El Prat airport may be a better option now that Hife are running at least 8 Buses from Tortosa (daily,but a few less at weekends) to Terminal 1.About Euros 20 for a one way ticket & Euros 30 for a return.Timetables record that driving time (From & to Tortosa) is about 2 hours as I assume they use the AP7.First stop after leaving Terminal 1 is l'Aldea train station or the AP7 Tortosa peatge.

http://www.hife.es/en/