Industrial sugar beets to biofuel: Field to fuel production system and cost estimates

Abstract

a b s t r a c tSpecialized varieties of sugar beets (Beta vulgaris L.) may be an eligible feedstock for advanced biofuel designation under the USA Energy Independence and Security Act of 2007. These non-food industrial beets could double ethanol production per hectare compared to alternative feedstocks. A mixed-integer mathematical programming model was constructed to determine the breakeven price of ethanol produced from industrial beets, and to determine the optimal size and biorefinery location. The model, based on limited field data, evaluates Southern Plains beet production in a 3-year crop rotation, and beet harvest, transportation, and processing. The optimal strategy depends critically on several assumptions including a just-in-time harvest and delivery system that remains to be tested in field trials. Based on a wet beet to ethanol conversion rate of 110 dm 3 Mg À1 and capital cost of 128 M$ for a 152 dam 3 y À1 biorefinery, the estimated breakeven ethanol price was 507 $ m À3 . The average breakeven production cost of corn (Zea mays L.) grain ethanol ranged from 430 to 552 $ m À3 based on average net corn feedstock cost of 254 and 396 $ m À3 in 2014 and 2013, respectively. The estimated net beet ethanol delivered cost of 207 $ m À3 was lower than the average net corn feedstock cost of 254e396$ m À3 in 2013 and 2014. If for a mature industry, the cost to process beets was equal to the cost to process corn, the beet breakeven ethanol price would be $387 m -3 (587 $ m À3 gasoline equivalent).

The costs of sugar production from different feedstocks and processing technologies

“…Sugarcane is mainly planted in southern states, including Florida, Louisiana, Texas, and Hawaii . Sugar beet is grown predominantly in the northern and parts of the central plains and the west, but mainly North Dakota and Minnesota …”

“…Generally, the sugar contents of sugarcane and sugar beet raw juices are 11–15% and 11–18%, respectively . Sweet sorghum is attracting increased interest as a sugar crop.…”

“…Haankuku et al . applied a power of 0.73 to estimate the capital costs of a sugar beet ethanol production plant . For the sugar produced from sweet sorghum, the base capacity reported by Gnansounou et al .…”

“…37 Sugar beet is grown predominantly in the northern and parts of the central plains and the west, but mainly North Dakota and Minnesota. 38,39 Generally, the sugar contents of sugarcane and sugar beet raw juices are 11-15% and 11-18%, respectively. 36,39,40 Sweet sorghum is attracting increased interest as a sugar crop.…”

“…38,39 Generally, the sugar contents of sugarcane and sugar beet raw juices are 11-15% and 11-18%, respectively. 36,39,40 Sweet sorghum is attracting increased interest as a sugar crop. When sweet sorghum is harvested, raw juice can be squeezed from the stems, which have a sugar content of 11-17%.…”