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Hydrogen in transport: everything you need to know in 10 questions

Aurélien Bigo
Aurélien Bigo
Research Associate of the Energy and Prosperity Chair at Institut Louis Bachelier
Key takeaways
  • Hydrogen is an energy vector generally produced from fossil fuels, which emit a lot of CO2 – reducing its carbon footprint is a major challenge.
  • It will account for only 0.003% of transport energy consumption worldwide in 2021.
  • Hydrogen is particularly valuable when used in conjunction with electricity, which is currently the preferred source of carbon reduction.
  • If hydrogen-powered bicycles or cars are energy inefficient, hydrogen could prove useful, especially for heavier vehicles (buses, trucks, etc.).
  • The potential of hydrogen must be studied with caution in view of the challenges that remain.

#1 What is hydrogen? Is it an energy source?

Hydro­gen is both the small­est and most abun­dant atom in the uni­verse. It is notably present in water (H2O) and often asso­ci­at­ed with car­bon in organ­ic mol­e­cules, and thus con­sti­tutes 92% of the atoms in the uni­verse and 63% of the atoms in our bod­ies (and respec­tive­ly 75% and 10% by mass)1.

But when we talk about hydro­gen in the ener­gy tran­si­tion, we are gen­er­al­ly talk­ing about the dihy­dro­gen (H2) mol­e­cule. With the excep­tion of a few lit­tle-known and lit­tle-exploit­ed native hydro­gen deposits, hydro­gen is not a source of ener­gy that can be found direct­ly in nature. It must there­fore be pro­duced from oth­er ener­gy sources and, as such, is referred to as an ener­gy car­ri­er (like elec­tric­i­ty). Hence, the ques­tion is whether or not this method of pro­duc­tion gen­er­ates sig­nif­i­cant CO2 emissions.

#2 How is hydrogen produced? Is it low-carbon?

There are sev­er­al meth­ods of pro­duc­ing hydro­gen. To date, hydro­gen is main­ly pro­duced from fos­sil fuels, mak­ing the pro­duc­tion process gen­er­ates a large amount of CO2. This is the case for 99.3% of the world’s hydro­gen pro­duc­tion, main­ly via the steam ref­or­ma­tion of methane from fos­sil gas (62% of pro­duc­tion), fol­lowed by coal gasi­fi­ca­tion or co-prod­ucts of oil refin­ing (19% and 18% respec­tive­ly). Low-car­bon pro­duc­tion is pos­si­ble via two main tech­niques, which rep­re­sent only a very small frac­tion of cur­rent pro­duc­tion. Fos­sil fuel-based pro­duc­tion, which is asso­ci­at­ed with car­bon cap­ture and stor­age, accounts for 0.7%, and water elec­trol­y­sis, which is expect­ed to increase sig­nif­i­cant­ly in the light of recent announce­ments, will account for only 0.04% by 20212.

Source: RTE (2022)3

In France, 95% of hydro­gen is pro­duced using fos­sil fuels. The remain­ing 5% comes from the elec­trol­y­sis of brine, main­ly for the pro­duc­tion of chlo­rine4. The 2018 French hydro­gen plan’s choice to decar­bonise pro­duc­tion focus­es on water elec­trol­y­sis, with the aim of account­ing for just over half of hydro­gen pro­duc­tion in 20305.

#3 What are the uses of hydrogen?

Hydro­gen can be used for two pur­pos­es: either as a reagent to pro­duce some­thing else, or as an ener­gy car­ri­er. Today, hydro­gen is main­ly used in indus­try as a reagent, both glob­al­ly and in France. In France, hydro­gen is used in par­tic­u­lar for fuel refin­ing (60%), to pro­duce ammo­nia main­ly for agri­cul­tur­al fer­tilis­ers (25%), and in chem­istry (10%)6.

