(Taken directly from the Codex for filler purposes)
Economy
Upgrading economy increases your daily income. For each point of economy you have on a star, you will earn an extra $10 per day. The standard price for an economy upgrade is calculated as
When a star is captured, the Economy of the star is destroyed. The conqueror receives $10 for each point destroyed.
Industry, Science and Warpgates are unaffected.