Direct conversion of wet algae to crude biodiesel under supercritical ethanol conditions

Direct transesterification of fresh microalgal cells

“…Griffiths et al (2010) achieved the direct transesterification of wet biomass via the addition of a water scavenger to ensure anhydrous reaction conditions. Wet biomass transesterification under supercritical conditions also has been explored (Reddy et al, 2014). However, to date, a convenient and reliable transesterification method for laboratory use in fatty acid analysis is still a technological requirement.…”

Sub and Supercritical Fluid Technologies for the Production of Renewable (Bio) Transportation Fuels

“…The algal biomass used in these studies has more unsaturated (~40-45%) and polyunsaturated fatty acids (PUFAs) (~10%); which are thermally unstable and causes the reduction of biodiesel yields at higher temperatures. The decomposition of PUFAs was observed at higher temperatures above the optimum reaction temperature in both studies [21,22]. When compared to biodiesel production using vegetable oils by supercritical alcohol process, nearly 2-3 times more alcohol is needed for algal biomass conversion.…”

A Review: Microalgae and Their Applications in CO2 Capture and Renewable Energy

“…Similar to methanol, the dielectric constant of ethanol decreases into the range of organic solvents with increasing temperature, and the exothermic hydrogen bonding in ethanol shifts toward the free monomer above critical conditions, permitting the extraction of lipids from wet microalgae and ethanol to perform the transesterification of triglycerides to fatty acid ethyl esters. Recently, supercritical ethanol was used for the simultaneous extraction and transesterification of lipids in algae to produce fatty acid ethyl esters (Reddy et al, 2014). A maximum yield of approximately 67% of fatty acid ethyl esters was obtained at 265°C with 20 min of reaction time and a 1:9 dry algae to ethanol (w/v) ratio.…”