So you've pressed your grapes and gotten all the juice out of them. Now what are you supposed to do with the leftover skins, pulp, seeds, and stalks. One enterprising PhD student at Swinburne University of Technology, Avinash Karpe, as the school's website reports, hopes to turn these leftovers into biofuels. The article maintains since animals aren't too keen to eat them because of digestibility issues (plus low nutrient value) and composting isn't effective because this "biomass waste" (aka pomace) doesn't degrade, other options need to be explored.
(I am skeptical about composting not being an option. "The Pomace Predicament" by Allison Crowe in WineMaker makes no mention of the difficulty of breaking down pomace. And, small world, because Crowe has been previously mentioned on Grape Collective. Other reports talk about grinding the grape stalks down to facilitate the breakdown process. You can Google search "wine making composting" for more sources. Or trust someone who's not a scientist nor plays one on TV.)
In his research, Karpe found that by using a four fungi cocktail (I'd rather have a Manhattan) along with some heat, the biomass could be broken down to produce "alcohols, acids and simple sugars of industrial and medicinal interest."
So maybe someday you'll visit a winery and have 'em fill up the tank while you're in the tasting room.