Complex sentence: From 2001 to 2005, Vectren installed four selective catalytic reduction (SCR) devices on all of the coal-fired units, which successfully cut nitrogen oxide emissions by 80 percent.
Split into simpler sentences: From 2001 to 2005, Vectren installed four selective catalytic reduction (SCR) devices on all of the coal-fired unit. The project successfully cut nitrogen oxide emissions by 80 percent.