Sev­er­al chal­lenges and uses of hydro­gen are envis­aged in the future for the ener­gy tran­si­tion, to be con­sid­ered in terms of order of mer­it7. First and fore­most, it is a ques­tion of reduc­ing car­bon emis­sions from the cur­rent uses of hydro­gen in indus­try. It may also be a ques­tion of replac­ing oth­er uses by low-car­bon hydro­gen, whether for the reduc­tion of car­bon emis­sions in indus­try or trans­port, or to par­tic­i­pate in the reduc­tion of car­bon emis­sions from cur­rent gas net­works. Final­ly, hydro­gen could con­tribute to the stor­age of elec­tric­i­ty, by offer­ing a flex­i­ble solu­tion to ensure the bal­ance of the elec­tric­i­ty network.

#4 Hydrogen and transport: where do we stand? What is the rollout timeframe?

Hydro­gen in trans­port is still in its infan­cy. Despite the 60% increase in con­sump­tion com­pared to 2020, hydro­gen will rep­re­sent only 0.003% of trans­port ener­gy con­sump­tion world­wide in 2021.

Hydro­gen is cur­rent­ly most wide­ly used in road vehi­cles, although at a very low lev­el. At the end of 2021 in France, there were only a few hun­dred hydro­gen-pow­ered cars (and about 1,000 few­er of them have been sold than elec­tric cars since the begin­ning of 20228), 2 heavy goods vehi­cles, 4 spe­cialised self-pro­pelled vehi­cles (SSVs: e.g. refuse col­lec­tion vehi­cles), and 22 bus­es (i.e. less than 0.1% of the fleet9). 

For rea­sons of ener­gy effi­cien­cy and car­bon foot­print, elec­tric is to be favoured where possible.

How­ev­er, heavy mobil­i­ty is the sec­ond focus of the 2018 French hydro­gen plan and the 2020 nation­al strat­e­gy for the devel­op­ment of low-car­bon hydro­gen10. The objec­tive set in 2018 is to reach 20,000 to 50,000 light com­mer­cial vehi­cles, the equiv­a­lent of 0.7% of the cur­rent vehi­cle fleet, and 800 to 2,000 heavy vehi­cles by the year 2028. The upper lim­its cor­re­spond to the equiv­a­lent of 0.9% of the cur­rent com­mer­cial vehi­cle fleet and 0.3% of the heavy vehi­cle fleet11.

For rail trans­port, hydro­gen-pow­ered trains are already run­ning in Ger­many and the first com­mer­cial runs are planned for 2025 in France12. For ships, exper­i­ments are under­way for low-capac­i­ty ships over lim­it­ed dis­tances. How­ev­er, oth­er decar­bon­i­sa­tion solu­tions are gen­er­al­ly pre­ferred to hydro­gen, par­tic­u­lar­ly for mar­itime trans­port (bio­gas, methanol, ammo­nia, etc.). Final­ly, Air­bus is tar­get­ing 2035 for the mar­ket­ing of a hydro­gen-pow­ered air­craft capa­ble of short and medi­um-haul flights.

#5 Decarbonisation of transport: which technology(ies) should be prioritised?

The with­draw­al of oil from trans­port is essen­tial to achieve the objec­tive of car­bon neu­tral­i­ty in France by 205013. There are four pos­si­ble ener­gy sources for trans­port: elec­tric­i­ty, hydro­gen, gaseous fuels (fos­sil or renew­able gas) and liq­uid fuels (oil or bio­fu­els). Syn­thet­ic fuels can also be pro­duced by com­bin­ing hydro­gen with CO2, a tech­nol­o­gy that is not yet ful­ly developed.

Among these dif­fer­ent tech­nolo­gies, elec­tric­i­ty is the least car­bon-inten­sive, at more than 90% in France, while the oth­er tech­nolo­gies (hydro­gen, gaseous and liq­uid fuels) are more than 90% depen­dent on fos­sil fuels. Fur­ther­more, the poten­tial for the pro­duc­tion of renew­able gas and bio­fu­els is severe­ly lim­it­ed by the avail­able bio­mass resources, which requires first and fore­most a sharp reduc­tion in the con­sump­tion of gas and liq­uid fuels in the econ­o­my in order to reduce their car­bon emissions.

