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A New Food/Fuel Issue: Urea for SCR Emissions Treatment?
16 November 2008
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| A urea-based SCR system on a heavy-duty truck. Click to enlarge. |
Increasingly stringent emissions requirements are resulting in a surge of applications of urea-based selective catalytic reduction systems in new diesel trucks, buses, cars and sport utility vehicles to reduce NOx to permitted levels. For example, urea-based systems will become standard equipment on most new diesel trucks, buses, sport utility vehicles (SUVs) and many cars for the US market after 2010. Already prevalent in heavy-duty vehicles in Europe, urea-based systems may be applied to meet coming Euro 6 requirements in lighter duty vehicles in Europe.
The automotive urea fluid, called diesel exhaust fluid (DEF) in the United States and AdBlue in Europe, is an aqueous urea solution 32 (AUS 32), a clear 32.5% nitrogen solution of high-purity urea in demineralized water. The SCR systems are thus creating a new demand for urea, the world’s most widely used nitrogen fertilizer. Worldwide use of urea as a nitrogen fertilizer and feed additive has increased more than 100-fold in the last four decades, with a doubling in just the past decade alone, according to researchers in a paper published in the journal Biogeochemistry in 2006.
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| (a) The change in world consumption (million mt of N) of total synthetic nitrogen fertilizers (solid line) and urea consumption (solid bars) since 1960. (b) Same data as in panel (a) with the fraction that is urea displayed as a percentage of the total nitrogen fertilizer. Click to enlarge. Source: Glibert et. al. 2006 |
(The concern in that paper (Glibert et al.) was that the surge in urea applications was contributing significantly to coastal eutrophication—the creation of dead zones.)
As late as the 1960s, urea represented only about 5% of world nitrogen fertilizer use. However, urea usage escalated in the 1980s, such that it represented about 40% of global nitrogen fertilizer by the early 1990s, and soon thereafter urea surpassed ammonium nitrate as the most common nitrogen fertilizer. It is now estimated that urea represents >50% of world nitrogen fertilizer. Assuming urea consumption continues at 5% year-1, as projected for many parts of the world, urea consumption may reach 70% of total nitrogen use by the end of the next decade: this is a dramatic global change in the composition of nitrogen applied to land throughout the globe.
—Glibert et al. (2006)
Some are now concerned that the automotive use will drive fertilizer prices higher. Others think it will be an incentive for manufacturers to increase production and thus, lower prices.
More than half a million diesel trucks in Europe now use urea SCR and the fleet is growing by about 25,000 trucks per month, according to Integer Research, a London-based market analysis firm specializing in urea SCR.
Kim Doran, spokesperson of the newly formed North American SCR Stakeholders Group says that SCR technology is being adopted by passenger car and light truck manufacturers serving the United States including Audi, BMW, Hyundai, Jeep, Kia, MiniCooper, and Volkswagen. Mercedes-Benz is introducing three new diesel-powered SUVs that use urea SCR technology into the United States in late 2008. Urea SCR is also used in Japan and Singapore and will soon be used in China.
Manufacturers in the commercial trucking industry adopting SCR include Freightliner, Kenworth, Mack, Peterbilt, and Volvo. Leading engine manufacturers using SCR include Cummins and Detroit Diesel Corp.
Consumption of the urea solution is about 3% of the diesel consumption. Diesel trucks average 6.5 miles per gallon (2.8 km/liter). An average diesel truck will need to refill its 20-gallon tank of DEF every 4,000 to 6,000 miles (76 liters every 6,400 to 9,600 km).
Urea to reduce NOx emissions now consumes 0.3 to 0.4 million metric tons (mt) of urea in Western Europe, says Stephen Zwart, Licensing Manager of Netherlands-based Stamicarbon, the world’s largest licensor of urea plant technology. In 10 years the current truck fleet in Western Europe will have been replaced, and urea use will be 3 to 4 million mt.
Future urea demands generated by SCR technology in the United States have been calculated by Dr. Carlos Baanante, International Center for Soil Fertility and Agricultural Development (IFDC) Agricultural Economist. In 2003, 213 billion liters of diesel fuel were used for transportation in Europe and 146 billion liters in the United States, according to EarthTrends, an initiative of the World Resources Institute. Baanante assumes that only 7% of the diesel trucks in the United States will use urea SCR in 2010—the new trucks purchased that year.
