Like, image some county that needs energy, has no natural gifts regarding that but has land to farm upon. Instead of exporting food and importing coal from somewhere to fire up a new plant, it could also exchange energy with a more gifted county that has plenty of green energy but doesn't need something from them.

To make this work, a higher level entity can force the exchange, and ensure that the whole area doesn't suffer from pollution despite that being the cheapest or even only possible way for the individual county. It COULD be solved there, but everyone is worse off by not cooperating.

Actually, the EU has a huge power potential if only the member states would finally cut back on individual national interests so that mutual agreements and shared legislation/taxes/military/... could be setup properly - which might worse some situations in the short term, but ensures greater wealth for everyone longterm. The "I I I" egoistic thinking of individual member states is the greatest weakness the EU has - unified we can achieve so much more!