What Is a Urea Tank?

Diesel engines have become more environmentally friendly.

Urea, as you might guess, comes from urine. More specifically, protein consumption leads to urea production. Kidneys filter from urea from the body. Urea tanks will be mandatory on all diesel engines made in the United States starting in 2010.

Purpose

Urea binds with the nitrogen oxide emitted by diesel engines, thus reducing diesel emissions responsible for smog and respiratory illnesses such as asthma.

Effectiveness

According to a spokesperson from the Selective Catalytic Reduction Stakeholders Group, urea tanks reduce the nitrogen oxide produced by diesel engines by as much as 90 percent.

Use of a diesel particulate filter can further reduce emissions to almost 100 percent.

Problems

Urea tanks must be filled every 10,000 to 15,000 miles, depending on the maker.

When the tank is empty a safety mechanism prevents the vehicle from starting, and some makers have not included a urea gauge to indicate urea level.

Most automobiles with urea tanks do have a warning system in place, but the system doesn't allow the level of awareness that a gauge would provide.

Production

Urea can be manufactured industrially by using ammonia/carbon dioxide technology. Under pressure and under high temperatures, ammonia and carbon dioxide react creating ammonia, ammonium carbamate and urea. The urea is crystallized and removed, and the ammonia and carbamate are recycled into the reactor.

Risks

Urea is a toxic chemical. Exposure to urea crystals can cause burning in the throat and lungs. Furthermore, urea is combustible. (Gasoline is both toxic and combustible as well when mishandled.)

References

• Bio-Medicine
• The New York Times
• The Washington Post

Resources

• Read this Article in Spanish
• ICIS