The biggest kitchen energy user is the refrigerator. Keep your refrigerator 38-40 degrees, and your freezer 3-5 degrees. Clean the condenser coils on the back once a year. Make sure the door gasket seals tight. Test it by closing the door on a piece of paper and pulling it out.
Or put a flashlight inside and see if the light leaks out when you close the door. If you see the light or the paper pulls out easily – you need a new gasket. Refrigerators work best when they are full, but not crowded. The stored food mass retains cold, so the temperature doesn't go up as drastically when doors are opened (or the power is off) as it does in a sparsely stocked refrigerator.
However, if it’s packed so tight that air can't circulate, efficiency goes down. And keep the door closed – take what you need and close the door.