Selective Catalytic Reduction Technology (SCR) for Tier-4 compliant diesel engines in construction machinery continues to grow. Its time surely has arrived with equipment manufacturers incorporating it into their products.
Simply stated, SCR reduces the formation of particulate matter in the combustion chamber by using diesel exhaust fluid
(DEF), a liquid reduction agent, to treat exhaust gases. This helps eliminate pollutants and increase engine efficiency.
According to EPA, more than 738,000 tons of nitrogen oxides and 129,000 tons of particulate matter will be eliminated by 2030 through Tier-4 compliant engines making SCR a long-term advantage for manufacturers and end-users mandated to reduce pollutants.
Frank Raczon, senior editor of Construction Equipment magazine and a writer for the publication's "Big Iron" blog, discussed the future of the technology in equipment.
“Some construction OEMs are already putting SCR engines in equipment for Tier 4-Interim and in advance of Tier 4-Final, which hits the 174-hp band next year, and the 75-174-hp band in 2015,” Raczon said.
Case Construction Equipment is a prime example with CAT, Deere, Volvo, JCB and others having introduced SCR to their lines. “Case’s larger wheel loaders, new large dozers, and larger excavators are already using SCR with diesel exhaust fluid
. Other OEMs and engine makers have announced they will use SCR technology either exclusively or as a part of their Tier 4-Final solutions,” according to Raczon. “You will really see it come into play in 2014-2015, particularly in the larger-horsepower units.”
Brad Stemper, solutions marketing manager for Case, is a noted authority on SCR. In an article on PitandQuarry.com, Stemper wrote, “Tier-4 mandates are a hot topic of conversation everywhere, from equipment dealer halls to quarries and loading yards.”
A legitimate concern of most maintenance shop supervisors is the effect of SCR on maintenance costs, fuel usage and types of engine oil. In Equipment Manager, the Association of Equipment Managers (AEMP) publication, Stemper said, “Maintenance for SCR machines is easier than most fleet managers could ever have anticipated.”
Furthermore, Stemper states, “Equipment managers will notice little change in the cost or complexity of maintaining SCR-equipped machines;” adding “machines will continue using standard oils without any concern for switching to low-ash oils or other more expensive formulations. Fuel usage is not an issue because SCR engines do not require any special fuel.”
On SCR’s future, Stemper said, “Preconceptions about SCR and the hassles of adding DEF will fade away as regeneration becomes a thing of the past, as fuel efficiency improves and as wheel loaders perform with strength and without hesitation.”
Potential barriers to increasing SCR-equipped machines include the continued lag in construction activity inhibiting sales of new equipment to replace existing fleets, and a traditionally slow-to-adopt end-user market.
Evidence shows that the technology will not add significantly to routine costs.
Mike Porcaro served as publisher of Construction Equipment, Better Roads, and Aggregates Manager magazines. He covers advances in the construction industry