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Ultimate Energy Storage: Ammonia

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Rami Reshef's picture
CEO GenCell Energy

Rami Reshef serves as the CEO of GenCell Energy, a developer of alkaline fuel cell solutions that generate clean, reliable off-grid and backup power for humanity.

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  • Jul 24, 2020

This item is part of the Energy Storage Insights - Summer 2020 SPECIAL ISSUE, click here for more

Challenges of Green Energy

With climate change causing more frequent extreme weather and the IPCC setting targets to reduce emissions to prevent a temperature rise of another 1.5 degrees, the world is making efforts to transition to Renewable Energy.  With the global transition from fossil fuels to green energy underway, there is a need for long-term storage and long-range transmission of this green energy. Ammonia is well-suited for both applications, in that at room temperature liquid ammonia is a highly efficient carrier of hydrogen that can be readily transported. Fuel cells that can harness hydrogen from ammonia offer significant breakthroughs in overcoming the key challenges of green energy:

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  • Providing green energy when other renewables are available intermittently

Solar energy is produced only when the sun shines. Wind energy is produced only when the wind blows.  The fact that the availability of these increasingly popular sources of renewable energy is limited by weather conditions grows in importance as these power sources make up a greater portion of the total energy generated.  The misalignment of renewable energy production vs consumer demand is demonstrated in the now famous Renewable Energy duck curve; the fluctuations in energy balances caused by Renewables create serious challenges for power utilities that must meet this demand. The answer to this challenge will come from readily available renewable energy storage solutions. High availability fuel cells can be an important component of these solutions.

  • Leveraging excess capacity from renewables   

Instead of curtailing the excess capacity generated by renewables, this excess energy can be stored as liquid ammonia for future use by fuel cells. This source of ammonia would be a clean alternative to the industrial ammonia that is produced via the Haber-Bosch production process.

  • Offering a green, lower cost alternative to diesel

    Diesel generators to date have played a major role in providing power in the poor-grid economies of developing countries. These generators are at least partially responsible for the air pollution from diesel and other fossil fuels that causes the death of 7 million people worldwide each year. Replacing diesel fuel with “green ammonia” as an energy carrier would make clean, reliable green energy available to the 3.5 billion people who live in off-grid or poor-grid areas. The launch of the GenCell A5 off-grid solution for telecom towers and rural electrification running on ammonia will enable access to energy for millions of people that are now still beyond the grid.

Approaches to Renewable Energy Storage

Until today, the energy market has been primarily focusing on two main approaches to Renewable Energy storage – rechargeable batteries and hydrogen. Varied technologies are used to develop rechargeable batteries of different types and sizes.  The advantages of batteries include energy efficiency and long lifespan thanks to charging and transportability. On the other hand, their disadvantages include their significant weight and footprint, their high production costs, rapid deterioration, safety hazards and problems around their disposal.

In parallel to batteries, another popular trend for energy storage is based on hydrogen technology, such as applications that leverage hydrogen to drive fuel cells, chargeable vehicles and mobile machinery, among other innovative applications.  Applications such as electrolysis produce clean, green hydrogen from water with the aid of surplus renewable energy; this hydrogen can be transported, stored and enable re-electrification using fuel cells.

The storage capacity of energy as hydrogen is far higher than that of batteries. So why hasn’t this technology conquered the market?  The reason is because energy storage as hydrogen is challenging. Building a viable hydrogen infrastructure for delivery from production to consumption sites is not a simple matter.  Mass, centralized hydrogen production, whether as gas or liquid, entails high delivery and distribution costs, while low-volume distributed production is prohibitively costly. Hydrogen delivery is constrained by high costs, energy efficiency losses in transit, hydrogen purity issues and propensity for leakage.

Scientists are working on novel hydrogen carriers to overcome these constraints. Hydrogen carriers can store hydrogen in a chemical state other than free hydrogen molecules. One interesting method to deliver hydrogen involves hydriding a chemical compound at the site of production and then dehydriding it at the point of delivery or within a fuel cell. Potential carriers include chemical and physical storage technologies such as metal hydrides, carbon or other nanostructures and reversible hydrocarbons. Other approaches involve pumping hydrogen into underground caverns, many of which were created by mining activities, where it is stored safely. Power to Gas technology injects hydrogen into natural gas that is transported via existing infrastructure. Combustion releases the energy; by replacing 20% of the carbon with hydrogen, emissions are similarly reduced by 20%.

