Green hydrogen

What do we need?

According to the International Renewable Energy Agency (Irena), the world will need 19 exajoules of green hydrogen in the energy system in 2050 — between 133.8 million and 158.3 million tonnes a year.

Recharge calculations show that producing such a volume would require at least 6,690TWh of dedicated electricity every year — the equivalent of 1 775GW of offshore wind farms, 2 243GW of onshore wind, 4 240 GW of solar PV or 957GW of nuclear power. By the end of 2018, the world had installed 540.4GW of onshore wind, 23.4GW of offshore wind, 480.4GW of solar PV and 397GW of operating nuclear reactors, according to Irena and the World Nuclear Association.

Demand for 2021 was 94 million tons.

Energy storage?

Data that Arjun Flora, director of energy finance studies for Europe at the Institute for Energy Economics and Financial Analysis, or IEEFA, presented from the Massachusetts Institute of Technology and scientific journal Nature Energy:

• The technology to convert power to hydrogen and back to power has a round-trip efficiency of 18%-46%.
• Pumped-storage hydropower boast round-trip efficiencies of 70%-85%
• Compressed air energy storage has 42%-67% efficiency.
• Flow batteries, a rechargeable fuel cell technology that is less mature, have a round-trip efficiency of 60%-80%.

Fertilizer

We use 178 kg hydrogen per 1000 kg ammonia, and we produce 150 million tons of fertilizer, so hydrogen consumption would be app. 26,7 million tons. A completely efficient electrolysis system would require 39 kWh of electricity to produce 1 kg of hydrogen. However, the devices commonly found in operation for this process are less efficient. A typical operational figure is about 48 kWh per kg of hydrogen, so 1283 TWh. Total production figures for 2021 is 1848 TWh wind power and 1021 TWh sun power. Today’s ammonia production accounts for 2% of total energy consumption, 2391 TWh – including or excluding production of the raw materials?

Transportation

A recent study by Whitehead et al. (2018) shows that fuel cell vehicles only have a 22% efficiency, compared to 67% for battery electrical vehicles. This translates into an energy use of 87 kWh per 100km for FCVs and 28 kWh per 100 km for BEVs.