CEE Oct-Dec 2012

and combustion efficiency, its overall fuel efficiency decrease is only about 2 per cent. The cloud point, or temperature at which pure biodiesel (B100) stars to gel, is about 32°F. A blend of B20 (20 per cent biodiesel , 80 per cent 0251t petrodiesel) generally does not gel in cold weather. Various additives will lower the gel point of B100. Biodiesel's flash point is 266 °F, significantly higher than petrodiesel's at 147 °F, or gasoline's at 52 °F. Biodiesel reduces particulate matter by 47 per cent as compared to petrodiesel and reduces the solid carbon fraction on the particulate matter while increasing the amount of oxygen. It has higher yield and hence lower costs. The most significant benefit however is in the yield of algal oil, and hence biodiesel. According to some estimates, the yield of oil from algae is 200 times more than that of the best-performing plant/vegetable oils. Soybean produces less than 50 gallons of oil per acre and rapeseed generates less than 130 gallons per acre while algae can yield up to 10,000 gallons per acre. Algae can grow practically in every place where there is enough sunshine. The biodiesel production from algae also has the beneficial by-product of reducing carbon and NOx (oxides of nitrogen) emissions from power plants, if the algae is grown using exhausts from the power plants. Algae produces a lot of polyunsaturates, which tend to decrease the stability of biodiesel. But polyunsaturates also have much lower melting points than monounsaturates or saturates, thus algal biodiesel would have much better cold weather properties than many other bio-feedstock. Since one of the disadvantages of biodiesel is their relatively poor performance in cold temperatures, it appears that algal biodiesel might score well on this point. Table 1 shows the comparison of biodiesel from microalgae. SWOT analysis A Strengths-Weaknesses-Opportunities-Threats (SWOT) analysis indicates that higher strength lies in the generation of algae culture on a large scale. The coastal stretch of India is long, measuring 7,500 kms, and is capable of generating massive amounts of algae. According to experts the country can become self-sufficient in liquid fuel if even 2-3 per cent of India's total land is utilized for Microalgae has the highest oil yield among various oil plants. It can produce up to 100,000 Its oil per hectare per year, much higher than palm, coconut, castor and sunflower Table 1. Comparison of biodiesel from microalgae with diesel fuel Propertl$s Blodlesel Diesel ASTM• from fuel blodlesel mlcroalgae standard Density (per kg) 0.864 0.838 0.86 -0.90 Viscosity (mm2 5.2 1.9-4.1 3.5-5.0 per s) Flash point ( 0 C) 115 75 Min.100 Solidifying point 12 50to10 (oC) Cloud point(°C) 11 3.0 Summer (max-6.7) max zero Winter max 15 Acid value (mg 0.374 Max.0.5 Max.0.5 KOH per gm) Heating value 41 40-45 (MJ per kg) H/C ratio 1.81 1.81 *American Standards Testing Measurements algae farming and since the opportunity of algal cultivation in the Indian context is very high many research institutes have started work on the same. Besides production, this process is useful in the generation of rural employment for the cultivation, processing and use of the microalgae. Additionally animal feed can also be generated from the waste. However, there are roadblocks in the process. Firstly, microal gae have high water content (80 to 90 per cent); and therefore, not all energy conversion processes of biomass can be applied to microalgae. Secondly, not all algae are capable of producing enough oils, and only those species which are capable of producing more than 50 per cent dry weight of extractable oil, are mai nly used. Botryococcus braunii contains an unusually high level of hydrocarbons (up to 80 per cent of the dry mass), making it a great option as a primary biofuel source. Hence the selection of the right kind of algae culture is essential. However, recent developments in biological sciences (recombinant deoxyribonucleic acid (DNA) technology) and the availability of user friendly technology may overcome these problems. Another issue is that first generation biofuels (bioethanol) compete with food production and create the 'food versus fuel' controversy. But second-generation biofuels derived from non-food sources like jatropha, karanj, microalgae, microbial sources, ligno– cellulosic biomass and bio-ethers are much better options for addressing energy security and environmental concerns. Among the second generation biofuels, microalgal biofuels appear to be the most promising. However, there are hurdles like the absence of Indian microalgal database 35