Source: Trans­port & Envi­ron­ment (2020)14

With regard to the elec­tric and hydro­gen tech­nolo­gies, hydro­gen is less ener­gy effi­cient than the direct use of elec­tric­i­ty in an elec­tric vehi­cle with bat­ter­ies. Hydro­gen can be used in a vehi­cle in two ways: either as a fuel in a hydro­gen engine, which is much less effi­cient than elec­tric engines; or by con­vert­ing the hydro­gen back into elec­tric­i­ty via a fuel cell locat­ed in the vehi­cle, and then using this elec­tric­i­ty in an elec­tric engine. In this sec­ond case, and giv­en the ener­gy loss­es of these trans­for­ma­tions, it takes about 2.3 times more elec­tric­i­ty to run a hydro­gen vehi­cle than an elec­tric vehi­cle15.

This low­er effi­cien­cy mul­ti­plies elec­tric­i­ty costs, as well as vehi­cle emis­sions if the elec­tric­i­ty used is not very low car­bon. It also requires larg­er vol­umes of elec­tric­i­ty to reduce the car­bon emis­sions of trans­port. Decar­bon­is­ing all land trans­port (cars, trucks, bus­es, trains, etc.) in Europe via elec­tric vehi­cles would require the equiv­a­lent of 43% of the elec­tric­i­ty pro­duced in 2015, and 108% in the case of hydro­gen vehi­cles. These fig­ures increase fur­ther when con­sid­er­ing ship­ping and avi­a­tion16.

To improve ener­gy effi­cien­cy and reduce car­bon foot­prints, elec­tric­i­ty is there­fore to be pri­ori­tised when­ev­er pos­si­ble, as is the case for light road vehi­cles (two-wheel­ers, cars, or even com­mer­cial vehi­cles). Hydro­gen will find its rel­e­vance as a com­ple­ment to elec­tric pow­er, par­tic­u­lar­ly when there is a need for high charge rates, long ranges and/or very short recharg­ing times. It is more­over through these advan­tages that hydro­gen gives hope or may give the illu­sion that it will be pos­si­ble to main­tain the trans­port behav­iours and uses cur­rent­ly per­mit­ted by oil in the future.

#6 What is the carbon footprint and other environmental impacts of transport?

When hydro­gen is pro­duced by elec­trol­y­sis with renew­able or nuclear elec­tric­i­ty, the life cycle green­house gas emis­sions of a bus sold in 2020 (or a truck sold in 2030) are reduced by 6 times com­pared to diesel. This places hydro­gen tech­nol­o­gy at sim­i­lar emis­sion lev­els to elec­tric bus­es or trucks recharged in France, as well as to vehi­cles using bio­gas. On the oth­er hand, if hydro­gen is pro­duced by elec­trol­y­sis with the aver­age French elec­tric­i­ty mix, the hydro­gen trac­tor unit goes from 6 times less to 3 times less emis­sions than the diesel trac­tor unit; it becomes slight­ly more emis­sive with the aver­age Euro­pean mix and even 60% more emis­sive with the Ger­man elec­tric­i­ty mix17.

Thus, the decar­bon­i­sa­tion of hydro­gen pro­duc­tion is an essen­tial con­di­tion to ensure sig­nif­i­cant cli­mate ben­e­fits from the devel­op­ment of hydro­gen in trans­port. The impact of emis­sions from the elec­tric­i­ty mix is even stronger for emis­sions from hydro­gen vehi­cles than for emis­sions from elec­tric vehi­cles, due to the low­er effi­cien­cy of the hydro­gen chain and thus the high­er quan­ti­ties of elec­tric­i­ty per kilo­me­tre travelled.

