Here's an idea: what would happen if the world's most popular fertilizer can double as energy storage? Maybe storage will inch that much closer to large-scale reality and ensure the future of renewables as our main source of energy. And maybe it will offer a necessary alternative to green hydrogen, hype and all.
Ammonia is one of the most massively produced chemicals in the world. Its most common use, the one everyone must have heard about and the one that takes 80 percent of output, is as fertilizer. Ammonia is also used in the production process of plastics, textiles, pesticides, and explosives. And it could also be used as energy storage.
The energy storage conundrum
Reliable energy storage has been identified as the make-or-break factor for the renewable power game. For all their advantages, chief among them zero emissions, solar and wind power installations have their fair share of disadvantages, chief among them that they cannot produce power in response to peaks and troughs in demand. They produce the power they can produce when the sun shines and the wind blows.
This is a problem because the sun does not constantly shine, even in the most solar farm-friendly places, and the wind does not constantly blow even in the windiest corners of the world. This means solar and wind capacity needs to be coupled with storage systems to ensure the reliable supply of power. Without storage, solar and wind become costly over the long term because of their unreliability. No wonder, then, that researchers are in a rush to find better and, importantly, cheaper energy storage.
The options
Batteries are the biggest headline huggers when it comes to energy storage. Just a few days ago, yet another megabattery project by Tesla in Australia took the spotlight with its 300 MW/450 MWh capacity that could power half a million households. But only for an hour. The project is valued at $84 million.
But lithium-ion batteries are not the only option. There are also solid batteries and liquid batteries out there, and many are showing promise. The drawback is that for many of them is that it is early and these emerging battery technologies need to be tested and retested before they prove economically viable as alternatives to lithium-ion. Related: Blackrock and Fidelity Are Betting Big On This $130 Trillion Mega-Trend
There is also hydrogen. Touted as both fuel in fuel-cell cars and as an energy carrier, hydrogen is one member of an energy storage family called chemical storage since it stores energy in the chemical bonds in molecules. It is quite energy-dense, which works in its favor, but it is also quite combustible, which doesn't.
Hydrogen's little daughter
Ammonia is a compound that contains one nitrogen atom and three hydrogen atoms. It is made from literally air and water, plus some electricity, and this electricity could be generated either from fossil fuels or from wind and solar. Then ammonia can be used either as a carbon-free fuel or cracked back into nitrogen and hydrogen to use the hydrogen as a fuel.
According to a recent report by the Oxford Institute for Energy Study, ammonia is a viable alternative to hydrogen when it comes to energy storage. The foul-smelling gas is more energy-dense in liquid form than liquid hydrogen; it has a much lower boiling point, which makes its liquefaction a lot cheaper; and it is not as easily combustible, which makes transportation a lot cheaper than the transportation of hydrogen, too.
Siemens built a green ammonia plant in Oxford, England, a couple of years ago. The plant was a proof-of-concept facility that produced ammonia from renewable power and then stored it before turning it back into electricity through simple combustion or converting it back into nitrogen and hydrogen.
In Australia, a scientist from Monash University developed ammonia-based fuel cells that "breathe nitrogen in and breathe ammonia out," according to their designer. The ammonia can then be used for any of a variety of purposes to produce energy.
"You can store it, ship it, burn it, and convert it back into hydrogen and nitrogen," according to Tim Hughes, an energy storage researcher with Siemens' ammonia project. "In many ways, it's ideal."
The problems
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Carbon-free though ammonia is, it is not emission-free. When combusted, it releases nitrous oxides. The combustion itself is nowhere as efficient as the combustion of fossil fuels. This is a drawback for the process. There are technologies available to reduce the nitrous oxides emissions from ammonia combustion, but this adds costs, Oxford Energy adds in its report.
A bigger problem is that ammonia is highly toxic. While the characteristic odor of the compound makes leak detection, and hence containment, easy, toxicity is a factor, and it is a big factor, especially in the court of public opinion. Add to this the fact that, although less flammable than hydrogen, ammonia is not inflammable, and it is easy to see why its progress on the energy scene has been slow and largely unnoticed.
No energy storage solution is without problems, whether it is cost, reliability, or side effects such as flammability. Yet each of them brings benefits to the table that are solid enough to be considered for future deployment. With many things still uncertain about the energy transition everyone is talking about, but one thing appears to be pretty certain: in the future, energy systems will not rely on one single solution to either energy generation or energy storage.
By Irina Slav for Oilprice.com
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