Ammonia has great potential as a hydrogen carrier due to its ease of storage and transport and its potential use directly in combustion, speakers said at an energy and climate tech conference in Tokyo in early October.

Ammonia—currently mostly produced by combining grey hydrogen and nitrogen—is already an established market serving the fertiliser, chemicals and plastics sectors. Some 35mn t/yr of grey hydrogen is used to produce 200mn t/yr of ammonia.

“Ammonia has huge potential for our carbon-free future,” Ann-Kathrin Merz, a research assistant at Columbia University’s Center on Global Energy Policy (CGEP), told the Innovation for Cool Earth Forum.

“Ammonia has huge potential for our carbon-free future” Merz, CGEP

“Low-carbon ammonia can produce significant greenhouse gas reductions in key sectors this decade and deep reductions in additional sectors by 2050.”

Sourcing hydrogen accounts for 90pc of the emissions created while producing ammonia and is why production of the fuel accounts for up to c.2pc of global CO₂ emissions, according to Merz, a coauthor of a low-carbon ammonia roadmap released at the event.

The IEA estimates direct emissions from ammonia production stand at 450mn t/yr, equivalent to emissions by South Africa’s coal-heavy energy system.

Going green

Ammonia’s emissions footprint can be addressed by green hydrogen, but the cost of the latter is the main obstacle.

“The good news is that the green technologies are going to become substantially cheaper in the future. In the same way we had these dramatic cost declines in the solar industry, we expect the same dramatic cost declines to happen for green ammonia production technology for the electrolysers,” says Merz.

She also points to recent gas price volatility that could change the cost profile of ammonia.

“In the last 20 years, natural gas prices were $100-600/t. In 2021, we crossed $1,000/t and then, in the US, we even crossed $1,500/t. The point is that, with this dramatic fluctuation, we cannot assume that natural gas-based ammonia is always going to be the cheapest option,” she adds.

While ammonia is a derivative of hydrogen, its physical properties make it more attractive as a transition fuel. It liquefies much more easily than hydrogen, has a higher energy density than liquid hydrogen, and can be substituted for dirtier and more carbon-intensive fuels— including coal, oil and gas.

This substitution can be either complete or partial by blending ammonia with other fuels, giving ammonia more flexibility in a wider range of applications than hydrogen.

Japan is already testing ammonia as a clean-burning fuel to co-fire coal power plants, reducing the amount of coal consumed during generation.

“That is reducing carbon emissions in the process because that ammonia, when burned does not create CO₂. There is tremendous potential here,” says David Sandalow, inaugural fellow at CGEP.

A 10pc ammonia co-firing in global coal plants would generate 200mn t/yr of ammonia demand, a potential market worth $100bn by 2050, according to consultancy Wood Mackenzie.

Ammonia as a drop-in replacement for conventional fuels is particularly attractive to Japan as it would allow the country to continue using its fossil fuel infrastructure. It would be relatively straightforward to convert LNG assets such as import terminals and storage to ammonia, requiring 11-20pc of the original capital cost of the project.

“That is not nothing, but it is also within the realm of what is possible if there is a commitment to this type of transition,” says Sandalow.

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Author: Shi Weijun