I don't know, but I preferred the paper bags with handles that the stores had for a while. Packed right, I can get far more into a paper bag than those plastic bags, so even if it uses more energy to recycle or manufacture, I use less of them overall.
I also had other uses for paper bags that I don't have for plastic bags before tossing them to the trash (we have no means of recycling the plastic bags here...the paper bags were also perfect for collecting the newspapers for recycling and then it all got recycled together). For example, instead of using paper towels to absorb grease from fried foods, I used to cut up paper bags. So, I saved on yet another use of paper products by reusing the paper bag.
But, finally, the grocery store near here is having some sort of contest to cut down on use of plastic bags (I don't know if it's a community thing, or a storewide thing to cut back on waste or what). The people working the checkout counters can win some extra money as a prize if they use the least bags or cut back use or something (I didn't get all the details, they were just chatting about it while I was having my order rung up yesterday). But, the nice thing about it is that they finally (FINALLY!) took care to pack the bags efficiently, so I actually had full bags, not 3 items per bag when the kids get lazy bagging. The way this grocery store is set up, there's no way to bag your own groceries, so it has been something that has driven me crazy since I started shopping here, and even prompted me to write to the store to tell them it's such a waste of bags and frustrating to the customer to not be able to bag their own groceries if the people doing the bagging don't know what they're doing. My solution for a while was that I'd rebag things before taking them home and leave all the extra bags in the shopping cart for them to deal with...I figured if nothing else works, maybe that would get them the hint that they're using too many bags.
I'm not so sure about using reusable bags though. How do you know how many to bring with you? And how do you remember to bring them, especially if you just realize you have a little extra time to make a run to the grocery store on your way home from something else? I wouldn't want to have a bunch of bags always taking up space in my trunk, or needing to store them somewhere in the house to clutter up everything. And what about when you buy things like meat that leak? I don't want to reuse a bag after it had blood drip all over it, or contaminate new food with whatever got on the bag after the last order and had time to grow in between. Plus, the grocery store has some canvas bags for sale, but they're pretty small...kind of the size of the plastic bags. If I'm going to buy bags to reuse, I want something a more decent size so I don't need so many of them.
What I really like are the stores that instead of bags, use the boxes that are left from everything being shipped to them. That way, instead of just sending the boxes for recycling, you can package your groceries in them, they're nice and sturdy to carry into the house, and you can fit a lot into them, they don't tip over in the trunk on the way home, if you need boxes for moving, you can save them, or else recycle them on your end.
