Technikally... (I know, internet though): Everything is a closed cycle. Oil is just carbon captured from plants and animals long ago, which got it from the land and air back then, so importing a tower of truck tires and burning it just to watch the smoke billow is technically closed-cycle.

On the other hand, in the realm of more restrictions in definitions: Due to transportation of goods and services, nothing is really zero net carbon. Because you're not, generally speaking, spawning the food for the animal to grow in from the aether. And getting it to market also has a footprint in processing and transit, too.