Hartmut Alder has been Ortsheimatpfleger for Salzgitter-Thiede since 1987. His fascination with local history began with a box that his grandfather kept locked in the hallway for a long time. When he and his sister opened it, they found, among other things, eight old postcards with pictures of the Thiede district. His wife inspired him to create his first exhibition of city views of Thiede. Over the course of more than 30 years as Ortsheimatpfleger, he has amassed a collection of around 120 files and over 5,000 pictures on the history of Steterburg, Thiede and the "Hütte". This has resulted in over 20 publications. In countless projects and lectures, he conveys history in a tangible way and takes his listeners on a journey through the history of the city of Salzgitter. Among other things, the "Green Path" in Thiede, the signposting of the Thieder Lindenberg with an information board and the publication of a nostalgia calendar of Thiede together with Klaus Harenberg are all thanks to his commitment.

Harmut Alder has also been active in local politics on a voluntary basis for many years. He has been involved in the Nordost local council for around 23 years. He was its mayor from 2013 to 2016. Since 2011, he has also contributed his historical expertise as a councillor on the Salzgitter City Council and, since 2016, as Chairman of the Urban Planning and Building Committee.