LOGAN, UT – Utah State University officials said they are happy with the school’s fleet of nine natural gas-powered buses, but the school is getting rid of seven natural gas-powered trucks, according to The Salt Lake Tribune. USU first began using both types of vehicles in the 1990s.

USU’s director of business services for the facilities department, Eileen Campbell, said problems with the trucks began almost immediately. They did not prove reliable, and the tanks took up a lot of room in the truck beds, according to The Herald Journal. Campbell also said just putting natural gas in the trucks was time-consuming and touchy: If the fuel was put in too quickly, air would get into the tank.

USU started returning the trucks this year to the state government, which leased the vehicles to them in 1998. USU is choosing standard gasoline vehicles to replace them for now — though it will consider using hybrid trucks or golf carts in the future.