The transport and power sectors will consume almost half of the 614 million tonnes (Mt) of hydrogen that would be produced annually in 2050 in a 1.5°C scenario, according to the International Renewable Energy Agency (Irena).

Hydrogen use in both industries is currently negligible — not to mention controversial — with Irena putting their 2020 consumption at zero.

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Green hydrogen — which Irena says will make up two thirds of the H2 consumed by mid-century — is produced from electricity in the first place. When converting renewable energy to hydrogen (via an electrolyser) and back again (via a fuel cell or turbine), 60-75% of the original power is lost in the process — meaning that up to four times as much green power is required than if it were used directly.

The notion of using hydrogen for road transport is also debateable. Many commentators argue that batteries offer a cheaper and more energy-efficient proposition for cars, vans and trucks — vehicles running on green hydrogen would require two to three times more renewable energy than battery-powered ones. But there are question marks over the time that might be required to charge electric trucks, and whether grids would be able to cope with high-volume fast-charging.

Irena itself states that batteries are a better option than hydrogen for cars and regional trucks, but it is on the fence for long-haul trucks.

According to figures provided to Recharge by Irena, the largest demand for hydrogen by mid-century — 201.7Mt, or 32.9% — would come from the chemicals industry, as it is today. Irena splits this sector into ammonia (74.6Mt), methanol (74.1Mt) and “high-value chemicals” (53Mt) — a commonly used petrochemicals term referring to oil-derived ethylene and its by-products, such as propylene, benzene and toluene.

The power sector comes second with 172.1Mt, or 28%.

“[Hydrogen use in the power sector] would meet the need for flexibility and thermal generation to compensate for fluctuations in renewable energy and complement other flexibility measures,” says Irena in its latest H2 report, Global Hydrogen Trade to Meet the 1.5°C Climate Goal — Part 1: Trade Outlook for 2050 and Way Forward.

Irena tells Recharge that the modelling used to calculate the sector-by-sector hydrogen demand in the new report proved not to work for the power industry, so the 172.1Mt figure was extrapolated by adding up the new calculations made for the other sectors and subtracting that total from the global 2050 demand figure (ie, 614Mt) published in previous Irena studies.

The transport sector is the third-largest consumer of hydrogen in 2050, according to the figures, consuming 134.1Mt, or 21.8%, of the total.

“Towards 2050, the largest area of growth will be the transport sector. Uses for pure hydrogen to complement electricity arise in the road and rail sectors, in which use of ammonia for international shipping and synthetic fuels for international aviation are among the largest uses,” says the report.

Irena splits the transport sector into six categories: road transport (57.8Mt), international shipping (40.5Mt), international aviation (13Mt), domestic shipping (8.6Mt), domestic aviation (8.5Mt), and rail (5.7Mt).

The remaining 17.3% of global hydrogen demand in 2050, under Irena’s 1.5°C scenario, comes from direct-reduced iron in the steel industry (55Mt), buildings (ie, heating and direct use of hydrogen in fuel cells) (26.9Mt), and “other industries” such as cement and concrete (20.2Mt).

The figure for buildings seems quite bullish, considering that Irena believes that residential heating is the worst possible use case for hydrogen. As the new report states: “For some applications, like low- and mid-temperature heating or road transport, electrification is not only more efficient but more cost-effective and can lead to decarbonisation today with available technologies.”

Irena admits to Recharge that a chart in its new report — which shows the sector-by-sector hydrogen demand in 2050 but does not provide exact figures — mistakenly used an incorrect figure for “other industries”.