Report to a moderator

I agree that the idea is not absolutely new, but it is still a great idea.

Small wind is much more expensive than big wind indeed, but thausands of these smaller Savonius turbines would cause NO Nimby whatsoever, on existing, grid-connected, highway-side streetlight poles (of which Belgium must have millions).

I don't think your design here can produce 2,5kW though. The swept area is simply too small, but even if it's only 500W a piece, it's still a good idea.

In light of Mollie's remark, i.e. the pole was not designed for these loads: small VAWT's don't produce a lot of electricity, so they also don't load the substructure much. The extra loads might very well be within design margins. If not, possibly a small alteration at pole-foundation level might do the trick.
Maintenance is not an issue at all: first, such devices are usually made maintenance-free, like small marine wind turbines, and second, it seems that the whole device could made so to slide down the pole when needed.

So go for it Jonas!
(but do correct match and don't ignore physical reality)