MHEV (mild hybrid ther­mal vehi­cle); bioGNC (bio­gas; CNG com­pressed nat­ur­al gas); PHEV (Plug-in Hybrid Vehi­cle); BEV (Bat­tery Elec­tric Vehi­cle); HEV (Hydro­gen Elec­tric Vehi­cle; Fuel Cell). Source: Car­bon 4 (2020)18

From an envi­ron­men­tal point of view, and com­pared to bat­tery-pow­ered elec­tric vehi­cles, the main advan­tage of hydro­gen is the low­er bat­tery capac­i­ty required. This reduces the pres­sure on resources and the pol­lu­tion caused by the exploita­tion of lithi­um, cobalt, or nick­el. The hydro­gen sec­tor also involves the con­sump­tion of met­als, in par­tic­u­lar plat­inum for fuel cells and elec­trol­y­sers, the crit­i­cal­i­ty of which will depend on the lev­el of devel­op­ment of the sec­tor19. Final­ly, the greater need for elec­tric­i­ty for hydro­gen vehi­cles (when pro­duced by elec­trol­y­sis) requires more met­als to pro­duce electricity.

#7 What are the costs of hydrogen?

Hydro­gen tech­nolo­gies are cur­rent­ly more expen­sive than oil or elec­tric­i­ty, both in terms of the cost of vehi­cles and of ener­gy. How­ev­er, the addi­tion­al pur­chase costs vary great­ly depend­ing on the mode of trans­port and the devel­op­ment of the vehi­cle mar­ket. And the addi­tion­al ener­gy costs depend heav­i­ly on the method of hydro­gen pro­duc­tion, with pro­duc­tion via elec­trol­y­sis being about twice as expen­sive today as steam reform­ing of fos­sil gas. Trans­port and dis­tri­b­u­tion costs are also sig­nif­i­cant, espe­cial­ly if there are sig­nif­i­cant dis­tances between the pro­duc­tion and con­sump­tion sites.

In total, the Depart­ment of Trans­porta­tion esti­mat­ed in 2018 that the total cost of own­er­ship is around 20–50% high­er for a hydro­gen vehi­cle than for the com­bus­tion equiv­a­lent. With hydro­gen from elec­trol­y­sis, the total cost of own­er­ship for trucks, bus­es and coach­es is 1.5 to 3 times high­er for hydro­gen than for diesel20. How­ev­er, costs are pro­ject­ed to fall by around half by 2030 for pro­duc­tion via elec­trol­y­sis, which will also affect cur­rent bal­ances21.

How­ev­er, cost pro­jec­tions between tech­nolo­gies and ener­gies are sub­ject to con­sid­er­able uncer­tain­ty. Hydro­gen’s com­pet­i­tive­ness could there­fore vary great­ly depend­ing on the evo­lu­tion of tech­ni­cal, geopo­lit­i­cal, resource or deploy­ment con­straints of the dif­fer­ent ener­gies. Final­ly, it will depend on the pos­si­ble sup­port or tax­a­tion lev­els of the ener­gies or tech­nolo­gies by the pub­lic authorities.

#8 What are the technical and organisational challenges for the future? 

The tech­ni­cal chal­lenges faced by the hydro­gen sec­tor remain con­sid­er­able if it is to be devel­oped for use in the trans­port sec­tor. As this gas is par­tic­u­lar­ly small, light, and flam­ma­ble, the risks of leaks or acci­dents must be con­trolled to ensure the safe­ty of vehi­cles, stor­age or trans­port of hydro­gen. Stor­age in vehi­cles also requires the com­pres­sion of hydro­gen, an ener­gy-inten­sive process, and the use of tanks that make vehi­cles very heavy.

Hydro­gen tech­nolo­gies are cur­rent­ly more expen­sive than oil or elec­tric­i­ty, both in terms of vehi­cle and ener­gy costs.

Also, the low vol­u­met­ric ener­gy den­si­ty (quan­ti­ty of ener­gy con­tained in a giv­en vol­ume) of hydro­gen requires that the pro­duc­tion of hydro­gen should take place as close as pos­si­ble to the place of con­sump­tion, in order to lim­it the ener­gy and finan­cial costs of its trans­porta­tion. This calls for con­sid­er­a­tion to be giv­en to the organ­i­sa­tion of ecosys­tems enabling pro­duc­tion and use to be shared between sev­er­al modes or eco­nom­ic sec­tors in the same place. To ensure the over­all coher­ence of these region­al plans, it will also be nec­es­sary to ensure a pro­gres­sive net­work of hydro­gen pro­duc­tion and dis­tri­b­u­tion infra­struc­tures for the heavy road modes.

