Methods of energy extraction from microalgal biomass: a review

Energy Balance of Biogas Production from Microalgae: Effect of Harvesting Method, Multiple Raceways, Scale of Plant and Combined Heat and Power Generation

“…The relatively high lipid content of some microalgae has focused much of the published research work on the production of biodiesel from the microalgal lipids via trans-esterification [6][7][8][9]. Achieving an energy return based on the production of biodiesel alone is extremely challenging, however, with 50% of studies on microalgal biodiesel reporting an EORI of <1 [10][11][12][13].…”

“…Achieving an energy return based on the production of biodiesel alone is extremely challenging, however, with 50% of studies on microalgal biodiesel reporting an EORI of <1 [10][11][12][13]. Anaerobic digestion of wet microalgae is potentially an energetically more favourable option as it utilises the entire biomass and does not require drying before digestion [9,[14][15][16] One of the major challenges in achieving an energy return from the production of biofuel from microalgae is harvesting and concentrating the algae [3,17,18]; this is due to a number of factors including the dilute nature of the algal suspension at 0.02%-0.05% dry solids [19,20]; the small size of micro-algal cells (most algae are below 30 µm) [21]; the similarity in density of the algal cells to that of the growth medium [22]; and the negative surface charge on the algae that results in dispersed stable algal suspensions [23][24][25].…”

Energy Balance of Biogas Production from Microalgae: Development of an Energy and Mass Balance Model

“…In theory a wide range of unit operations can be combined to form microalgal biofuel production systems; as yet, however, there is no successful commercial system producing such biofuel (2)(3)(4). This suggests that there are major technical and engineering difficulties to be resolved before economically viable microalgal biofuel production can be achieved.…”

Slow Pyrolysis as a Method for the Destruction of Japanese Wireweed, Sargassum muticum

“…Pyrolysis processes can be classified by temperature and processing time. While there are no formal definitions, slow pyrolysis is characterised by long residence times (from minutes to days for solids) at low reactor temperatures (< 400 o C) with very low rates of heating (0.01 -2 o C s -1 ) (Milledge & Heaven, 2014;Peacocke & Joseph, ND), with slow pyrolysis resulting in higher yields of char rather than the liquid or gaseous products from higher temperature process (Brennan & Owende, 2010;Ghasemi et al, 2012). Charcoal was traditional produced in earth kilns with pyrolysis, gasification, and combustion processes occurring in kiln.…”

“…Research on the pyrolysis of microalgae is 'quite extensive' and has achieved reliable and promising outcomes (Marcilla, Catalá, García-Quesada, Valdés, & Hernández, 2013), but there appears to be less work on seaweed and much of the work carried out has used fast rather than slow pyrolysis for the production of oil rather than char (Milledge & Heaven, 2014;Milledge, Smith, Dyer, & Harvey, 2014;Yanik, Stahl, Troeger, & Sinag, 2013;Zhou, Zhang, Zhang, Fu, & Chen, 2010). The char from the pyrolysis of algae, however, has been found to be an effective soil ameliorant and fertiliser and could be an additional revenue stream (Bird & Benson, 1987), but the thermal behaviour of seaweeds is complex with a myriad of diverse reactions and thermolysis pathways (Rowbotham, Dyer, Greenwell, Selby, & Theodorou, 2013).…”