“Green ammonia” for energy storage.

Yesterday a massive new wind and solar powered hydrogen generation plant was announced in Western Australia. The Western Green Energy Hub will produce up to 3.5 million tons of green hydrogen, or 20 million tons of green ammonia in a year, powered by 50GW of hybrid solar and wind. For context, according to the Australian Energy Regulator, the entire country has just over 50GW of total capacity today. This is truly a massive plant.

Why produce all that electricity, only to convert it into hydrogen or ammonia? And why ammonia?

Hydrogen is an efficient means to store energy, but with many drawbacks. Transporting liquid hydrogen directly, for example, requires storing the gas at -233C. It turns out that ammonia is also a very efficient means to store energy. Ammonia’s energy density by volume is 1.7x that of liquid hydrogen, and it’s more easily stored and transported as well. Japan intends to use hydrogen and ammonia fired systems for power generation. Mitsubishi is also developing 100% ammonia fired turbines intended for deployment in 2025.

The big drawback to ammonia is the Haber-Bosch process used to produce it at industrial scale today. We use vast amounts of ammonia globally, mostly for fertilizer. Indeed, we could not feed the planet without the Haber-Bosch process. However, the Haber-Bosch process consumes large amounts of energy (1-2% of world energy), takes natural gas as an input to generate hydrogen (3-5% of global production), and emits CO2 directly as a byproduct. “Green ammonia” production uses water electrolysis to generate hydrogen instead of natural gas, which eliminates the emission of CO2, and powers the Haber-Bosch process by renewable electricity. It still consumes large amounts of electricity, but generated from renewable sources instead. Hence the need for a power generation plant capable of powering the entire continent of Australia!

Green ammonia seems promising, although not implemented at scale yet. Multiple energy storage projects are in progress globally. Yesterday’s Western Green Energy Hub announcement from Australia only adds to the momentum.

Lastly, there are still many possible efficiencies around the production of ammonia. For example, promising work is underway to produce ammonia using reverse fuel-cell processes directly from water and nitrogen gas. No electrolysis, no Haber-Bosch process, very low energy requirements.

Perhaps one day ammonia will help us to both power and feed the planet, without the emissions downside it creates today.