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    Moving Towards Fossil-Energy-Independent Nitrogen Fertilizer
    By Steve Savage | April 2nd 2013 12:26 AM | 10 comments | Print | E-mail | Track Comments
    About Steve

    Trained as a plant pathologist (Ph.D. UC Davis 1982), I've worked now for >30 years in many aspects of agricultural technology (Colorado State...

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    It takes about as much energy to make the nitrogen fertilizer for an acre of corn (150 lbs) as it takes to drive a car 600 miles, and because it is made using natural gas it has a carbon footprint equivalent to driving the car 650 miles.  Now imagine that for more than 90 million acres of corn.  That is a lot of energy.  But what if that energy and greenhouse gas footprint could disappear?  This might actually be possible.  

    By way of background, nitrogen is one of the three most important minerals that plants need to grow, and the basis of the protein we require in our diets.  Some plants call legumes “fix” their own nitrogen with the help through a mutualistic relationship with a particular kind of bacteria.  From an environmental point of view, this sort of  biological nitrogen fixation is the best way to make nitrogen fertilizer.   US farmers already plant about 100 million acres of legume crops (soybeans, alfalfa...).  We could probably supply a fair amount of additional nitrogen if legume-containing winter cover crop mixes were more broadly used.  Still, to grow our conventional crops like corn, wheat, barley, fruits, most vegetables.... we need to make synthetic nitrogen.  Even organic is dependent on that flow (see previous post, Cows Don’t Make Fertilizer).

    Large scale, crop-available nitrogen production became possible about 100 years ago when two German scientists named Haber and Bosch sequentially figured out how to turn the nearly 80% nitrogen in the atmosphere into plant available forms.  All it takes is a source of hydrogen, the air, and a catalyst to make ammonia. They got a Nobel Prize for this, but the big down-side has been that the most cost effective way to do the Haber-Bosch process has been to get the hydrogen from natural gas.  The question is whether there is an alternative to this major use of a fossil fuel (~5% of total natural gas use).

    The Answer My Friend, Is Blowin' In The Wind

    Bob Dylan was famously vague about what "the answer" actually was, but I'm guessing that he wasn't thinking about a solution to the fossil fuel dependency of crop fertilizers.  Even so, his reference to wind may actually be part of the answer to this real-world dilemma.   The Haber-Bosch process just requires hydrogen and that can easily be made using electricity and water (electrolysis).  The electricity could be from a renewable source like wind, solar, hydro etc.  I once wrote a blog post wondering if it might be possible for someone to develop a small-scale Haber-Bosch process that could be run using something like wind energy.  It turns out that at least three groups were already working on different approaches to just such an invention ( University of MinnesotaElectrogen HydrofuelsAltmerge).  I am really excited about this possibility, particularly the later two because they are working on very small scale units.  For instance the one from Electrogen is designed to fit in a standard truck/rail container.

    If any of these processes can be successfully commercialized, it could dramatically alter the fertilizer paradigm.  It would give farmers a way to locally and independently produce their own fertilizer and thus avoid the price fluctuations driven by the general energy market.  A farm could install a wind turbine and one of these units and let it make the next season’s fertilizer any day that the wind blew.  These companies are also working on ways to turn the ammonia generated into something easier to store like liquid ammonium nitrate (not the dry form that can be turned into a bomb).  

    Such a system might also be able to provide village-level fertilizer generation in parts of the world where small-holder farmers don't have practical access to nitrogen fertilizer today.  

    This nitrogen fertilizer would be "carbon neutral" from a manufacturing perspective.  Since the energy used to make fertilizer is a large part of the overall carbon footprint of agriculture (about 40% for a corn crop), this change would be highly significant.  Nitrogen fertilizers will still always have other environmental issues, but there are sustainable soil health management systems that best address those.