US urea consumption for transportation will probably be the urea fertilizer equivalent of about 210,000 tons in 2010—but will be at least double that amount in 2011 and will increase rapidly afterward as older trucks are replaced with newer models that carry urea tanks.
—Carlos Baanante
The estimates assume that a liter of the solution weighs about 1 kg and the urea fertilizer contains 46% N, Baanante explains. Thus, 1 kg of urea solution would consume the N needed to produce 0.7065 kg of urea fertilizer. A conversion factor of 0.7065 is used to calculate urea solution consumption in terms of mt of urea-fertilizer equivalent.
Baanante points out that more than 90% of the world’s urea production is for fertilizers—but notes that the new demands for urea SCR may change that. Urea is also used in animal feed, plastic and glue manufacture, highway de-icing, cloud seeding to induce rain, and tooth-whitening products.
Doran of SCR Stakeholders says that demand for AUS 32 for automotive applications is not expected to exceed 5% of the world’s production, and notes that the use of urea to control vehicle emissions could lead to increased investment and expand world capacity for urea production. However, Keith Stokes, proprietor of Stokes Engineering and IFDC consultant on urea production, says, that urea for NOx reduction will create a new demand that could drive up fertilizer prices.
In Europe, AdBlue prices have almost doubled since mid-2007 and producers are finding it difficult to absorb cost increases for urea, according to an 18 July report in Today’s Trucking citing Integer Research. “Add the fact that producers are getting better returns on urea when it is sold as fertilizer, and no wonder that prices have driven up,” the report stated.
Traditional fertilizer manufacturers will probably produce most DEF urea used in the United States. Producers in the SCR Stakeholders Group include Agrium, Brenntag North America, Dyno Nobel, Koch Industries, Potash Corporation of Saskatchewan, and Terra Industries.
The new demands for urea to treat diesel exhausts will make research to improve the efficiency of its use as a fertilizer even more important. IFDC works in three main areas to increase the efficiency of urea use: through deep placement of urea briquettes, especially in irrigated rice fields; through controlled-release fertilizers; and through nitrification and urease inhibitors that decrease nitrogen losses to the air through volatization and to groundwater through leaching. New urea plants are also being built. For example, two large urea plants are opening in Iran and one each in Egypt, Nigeria, Oman, and Russia.
—Ramon Lazo de la Vega, IFDC Senior Engineering Specialist
The manufacturing process. The commercial production of urea began in the 1920s, following the development of the Haber-Bosch process for the synthesis of ammonia. (Haber filed his original patent on ammonia synthesis in October 1908—this year thus marked the centennial of that event.) The Haber-Bosch process (invented by Fritz Haber and commercialized by Carl Bosch of BASF) synthesizes ammonia at high temperatures (350-550° C) and pressures (150-350 atmospheres) from atmospheric nitrogen (N2 and hydrogen (H2) (produced from natural gas) with an iron-based catalyst.
Haber-Bosch—which has been called perhaps the most important industrial process ever developed and is responsible for a dramatic increase in the population of the earth during the 20th century (Smil, 1999)—is a high-pressure, high-temperature process, and accounts for an estimated 1% of total global energy consumption.
Urea production also consumes large amounts of energy. Urea is produced by reacting carbon dioxide with anhydrous ammonia under high pressure at high temperatures.
Most basic fertilizer products used today—including major improvements of farm-use urea—were developed by the fertilizer program of the US-based Tennessee Valley Authority (TVA) in the 1950s to 1970s when energy seemed cheap. With current manufacturing technology, the energy equivalent of four barrels of oil is used to convert ‘free’ atmospheric nitrogen to 1 ton of urea. The new demands emphasize the need for research to develop a new range of more energy-efficient technology—not only for food but now for use with fuel.
