Renewable Energy vs Fossil Fuel Energy Fossil fuel reserves are limited and will be depleted. Burning fossil fuels causes environmental concerns eg. GHG emmission. Energy from biomass releases CO2, but the CO2 is utilized for biosynthesis during the growth of biomass.
Sugar Crops Includes sugarcane, sugar beets, sweet sorghum, apples, grapes etc. Molasses – residual syrup remaining from crystallization of sugar from sugarcane and sugarbeets, is also a common feedstock Pulp and papermill sludges contain 40-50 wt% glucose These sugars can be directly fermented by yeast Saccharomyces cerevisiae.
Sugarcane Brazil is the largest producer (514 million tons in 2007) India is the second largest producer, followed by China. It has stalks bunched in stools of 5-50 stalks Can be grown in regular rotation with other crops. Requires tropical or subtropical climate. Time to maturity is between 8-24 months. Strong sunlight and plentiful water is needed to meet the considerable growth potential.
Sugar Beet A biennial root vegetable High content of sucrose in its root. Grown in temperate climates Average sugar (sucrose) content is around 17% of total raw biomass. World’s largest sugar beet producer: France, USA and Russia
Sweet Sorghum Used in the production of sugar, syrup, fuel and roofing applications. Thrive under drier and warmer conditions. Largely produced in Asia, followed by North America. The juice contains 56% sucrose, 30% glucose, 14% fructose.
Starch and Inulin Crops Corn, potatoes, cassava etc. Starch is a glucose polymer with 2 main components: amylose and amylopectin Inulin, like starch, is a storage carbohydrate, but its basic unit is fructose rather than glucose Inulin is commonly found in tuber crops such as dahlia and Jerusalem artichoke.
Corn Typically planted in the spring when warm temperatures are condusive for growth. Soil moisture is another key factor that determines the adaptability of corn to an area. Predominant component of corn is starch, 64-78% of the total mass on a dry basis. Other carbohydrates include cellulose fiber, pentosans, sucrose and monomeric sugars such as glucose, fructose and raffinose.
Wheat China – largest producer, followed by India Contains 77% starch content (dry basis)
Agricultural Residues It refers to either crop residues or processing residues. Corn stover – remains in a field after harvesting corn, includes stalks (50%), leaves (22%), cobs (15%) and husks (13%). Wheat straw Rice straw
Biofuel Characteristics Biofuel – a solid, gaseous or liquid fuel produced from biomass Ethanol, butanol, diesel etc. 1 st generation biofuel – food based material 2 nd generation biofuel – cellulosic materials 3 rd generation biofuel - algae
Comparison of Transportation Fuels Fossil Fuel - derivedBiorenewable Resource - Derived Fuel TypeGasolineNo 2 Diesel Fuel MethanolEthanolMethyl ester (from soybean) Specific gravity @ 16 C 0.72 – 0.78 0.850.7960.7940.886 Kinematic viscosity @ 20 C (m/s) 0.8 x 10 -6 2.5 x 10 -6 0.75 x 10 -6 151 x 10 -6 3.9 x 10 -6 Boiling point ( C) 30-225210-2356578339 Flash point ( C) -43521113188 Autoignition temp ( C) 370254464423- Octane no. (research)91-100-109 - Octane no. (motor)82-92-8990- Cetane no.< 1537-56< 15 55 Heat of vaporization (kJ/kg) 3803751185920 Lower heating value (MJ/kg) 43.54520.12737 Source: Brown, R.C. (2003) Biorenewable Resources