Feedstock Feedstock availability

Composition, % w/w

Pretreatment

Hydrolysis and fermentation

Ethanol

Reference

Corn stover (agricultural by-product 80 - 100 million dry tonnes annum1 [40]

Glucan-41.0% Xylan-25.3% Arabinan-6.1% Galactan-3.0% Lignin-21.0%

Steam pretreatment of SO2 impregnated corn stover at 200˚C for 5 min

SSF at 10% WIS using cellulase and β-glucosidase mixture and S. cerevisiae (Baker’s yeast); fermentation at 30˚C, pH 5, 72 h and inoculum 2 g yeast∙L1

74% of the theoretical ethanol yield, ethanol 25 g∙L1

[41]

Corn stover

Glucan-42.2%

Xylan-19.6%

Arabinan-2.9%

Galactan-1.1%

Lignin-20.8%

Steam pretreatment as described in [41]

Pre enzymatic hydrolysis using Thermo-active enzyme mixture followed by SSF using S. cerevisiae (Baker’s yeast) at 11.50% WIS; fermentation at 35˚C, pH 5, 96 h and inoculum 1.8 g yeast 100 mL1

Ethanol 33.8 g∙L1, 80.2% overall ethanol yield

[42]

Corn stover

Steam pretreatment as described in [41] Ohgren et al., 2006

8% WIS and 10 FPU/g WIS SSF Vs. SHF; S. cerevisiae in fermentation at 35˚C, pH 5, 144 h and inoculum 1 g dry yeast L1

Theoretical ethanol yield in SSF-72.4 % and in SHF-59.1 %

[43]

Japanese cedar (Cryptomeria japonica) 7.6 million tonnes annum1 forest residues

Crushed to 20 micron of particle size using Cogwheel mill

SSF using commercial cellulase and S. cerevisiae after 24 h. Fermentation conditions not available

270 L ethanol tonne1 of Japanese cedar, 0.2 g ethanol g1 of Japanese cedar

[44]

Wheat straw 84.5 million dry tonnes of wheat straw annum1 at residue to wheat grain ratio of 1.3 - 1.7:1 [45]

Cellulose 33.5%,

Hemicellulose 22.4%, Klason lignin 16.4%, Ash 5.8%, Residual 21.8%

A three step pretreatment: Presoaking at 80˚C for 20 min followed by thermal treatment at 170˚C - 180˚C for 7.5 - 15 min then steam treatment at 195˚C for 3 min

Enzymatic hydrolysis of the solid residue using Cellubrix L enzyme

203 - 205 kg ethanol tonne1 of straw from cellulose fraction; 350.5 kg tonne1 from both cellulose and hemicelluloses fractions (calculated based on sugars obtained in hydrolysis step)

[46]

Cassava stems and peelings Cassava stems and peelings: 403 tonnes∙ha1

Cellulose 28.9%, 9.7% Hemicellulose 21.1%, 32.3% Klason lignin 30.6%, 16.9% Proteins 1.4%, 3.7% Ash 7.3%, 11.3% Lipids 0.7%, 1.7% others 9.9%, 24.2% in stems, peelings, respectively

Thermohydrolysis at 225˚C for 50 min

Enzymatic hydrolysis using Cellulase followed by fermentation using S. cerevisiae or Rhyzopus spp. at 1 g dry biomass inoculum per 100 mL hydrolyzate and other fermentation conditions not available

Stems: 5.2 g ethanol 100 g1 stems Peelings: 2.6 g ethanol 100 g1 peelings

[47]

Cassava cellulosic wastes from starch processing Liquid waste (1% total solids): 8.9 - 10.6 tonnes and Wet cassava bagasse: 0.9 - 1.1 tonnes from 1 tonne of dry cassava processed [48]

Carbohydrate 76.6% Starch 60.8% Fibre 15.8% Protein 0.8%

Hydrolysis using α-amylase for 1 h at 97˚C - 100˚C followed by Dilute HCl hydrolysis

Saccharification of hydrolyzed starch using amyloglucosidase at 50˚C - 60˚C followed by fermentation using S. cerevisiae at 40˚C - 50˚C, pH 4.6 - 5.5, 8 h and inoculum 0.2 g dry biomass per 100 mL hydrolyzate

2.7 g ethanol 15 g1 cassava cellulosic waste, 32.4% w/w ethanol concentration

[49]

Sugar cane bagasse

276 kg bagasse∙tonne1 of sugarcane; Sugarcane harvest in South Central Brazil 516 million tonnes in 2011/2012 [50]

Cellulose 52% Hemicellulose 20% Lignin 24% [51]

Delignification using NaOH (1N) at reflux temperature for 2 h

SSF using cellulase and S. cerevisiae using 1 g de-lignified bagasse per 20 mL medium; fermentation 5 days and other conditions not available

11.8 g ethanol∙L1

[52]