the rewards  are he  following

100 energy recharged: 10xp
200 energy recharged: 20 q5 food
300 energy recharged: 20 (your countries money)
500 energy recharged: 5 strengh
700 energy recharged: q1 damager booster
900 energy recharged: 20 q5 tanks
1200 energy recharged: 20 q5 helis
1400 energy recharged: q3 damage booster