Comments on Managing the Nitrogen Cycle

Wastewater streams are an example of low-hanging fruit from which nitrogen can be removed. These are far more controlled than 'diffuse' nitrogen sources such as agricultural runoff. An additional benefit of removing nitrogen from the aqueous phase is that gaseous emissions of nitrous oxide (a greenhouse gas 300 times more potent than CO2) can be also reduced concurrently. A link to a recent article on this topic is as follows:

http://pubs.acs.org/doi/abs/10.1021/es200419h

Unfortunately, we seem to have lost control of all the elements on the table, with nitrogen perhaps not even the most acute of problems (plutonium probably tops the list in Washington). The Netherlands in North-west Europe, is by far the most nitrogen-intensive economy in the world. As such many studies have been conducted and engineering innovations are at a very high level. (We have here what is called ´food-valley´ centered around the agricult. university of Wageningen). In general I wish there would be more student-exchanges for young engineers, and more cooperation on matters such as intellectual property rights, agricultural policy, between the U.S., the E.U. and most importantly: China. Because China is definitely the lowest hanging fruit: it will have a huge future problem with its nitrogen run-offs. From a nitrogen viewpoint there are 3 main routes towards a more sustainable, durable food-chain:

1 incease of the N-efficiency of production. By the use of better genetically modified races. By adjustments in agricultural management (mineral bookkeeping, guided fertilizing machinery, manure-processing installations on the premise of diaries and cattle farms combined with power production, more use of biological N-binding). By the growth of vegetables without the use of soil: hydroponics by computer controlled greenhouses that recycle the watersoluble fertilizers constanly.

2 A relocation of food production to regions that because of their climate and physical environment allows higher N-efficiencies to be achieved. In practice this means an end to all agricultural subsidies eg such as those for corn-ethanol.

3 Increase of the N-efficiency of consumption. By less protein consumption: U.S. citizens and North, East-Europeans are 30-50% above the daily recommended levels. By more consumption of proteins that can be produced with a higher N-efficiency, mainly vegetables, poultry, cheeses (an excellent way to store fat) and cultured fish at the cost of beef consumption. Here I see a great future for algae-based aquaculture (see: algaelink.com). Agriculture + Aquaculture = more Culture. Algae mass DOUBLES from 0.3 to 3 times a day, depending on strain selection. This means exponential growth, and by modular bioreactor expansion at ethanol fermentation plants, breweries, and clean powerplants, local markets everywhere in the world (where there is pure CO2) can be flooded with FRESH uncontaminated tuna, clams, lobster, trout, shrimp, mussels, salmon, carp, catfish, tilapia and of course: oysters. Enjoy your lunch.

NOx and N2O are quite separate issues. I will talk about one, NOx. Here is my breakdown on where the NOx is coming from in the U.S. (data about seven years old) Gasoline engines..........18% Diesel engines...............35 Power plants.................22 Process heat.................16 I think gasoline engines (mostly cars) are making great progress, and we can expect less use of gasoline engines in the future. So this matter is under control. I will offer ideas on the remaining sources. DIESEL ENGINES Thermodynamics created the problem (the heat engine) and I think we should look to thermodynamics for the solution. Above about 2200 deg K, NOx forms. Below 1900 K, it doesn't. It's generally believed that high temperature is needed to obtain high energy efficiency and good combustion efficiency. Going back and checking the thermodynamics, we see that it is not the source temperature that is essential, but the ratio of source temperature to sink temperature. And, this in turn is closely connected to the compression ratio. From this viewpoint, solving the NOx emissions of diesel engines seems simple-- keep the compression ratio high but devise to keep the local flame temperature low everywhere. The other issue is to maintain efficient combustion with a lower flame temperature. There are many possibilities here. (HCCI is sometimes mentioned.) I suggest reconsidering the type of fuel that is burned in diesel engines. Diesel engines can be operated on gaseous fuels (such as methane) with essentially no NOx emissions. But, I would hope that another fuel could be found, dimethyl ether being one possibility. In summary, the performance of the diesel engine can be maintained very high, but with very low NOx emissions, by redesigning the engine-fuel system. POWER PLANTS AND PROCESS HEAT At least for coal power plants, great efforts are being made to clean them up, and I can't see to add much there. But, maybe there is another approach. Could it be practical to work on capturing ALL of the remaining pollutants after they leave the plant? Why not? A couple of ideas-- We are having trouble finding enough productive land to meet our agricultural needs. Could we use the plant exhaust to provide a nutrient-rich "produce factory?" Here, you have heat, fixed nitrogen, moisture, and elevated CO2, just what every farm crop dreams of having. Some sunshine and minerals complete the farm requirements. Maybe biologists could work out an aquatic system that thrives on the plant exhaust. Growing algae for biofuel has been suggested, but there may be better possibilities. Most of what I've said about power plants could apply to process heat. Additionally, most process heat requirements are for temperatures below the NOx formation temperature of 1900 deg. K, suggesting research toward "very low NOx" burners.. Further, with some imagination, many process heat requirements might be met by solar heat. I appreciate what you are doing with this web site. GOOD JOB! Ernie Rogers

