Nitrogen challenges CO2 for media spotlight

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Nitrogen is common in the Earth’s atmosphere, far more common than carbon-based gases.  Nitrogen makes up roughly 78% of the atmosphere, while CO2 makes up less than 1%.  It occurs in all living organisms and makes up about 3% of the weight of the human body.  It is an essential building block of amino and nucleic acids necessary to create and sustain life.

Nitrogen oxides, NOx, are a broad category of gases that mainly form when fuels are burned at high temperatures like in the combustion process. NOx emissions come from many sectors including industrial/commercial/ residential, utilities, and motor vehicles (motor vehicles account for nearly 50% of all NOx emissions).  While some NOx occurs naturally (lightning and microbes), the majority of it, as of the recent past, comes from combusting fuel.

Nitrogen dioxide, NO2, is a common pollutant (toxic gas), not good for air or water resources or human health for that matter.  It is heavily responsible for urban smog and contributes to acid rain.  Nitric oxide, NO, is a participant in ozone depletion and can combine with oxygen in the air to create NO2.  Both are primarily released into the atmosphere through our automobiles, but neither is very prevalent.  Small amounts seem to produce significant effects, as noted in the atmospheric and environmental changes currently going on around us.

Nitrogen is also a major player in agricultural fertilizers.  With biofuels being proposed as an alternative to gasoline, the concept of the nitrogen cycle has stepped into the spotlight.  Typically, biofuels produce less NOx than conventional fuels when burned, but growing the feedstocks of first generation fuels has required more chemical fertilizers.  Do we trade off less NOx in the atmosphere for more nitrogen fertilizers in the ground?  Are dead zones along rivers where biofuel feedstocks are grown a good trade-off for cleaner air?  By addressing some of the issues concerning the nitrogen cycle, second generation biofuels can become a viable alternative.

Like CO2, not only is nitrogen impacting the atmosphere, but it is also impacting ecosystems on the ground.  Not until the widespread use of chemical fertilizers in modern agriculture developed did the concept of ‘dead zones’ spread around the planet.  These dead zones are spreading alongside chemical fertilizer use.  The Haber Process, developed on an industrial scale by BASF in 1913 and a major contributor to the population explosion of the 20th century, sought “to harness the atmospheric abundance of nitrogen to create ammonia, which could then be oxidized to make the nitrates and nitrites essential for the production of nitrate fertilizers”.  German chemist Fritz Haber made possible the agricultural revolution that took place in the 20th century, but he also made possible major changes in the nitrogen cycle of the planet.

Taking nitrogen out of the atmosphere to make fertilizer that is then spread on the ground and concentrated in rivers while simultaneously burning fuels at temperatures to create NOx that is deposited into the atmosphere is worth looking into.  After 100 years of industrialization, the human impact on the nitrogen cycle is becoming apparent in the atmosphere and the ecosystems around us.  Alongside understanding CO2’s role in climate change, understanding the nitrogen cycle better will provide some insight into the human species impact on the planet.  

Through the use of energy, transportation, and agriculture, humans have sped up a naturally occurring process without understanding the ramifications of global changes in the carbon and the nitrogen cycles, and the time has come to take stock of the situation.  The database has grown on CO2, now it is time to expand our understanding of the nitrogen cycle.

Alan Townsend from the University of Colorado at Boulder is trying to calculate the extent of the changes going on in the nitrogen cycle of the planet.  In his initial studies, what seems certain is that “the nitrogen cycle is changing faster and more profoundly than the carbon cycle”.  While CO2 makes up less than 1% of the atmosphere, it has attracted much more attention; Townsend hopes to bring attention to the impacts surrounding humanity’s use of nitrogen from agriculture to transportation.

Nowhere is the nitrogen exchange in relation to CO2 emissions more apparent than in biofuel production.  Critics of biofuels cite the fact that first generation biofuels require more fertilizers to grow, thus causing dead zones to spread; but biofuels release less NOx into the atmosphere when burned in automobiles.  Subsequent generations of biofuels seek to use feedstocks that require little to no fertilizer in order to cut down on nitrogen’s impact in our atmosphere and ecosystems. In these types of scenarios, biofuels contribute to cleaner systems.

The U.S. Energy Independence and Security Act of 2007 “set a goal of producing 14 billion gallons of ethanol from corn by 2022”. If we continue with the process of using fertilizer-intensive corn to make ethanol, then meeting the goal of 14 billion gallons could increase nitrogen levels in the Mississippi by almost 40%. Such a scenario would pit ethanol production against the already established national goal of reducing nitrogen levels in the Mississippi by at least 40% in order to try to reduce the size of the dead zone in the Gulf of Mexico.

CO2 is a popular gas, but nitrogen is far more abundant.  Understanding the nitrogen cycle better will impact the transportation and agricultural sectors in ways that hopefully make energy cleaner, as well as people and ecosystems healthier.  To take nitrogen from the air and place it in the soil, and to deposit various NOx into the atmosphere on an industrial scale for 100 years is bound to have an impact.  The general public is aware of CO2, but NOx are only now beginning to break onto the scene.

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See other articles by 72JAG, John Guerrerio HERE.