Ammonia as an Energy Carrier

Another option is to use ammonia as an energy carrier. The advantages are many. Firstly, ammonia is economical. Availability – the second most widely produced chemical in the world, 200 million tons of ammonia are produced per year. Transportability – ammonia is easy to store and doesn’t require high-pressure storage. Another key advantage is ammonia’s chemical compatibility with alkaline fuel cells which use an alkaline electrolyte.  And when ammonia is cracked to produce hydrogen, no harmful pollutants are emitted.  As there is no carbon, no carbon by-products are produced – so ammonia is thus a "carbon neutral" option for the future.  While ammonia is a toxic chemical with a potent odor, when handled with care and in accordance with regulations it is safely used in agriculture, refrigeration, semiconductors, hair dyes and water purification among other applications. But the biggest advantage of ammonia as a hydrogen carrier is the fact that as a liquid, with mild pressurization and without cryogenic constraints, it offers a high hydrogen storage density. 

Already today GenCell has developed a fuel cell that leverages liquid ammonia to fuel an off-grid power solution which acts as an autonomous “nano-power plant” beyond the grid, enabling us to replace pollutant diesel generators in providing electricity beyond the grid. Today these fuel cells run on industrially produced ammonia, mainly produced via the commonly used but highly pollutant Haber-Bosch process. In the Haber-Bosch ammonia synthesis process, nitrogen reacts with hydrogen using a metal catalyst. The process is conducted at a pressure of 200 atm and high reaction temperatures of nearly 500°C. There are claims that the Haber-Bosch process is one of the largest contributors to a build-up of reactive nitrogen in the biosphere. To offer completely green power, we are working on the development of an eco-friendly process to create green ammonia that can displace the pollutant Haber-Bosch process. This would enable industrial production of clean ammonia using renewable energy for a wide range of applications, from fertilizers and water purification to providing fuel for alkaline fuel cell solutions. Because this equation includes no carbon, when matured, this technology will allow us to have 100% green distributed power generation. We envision enabling a fully clean energy loop by producing green ammonia on-site using solar and wind energy, using the ammonia to run alkaline fuel cell generators anywhere beyond the grid, enabling rural electrification and bringing the world closer to grid parity.  For more information, contact us at

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Matt Chester's picture
Matt Chester on Jul 27, 2020

Do you see energy stored as ammonia predominantly being used as a direct fuel-- is there any work being done to then use ammonia-to-power, or would the inefficiencies created in that process make it uneconomical?

Rami Reshef's picture
Rami Reshef on Jul 27, 2020

Whe you say direct fuel I assume you are referring to the use of ammonia as a fuel for a combustion engine. I am aware of many studies considering this proposition, although there are several challenges in ammonia combustion, such as low flammability, high NOx emission, and low radiation intensity.   

On the other hand, the idea of using ammonia-to-power technologies as a carrier for hydrogen to be used with fuel cells and for decarbonization of carbon-intensive industries such as shipping is gaining traction and support in both R&D and industrial settings around the world. To learn more, check out 

Charley Rattan's picture
Charley Rattan on Jul 27, 2020

The advantages are many. Firstly, ammonia is economical. Availability – the second most widely produced chemical in the world, 200 million tons of ammonia are produced per year. Transportability – ammonia is easy to store and doesn’t require high-pressure storage. Another key advantage is ammonia’s chemical compatibility with alkaline fuel cells which use an alkaline electrolyte.  And when ammonia is cracked to produce hydrogen, no harmful pollutants are emitted.  As there is no carbon, no carbon by-products are produced – so ammonia is thus a "carbon neutral" option for the future

Gary Hilberg's picture
Gary Hilberg on Aug 3, 2020

This certainly is an interesting path, but we must remember that the highly available Ammonia is all based on fossil fuels such as natural gas and coal.  If there is a "green" Ammonia would the better solution be to displace the current primary use as fertilizer?  We in the energy sector are very focused on our segment while agriculture productivity is highly dependent on fertilizer, quite simply without modern agricultural techniques the world will starve.  So as we move down these various paths we need to consider all aspects.  The first step would be eliminate all the Ammonia produced by coal - fortunately economics are doing a good job with this, but there is still considerable Ammonia capacity using coal as a feed stock.  

Rami Reshef's picture
Rami Reshef on Aug 11, 2020

Hi Gary, I would venture to say that using green ammonia to reduce the enormous costs of building a hydrogen supply chain infrastructure for the energy sector and using green ammonia to decarbonize fertilizer production are two separate yet equally important and valid efforts. Producing green ammonia is intensive in terms of both energy and money, but like any operation, its costs will benefit from economy of scale, so in that way expanding in parallel both ammonia to energy and ammonia for agriculture can be mutually beneficial.

