More than 60 million tonnes of hydrogen are produced annually for a range of industrial purposes including ammonia production, hydrocracking, and removing sulphur from fossil fuels.

 

The vast majority of this industrial hydrogen is produced from coal gasification or steam methane reforming (SMR), both of which need a lot of energy and generate significant carbon dioxide emissions. 

 

A much smaller proportion of hydrogen is produced via electrolysis of water, which IEA senior energy analyst Cedric Philibert says can be a far more sustainable method if the electricity is produced from renewable sources.

 

Producing hydrogen via renewable energy is not a new idea. 

 

Until the 1960s, hydrogen from hydropower-based electrolysis in Norway was used to make ammonia - a key ingredient for agricultural fertilizers; but low gas prices and the emergence of SMR made that technology less fashionable when carbon emissions were not a big deal.

 

Yet Philibert says that increasingly lower renewable costs could make renewables-based hydrogen production more competitive with SMR. 

 

"For example, regions with abundant hydropower, or hydropower and geothermal resources such as Iceland or Norway, are possible choices for siting electrolysers," he said. 

 

"Newly-built wind farms in Morocco and solar plants in Dubai and Chile, where electricity costs are around $30/MWh, could also be competitive with SMR paired with carbon capture and storage."

 

Price is not the only consideration however. Philibert says that to be competitive, the electroylzers would have to have relatively high utilisation factors - that is, they would have to run for several thousand hours per year.

 

Yet the analyst says that under the right conditions, producing industrial hydrogen that way could have "massive" consequences for the sustainability of agriculture, as about half of industrial hydrogen is used in ammonia production, which alone is responsible for about 360 million tonnes of CO2 emissions a year.

 

This equates to about 1% of the world's total emissions. 

 

By 2050, the IEA expects ammonia consumption will increase by about 60%.

 

While China and the US, which have the best resources, are far from fertiliser demand centres, both electricity and ammonia can be transported. 

 

"Other places, such as Western Australia, Western Sahara, the horn of Africa or Patagonia to name some, may also be very far from demand but they offer large sparsely-populated areas and have access to oceans. In that case, ammonia plants would likely be sited directly next to the electrolysers," Philibert said.

 

"In some not-too-distant future, ammonia could be used on its own as a carbon-free fuel or as an energy carrier to store and transport energy conveniently. Hydrogen could also be used as a process agent in CO2 emissions-free steelmaking."

 

He said the market for climate-friendly hydrogen generating technologies could only expand in a world striving to mitigate climate change. 

 

While SMR with carbon capture and storage remains an economic option, the fact that many countries are considering how to produce synthetic methane or other hydrocarbons from renewable hydrogen - exactly the inverse of SMR - Philibert  said that manufacturing ammonia with renewables-based hydrogen was the simplest first step.