Turning Wine Waste into Fuel
Marketing and packaging aren't the only innovations in the wine world. As you've probably noticed as you read through this list, winemakers tend to be a pretty environmentally minded bunch, so it's no surprise that wineries are trying to use all of that waste from pressed grapes (more than 100,000 tons or 90,718 metric tons in California alone) to create alternative fuels.
A lot like making biofuel from other agricultural waste, creating biofuel from grape leavings -- called "grape pomace" -- uses microbes to break the sugars down into water and hydrogen, and the hydrogen is converted into energy [source: Choi].
Researchers from Penn State teamed up with the Napa Wine Company to turn their wine waste into fuel, a project they began in 2009 and continue today [source: Gangi]. The process produces hydrogen -- which they use to create biofuel -- and waste water. After a little bit more processing, the wastewater goes back to the fields to irrigate grape vines. Even cooler? Visitors to the vineyard can now see alternative energy demonstrations as part of their wine tour experience!
The problem with converting wine waste into fuel is that those grape stems, seeds, and skins don't have a ton of sugar, since most of the sugary juice goes into the wine. Those leftovers would be a lot more valuable if scientists could convert more than just the sugars into biofuel, and researchers are working on that. Instead of creating hydrogen fuel from the scarce sugar in grape pomace, Danish chemist Yi Zheng is developing a way to turn the cellulose from the skins and seeds into ethanol, which would significantly up grape pomace's efficiency as a biofuel feedstock [source: Schrope].