Is ammonia the holy grail for renewable energy storage?

"If you want to beat carbon, it's the only way to do it unless you change the chemical charts." So says Jack Robertson about the prospects for making ammonia the world's go-to liquid fuel and renewable energy storage medium.

Robertson is chairman and CEO of Light Water Inc., an ammonia energy storage startup. The carbon he mentions refers, of course, to the major carbon-based fuels of oil, natural gas and coal that provide more than 80 percent of the world's energy. The charts he mentions refers to the periodic table of elements, a listing of the basic elements of the universe which are about as likely to change their properties as the proverbial leopard is to change his spots.

Most of us think of ammonia as a pungent household cleaning agent that disinfects and deodorizes. Farmers are familiar with anhydrous ammonia (essentially ammonia that is not mixed with water) that is a common nitrogen fertilizer.

But the idea that ammonia can be used as a fuel, while not new, is not widely known. That's not really surprising since the last 150 years have been powered by another better-known liquid fuel called oil. And, the ubiquitousness and historically low price of oil prevented other liquid fuels from gaining a foothold in the marketplace. The use of historically cheap coal and natural gas has kept ammonia on the sidelines in the electricity market as well.

But now, two things have changed. First, concern about climate change has policymakers scrambling to figure out how to reduce carbon emissions. Second, the world's primary liquid fuel, oil, has been trading at its highest daily average price ever for the last three years. In 2011 the average daily price of Brent Crude, the world benchmark, was a record $111.26 a barrel--which was followed by another record in 2012 of $111.63. The year just finished saw Brent Crude a bit lower on average at $108.56, a figure higher than all but the two previous years.

(Despite all the hoopla about rising American crude production, the rate of oil production worldwide has eked out only a small gain of 2.7 percent between 2005 and 2012, about a quarter of the growth rate of the previous seven-year period. And, this slower growth in the face of rising demand in India and China has led to record prices.)

What makes ammonia so attractive as a fuel is sixfold. First, it contains no carbon. The ammonia molecule is composed of one atom of nitrogen and three atoms of hydrogen. Therefore, when ammonia-based fuel is burned, it produces very little in the way of greenhouse gases. The small amount of oxides of nitrogen that it does produce can be neutralized by ammonia itself. Second, we already have well-known processes for making ammonia. We don't need new or exotic technology to produce it. Third, these processes have long ago demonstrated that they can be scaled up to form a worldwide ammonia production industry. Fourth, an ammonia distribution system is already in place that includes rail tankers, tanker trucks, ships, barges and ammonia pipelines, a system that uses pressures no higher than that found in a bicycle tire to keep ammonia in its liquid state. While that infrastructure would need to be expanded, no new technology is required to transport ammonia from where it is made to where it is used.

Fifth, ammonia has an enviable safety record. There have been mishaps. But they don't involve fire since ammonia is not easily combustible. Those who've used ammonia cleaners will understand that it is the fumes which pose a danger if they are too concentrated. On the other hand, humans can detect the strong smell of ammonia at very low levels, long before it ever reaches toxic concentrations. And, this means that in the event of an accident, humans can flee or take measures to protect themselves from harm before it's too late.

Sixth, if manufactured using renewable energy, ammonia, when produced and then burned as a fuel, creates little that can be classed as pollution (except a small amount of oxides of nitrogen mentioned above which can be neutralized by the ammonia itself). When ammonia molecules are broken down into their constituent parts during combustion, the nitrogen returns to the atmosphere and the hydrogen reacts with the oxygen in the air during combustion to form water.

Ammonia energy research is part of the hunt for a cheap method of storing intermittent flows of energy from wind and solar power generation, a major problem that has plagued the expansion of these low-carbon technologies. The wind, of course, doesn't always blow and the sun doesn't always shine. To make matters worse, when the wind blows most and the sun shines its brightest, sometimes too much electricity is produced and some of it must essentially be dumped. A similar problem plagues hydroelectric dams as I will explain below.

