At the University of Konstanz, the International Office together with the student-run Sustainability Office (Green Office) and Student Council (StuVe) have been awarding sustainability travel grants for interrail tickets to Erasmus outgoings since 2017 - get inspired by these travel stories:
https://www.uni-konstanz.de/international-office/wege-ins-ausland/nachhaltig-reisen/
This page compiles sustainable travel reports to and from Konstanz as well as helpful links around "sustainable travel" within Europe.