The Potential of Cellulosic Ethanol Production from Grasses in Thailand

Abstract

The grasses in Thailand were analyzed for the potentiality as the alternative energy crops for cellulosic ethanol production by biological process. The average percentage composition of cellulose, hemicellulose, and lignin in the samples of 18 types of grasses from various provinces was determined as 31.85–38.51, 31.13–42.61, and 3.10–5.64, respectively. The samples were initially pretreated with alkaline peroxide followed by enzymatic hydrolysis to investigate the enzymatic saccharification. The total reducing sugars in most grasses ranging from 500–600 mg/g grasses (70–80% yield) were obtained. Subsequently, 11 types of grasses were selected as feedstocks for the ethanol production by simultaneous saccharification and cofermentation (SSCF). The enzymes, cellulase and xylanase, were utilized for hydrolysis and the yeasts, Saccharomyces cerevisiae and Pichia stipitis, were applied for cofermentation at 35°C for 7 days. From the results, the highest yield of ethanol, 1.14 g/L or 0.14 g/g substrate equivalent to 32.72% of the theoretical values was obtained from Sri Lanka ecotype vetiver grass. When the yields of dry matter were included in the calculations, Sri Lanka ecotype vetiver grass gave the yield of ethanol at 1,091.84 L/ha/year, whereas the leaves of dwarf napier grass showed the maximum yield of 2,720.55 L/ha/year (0.98 g/L or 0.12 g/g substrate equivalent to 30.60% of the theoretical values).

Modelling and optimization of xylose and glucose production from napier grass using hybrid pre-treatment techniques

“…The dry mass fractions of cellulose and hemicellulose in raw Napier grass was as high as 28.9% and 30.6% respectively, thus evidencing its potential as a valuable source of fermentable sugars, as earlier reported by Wongwatanapaiboon et al [20]. The optimized hybrid pre-treatment of HM gave polymers solubilization of 19%, 83.3% and 8.4% (dry mass fractions) of cellulose, hemicellulose and lignin respectively.…”

“…These findings differ from the report of Liong et al [21] who obtained a glucose yield of 7.3 gL À1 from Napier grass pretreated with 7% NaOH for 4 h at 35 C. Yasuda et al [22] observed 807 mg xylose yield when 100 g Napier grass was treated with low-moisture anhydrous ammonia (LMAA) at room temperature for 4 weeks. Wongwatanapaiboon et al [20] reported 4.14 gL À1 total reducing sugar yield when Napier grass was treated with 7.5% alkaline peroxide at 35 C for 24 h. According to Moiser et al [23], alkaline pre-treatment yields high sugar concentrations under long resident time (measured in days) at ambient temperature. It is postulated that long process times are necessary because alkaline causes chemical swelling of cellulose fibres in which saponification (base hydrolysis) reaction occurs, thus causing disruption of hemicellulose cross links and increasing porosity of biomass [23].…”

Evaluation of different pretreatments of Napier grass for enzymatic saccharification and ethanol production

“…These pretreatments afford the recovery of cellulosic content from grass biomass, the removal of structural components such as lignin, pectin, or hemicellulose, and the breakdown of the crystal region in the cellulose bunch to render it digestible for cellulolytic enzymes. Chemical methods for Napier grass biomass pretreatment involve the use of sodium hydroxide, liquid ammonia, dilute sulfuric acid, dilute acetic acid, and hydrogen peroxide . Napier grass biomass has also been subjected to hot water pretreatment at 100°C for a period of 25 minutes in a batch autoclave reactor .…”

“…Chemical methods for Napier grass biomass pretreatment involve the use of sodium hydroxide, 6 liquid ammonia, 7 dilute sulfuric acid, 7 dilute acetic acid, 8 and hydrogen peroxide. 9 Napier grass biomass has also been subjected to hot water pretreatment at 100°C for a period of 25 minutes in a batch autoclave reactor. 10 The use of acid or alkali, combined with heat or microwave, has also been proposed for the pretreatment of Napier grass.…”

Arbuscular mycorrhizal association enhances drought tolerance potential of promising bioenergy grass (Saccharum arundinaceum retz.)

“…But the production of biomass from food crops has led to food crisis at least in some parts of the world, and hence, the use of lignocellulosic biomass produced from non-food crops has evolved as the one having great potential to replace fossil fuels (Huang et al 2011). In this scenario, the use of perennial grasses for the lignocellulosic bioenergy production has gained more attention because of its abundancy, availability, regeneration capacity and ability to withstand drought (Wongwatanapaiboon et al 2012). S. arundinaceum, a perennial grass, has proved to be a promising bioenergy crop, which exhibits sustainable biomass yield (Feng et al 2015) and tolerance to salinity stress (Mirshad et al 2014).…”