My prediction has come true! An Energy to SD question! I should buy a lotto ticket.
*ahem* Now to the point at hand.
Your scenario...
10,000,000 Colonists
30% of the planets resources making ENERGY (assuming no planetary +/- bonus or penalty to energy and that the planet can produce 100% energy)
250 Colonists to produce 1 Energy (current beta - I wish PJ would use minor beta revision #'s like AAT .30.070 cause this has to be about the 7th release!)
0.6 Unit of Energy used per sector fighter
-------------
First lets find out how much energy you produce -
10,000,000 x .30 = 3,000,000 / 250 = 12,000 units of energy per "turn" (300 seconds).
Now let's find out how many fighters that will support -
12,000 / 0.6 = 20,000
You can find the variables on the "settings" pick when you go to log into the beta.
...OH ...MY ..GOD!!
and tons of "termites" start coming outta the woodwork ..