You can send documents via PEPPOL using Tradeshift's PEPPOL Access app. You can use the app with a GLN (Global Location Number) or EAN (European Article Number, also called International Article Number). You can purchase a GLN from GS1. 

The receiver must be registered at one of the PEPPOL service providers with one of its business identifiers (GLN, VAT, etc.).

You can read more about PEPPOL here.