I suggest this idea because electricity is major block for development of human civilization.

In infra i suggest power plants like: geothermal, solar, wind, coal, petrol, tidal, etc.

These are things which produce electricity but the thing is how to reach destination is by make network of high tension tower which will be joint to substation. 

If power generation is OK there will be normal production, then production increase in industrial sector and mining,  and little increase in income.

If power production is high then growth of industrial and mining production will increase to high.

If power production is below demand then it will effect stability and decrease the production.

To trade electricity the two civ have to accept deal and then we have to make project in it high tension tower and substation will be built to border and dealing country will do same.

The deal will be like:

1kilo watt per turn =10 gold

We will get gold when electric supply will be provided.

It will be benificial to civ cannot afford war or not interested in war or can be better option for more economical advantage than buying resource.

Beware: If relation get detiorated the civ can stop transmission or change price or can be destroyed by other civ.