Biomass is considered to have potential to be used as an alternative energy source. High carbon content present in biomass converts it into high energy biochar on thermochemical treatment. Among few well established thermochemical technologies for the treatment of biomass and biogenic waste to produce high energy char along with oil and gaseous yield, pyrolysis is the most studied and discussed technique in the recent past. A comparison between the existing techniques is established in the present work. Production of char from the biomass and biogenic wastes is reviewed and it was found that yield of the biochar depends upon the biomass composition like moisture content and presence of cellulose or lignin. Pyrolysis product distribution and their quality strongly depend upon the process parameters. Different biomasses which can be used as raw material in pyrolysis are also reviewed and categorized depending upon their source. Pyrolysis process parameters such as temperature, heating rate, residence time etc. also influence the biochar yield. This study discusses the effect of these process parameters on the production of biochar through pyrolysis of biomass.

Effect of process parameters on production of biochar from biomass waste through pyrolysis: A review

http://biodiesel.persiangig.com/Cultivation/(3)Microalgae%20biofuels-%20A%20critical%20review%20of%20issues,%20problems%20and%20the%20way%20forward%20Review%20Article.pdf

Microalgae biofuels: A critical review of issues, problems and the way forward

The rapid depletion of conventional fossil fuels and day-by-day growth of environmental pollution due to use of extensive use of fossil fuels have raised concerns over the use of the fossil fuels; and thus search for alternate renewable and sustainable sources for fuels has started in the last few decades. In this context biomass derived fuels seems to be the promising path; and various routes are available for the biomass processing such as pyrolysis, transesterification, hydrothermal liquefaction, steam reforming, etc.; and the hydrothermal liquefaction (HTL) of wet biomass seems to be the promising route. Therefore, this article briefly enlightened a few concepts of HTL such as the elemental composition of bio-crude obtained by HTL, different types of feedstock adopted for HTL, mechanism of HTL processes, possible process flow diagrams for HTL of both wet and dry biomass and energy efficiency of the process. In addition, this article also enlisted possible future research scope for concerned researchers and a few of them are setting up HTL plant suitable for both wet and dry biomass feedstock; analysing influence of parameters such as temperature, pressure, residence time, catalytic effects, etc.; deriving optimized pathways for better conversion; and development of theoretical models representing the process to the best possible accuracy depending on nature of feedstock.

A review on hydrothermal liquefaction of biomass

https://eprints.whiterose.ac.uk/82741/1/1-s2.0-S0960852414013911-main.pdf

Hydrothermal liquefaction of biomass: Developments from batch to continuous process

Economic and technical problems related to the reduction of petroleum resources require the valorisation of renewable raw material Recently, microalgae emerged as promising alternative feedstock that represents an enormous biodiversity with multiple benefits exceeding the potential of conventional agricultural feedstock Thus, this comprehensive review article spots the light on one of the most interesting microalga Chlorella vulgaris It assembles the history and a thorough description of its ultrastructure and composition according to growth conditions The harvesting techniques are presented in relation to the novel algo-refinery concept, with their technological advancements and potential applications in the market

/pdf/morphology-composition-production-processing-and-5458j8vfab.pdf

Morphology, composition, production, processing and applications of Chlorella vulgaris: A review

Two major considerations of the emerging algae biofuel industry are the energy intensive dewatering of the algae slurry and nutrient management. The proposed closed loop process which involves nutrient recycling of the aqueous phase from the hydrothermal liquefaction of microalgae offers a solution to both aspects. Hydrothermal liquefaction has been shown to be a low energy process for bio-crude production from microalgae. For the purpose of this research, microalgae strains of Chlorella vulgaris , Scenedesmus dimorphus and the cyanobacteria Spirulina platensis and Chlorogloeopsis fritschii were processed in batch reactors at 300 °C and 350 °C. Following liquefaction the product phases were separated and the water phase recovered. The bio-crude yields ranged from 27 to 47 wt.%. The bio-crudes were of low O and N content and high heating value making them suitable for further processing. The water phase was analysed for all major nutrients, TOC and TN to determine the suitability of the recycled aqueous phase for algae cultivation. Growth trials were performed for each algae strain in a standard growth medium and compared to the growth rates in a series of dilutions of the recycled process water phase. Growth was determined by cell count and chlorophyll a absorbance. Growth occurred in heavy dilutions where the amount of growth inhibitors was not too high. The results show that the closed loop system using the recovered aqueous phase offers a promising route for sustainable oil production and nutrient management for microalgae.

R. Riley

Papers

Nutrient recycling of aqueous phase for microalgae cultivation from the hydrothermal liquefaction process

Catalytic hydrothermal processing of microalgae: decomposition and upgrading of lipids.

Microalgae biorefinery concept based on hydrothermal microwave pyrolysis