Calculate the battery life of a sensor node
When calculating battery life, I personally like to use mAh instead of Watt. This is because the battery voltage will drop with time.

For your case:

1.5V alkaline AAs is 750mAh, so in total is 4x750mAh = 3000mAh.

current per day is (80mA*6s + 4mA*30s + 0.018mA*86364s)/3600 = 0.60mAh/day

so battery life is 3000/0.60/365 = 13.70year