Narasimharao Kondamudi, Susanta K. Mohapatra, and Mano Misra examined Spent Coffee Grounds as a Versatile Source of Green Energy (PDF) and estimated that one could produce 2,920,000 gallons of biodiesel from the 210,000,000 pounds of coffee grounds Starbucks throws out each year, which would bring in $13,140,000 of revenue — assuming a price of $4.50 per gallon of biodiesel, which sounds like an after-tax retail price — for “just” $25,200,000 in operating costs.
What makes this whole thing look profitable is that one can still sell the non-biodiesel waste as fuel pellets — 89,150 tons for $20,080,000 — bringing the whole thing into the black, with profits of $8,020,000 per year.
I guess we have to ask, What portion of those operating costs go toward producing biodiesel versus fuel pellets?, and, Do those operating costs include the logistical costs of collecting all those coffee grounds?