Have I been doing something incredibly stupid all along? I thought refineries were a good thing. :l
I'd like to hear more about this also. I seem to see the refineries as a big prize, and they've helped me get out of a scarce resource situation (other empire had most of the volcanic/metal planets).
In practice trade ports almost in every occasion give more money, and cheaper to build, and it is better to buy resources from the black market due to your extreme credit income if you have swarms of trade ports.
To elaborate on Turchany's point, refineries have four huge weaknesses that make them inferior in almost every way.
A. They're more expensive and harder to research than tradeports.
B. There is a fixed limit on the number of refineries (resource asteroids can only be serviced by 3 or 4 refineries). There is no diminishing returns whatsoever on tradeports.
C. Refineries only provide good income when you have a lot of adjacent resource extractors. So unless your planet is connected to several planets with 4 extractors, it is unlikely refineries will ever be better than tradeports. Tradeports meanwhile are good on most planets (save the unusual case where building a tradeport will reduce your longest trade chain, or if a planet has a bonus that reduces trade income, but usually you don't have to worry about such things).
D. Even if you have a planet where refineries would provide more income, refinery growth only increases linearly as your empire expands. Tradeports income expands exponentially as you add more planets to your Empire's trade route (the longer the trade route, the more each trade port produces), so that eventually even on a planet perfect for refineries, tradeports will still become better with a long enough trade chain.
Thus while there are some specific circumstances where refineries maybe more profitable, these situations are so rare that for the average players its better just to always build trade ports for credits and to then use the credits on the black market.