Final­ly, the tech­ni­cal chal­lenges vary accord­ing to the mode of trans­port or the vehi­cle, which also deter­mines the time­frame for the dif­fu­sion of hydro­gen. For exam­ple, for air trans­port, the low vol­ume den­si­ty poten­tial­ly requires a review of the shape of the air­craft or at least the shape, weight and size of the tanks, which is one of the major tech­ni­cal chal­lenges in the devel­op­ment of a hydro­gen pow­ered aircraft.

#9 What is the future for different modes of transport? 

For road trans­port, hydro­gen will not be rel­e­vant for the light­est vehi­cles, which are bet­ter suit­ed to bat­tery-pow­ered elec­tric vehi­cles. Hydro­gen-pow­ered bicy­cles or cars, which are ener­gy inef­fi­cient and much more expen­sive finan­cial­ly, should there­fore be for­got­ten as mass-mar­ket solu­tions, apart from a few niche uses. On the oth­er hand, hydro­gen could be more use­ful for the heav­i­est modes (heavy goods vehi­cles, bus­es, and coach­es, etc.) and when the dis­tances are too long for bat­tery pow­ered elec­tric vehicles.

As far as rail is con­cerned, hydro­gen trains could be a good alter­na­tive to diesel and when traf­fic is too low to jus­ti­fy the elec­tri­fi­ca­tion of the line22. For ships, hydro­gen will be too dif­fi­cult to use to reduce the car­bon foot­print of long-dis­tance mar­itime trans­port, which could, how­ev­er, turn to hydro­gen deriv­a­tives such as ammo­nia, methanol or elec­tro­fu­els. On the oth­er hand, hydro­gen could be adapt­ed for riv­er trans­port, which cor­re­sponds to small­er vol­umes and distances.

Final­ly, when it comes to air trans­port, the tech­no­log­i­cal gam­ble has already been set in motion and is jus­ti­fied by the lim­its of the oth­er alter­na­tives to oil, in par­tic­u­lar the com­pe­ti­tion for the use of bio­mass for bio­fu­els, as well as the fact that the devel­op­ment of syn­thet­ic fuels and hydro­gen deriv­a­tives is still in its ear­ly stages. On the oth­er hand, this gam­ble is still sub­ject to con­sid­er­able uncer­tain­ty. There­fore, by 2050, hydro­gen will only be able to rep­re­sent a small part of the sec­tor’s con­sump­tion, up to a max­i­mum of 7% of flights depart­ing from and arriv­ing in France, accord­ing to ADE­ME’s three sce­nar­ios for the eco­log­i­cal tran­si­tion of the avi­a­tion sector. 

Elec­tro­fu­els, deriv­a­tives of hydro­gen, rep­re­sent a greater poten­tial for the reduc­tion of car­bon emis­sions, up to 38% of the ener­gy mix in 2050. How­ev­er, they only become sig­nif­i­cant in the 2030s, with major scal­ing up chal­lenges and the require­ment to be pro­duced with very low car­bon elec­tric­i­ty to be advan­ta­geous from a cli­mate point of view23.

#10 So what should we learn from this?

Hydro­gen should not be seen as a mir­a­cle solu­tion for reduc­ing the car­bon foot­print of trans­port, because it is not. It is less ener­gy effi­cient, large­ly car­bon-based and more expen­sive than elec­tric pow­er today, and the pro­duc­tion of low-car­bon hydro­gen may not be on a grand scale for sev­er­al more years, which lim­its its capac­i­ty to con­tribute to the nec­es­sary reduc­tion in emis­sions from the sec­tor in the short term24.

