Known also as an Ultra Low Emissions Locomotive (ULEL), the GenSet engine was the brainchild of Mike Iden of the Union Pacific. Looking to reduce fuel consumption and emissions, Iden envisioned a diesel locomotive with multiple engine/generator sets, each of which would turn on only when needed. Working with diesel builder and remanufacturer National Railway Equipment, Iden created an experimental prototype that proved its worth in 2005 and spawned a new type of road switcher - the ultimate "smart" locomotive.