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Table 1 Bio-energetic product yields, utility demands and energy efficiencies (optimized by pinch point analysis) (CD/CHPSC – Ethanol Production with Conventional Distillation with energy generation from pretreatment residues using CHPSC; CD/BIGCC – Ethanol production with Conventional Distillation with energy generation from pretreatment residues using BIGCC; VD/CHPSC – Ethanol Production with Vacuum Distillation with energy generation from pretreatment residues using CHPSC; VD/BIGCC – Ethanol production with Vacuum Distillation with energy generation from pretreatment residues using BIGCC; CHPSC-EE – Exclusive electricity generation from residues using CHPSC; CHPSC-EE (Dryer) – Exclusive electricity generation from residues using CHPSC where biomass is dried; BIGCC-EE – Exclusive electricity generation from residues using BIGCC)

From: Techno-economic comparison of ethanol and electricity coproduction schemes from sugarcane residues at existing sugar mills in Southern Africa

 

Ethanol cogeneration

Exclusive electricity

Scenarios

CD/CHPSC

CD/BIGCC

VD/CHPSC

VD/BIGCC

CHPSC-EE

CHPSC –EE (Dryer)

BIGCC-EE

Net Outputs

Bioethanol Production (l/hr)

9601

9577

9599

9575

   

Electricity Production (MW)

22.06

33.94

23.42

46.47

51.00

55.85

88.63

Steam Generation and Requirements

Gross Steam Generation (tons/hr)

204.58

146.43

204.58

146.42

277.22

294.71

191.98

Mill Steam Demand (tons/hr)

120.00

120.00

120.00

120.00

120.00

120.00

120.00

Ethanol Generation Steam Demand (tons/hr)

51.06

51.06

30.25

30.25

   

Steam Contingency (tons/hr)

33.53

−24.63

54.34

−3.83

157.22

174.71

71.98

As percentage of Total Steam Demand

19.60

−14.40

36.17

−2.55

131.02

145.59

59.99

Electricity Generation and Requirements

Gross Electricity Generation (MW)

38.52

187.50

40.76

187.51

65.49

70.50

263.36

Power (MW)

1.17

122.63

1.36

122.63

2.00

2.15

162.24

Ethanol Utilities (MW)

2.81

18.44

3.49

5.91

   

Mill Electricity Demand (MW)

12.49

12.49

12.49

12.49

12.49

12.49

12.49

Net Energy Efficiency

25.57%

29.17%

25.98%

32.91%

15.44%

16.86%

26.83%