— Dr. Amit Roy, President and CEO IFDC
Resources
Patricia Glibert, John Harrison, Cynthia Heil and Sybil Seitzinger (2006) Escalating worldwide use of urea—a global change contributing to coastal eutrophication. Biogeochemistry 77: 441–463 doi: 10.1007/s10533-005-3070-5
Vaclav Smil (1999) Detonator of the population explosion Nature 400, 415 doi: 10.1038/22672
November 16, 2008 in Emissions | Permalink | Comments (25) | TrackBack (0)
Comments
Posted by: | November 16, 2008 at 08:58 AM
its good that big companies do care about nature, just like Volkswagen every car they sell a new tree is planting in the ground so they keep nature in balance.
Posted by: CrateWasher | November 16, 2008 at 09:03 AM
I have hard time to imagine that the urea consummed for cleaning diesel exhaust can be significant comapared to fertilizer use, I might be wrong but I'd like to see the numbers which they fail to give in this article. But anyway they won't be any way out without energy conservation, increase of fuel efficiency. Use more rail than truck wherever is possible in the first place.
Posted by: Treehugger | November 16, 2008 at 09:30 AM
BTW in addition to the above uses, ammonia can be used as a fuel.
Ammonia was used during World War II to power buses in Belgium, and in engine and solar energy applications prior to 1900. Liquid ammonia was used as the fuel of the rocket airplane, the X-15. Although not as powerful as other fuels, it left no soot in the reusable rocket engine and its density approximately matches that for the oxidizer, liquid oxygen, which simplified the aircraft's design. Ammonia is proposed as a practical and clean alternative to fossil fuel for internal combustion engines (the combustion products are nitrogen and water) and can even be used in fuel cells. In 1981 a Canadian company converted a 1981 Chevrolet Impala to operate using ammonia as fuel. The use of ammonia as fuel continues to be discussed.
The calorific value of ammonia is 22.5 MJ/kg (9690 BTU/lb) which is about half that of diesel. In a normal engine, in which the water vapour is not condensed, the calorific value of ammonia will be about 21% less than this figure.
Side note: Some years ago I heard one guy propose using ammonia as fuel as a way to use more solar and wind energy; solar and wind energy can not be used in large percentages in the electrical grid because they are not 'load following' but a process of making ammonia from N2 in the air and H2 from water could 'follow the supply' of energy.
Posted by: ai_vin | November 16, 2008 at 12:57 PM
As T. Boone Pickens has been telling us we could free up natural gas supplies by not using it to generate electricity. More would then be available for nitrogen fertilisers like urea and for CNG truck fuel which has lower NOx anyway I believe. I suspect that petro-diesel has only got maybe five good years left. Biodiesel will always be limited (algae notwithstanding) and for some reason Choren type BTL diesel isn't scaling up. The problem will solve itself though not in a nice way.
Posted by: Aussie | November 16, 2008 at 01:13 PM
It would be a pissing shame to waste Urea ;-)
Posted by: DS | November 16, 2008 at 01:17 PM
Actually, diverting the output from stadium and pub urinals has been discussed...it doesnt seem right to let a relatively easy collection go down the drain.
Posted by: fred | November 16, 2008 at 01:41 PM
@Aussie
You could "free up" even more NG by moving away from fossil fuel powered cars. NG powered cars aren't the only ones that use NG in their engines; in a way, they all do. The oil industry uses natural gas as a hydrogen source and use the H2 to change the properties of the refined oil. I believe they also burn NG as a heat source in the refining process itself.
Posted by: ai_vin | November 16, 2008 at 03:05 PM
This article is so much nonsense. What about all the urea from pig farms in South and North Carolina that is stored in open reservoirs and holding ponds. There is so much of the stuff it's becoming a health hazard.
Posted by: Mannstein | November 16, 2008 at 04:12 PM
Current ag nitrogen demand is a little over 90 million ton total N per year. China is the largest consumer followed by the US. Ag N demand in 1980 was about 60 million tons total N/year. Current anhydrous ammonia production is about 180 million tons NH3/year (82% N). Depending on size and technology of an ammonia plant it takes approx 32 to 36 mmbtu of natural gas to make a ton of ammonia (NH3.) For each ton of NH3 produced, approx one ton of CO2 is produced. So both feedstock for urea production are outputs of an ammonia plant Urea is 46% N. Urea is highest concentration of N i a sold form. In the last twenty years ammonia production has continued to shift from destination (US) to low cost natural gas (captive gas, ie Trinidad, Arab Gulf). The price of urea has recently dropped from $800/ton to $275/ton
Legumes (ie soybeans) don't need nitrogen fertilizers as they receive N from N fixing bacteria (rhizobia) that live (symbiotic) at their roots. The implications of N fixation for corn would be huge.