    The irony is that this sort of carbon-neutral nitrogen fertilizer wouldn't qualify under the current rules for use in organic because it would still be “synthetic.”  Of course plants don’t care about this.  They can only absorb nitrogen in its nitrate or ammonium ion form which is the same whether it originated as synthetic or natural fertilizer.  

    Wind turbine image from SustainableDevelopment's photostream

    You are welcome to comment here and/or to email me at savage.sd@gmail.com


    In your reference it's interesting to see boron listed as a micronutrient required by Rhizobium, the bacterium involved in fixing nitrogen for leguminous plants. It's known, of course, that a boron-containing molecule is involved in "quorum-sensing" among bacteria. Without small quantities of boron in the soil, fewer of the legume-root's cells become infected.
    Enrico,Yes, it is interesting about Boron.  Some soils have problematically high levels (like near UC Davis where I gardened in grad school), and other soils are deficient.  Sulfur is interesting too.  It is the most needed element after NP and K, but for a long time it was never something farmers had to apply because it came for free in the rain (not a great thing).  We've cleaned up the air enough now that sulfur deficiency is showing up where it never used to.  Of course there is no shortage of sulfur since power plants etc have huge piles to deal with
    Steve Savage
    Thor Russell
    Yes that sure would be a great use for wind power. If someone could also use electricity to suck CO2 from the air and turn it into ethanol or a similar hydrocarbon cheaply and efficiently then they would also deserve something like a nobel prize.
    Thor Russell
    That is what plants do.  For instance you can grow trees, put them through a fast-pyrolysis system and generate biochar, some forms of which are then stable sequestered carbon that can last 1000 years in the soil.  
    Steve Savage
    Thor Russell
    I know plants do that, but not very efficiently and also not so much when you have stranded electricity not anywhere near the necessary water/topsoil/climate etc. so there is an opportunity there as far as I can see.
    Thor Russell
    Why not take the carbon from biochar, and just dump it in the really deep abandoned mines? You'd probably want to wash out the various other elements, such as potassium, but once that's done and it's pretty much pure carbon - down a mine, down into a subduction zone sending it into the mantle to one day come up diamonds... (Yeah, sure, the diamonds will be delivered in 50 million years or so - I can wait.)

    Tara Li,The mine idea is ok, but biochar has been claimed to be able to improve soil quality without the need for breakdown back into CO2.  If that is true, it might be better used in the plant rooting space.  No diamonds, but 50 million years is a rather long time to wait!

    Steve Savage
    Why not just use the electricity from the windmill to power the grid instead of burning natural gas. Takes a lot less infrastructure and equipment. Keep the gas for the ammonia production which is the most effective use.

    Wind power is abundant in rural areas, but it is often "stranded" in that it is not that practical to connect to the grid.  For wind power that is connected to the grid, there are times when its contribution is not needed by the larger system and it could be devoted to making ammonia.
    Steve Savage
    Mr. Savage,

    I certainly agree with you that first, *wind energy* is a part of mono oxydes and di oxydes footprints pollution over a global warming atmosphere (climate), but we could not do it by encroaching biodiversity and natural aspect of earth lithosphere. Second, diversification of proper energies should be done by using abundant and non polluting source of these and with a consideration of non destructive and regenerative potential from these.

    In my second point, nitrogen fertilizers and synthetic hybrids from that element are not part of a normal synthesis of oligo elements from soil to plants, and even in the case that soils bacteria could potentially mutate and assimilate non natural nitrogen sources, they are not directly part of transgenase adductance of nitrogen from soil to plants because we can think that biodegradability bacteria involved in this natural process are not part of environnement sources but a chloro transgenase mecanism from which it is developped. Then, we could think that this natural process is stopped when specific bacteria are missing bio organics matter from which they are evolved, and second, once bio organics matter is decomposed to required oligo elements needed by the *specimen plants*, no bacteria are involved in the assimilation process of *nitrogen* and others oligo elements. Finally, we can certainly think that there is an hybrydation of nitrogen adductive molecule when requiring to synthesis chemical products.