The biggest difficulty I could see in doing this is that the grounds wold have water in them, so as you press the oil out, you're going to get a lot of water with it. Then you'd have to separate the oil and water. Not a really big deal, since people regularly do a water wash of the finished product and settle the water out of it anyway. Just adds one more step to the process.

I wonder how many pounds of grounds the average store goes through per day or week? The article says the grounds are 15% oil - presumably measured by weight - so if they were going through say 100 pounds a day, that's 15 pounds of oil - about 2 gallons. 7 days a week = 14 gallons a week of oil that could be extracted from their waste grounds.

If a guy had a press handy, that might be worth the effort, given that wvo has become so hard to find these days. Unfortunately, building or buying a press would probably be way to costly of an "extra" expense to make it worthwhile for the average Joe to make bio from Joe...

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1984 300 Coupe TurboDiesel
Silver blue paint over navy blue interior
2nd owner & 2nd engine in an otherwise
99% original unmolested car
~210k miles on the clock

1986 Ford F250 4x4 Supercab
Charcoal & blue two tone paint over burgundy interior
Banks turbo, DRW, ZF-5 & SMF conversion
152k on the clock - actual mileage unknown