In France, the hydro­gen plan fore­sees a reduc­tion in emis­sions of around 6 MtCO2 by 203025, i.e. a reduc­tion equiv­a­lent to 1.4% of cur­rent nation­al emis­sions (418 MtCO2e in 202126). While the poten­tial is far from neg­li­gi­ble, it remains lim­it­ed, giv­en that the Euro­pean objec­tive is now to reduce emis­sions by 55% by 2030 com­pared to 199027.

Hydro­gen should not be seen as a mir­a­cle solu­tion for reduc­ing the car­bon foot­print of trans­port, because it is not. 

How­ev­er, the poten­tial of low-car­bon hydro­gen should not be total­ly dis­count­ed, espe­cial­ly for indus­try or as a com­ple­men­tary solu­tion for trans­port in the longer term – which requires invest­ment and a boost to the sec­tor today28. A cer­tain amount of pub­lic sup­port for the devel­op­ment of the sec­tor is there­fore nec­es­sary, but with three caveats:

  • The pos­si­bil­i­ties must be care­ful­ly exam­ined and devel­oped with­out haste, in view of the many chal­lenges (tech­ni­cal, eco­nom­ic, low-car­bon pro­duc­tion, etc.) that remain for the sec­tor. With­out this nec­es­sary vig­i­lance, there would be a great risk of rush­ing to devel­op uses that would remain car­bon-based in the future
  • The devel­op­ment of hydro­gen in trans­port must above all be devel­oped prag­mat­i­cal­ly, rather than on the basis of false beliefs and tech­no­log­i­cal illu­sions, which is still too often the case.
  • Above all, as with oth­er decar­bon­a­tion tech­nolo­gies, hydro­gen must not be used as a pre­text to hide the urgency of ener­gy sobri­ety in trans­port in order to rapid­ly reduce its emis­sions… an argu­ment abun­dant­ly used for exam­ple by the air­line sec­tor with the hydro­gen plane, in order to dis­tract from the nec­es­sary mod­er­a­tion of its traffic.

With­out these pre­cau­tions, hydro­gen could do more harm than good to the ener­gy tran­si­tion in transport…

