“Clean hydrogen” is now seeing a revival in interest by policymakers worldwide, branded as “a source of next-generation clean energy” and “the missing link to the energy transition” . The 2020 Tokyo Olympics and Paralympics, postponed due to COVID-19 emergency, would have shown “a hydrogen society as its legacy” and demonstrated its technological feasibility.
Global energy forecast reports and hydrogen regional studies are prospecting in the near future where to cost-effectively produce “clean hydrogen”, in order to satisfy a potential demand vastly bigger than nowadays. These same reports point out significant investments required in hydrogen production facilities and dedicated infrastructure linking together regional markets. For example, the Hydrogen Europe “2×40 GW Green Hydrogen” roadmap envisages a transnational hydrogen “backbone” infrastructure for “clean hydrogen” from renewables electrolysis, extending over EU, Ukraine and North Africa by 2030. Additionally, a joint statement of cooperation between the Australian and Japanese governments confirmed in March 2020 “the efforts towards the world’s first international liquid hydrogen supply chain”, sourced from both renewables’ electrolysis and fossil-fuels combined with CCUS.
Compared to liquid fossil-fuel molecules like gasoline and diesel, hydrogen molecules (H2) contain almost 1.6 times more energy at parity of mass. Although the same cannot be said at parity of volume. Hydrogen molecules exist in gaseous form at room temperature and atmospheric pressure. But their volatility is such that in the Earth’s atmosphere only a rather small amount can be found (less than one part per million, in terms of chemical concentration). Therefore, this molecule must be derived from another fuel through chemical conversion processes. Deriving artificially “clean” hydrogen from water for energy purposes was already part of the public’s imaginary in 1874, as mentioned by Jules Vernes in his work. After more than 145 years, where do we stand?
The International Energy Agency (IEA) estimated that in 2018 around 115 Mt of hydrogen molecules were requested worldwide (corresponding to 1.37*1012 m3 or 1370 bcm of gas, compared to the world natural gas production of 3937 bcm in 2018). Most of this request came from “non-energy” applications which need this molecule as a feedstock to enable chemical processes, rather than for its fuel calorific value. These applications include:
1) processes for impurities removal from crude oil in refinery stations (38 Mt),
2) chemical plants producing ammonia, methanol and other molecules (46 Mt),
3) steel production through the DRI technological route (4 Mt) and
4) others (27 Mt). IEA has mapped the current geographical distribution of some of the large industrial plants demanding hydrogen: refineries stations, chemical cracker plants (specifically, for production of ethylene and propylene) and steel plants. In particular, some regional coastal clusters were identified in USA, Netherlands, Brazil and other countries.
In order to satisfy this demand, hydrogen production was done at a regional level and without relying on hydrogen imports from other regional markets fact, the majority (of hydrogen) is either produced and consumed on-site (around 85%) or transported via trucks or pipelines (around 15%). However, this entails in dependence on the regional availability of cheap fuels or of the respective transport infrastructure. In order to derive around 95% of these 115 Mt, natural gas and coal were sourced. Instead, the other 5% was generated through electrolysis from water and electricity. Only less than 0.7% of those 115 Mt could be considered “clean hydrogen”, sourced either from renewables electrolysis (“green hydrogen”) or from natural gas processes coupled with CCUS (“blue hydrogen”) [10]. This resulted in the emission of around 0.83 Gt CO2, 2.5% of global CO2 emissions in 2018.
We identify two technologies for hydrogen interregional long-distance transport. Some varieties of each are already currently deployed, either transporting hydrogen in pure form or in a gas mix or stored in molecules more easily transportable [11]. These two technologies, respectively at the core of the examples of “2×40 GW Green Hydrogen” and joint Australian-Japanese statement of cooperation, are:
1) pipelines and
2) shipping.
Pipelines can consist in re-used natural gas pipelines with due upgrades based on the level of hydrogen blending , or in “new” dedicated hydrogen pipelines. According to IEA , there are circa 3 million kilometres of natural gas transmission pipelines around the world and 37 demonstration projects looking into hydrogen blending in gas gridsInstead, there are close to 5000 km of hydrogen pipelines worldwide (2600 km in USA, 600 km in Belgium, …). Shipping hydrogen in pure form is not done yet The world’s first liquid hydrogen ship debuted in Japan in December 2019 with a storage capacity of 1250 m3 (88.5 t of H2) but is yet to be completed. A first proof-of-concept shipping of green hydrogen, stored into Liquid Organic Hydrogen Carrier molecules, occurred from Japan to Australia in March 2019. Please note that there is already a routine sea trade of ammonia equivalent to around 3 MtH2/year.
