The production of fuel grade ethanol from nonfood grade
crops in
South Africa has the potential to reduce reliance on imported oil
and minimize the negative environmental consequences of fossil fuels.
This article presents a preliminary assessment of the technical and
economic feasibility of producing fuel-grade ethanol from nonfood,
small grain crops cultivated on marginal lands in the Western Cape
of South Africa, namely triticale, low-grade wheat, feed barley, and
malt barley. It also explores the potential of grain fiber fractionation
(separation of starch from bran) on process economics for a dry-mill
process. A conservative “base-case” economic model was
developed for a processing capacity of 200 000 metric tonnes
per annum (tpa) at maximum expected feedstock prices. The overall
average unit costs of production for each grain were compared for
three possible process configurations, i.e. a conventional dry-mill
starch-to-ethanol plant, an advanced starch-to-ethanol plant with
fractionation and energy recovery from bran, and a hybrid integrated
cellulosic plant with fractionation, hydrolysis, and fermentation
of bran. Triticale demonstrated the greatest economic potential of
all grains, regardless of technology type, while the advanced process
technology optionfiber fractionation and steam generation
from bran combustionachieved the lowest overall costs of production,
across all grain types. For the conservative base-case model, it was
found that the government subsidy of ZAR 1.50/L proposed under the
South African Biofuels Strategy is insufficient to ensure economic
feasibility for any of the grains or technology options under scenarios
with high feedstock costs. The government subsidy would need to be
increased by at least 124% before profitable operation during times
with high feedstock prices would be possible. A sensitivity analysis
of the economic assumptions of the base-case model demonstrated that
feedstock price is the most important determinant of production costs
and that the economic feasibility of such technologies relies heavily
on a favorable ethanol selling price. When assuming maximum theoretical
starch–ethanol yields, and considering fluctuation in feedstock
prices in the range from ZAR 1589/t to ZAR 3680/t (as observed in
South Africa during the period between 2005 and 2012), the best economic
results were observed for an advanced starch-to-ethanol plant processing
triticale grain at a rate of 200 000 tpa (production cost between
ZAR 4.25/L and ZAR 8.48/L). Due to uncertainty of commodity price
fluctuations, it is recommended that static, deterministic models
for economic feasibility should therefore be enhanced to incorporate
uncertainty and quantitative risk assessment in process and economic
parameters, by adopting stochastic simulation methods to account for
price volatility.