What do you think they do with potato skins from frozen fry factories?

I watched "How It's Made" this morning and they explained the process of making frozen fries very well.

Once the potatoes are cleaned, they are steamed with very hot vapor which makes the skins come off with brushes in a drum. The whole potato escapes, but the skin remains.

The show is usually good about explaining what happens to waste products, but they didn't explain what happened with the potato skins at this factory.

No internet searches came up with anything useful either.

Anyone know?

TIA