Notes on Coskata (and other gasification and cellulosic) yields
There has been a lot of discussion of the viability of cellulosic ethanol production models in the scientific literature, but just a few in popular media. Herewith are some notes on how cellulosic yields work out in real-world situations.
The Coskata model presupposes a yield of around 100 gallons per ton of biomass. ZeaChem is seeing up to 160 theoretical gallons per ton and 135 in the real-world in its process tests, and Syntec has been discussing yields in the 100-120 gpt range, so this is consistent (and to some extent conservative) with yields that have been seen elsewhere.
Let’s use sugar cane as a target biomass source, since Coskata’s first proposed 100 million gallon plant is planned for the sugarcane fields of southern Florida. Sugar cane grows at around 70.9 tonnes per hectare in India, and at 71 in Brazil; in Florida, yields are at 68 tonnes per hectare. 12 percent of that cane is sugar, which yields 1700 gallons of ethanol per acre, or more. The remaining 88 percent is bagasse for a Coskata process, or about 60 tonnes per hectare.
To generate 100 million gallons in this model, Coskata will need 1 million tons, or 900,000 tonnes of biomass. That will require 15,00 hectares, or 32,500 acres.
That’s 51 square miles, or the area within 4 miles of a 100 million gallon refinery. A mighty plantation, but not long hauling distances.
Bottom line? Feasible.
