I thought that it was possible to travel in the EU with a national identity card rather than a passport. However, some friends in Denmark say that is no longer true and they need a full passport even to go to Sweden. Is this so? I have not heard it from other sources.
I had just started to travel in the EU with my Irish passport card and I have had no serious problem yet. I even went to Denmark with it but since I changed planes in Amsterdam, I did not need to show it in Copenhagen.
Denmark has never issued ID cards of the kind that some other EU member states do. This is why a passport is the only option for Danes traveling within the EU.
If Denmark chose to start issuing such ID cards, they would be valid for travel to other EU member states too.
What is new(ish) is that citizens used to be able to travel between the Nordic countries with neither passport nor ID card. This ended several years ago when Sweden introduced (now irregular) ID checks at the border to Denmark.
It has always been the case that Danes were supposed to carry passports when traveling outside the Nordic countries, such as to Germany. After we joined Schengen, passports are not checked systematically when entering Germany, but many people seem not to know that they are still supposed to be able to show them if they're stopped by German police inside Germany.
Your passport card remains fully valid across the EU/EFTA (and most other European countries for that matter). Your Danish friends say otherwise because Denmark has never even had a national ID card, and so they cannot relate to this.
