet]. Saint-Ouen: Alstom; 2020 Nov 26 [cited 2022 Jan 12]. Available from: https://www.alstom. com/press-releases-news/2020/11/alstom-supply-italys-first-hydrogen-trains.

[ 5 ] Lewis M. EGEB: world’s first hydrogen fuel cell train is approved in Austria [Internet]. Fremont: Electrek; 2020 Dec 1 [cited 2022 Jan 12]. Available from: https://electrek.co/2020/12/01/egeb-alstom-hydrogen-fuel-cell-train-austriagiving-tuesday/. link1

[ 6 ] Sapien JC. Alstom and Eversholt Rail sign hydrogen train fleet agreement [Internet]. Exeter: Railway News; 2021 Nov 10 [cited 2022 Jan 12]. Available from: https://railway-news.com/alstom-and-eversholt-rail-sign-hydrogentrain-fleet-agreement/. link1

[ 7 ] Smith R. Alstom and MOL of Hungary agree joint research into use of hydrogen for rail transport [Internet]. Leyland: Rail Advent; 2021 Dec 11 [cited 2022 Jan 12]. Available from: https://www.railadvent.co.uk/2021/12/alstom-and-molof-hungary-agree-joint-research-into-use-of-hydrogen-for-rail-transport.html. link1

[ 8 ] Palmer C. Hydrogen power focus shifts from cars to heavy vehicles. Engineering 2020;6(12):1333–5. link1

[ 9 ] Schmidt N. This hydrogen-powered train emits only water [Internet]. Atlanta: CNN; 2017 Apr 12 [cited 2022 Jan 20]. Available from: https://money.cnn.com/ 2017/04/12/technology/germany-hydrogen-powered-train/index.html. link1

[10] Blenkinsop P. EU reaches provisional deal on 55% greenhouse gas cut by 2030 [Internet]. London: Reuters; 2021 Apr 20 [cited 2022 Jan 12]. Available from: https://www.reuters.com/business/environment/eu-reaches-provisionaldeal-55-greenhouse-gas-cut-by-2030-2021-04-21/. link1

[11] Briginshaw D. SNCF aims for zero emissions by 2035 [Internet]. New York City: International Railway Journal; 2019 Jun 26 [cited 2022 Jan 12]. Available from: https://www.railjournal.com/news/sncf-aims-for-zero-emissions-by-2035/. link1

[12] Lewis M. Scotland will decarbonize passenger rail services by 2035 [Internet]. Fremont: Electrek; 2020 Aug 3 [cited 2022 Jan 12]. Available from: https://electrek.co/2020/08/03/scotland-decarbonize-passenger-rail-services2035/. link1

[13] Geerts E. Hydrogen trains will replace diesel units in Groningen [Internet]. Rotterdam: Railtech; 2020 Jan 10 [cited 2022 Jan 12]. Available from: https:// www.railtech.com/rolling-stock/2020/10/01/hydrogen-trains-will-replacediesel-units-in-groningen/. link1

[14] Zasiadko M. Deutsche Bahn to become carbon neutral by 2050 [Internet]. Rotterdam: Railtech; 2020 Jan 10 [cited 2022 Jan 12]. Available from: https:// www.railtech.com/policy/2020/09/07/deutsche-bahn-to-become-carbonneutral-by-2050. link1

[15] Steffen AD. Britain’s strategy to decarbonize 15 140 km of train lines [Internet]. Bristol: Intelligent Living; 2020 Sep 10 [cited 2022 Jan 12]. Available from: https://www.intelligentliving.co/britains-decarbonize-train-lines/. link1

[16] Rapier R. Estimating the carbon footprint of hydrogen production [Internet]. Jersey City: Forbes; 2020 Jun 6 [cited 2022 Jan 20]. Available from: https:// www.forbes.com/sites/rrapier/2020/06/06/estimating-the-carbon-footprintof-hydrogen-production/?sh=11b81a6024bd. link1

[17] Hydrogen economy outlook [Internet]. New York City: Bloomberg NEF; 2020 Mar 30 [cited 2022 Jan 12]. Available from: https://data.bloomberglp.com/ professional/sites/24/BNEF-Hydrogen-Economy-Outlook-Key-Messages-30- Mar-2020.pdf. link1

[18] ‘Green’ hydrogen to outcompete ‘Blue’ everywhere by 2030 [Internet]. New York City: Bloomberg NEF; 2021 May 5 [cited 2022 Jan 12]. Available from: https://about.bnef.com/blog/green-hydrogen-to-outcompete-blueeverywhere-by-2030/. link1

[19] Molitor P. Alstom and hynamics (EDF) sign a partnership agreement to optimise the fueling of hydrogen trains [Internet]. Saint-Ouen: Alstom; 2020 Sep 10 [cited 2022 Jan 12]. Available from: https://www.alstom.com/ press-releases-news/2021/11/alstom-and-hynamics-edf-sign-partnershipagreement-optimise-fuelling. link1

