The TYNDPs are infrastructure development plans to ensure a coordinated pan-European approach to electricity and gas grid development, drawn up by ENTSO-E and ENTSOG respectively.
Regulation ( EU ) 347/2013 requires that ENTSO-E and ENTSOG use scenarios for their respective TYNDPs. TYNDP 2018 was the first time ENTSOG and ENTSO-E cooperated jointly on scenario development and this cooperation is now a requirement.
The TYNDP is published every two years. The current TYNDP reports can be found here (electricity) and here (gas).