From the article: "In addressing the nitrogen cycle problem, experts must remember that fertilizers and farming have played a central role in boosting worldwide food production," Boosting food production provides more food at a discounted price. This low price and increased production creates hidden costs to society. We have more children because food is remains cheap and we are relatively oblivious to the costs imparted to the Earth, which it will not pay (we will later & highly taxed at that). I believe the lowest hanging piece of fruit is population control (education). This may not produce the quickest results, but the longer this is not addressed...the worse it will be....exponentially. I do not believe technology will have a chance to compete with the effects of growth and consumption. We are already well past the point of continuing our existence on the supplies the Earth has to offer. It will be "fun" and "interesting" to see what we, as a scientific community, create in coming years. Sadly, the destruction of the Earth due to overconsumption and destruction will overcome scientific novelties. Evan Larson, PE B.S. / M.S. Civil & Environmental Engineering 2003 Cal Poly SLO

Thermodynamics: Engineers know that a statistical interpretation of the 2nd Law of Thermodynamics implies that increasing the per capita ENERGY input to ANY system of entities (including human populations) results in increased ORDER or lower ENTROPY of that system. By this analysis the ONLY engineering solutions required for the N-Cycle problem are to use hot rock GEOTHERMAL power as the major metropolitan and industrial human power source, stabilise global population to between 6 & 7 billion people and use engineered wetlands to reduce raw wastes entering coastal seas by 75% of current levels, all within a decade. These INPUT, PROCESSING and WASTE initiatives all work synergistically to lower per capita ENTROPY. This is effectively a BRAIN BOOST for all mankind that will see the brain boost from the internet revolution pale. Although the term 'brain boost' is literary and widely derided, thermodynamic considerations dictate the reality of its existence. Simply put, the lower the entropy the units within a system are the longer the system takes to decay. The only way that can be in thinking units like hamans within civil populations is if INTELLIGENCE is correspondingly increased. I submit that this is at the root of the N-cycle problem and the only engineering solution required for the N-cycle problem to be solved within a decade. Geothermal considerations: Until direct extraction of energy from close orbits to the Sun is possible Geothermal power can be shown by thermodynamic analyses based on EMERGY (see dieofforg.com) to be THE ONLY SUSTAINABE power source. Power station construction times (@ 5Km depth) of between 6-9 months should be targetted within a decade. Laser drilling technologies MUST be used and perfected and any resistance to their use from competing OIL interests must be quashed. Population control: The concept of rights for the unborn must be reevaluated in light of the imminence of a PEAKOIL2025 chaotic meltdown possibly reducing human numbers to 2 billion impoverished people within 6 months of a PEAKOIL crisis commencing. A one child per woman policy Engineered wetlands: the final and perhaps the most important step in the Thermodynamic Cycle is the waste elimination. Engineered wetlands can replace all the wetlands destroyed in the last 200 years with less than 100th the acreage and many times the efficiency of using INSOLATION to slow-time convert wastes at BMP(Best Management Practice) to easily transportable waste streams, most of which will be reuseable. This is the most direct solution to the N-cycle problem as it will potentially capture through waterway ENDPOINTS nearly all of humanity's fixed-nitrogen waste. Plug the inequities of free enterprise capitalism: Inequities in existing capitalism models actively resist solutions to all 14 engineering challenges because those solutions present challenges to staus quo monopolies that have been carefully crafted over the decades since WWII. Unfortunately America is at the forefront of these ineqiuities and the aroma of straw(man) hangs over this engineering challenge accordingly. In short all CEOs of US companies must have salaries and remunerations legislated to be no more than twice that of elected government officials. This will allow free enterprise to thrive whilst removing corruption, monopoly, collusion and inequities that are holding back engineering and scientific breakthroughs in all 14 engineering challenges. Rather than reducing competition for talented executives, this US initiative would send a message to the rest of the world that corruption, the breeding of future Adolph Hitler CEOs beyond all government control and ensuing global warfare a la 'Omega Man' and 'Soylent Green' scenarios is the most serious threat to the sustainability of the human race over the next 2 decades. I chose the N-Cycle challenge to draw out this Thermodynamic Cycle approach because as a CYCLE it fits well with the entire concpt of life, death, preserving the collective historical OUTPUT of humanity and its future sustainability both on this planet and beyond.