I don't think AdBlue makes much of a dent in urea production however packaging, distribution, and controls present challenges. Its not a very elegant solution.
Posted by: Tom | November 16, 2008 at 05:15 PM
I think one point mentioned but passed over is the potential for this fertiliser to contribute to ocean dead zones. It is unclear whether the compounds emitted are likely to dissipate to the atmosphere and possibly fall with rain or if the compounds fall to ground near to the source.
While some forms of nitrogen are useful for enhancing plant growth it does not follow that continuous unregulated dispersal is a benefit. Water storage areas -rivers dams lakes and seas generally don't respond well o nitrogen inputs and along with phosphorous are major polluters.
Also nitrogen can dramatically alter the balance of vegetation towards rapid growing weed species and alter the growth rate and health of indigenous specie..
NOx are also a 310 * greenhouse gas.
Posted by: arnold | November 16, 2008 at 05:17 PM
If the NOx are reduced to N2 (a gas) and disperses into the atmosphere wich is 78% N2 then its hard to see it causing pollution problems.
Otherwise as stated it may or not increase the cost of fertilizer.
Posted by: arnold | November 16, 2008 at 05:50 PM
In a prior article, a system was shown that makes hydrogen and CO from diesel and recycled exhaust to reduce the the NOX. It is hoped that this system will replace the Urea method soon. ..HG..
Posted by: Henry Gibson | November 16, 2008 at 09:56 PM
The NXTgen system may eliminate the need for Urea ..HG..
Posted by: Henry Gibson | November 16, 2008 at 10:39 PM
This is funny. Our collective ability to produce urea which is a by product of urine has become a food or fuel issue. Hey! Just. Figure. out. a. way. to. collect. more. of. our. urine! Sheesh!
Posted by: Gerald Shields | November 17, 2008 at 01:43 AM
Interesting. Now, if you'll excuse me, I have to take a leak.
Posted by: Cyril R. | November 18, 2008 at 01:49 AM
Ok, bear with me, everyone to the loo, right now! We have to solve this problem together!
Yes, we can!
Posted by: | November 18, 2008 at 01:51 AM
a bit off-topic but ai vin said:
"solar and wind energy can not be used in large percentages in the electrical grid because they are not 'load following'"
I wonder about this. Couldn't the average homeowner or business who has a roof covered in solar panels who is selling that excess power to the grid also have a lead acid battery storage system, and receive signals over the internet about the status of the current grid energy demand and use this to either 1) sell electricity to the grid or 2) charge their batteries for future use.
This could make solar and wind a major part of the grid power. The base load is powered by unresponsive large wind and solar farms in the Nevada desert, and the remaining fine tuning is done by buying it from home owners whose rooftop systems can be turned on or off via the web.
Posted by: Mark_BC | November 18, 2008 at 08:54 AM
al_vin is certainly correct that wind and solar are not load following. Output has little or nothing to do with demand. Power si generated when the wind blows or the sun is not obscured by clouds,and not as the demand for power changes.
But that is only one drawback to the use of these phony renewables in large amounts. Their intermittent output disrupts and destabilizes the electrical grid leading to large oscillations in power outputs, that threaten transformers, generators and grid stability itself.
T Boone Pickens has discovered the detrimental effects of renewables on his Texas grid stability, and now has spent almost 50 million in adverts to gert you to bail out his renewable Texas wind farms from economic disaster...
For those that think they can always sell daytime solar to the power company and buy power to charge their PHEV at night, they are dreaming. The power companies pay well when they need it, and pay less or nothing at all, when they don't. If load demand shifts to night with the coming of PHEVs, your solar installation will be junk.