John Simonelli's picture
John Simonelli on Aug 4, 2020

While the use of ammonia as a storage medium is indeed very interesting and plausible, it's hard to fathom it meeting the needs of the massive amount of storage that will be required as the industry pushes to 100% renewables. Let's face it when one looks at the projected load duration curves with higher penetrations of renewables, you would literally have to produce exponentially higher amounts of ammonia. So unless one figures out a way to use it all, its application is primarily suited for small scale storage projects.

Matt Chester's picture
Matt Chester on Aug 4, 2020

Isn't there still an application for energy stored via ammonia that isn't being the sole source of energy backup for the entire grid? I would think that a grid that reaches massive penetrations of renewables-- say 80% for now rather than focusing on 100%-- would have diverse energy storage uses. Ammonia could be utilized in the instances where supply is far exceeding demand for some appreciable amount of time and serve as an economic source for excess renewable generation to go rather than curtailing it, storing it for a later season. That would help with the cost effectiveness of building out new generation sources as well because there would be a use for overbuild and overgeneration. 

Roger Arnold's picture
Roger Arnold on Aug 5, 2020

There's no "one size fits all" solution for energy storage, and I doubt that there ever will be. You have to look at different markets and applications. If you're looking at "the massive amount of storage that will be required as the industry pushes to 100% renewables", no technology that's currently available is all that good. That's in fact the nub of the problem with 100% renewables as a concept.

For a complete seasonal energy solution in a 100% renewables scenario, you're looking at storage totaling 1000's of TWh. Hydrogen is what's usually proposed. Technically speaking, it could work. But to store the required amount of gaseous hydrogen, you're looking at the same options used for seasonal storage of natural gas. I.e., giant salt caverns or capped sedimentary rock formations with adequate porosity and permeability. Those exist, but they're geographically limited. Hence for hydrogen as a seasonal energy storage solution, you're also looking at pipeline infrastructure at least as extensive as the current natural gas system, but for hydrogen. It won't be easy to get there.

Ammonia alleviates gaseous hydrogen's storage problems. Seasonal supplies of ammonia can easily be stored in mildly pressurized and widely distributed above-ground tanks. Energy efficiency is only a little worse than it is for gaseous hydrogen. If and when direct electrolytic production of ammonia is perfected, overall energy efficiency could match or even exceed that of gaseous hydrogen.

Most important, in my opinion, is that ammonia offers a more viable evolutionary path for business development. There are already at least two market segments for which ammonia and fuel cells offer an environmentally -- and perhaps economically -- superior solution to incumbent diesel generator technology. Those are long duration backup capability for facilities that require uninterruptable power, and reliable power to remote facilities.

Ammonia can be stored indefinitely without degrading.  Ordinary diesel fuel, in contrast, contains reactive hydrocarbon species that can slowly polymerize and "gunk up" the fuel system. Fuel additives slow the process, but can't elimate it altogether. Standby diesel generators need to be run for a few hours every month to turn over their fuel supply.

A natural growth path for ammonia + fuel cells would be for backup supply to microgrids of the sort being set up to serve communities likely to be affected by public safety power shutoffs in fire-prone areas. Emergency backup for power shutoffs can grow into routine backup generation for variable renewables. The NH3 fuel supply could be trucked in as easily as diesel is now.

Rami Reshef's picture
Rami Reshef on Aug 11, 2020

Hello Roger, we have been thinking exactly along these lines. It is indeed a cruel irony to think that PG&E in California - thought of by many as one of the most sustainable and progressive geographies in terms of renewable energy - home of high ratios of residential solar and EVs - is in fact now installing thousands of temporary diesel generators for backup power during planned shutdowns they must carry out for wildfire prevention... certainly with better planning hybrid solutions incorporating renewables and innovative energy storage technologies - leveraging ammonia and fuel cells to complement intermittent solar or wind and batteries - would be a far wiser investment for the long-term and for protecting the environment. Read more: Mandatory Backup Power for Cell Towers in California: How Can Californians Enjoy Uninterrupted Service, Power Resilience and Clean Air?

Gerard Reid's picture
Gerard Reid on Aug 8, 2020

I see a great future for ammonia but the key focus must be on decarbonising existing ammonia production which is mainly used for fertiliser...

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