Gasification of alga Nannochloropsis sp. in supercritical water

Methods of energy extraction from microalgal biomass: a review

“…Conventional biomass gasification processes require dry feedstock (Guan et al 2012a), but supercritical water gasification (SCWG) is an alternative gasification technology for the conversion of high moisture biomass and it is suggested that in well-engineered systems it can be net energy positive (Guan et al 2012b). Chakinala et al (2010) found that higher temperatures, low microalgal concentrations, and longer residence times improved the efficiency of SCWG of Chlorella vulgaris.…”

“…Chakinala et al (2010) found that higher temperatures, low microalgal concentrations, and longer residence times improved the efficiency of SCWG of Chlorella vulgaris. The enthalpy change needed to take ambient liquid water to a low-density supercritical state (400 °C and 250 bar) is similar to that required to vaporise liquid water at ambient temperature, but the advantage of the SCWG process is that much of the energy invested in reaching a supercritical state can be captured and used again, with the hot effluent from the gasification reactor being used to preheat the wet biomass feed stream (Guan et al 2012a). …”

“…Experimental studies on SCWG at 550 °C of Nannochloropsis found energy conversion of biomass to syngas of up to 60 % (Guan et al 2012a). A theoretical study of the production of methanol from Spirulina, using the maximum theoretical yield of 0.64 g methanol g -1 dry microalgal biomass, gave a ratio of produced energy to required energy of 1.1, with the gasification and methanol synthesis process using some 25 % of the total process energy (Hirano et al 1998).…”

“…It has been suggested that for every 4.5 J of energy in the syngas gas, 1.0 J of unrecovered heat energy is required for SCWG (Guan et al 2012a), equivalent to an energy input of 22 % of the syngas or 21 % of the calorific value of the original microalgal biomass.…”

Supercritical Water Gasification of Municipal Sludge: A Novel Approach to Waste Treatment and Energy Recovery

“…When pre-heated to about 150°C at relatively low pressure (about 10 bar), walls of sludgeentrained cellular bodies are destroyed, thus decreasing sludge viscosity and making the cell contents more available to catalytic, oxidative, and thermal degradation (Abelleira et al, 2011). Preheating the wet organic feedstock with heat recycled from the hot reaction gases is also important in terms of reaching a self-sustaining, process threshold (Abelleira et al, 2011;Cocero, 2001;Guan et al, 2011;Matsumura et al, 2005).…”