You can use Protein Bars if you need something to carry with you.
I'm sure most people would have concerns about them not being as healthy as natural food.No doubt.But they can be convenient in a pinch.
I just saw an article, 3 DIY Protein Bars, on the large Bodybuilding site (I'm sure you can find it) about making homemade bars from protein powder.
The recipes are for using protein powder,some kind of uncooked flour,milk,add ins,and coating them with dark chocolate.
I haven't tried any yet.Might be interesting.