About 50 on-island DEF dispensers are planned for TravelCenters of America locations nation-wide in 2011. TravelCenters of America LLC (TA) has installed an on-island DEF dispenser at both its Kingman, Ariz., and Spokane, Wash., Petro locations. These become the third and fourth at island locations launched within the last 30 days. TA expects to install…