So, how exactly would ammonia be used for renewable energy storage? While others have been working on this problem, Robertson's story is instructive. After many years as an aide for the late U.S. Senator Mark Hatfield of Oregon, Robertson returned to Oregon to work for the Bonneville Power Administration (BPA) where he eventually rose to the rank of deputy administrator.

Each spring from his perch at BPA he watched enormous amounts of water run down the Columbia River, much of which would never generate electricity at the agency's hydroelectric dams because there was simply too much water. Even the electricity that was generated from the dams and later from the huge wind farms installed along the river would often be sold for almost nothing during the spring. Occasionally, the BPA actually had to pay others to take its excess electricity.

Robertson wondered if there might be some way to store all this excess power and then use it in other seasons when supply from the dams and wind farms was lower and electricity prices were higher.

After an early retirement he went to work on the problem in a more systematic way, first founding a nonprofit that studied the issue. One of the possible answers was to produce ammonia using the excess power. Robertson realized that in order to bring that idea to fruition he would need to raise private capital and formed Light Water Inc.--so named because ammonia produces light if used to generate electricity and also water as hydrogen combines with the oxygen in the air during combustion (as previously noted).

Robertson's aim is to produce "green" ammonia. By "green" he means produced using only renewable energy to separate hydrogen from oxygen in water molecules using electrolysis. (Ammonia is currently most often made using hydrogen stripped from methane or coal.) The "green" hydrogen would then be combined with nitrogen drawn from the air (which is 78 percent nitrogen) to form ammonia through the well-known and widely used Haber-Bosch process. The huge excess power available in spring from the BPA's system of dams and wind farms along the Columbia now doesn't have to be wasted, he believes.

It could be used to make ammonia in quantities so large that the resulting volumes could be sold to provide power and fuel for other parts of the country. The most likely interim step would be to trade green ammonia certifications to utilities and others that have access to fossil-fuel based ammonia but would benefit from that certification for regulatory reasons such as credits and incentives for using renewable energy. It would be similar to buying carbon offsets. Once the green ammonia certification is traded, the actual green ammonia would lose its certification and enter the general ammonia supply. The arrangement provides incentive for producing green ammonia that displaces fossil-fuel based ammonia locally without incurring the financial and energy costs of transport.

Of course, wherever hydroelectric power and wind and solar energy are in large surplus at various times of the year (or in the case of wind and solar energy, various times of the day), ammonia-producing plants could be set up to store that excess energy for later use and/or sale to or certification trading with more distant locales.

Robertson has combined his efforts with several others to seek funding from the California Energy Commission to test high-efficiency, high-compression engines fueled by ammonia as a way of producing electricity. (Even standard diesel and gasoline engines can be adapted to burn ammonia. But this is not the focus of Robertson's project.)

If the project is funded, a successful test could pave the way for private funding that would take the concept to the next step, a working pilot plant and then a commercial-scale plant that make ammonia and use it to generate electricity for utilities during peak load hours.

Robertson's project is but one example among many of experiments with ammonia as a fuel. The NH3 Fuel Association lists several efforts on its website.

The public has been previously tantalized by supposed energy breakthroughs such as ethanol and cold fusion--only to be disappointed when the results failed to match the hype or were nonexistent. But, the world already has long experience with ammonia, and so most of the questions surrounding its use, safety and scalability have already been answered--except one. Can it become a breakthrough alternative liquid fuel and storage medium for renewable energy?

The evidence so far suggests that it has a far better chance of succeeding than many of its current competitors.

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This piece was updated on 2/26/14 to reflect additional information and corrections discussed in my comment below.

Kurt Cobb is an author, speaker, and columnist focusing on energy and the environment. He is a regular contributor to the Energy Voices section of The Christian Science Monitor and author of the peak-oil-themed novel Prelude. In addition, he has written columns for the Paris-based science news site Scitizen, and his work has been featured on Energy Bulletin (now Resilience.org), The Oil Drum, OilPrice.com, Econ Matters, Peak Oil Review, 321energy, Common Dreams, Le Monde Diplomatique and many other sites. He maintains a blog called Resource Insights and can be contacted at kurtcobb2001@yahoo.com.