1Rodolphe Mey­er, Le Réveilleur, 2020. Hydrogène: com­ment le pro­duire ? https://www.youtube.com/watch?v=_sqYx8K_m9c&ab_channel=LeRéveilleur
2IEA, 2022. Glob­al Hydro­gen Review 2022. https://​www​.iea​.org/​r​e​p​o​r​t​s​/​g​l​o​b​a​l​-​h​y​d​r​o​g​e​n​-​r​e​v​i​e​w​-2022
4RTE, 2020. La tran­si­tion vers un hydrogène bas car­bone. Atouts et enjeux pour le sys­tème élec­trique à l’horizon 2030–2035. https://assets.rte-france.com/prod/public/2020–07/rapport%20hydrogene.pdf
5France Hydrogène, site Vig’Hy, Key fig­ures. https://​vighy​.france​-hydro​gene​.org/​c​h​i​f​f​r​e​s​-​cles/
6MTES, 2018. Plan de déploiement de l’hy­drogène pour la tran­si­tion énergé­tique. https://​www​.ecolo​gie​.gouv​.fr/​s​i​t​e​s​/​d​e​f​a​u​l​t​/​f​i​l​e​s​/​P​l​a​n​_​d​e​p​l​o​i​e​m​e​n​t​_​h​y​d​r​o​g​e​n​e.pdf
7Ueck­erdt, et al, 2021. Poten­tial and risks of hydro­gen-based e‑fuels in cli­mate change mit­i­ga­tion. Nature Cli­mate Change. https://dx.doi.org/10.1038/s41558-021–01032‑7
8CCFA, press kit Octo­ber 2022. https://​ccfa​.fr/​d​o​s​s​i​e​r​s​-​d​e​-​p​r​esse/
9CGDD, 2021, Annu­al Trans­port Review. https://​www​.sta​tis​tiques​.devel​oppe​ment​-durable​.gouv​.fr/​b​i​l​a​n​-​a​n​n​u​e​l​-​d​e​s​-​t​r​a​n​s​p​o​r​t​s​-​e​n​-2020
10Min­istère de l’Économie, 9 Sep­tem­ber 2020. https://​www​.economie​.gouv​.fr/​p​r​e​s​e​n​t​a​t​i​o​n​-​s​t​r​a​t​e​g​i​e​-​n​a​t​i​o​n​a​l​e​-​d​e​v​e​l​o​p​p​e​m​e​n​t​-​h​y​d​r​o​g​e​n​e​-​d​e​c​a​r​b​o​n​e​-​f​rance
11Parc de véhicules provenant du CGDD, bilans annuels des trans­ports : https://​www​.sta​tis​tiques​.devel​oppe​ment​-durable​.gouv​.fr/​b​i​l​a​n​-​a​n​n​u​e​l​-​d​e​s​-​t​r​a​n​s​p​o​r​t​s​-​e​n​-2020
12SNCF, 2022. Trains hydrogène : pre­mière com­mande lancée. https://​www​.sncf​.com/​f​r​/​e​n​g​a​g​e​m​e​n​t​s​/​e​n​j​e​u​x​-​r​s​e​/​s​n​c​f​-​a​c​c​e​l​e​r​e​-​t​r​a​i​n​-​a​-​h​y​d​r​ogene
13Min­istère de la tran­si­tion écologique, Stratégie nationale bas-car­bone (SNBC). https://​www​.ecolo​gie​.gouv​.fr/​s​t​r​a​t​e​g​i​e​-​n​a​t​i​o​n​a​l​e​-​b​a​s​-​c​a​r​b​o​n​e​-snbc
15This order of mag­ni­tude is valid for hydro­gen pro­duced from water elec­trol­y­sis and used in a fuel cell. The over­all effi­cien­cy is esti­mat­ed at 77% in 2020 for direct elec­tri­fi­ca­tion and 33% for the hydro­gen chain, a ratio of 2.33. By 2050, these fig­ures increase to 81% and 42% respec­tive­ly, and the ratio reduces to 1.93. T&E, 2020.https://​www​.trans​porten​vi​ron​ment​.org/​w​p​-​c​o​n​t​e​n​t​/​u​p​l​o​a​d​s​/​2​0​2​0​/​1​2​/​2​0​2​0​_​1​2​_​B​r​i​e​f​i​n​g​_​f​e​a​s​i​b​i​l​i​t​y​_​s​t​u​d​y​_​r​e​n​e​w​a​b​l​e​s​_​d​e​c​a​r​b​o​n​i​s​a​t​i​o​n.pdf.A sim­i­lar order of mag­ni­tude can be found in the ADEME study, 2020. Life cycle assess­ment of hydro­gen. https://​librairie​.ademe​.fr/​c​h​a​n​g​e​m​e​n​t​-​c​l​i​m​a​t​i​q​u​e​-​e​t​-​e​n​e​r​g​i​e​/​4​2​1​3​-​a​n​a​l​y​s​e​-​d​e​-​c​y​c​l​e​-​d​e​-​v​i​e​-​r​e​l​a​t​i​v​e​-​a​-​l​-​h​y​d​r​o​g​e​n​e​.html
