Tractors with selective catalytic reduction (SCR), such as this Massey Ferguson 8680 Dyna VT, have an additional tank for diesel exhaust fluid. This tractor was the first profi tested that was outfitted with SCR.
To meet Tier 4 Interim regulations, the ag equipment industry has introduced two strategies to lower emissions: selective catalytic reduction (SCR) and exhaust gas recirculation (EGR) particulate filters. All self-propelled equipment 174 hp or greater are outfitted with one of these options as of January.
The big questions surrounding the new technologies are how to decide between the choices, how to operate equipment with these systems and what’s coming next?
Pluses and minuses. Both strategies have advantages and disadvantages. When using SCR, the engine and the process of burning fuel are free of restrictions and optimized to use the best fuel efficiency (similar to Tier 0) because the emission cleaning happens behind the engine in the catalyst process. On the flip side, you need diesel exhaust fluid (DEF), which is based on urea,
in a second tank on the tractor and stored on the farm.
The EGR system, used in Tier 3, has an additional particulate filter and regeneration to comply with Tier 4 Interim. This system is used by Caterpillar, Cummins and John Deere. With EGR, you do not need DEF. The disadvantage is that the engine is similar to Tier 3: still optimized for emission savings, but not for fuel efficiency. Technically, the particulate filter needs to be cleaned and regenerated every now and then (under normal working conditions, the driver will not even notice the automatic process).
Because the first tractors with SCR technology have been available for 24 months, profi has already tested the technology. In the initial tests, fuel use was significantly lower, generating 10% in savings.
The additional use of DEF varies between 3% and 7% (DEF is cheaper than diesel, at least in Europe), which is why SCR receives a plus for better efficiency than the Tier 3 systems. John Deere says its EGR technology will match the results of its Tier 3 systems.
On-farm performance. How do you operate equipment with these technologies? The response from farmers has been, “I don’t need it, I don’t want it, I hate to deal with it—but I have to!” Engine manufacturers say the price for an engine tripled from Tier 0 to today’s Tier 4 Interim technologies. All farmers pay for the emission technology, and many customers spend $1,000 on aftermarket purchases to tune the machine and get rid of the systems, which slows the engine power down and raises fuel consumption.
To complicate matters, there are two ways to hold out on Tier 4 a little longer: bunkering (legal and done by manufacturers) or tuning (not legal in the U.S.).
With bunkering, the manufacturers were allowed to buy Tier 3 engines before Dec. 31, 2010, to outfit on machines for the next 24 months. This means some manufacturers will have enough Tier 3 engines bunkered to offer Tier 3 models in 2011 and even in 2012.
The idea of tuning SCR systems to run without DEF comes from Europe. Even though you’ll hear about it, tuning isn’t an option for U.S. farmers because it is mandated that the tractor loses about 30% of its horsepower as soon as the DEF tank is empty.
When purchasing new machines, don’t base your decision solely on emission technology. Both systems comply with legal regulations and both can muscle field work. More important are machine functions, options, dealer support and price.
What about the future? With engine emission regulations, there are three important points to remember:
- Currently, Tier 4 Interim emission regulations apply for engines above 174 hp. They extend down the power range in 2012 and 2013.
- Above 174 hp, Tier 4 Interim regulations are valid until Tier 4 Final starts in 2014. Experts used to believe the strategies used today (SCR and EGR with particulate filter) would be combined for Tier 4 Final. That’s not the case anymore.
- Tier 4 Final will require engine emissions to be cleaner than incoming air. In 2014, we’ll basically be using air cleaners on our farms.
- February 2011