[20] Geerts E. Hydrogen trains: DB develops rapid refueling [Internet]. Rotterdam: Railtech; 2021 Aug 7 [cited 2022 Jan 12]. Available from: https://www. railtech.com/rolling-stock/2021/07/08/hydrogen-trains-db-develops-rapidrefueling/. link1

[21] EU selects CAF-led hydrogen train development project for €10m grant [Internet]. London: Railway Technology; 2020 Nov 5 [cited 2022 Jan 12]. Available from: https://www.railway-technology.com/news/eu-grant-caf-ledhydrogen-train-development-project/. link1

[22] Revill J. Siemens on track for long-range hydrogen-powered trains [Internet]. London: Reuters; 2021 Dec 2 [cited 2022 Jan 12]. Available from: https://www.reuters.com/markets/commodities/siemens-track-long-rangehydrogen-powered-trains-2021-12-02/. link1

[23] McKelvie R. All aboard Hydroflex, the UK’s first hydrogen-powered passenger train [Internet]. London: Independent; 2021 Nov 12 [cited 2022 Jan 12]. Available from: https://www.independent.co.uk/travel/news-and-advice/ hydroflex-hydrogen-train-green-rail-b1956618.html. link1

[24] Stadler to deliver hydrogen-powered train to SBCTA [Internet]. London: Railway Technology; 2019 Nov 15 [cited 2022 Jan 12]. Available from: https://www.railway-technology.com/news/stadler-deliver-hydrogenpowered-train-sbcta/. link1

[25] China’s first hydrogen fuel cell hybrid locomotive starts trial run [Internet]. Beijing: China Daily; 2021 Oct 29 [cited 2022 Jan 12]. Available from: https:// www.greencarcongress.com/2021/11/20211102-chinah2loco.html. link1

[26] JR East, Hitachi, and Toyota to develop hydrogen-powered railway vehicles [Internet]. London: Railway Technology; 2020 Oct 7 [cited 2022 Jan 12]. Available from: https://www.railway-technology.com/news/jr-east-toyotarailway-vehicles/. link1

[27] Waterson L. Green trains on their way to power one of the world’s most abundant mining regions [Internet]. Sydney: Australian Broadcasting Corporation; 2021 Dec 28 [cited 2022 Jan 12]. Available from: https://www. abc.net.au/news/2021-12-29/hydrogen-powered-freight-trains-north-westminerals-province/100728682. link1

[28] Spurr B. After four years and $7 million, Metrolinx quietly drops proposal for hydrogen-powered GO trains [Internet]. Toronto: Toronto Star; 2021 Mar 1 [cited 2022 Jan 12]. Available from: https://www.thestar.com/news/gta/2021/ 03/01/after-four-years-and-7-million-metrolinx-quietly-drops-proposal-forhydrogen-powered-go-trains.html. link1

[29] Smith K. CRRC Tangshan trials new hydrogen-fueled tram [Internet]. New York City: International Railway Journal; 2017 Oct 31 [cited 2022 Jan 12]. Available from: https://www.railjournal.com/passenger/light-rail/crrc-tangshan-trialsnew-hydrogen-fuelled-tram/. link1

[30] Smith K. Chinese demand drives fuel-cell adoption [Internet]. New York City: International Railway Journal; 2018 Jan 15 [cited 2022 Jan 12]. Available from: https://www.railjournal.com/in_depth/chinese-demand-drives-fuelcell-adoption/. link1

[31] Stephens B. Canadian Pacific’s hydrogen fuel cell locomotive to debut before year’s end [Internet]. Waukesha: Trains; 2021 Nov 30 [cited 2022 Jan 12]. Available from: https://www.trains.com/trn/news-reviews/newswire/canadian-pacifics-hydrogen-fuel-cell-locomotive-to-debut-before-yearsend. link1

[32] Heynes G. Ballard to provide fuel cell modules for hydrogen-powered train in Germany [Internet]. Truro: H2 View; 2021 Jul 15 [cited 2022 Jan 12]. Available from: https://www.h2-view.com/story/ballard-to-provide-fuel-cell-modulesfor-hydrogen-powered-train-in-germany/.

[33] Charlton K. Ballard to power Talgo fuel cell passenger train in European trial, ahead of planned 2023 launch [Internet]. Truro: Yahoo Finance; 2021 Oct 12 [cited 2022 Jan 12]. Available from: https://finance.yahoo.com/news/ballardpower-talgo-fuel-cell-123000991.html. link1

[34] Krastev I, Tricoli P. Boost multilevel cascade inverter for hydrogen fuel cell light railway vehicles. IEEE Trans Ind Electron 2021;69(8):7837–47. link1

[35] Wang Z, Luo Y, Hisatomi T, Vequizo JJM, Suzuki S, Chen S, et al. Sequential cocatalyst decoration on BaTaO2N towards highly-active Z-scheme water splitting. Nat Commun 2021;12(1):1005. link1

[36] Bauer S. On-site hydrogen production technology accelerates to market [Internet]. Richland: PNNL; 2021 May 26 [cited 2022 Jan 12]. Available from: https://www.pnnl.gov/news-media/site-hydrogen-productiontechnology-accelerates-market. link1