16In this study, the effi­cien­cy ratio between elec­tric and hydro­gen was 2.5. T&E, 2018. How to decar­bonise Euro­pean trans­port by 2050. https://​www​.trans​porten​vi​ron​ment​.org/​p​u​b​l​i​c​a​t​i​o​n​s​/​h​o​w​-​d​e​c​a​r​b​o​n​i​s​e​-​e​u​r​o​p​e​a​n​-​t​r​a​n​s​p​o​r​t​-2050
17Car­bone 4, 2020. Trans­port routi­er : quelles motori­sa­tions alter­na­tives pour le cli­mat ? http://​www​.car​bone4​.com/​p​u​b​l​i​c​a​t​i​o​n​-​t​r​a​n​s​p​o​r​t​-​r​o​u​t​i​e​r​-​m​o​t​o​r​i​s​a​t​i​o​n​-​a​l​t​e​r​n​a​t​ives/ ; ADEME, 2022. « TRANPLHYN » Trans­ports lourds fonc­tion­nant à l’hy­drogène. https://librairie.ademe.fr/mobilite-et-transport/5722–tranplhyn-transports-lourds-fonctionnant-a-l-hydrogene.html
19IEA, 2021. The Role of Crit­i­cal Min­er­als in Clean Ener­gy Tran­si­tions. https://​www​.iea​.org/​r​e​p​o​r​t​s​/​t​h​e​-​r​o​l​e​-​o​f​-​c​r​i​t​i​c​a​l​-​m​i​n​e​r​a​l​s​-​i​n​-​c​l​e​a​n​-​e​n​e​r​g​y​-​t​r​a​n​s​i​tions
20ADEME, 2022, ibid.
21MTES, 2018, ibid.
22ADEME, 2021. Etude sur les per­spec­tives du train hydrogène en France. https://​librairie​.ademe​.fr/​m​o​b​i​l​i​t​e​-​e​t​-​t​r​a​n​s​p​o​r​t​/​4​1​7​1​-​e​t​u​d​e​-​s​u​r​-​l​e​s​-​p​e​r​s​p​e​c​t​i​v​e​s​-​d​u​-​t​r​a​i​n​-​h​y​d​r​o​g​e​n​e​-​e​n​-​f​r​a​n​c​e​.html https://​www​.con​nais​sancedesen​er​gies​.org/​c​l​a​s​s​e​m​e​n​t​/​e​l​e​c​t​r​i​c​i​t​e​-​e​t​-​h​y​d​r​o​g​e​n​e​#​f​i​c​h​e​_​p​e​d​a​g​o​gique
231%, 4% and 7% share of hydro­gen in air trans­port ener­gy mix in 2050, in ADEME, 2022. Élab­o­ra­tion de scé­nar­ios de tran­si­tion écologique du secteur aérien. https://​librairie​.ademe​.fr/​m​o​b​i​l​i​t​e​-​e​t​-​t​r​a​n​s​p​o​r​t​/​5​8​1​5​-​e​l​a​b​o​r​a​t​i​o​n​-​d​e​-​s​c​e​n​a​r​i​o​s​-​d​e​-​t​r​a​n​s​i​t​i​o​n​-​e​c​o​l​o​g​i​q​u​e​-​d​u​-​s​e​c​t​e​u​r​-​a​e​r​i​e​n​.html
24Car­bone 4, 2022. Hydrogène bas-car­bone : quels usages per­ti­nents à moyen terme dans un monde décar­boné ? https://​www​.car​bone4​.com/​p​u​b​l​i​c​a​t​i​o​n​-​h​y​d​r​o​g​e​n​e​-​b​a​s​-​c​a​rbone
25France Hydrogène, ibid.
26Chiffres Citepa 2022. https://​www​.citepa​.org/​f​r​/​s​e​cten/
27Accord­ing to the High Coun­cil for the Cli­mate, France should raise its gross emis­sions reduc­tion tar­get to ‑50% between 1990 and 2030 in order to meet the Euro­pean objec­tive. This cor­re­sponds to a 35% reduc­tion com­pared to 2021 emis­sions. HCC, 2022. Annu­al report. https://​www​.haut​con​seil​cli​mat​.fr/​p​u​b​l​i​c​a​t​i​o​n​s​/​r​a​p​p​o​r​t​-​a​n​n​u​e​l​-​2​0​2​2​-​d​e​p​a​s​s​e​r​-​l​e​s​-​c​o​n​s​t​a​t​s​-​m​e​t​t​r​e​-​e​n​-​o​e​u​v​r​e​-​l​e​s​-​s​o​l​u​t​ions/
28I4CE, 2020. Hydrogène : la France a encore de nom­breux défis à relever. Bil­let d’analyse, Jean-Pierre Pon­ssard et Guy Meu­nier. https://​www​.i4ce​.org/​h​y​d​r​o​g​e​n​e​-​e​n​-​f​r​a​n​c​e​-​c​l​imat/

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