Pneumatic Linear Generator

In this viedeo I build a pneumatically driven linear generator. You could blow the exhaust air from pneumatic systems into a generator. This would recover some energy. Compressed air is expensive.
The pneumatic linear generator is not fully developed. Some problems have been encountered. One of the main problems is the precision of a 3D printer.
I have built 2 versions. You can download all 3D printed parts. 20mm PVC pipes were used. The magnets have a diameter of 15mm.

Youtube: https://www.youtube.com/watch?v=LGedahiI3L4&list=PL9Jzxu1vDldPy2bK8hG3s78jLnHpclBQm