Speaking at the event's opening address, Gabriel said although turbine and project costs had been reduced, the resources required to integrate wind power into the grid continue to rise.
However, the minister had encouraging words for the wind industry, which he described as the "backbone of the Energiewiende", Germany's push for renewables.
He said: "The efficiency of wind energy has increased to the extent that no one would have thought possible two years ago."
Interestingly Gabriel made the point that the country's push for wind power was in order to replace nuclear power. The environment and the reduction of carbon footprint was not the main factor in the decision.
This is the first year the event is being held in Hamburg since it was moved from Husum in northern Germany. In a conciliatory gesture, Gabriel credited Husum with having nurtured the event through the early days of wind power.