Posted by: stas peterson | November 18, 2008 at 09:46 AM
@stas
"if" is a big word. It will be a long time before you get to that state. Germany gets 15% of its electricity from "phony renewables" where America only gets 2% so your grid is safe and will be for a long time. And by the time you are generating so much "phony renewable" power that the current grid would be threatened - well it wont be the 'current grid' anymore, will it?
Posted by: ai_vin | November 18, 2008 at 12:35 PM
@Mark_BC
“Couldn't the average homeowner or business who has a roof covered in solar panels who is selling that excess power to the grid also have a lead acid battery storage system….”
Mark you could spend $50k on a system that would might have 2 kw extra for 4 hours on a sunny day. That would be 8 kwh extra to sell. This would allow you to make 80 cents a day. If the state mandated a ceiling of 10 times the average cost of making electricity, which would be $8 a day.
Contrary to what some will have you believe, electricity is a very cheap commodity. It is not possible for you to make your electricity cleaner, safer, or cheaper than your utility does.
Posted by: Kit P | November 18, 2008 at 01:26 PM
Also, 'intermittent output disrupts that destabilizes the electrical grid leading to large oscillations in power outputs, that threaten transformers, generators and grid stability' are already a big part of a utility manager's life. If they can handle the variables of demand why can't they handle the variables of supply?
Posted by: ai_vin | November 18, 2008 at 02:20 PM
Cogeneration heat and power is capable of producing electrical energy at <.05 cents per kWh. To rely on single point energy and old fashioned grids is a recipe for petroleum-type failure.
Posted by: sulleny | November 18, 2008 at 11:01 PM
@sulleny
Not that cogeneration is a bad idea, but apparently sullenly is clueless about the limitations of CHP.
As I stated before, I am big advocate utilities producing electricity because the clueless are so bad at doing it. So sullenly, how is your system working? What is the fuel source? What did it cost? What are the O&M cost? What are the safety issues? Does it make lots of noise that might bother your neighbors? What are the environment issues associated with millions of point sources?
What is old fashioned about the grid? It works very well for me, allowing many sources of electricity to ensure reliable power that would be the envy of most of the world. I do have a plan for a hurricane or ice storm that does not depend on government.
What petroleum-type failures are you talking about? It is hard to understand why discussions of transportation fuels get mixed up with producing electricity other than the general lack of education on energy issues.
Back to urea, if sullenly has more than 1000 dairy cows and uses lots of propane to make hot water; then he can make electricity at close to 5 cents per kwh. Sullenly will then need to obtain bank financing for several million dollars. Here is the catch. Anyone with 1000 dairy cows understands risk and benefits. So how much will the added risk of making electricity result increased profits? Generally not enough to accept the risk.
Posted by: Kit P | November 19, 2008 at 06:28 AM
One way to reduce the intermittency risk of wind turbines is to collocate them with or nearby hydro plants and/or power lines.
1) Install as many wind turbines as required to meet 100% of the base load. Use 100% of the wind turbines production at all times.
2) Reduce or increase water turbines production to meet peak loads and to replace wind turbines whenever wind energy is low. Accumulate water in the huge reservoirs when water turbines run at reduced power or are not needed. There is no need to pump water back into the reservoirs.
In other words, the huge water reservoirs are used as energy accumulators (batteries) and very effectively used during peak demands periods and when wind in low.
Since water usage would be reduced by whichever power in produced by the wind turbines, extra water turbines could be installed to maximize the combined power plants total power production and availability.
Wind variability would have no effect on the power availability.
The Labrador and Hudson Bay coasts have high quality winds and could be equipped with up to 30 000 very large wind turbines + another 30 000 to 40 000 mega-watt of new hydro power. That would be enough to supply 60 + million PHEVs and/or BEVs.
Note: Increasing base load with night time recharge of PHEVs and BEVs would in fact increase base load and justify the installation of more wind turbines
Posted by: HarveyD | November 19, 2008 at 09:27 AM
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If we want to discuss wasted dollars - let's look at money given in grants to organizations paid to find and promulgate controversy. Hence the state of global economy.
Good thing the story on nitrogen fixing cyanobacteria arrives in a curiously synced time frame.
http://www.greencarcongress.com/2008/11/newly-discove-1.html