A Bolivian smelter is the unlikely setting for a technology experiment that could upset hydrogen’s incipient lead as an alternative energy storage and fuel source. Last September the smelter, run by the Royal Silver Company, became the first business on the planet to commission a commercial-scale solid-state ammonia synthesis (SSAS) plant.

Along with hydrogen, ammonia has long been touted as an alternative to hydrocarbon-based fuels and can also be used for energy storage. Commercialisation of ammonia technology has thus far lagged behind that for hydrogen, however.

But with the Royal Silver Company project, which is being carried out by SSAS-patent holder NHThree of Washington State, USA, ammonia could be back in the running.

“Using SSAS, ammonia … can be synthesized directly from air and water and electricity, surpassing the current technology invented 100 years ago by which all of the world’s ammonia is made from fossils fuels, mostly natural gas,” said NHThree in a press release.

“Using SSAS, solar, wind, hydro and other sources of electricity could be converted directly into fuel, into fertilizer, and into additional ammonia that then could be converted back into electricity at night or when the wind stops blowing.”



A range of applications

Royal Silver Company needs the ammonia for a zero-emissions mineral purifying process. But observers believe ammonia could be used in other situations, too.

Ammonia advocate Dr Barrie Pittock, a retired honorary fellow of the Commonwealth Scientific and Industrial Research Organisation in Australia, says the compound could even be used to power vehicles using modified internal combustion engines or fuel cells.

Ammonia has a number of potential advantages over hydrogen, he adds. It has a higher energy density per unit volume and is a liquid at normal pressures, making it easier to store and transport. This is significant because it could transported in tankers or pumped over existing gas pipelines.

Pittock suggests ammonia might be a good candidate for proposed pan-regional energy exchanges such as the Grenatec network. Although it is poisonous, security concerns over ammonia need to be tempered by the fact that its characteristic smell would quickly give away the presence of leaks. Hydrogen, stored at higher pressures, is likely much more dangerous.

Zero-emission production

Furthermore, when hydrogen is produced by water electrolysis the process is inefficient. Hydrogen thus tends to be made by steam reforming of natural gas, producing carbon dioxide.

In contrast, ammonia can be produced with zero emissions either by SSAS or via the electrolysis of water followed by a high-temperature reaction of the ensuing hydrogen with air, for example in a concentrated solar power (CSP) plant. Another advantage of this is that it could help overcome some of the challenges facing energy storage in CSP.

This currently relies on molten salt, which cannot store energy for long and has limited applications outside of CSP.

At the moment, one of the main arguments against incorporating ammonia into existing energy systems is that natural gas is a cheaper alternative. But if the objective is to eliminate greenhouse gas emissions, or gas is difficult to come by, there is no reason why producing ammonia shouldn’t make sense.

If you are making it from excess renewable energy power, via SSAS, presumably the business case looks even better. Whether ammonia will ever beat hydrogen, though, is very much open to debate. As a cursory glance through our news headlines shows, hydrogen is growing in importance across the energy landscape daily.

Therefore the question for ammonia is perhaps not so much if it could be better than hydrogen… but if it could be faster to market. And that’s a big ‘if’.

Written by Jason Deign