ETHANOL FROM SUGAR BEET - Sugar Beets - page 15

blend and longest distances (about 800 km). The rest is distributed directly by trucks. Tank
trucks are always used for the final distribution to the refueling stations. Their average trip is
assumed around 50 km (distances can be much smaller in urban area but with truck engine
operating less efficiently). Using the specific consumption for each mode of transport, the
overall consumption is R dist = 0 . 0075 J tot · J − OH , or 0 . 006 J LHV · J − OH [14]. In spite of
much larger distance than for beet transport, distribution contribution to R is lower because
of the high energy content of the load - ethanol itself - and the use of efficient modes.

4.6. The Factory Operations

Figure 4. Main factory operations to process beet root into ethanol and its by-products, as
well as their inputs and outputs. Contents of sugar S, dry matter DM of pulp or stillage, or
ethanol OH in the flows are specified. Sources: [2, 28, 29], Internet site of Téréos Co.

Fig. 4 shows the factory operations and their flows. Their contents in sugar, dry matter
of pulp or stillage, or ethanol are specified as well. Relative to sugar or pure ethanol produc-
tion, juice purification and rectification are not necessary, consequently saving some energy.
Juice extraction generates a residue - pulp -, and ethanol distillation produces stillage. Both
by-products must be treated, at least dried and/or concentrated, before their disposal.
The direct use of raw juice is only possible during the harvest time from September
to December, which amounts currently to 110 days [3]. Once dug up the roots can not be
stored for long as their metabolism consumes progressively the sucrose (about 0.3 kg · t − 1

A
per day). There is as well the risk of frost and thaw cycles, which degrade the sugar quality.
Moreover, the raw juice is difficult to preserve thanks to its high moisture content.
Consequently, all roots are processed during the harvest period and raw juice is either
concentrated into syrup or directly fermented into alcohol. We assume that 40% of the

yearly beer production occurs during the harvest period.
Moreover, sugar of the raw juice must be concentrated before the fermentation operation
owing to syrup addition, in order to reach the required ethanol grade C OH . In French
factories the grade is C OH = 7 . 8% (corresponding to C OH = 10% in volume or a mass
ratio of ethanol to the rest of the beer = 0.085) [2, 30]. Assuming a conversion rate at the
fermentation step α OH = 0 . 88 (see Subsection 3.3.), liquor to be fermented has a sugar
content of C 0 S = 16% (or a ratio of sugar to the rest of the liquor = 0.19). As a result, 1 t of
liquor at C 0 S requires about 0.95 t of raw juice at C S = 13 . 5% and 0.05 t of syrup during
the harvest period, while it consumes 0.26 t of syrup for the rest of the year. 1 t of syrup in
turn necessitates 4.5 t of raw juice.