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Table 1 Recent studies of bioenergy conversion using different methods

From: Waste to bioenergy: a review on the recent conversion technologies

Method Type of bioenergy Type of feedstock Composition/Yield/ Efficiency/Energy recovery Operating condition Reference
Gasification Fuel gas Pine woodchips Syngas composition:
H2 gas: 26–42%
CO gas: 25–37%
CO2 gas: 16–19%
CH4 gas: 8–11%
Dual circulating fluidized-bed gasifier
Temperature: 700–900 °C
Steam to fuel ratio: 0.3 kg·kg− 1
[23]
Bioelectricity MSW and hazardous waste Plant efficiency: 41.1%
Power: 81 MW
Co-gasification using plasma gasifier. Composition of MSW: 90%wt Oxygen volume: 95% [24]
Fuel gas Eucalyptus chips and coffee husk Higher heating value (MJ·N− 1 m− 3):
Eucalyptus chips: 6.81
Coffee husk: 7.76
Eucalyptus chip
Temperature: 22.1 °C
Air input flow: 182.7 Nm3·s− 1
Air consumption: 38.2 Nm− 3
Coffee husk
Temperature: 26.3 °C
Air input flow: 124 Nm3·s− 1
Air consumption: 13.4 Nm− 3
[25]
Fuel gas Rice straw Efficiency: 33.78%
CO gas: 2.01%
H2 gas: 5.48%
CH4 gas: 0.51%
Temperature: 600–800 °C
Oxygen ratio: 33%
Air flow: 0.6 Nm3·h− 1
Feed rate: 1.12 kg·h− 1
Equivalence ratio: 0.2
[26]
Fuel gas Acid hydrolysis residues and sewage sludge Cold gas efficiency: 70.68% Co-gasification using downdraft fixed gasifier at atmosphere pressure. Temperature: 800 °C
Catalyst: CaO
Sewage sludge composition: 50 wt% CaO/C (molar ratio):1.0
Equivalence ratio: 0.22
[27]
Liquefaction Bio-crude oil Microalgae Yield: 60.0% Temperature: 350 °C
Reaction time: 15 min
[28]
Bio-crude oil Jatropha curcas cake Energy recovery: 41.48–54.78% Temperature: 250 °C
Catalyst: ChCl–KOH DESs
Reaction time: 40 min
[29]
Bio-crude oil Human faeces Yield: 34.44% Temperature: 300 °C
Reaction time: 30 min
Total solid content: 25%
[30]
Bio oil Domestic sewage in high-rate ponds Yield: 44.4% Temperature: 300 °C
Operation time: 15 min
Biomass/water ratio: 1/10 (kg·kg− 1)
[31]
Crude biodiesel Wet & dry microalgae (Nannochloropsis sp) Biodiesel yield
Wet microalgae: 14.18%
Dry microalgae: 12.48%
Fermentation and Ethanol assisted liquefaction
Temperature: 265 °C
Ethanol: 15% (v/v)
Ethanol to algae ratio: 2:1
[32]
Methane and Energy Microalgae Chlorella 1067 Methane: 32–117%
Energy recovery: 70.5%
Integrating HTL and anaerobic digestion with zeolite adsorption process.
HTL process:
Temperature: 300 °C
Reaction time: 30 min
Air pressure: 20 bar
[33]
Pyrolysis Bio-oil Sugarcane residues sugarcane leaves and tops Yield:
Sugarcane leaves: 52.5 wt%
Sugarcane tops: 59.0 wt%
Fast pyrolysis
Temperature:
Sugarcane leaves: 429 °C and sugarcane tops: 403 °C
Nitrogen gas flow rate: 7 L·min− 1
Biomass feed rate: 300 g·h− 1
[34]
Biochar, Bio-oil and gas Greenhouse vegetable wastes and coal Biochar yield:
40.22, 54.65, 45.93%
Fast pyrolysis
Temperature: 500 °C
Catalyst: calcite, dolomite, and zeolite
Nitrogen gas flow: 1450 mL·min− 1
[35]
Syngas (H2 and CO) Spent coffee grounds loaded with cobalt Yield concentration
H2: 1.6 mol%
CO: 4.7 mol%
Catalyst: Co-biochar
Generation of H2: CO2 as atmospheric pressure
Reaction time: 110 min
Generation of CO: Temperature 700 °C
[36]
Bio-oil Pinyon-juniper wood chips Yield: 47.8 wt% Temperature: 400 °C
Catalyst: Red mud
Feeding rate: 0.9 kg·h− 1
HDO of oil produced: Temperature: 350 °C
Catalyst Ni/red mud
[37]
Bio-oil beech wood Yield: 86.1% Hydrotreatment
Temperature: 250 °C
Catalyst: NiCu/Al2O3
[38]
Anaerobic digestion Methane Sewage sludge 181 mL CH4/g volatile solids Thermal pretreatment
Temperature: 95 °C
Reaction time: 10 h
Anaerobic incubation temperature: 35 °C
[39]
Methane Biomass from co-culture of microalgae and bacteria 325 mL CH4/g volatile solids CaO pretreatment
Temperature: 72 °C
Reaction time: 24 h
Anaerobic incubation temperature: 35 °C
[40]
Methane Biomass from mixed culture of 3 microalgae strains 146 mL CH4/g COD Batch culture of biomass
Ammonia concentration: 250 mg NH4+·L− 1
Temperature: 23 °C
Reaction time: 14 h
Illumination 10 days
Anaerobic incubation with sludge from wastewater plant
Temperature: 35 °C
[41]
171 mL CH4/g COD Semi-continuous culture of biomass Ammonia concentration: 300 mg NH4+·L− 1
Temperature: 23 °C
Reaction time: 14 h
Illumination 25 days
Anaerobic incubation
Temperature: 35 °C
Alcoholic fermentation Bioethanol Microalgae biomass (Chlamydomonas mexicana) 0.22 g ethanol·L− 1 h− 1 Simultaneous enzyme hydrolysis of biomass and fermentation with immobilized yeast
Anaerobic incubation
Temperature: 30 °C
RPM: 120
[42]
Bioethanol Biomass of 2 microalgae strains 0.18 kg·kg− 1 biomass Combined sonication, heat, and enzyme pretreatment of biomass
Anaerobic incubation
Temperature: 37 °C
pH 5.5
Hydraulic retention time: 2.5 days
[43]
Mixture of acetone, butanol, and ethanol Microalgae biomass (Chlorella vulgaris) 0.32 g·L− 1 h− 1 Lipid extraction of biomass: ionic liquid, acid hydrolysis (2% H2SO4) and detoxification (resin L-493) of biomass residue, then fed to yeast under anaerobic condition [44]
0.35 g·L− 1 h− 1 Lipid extraction of biomass: hexane/2-propanol, acid hydrolysis (2% H2SO4) and detoxification (resin L-493) of biomass residue, then fed to yeast under anaerobic condition
Photobiological hydrogen production Hydrogen Microalgae biomass (Chlorella sp.) 11.65 mL·L− 1 Medium: modified TAP
Glycerol concentration: 16 g·L− 1
Anaerobic condition
pH: 6.8
Light intensity: 48 μmol·m− 2 s− 1
Temperature: 30 °C
Reaction time: 24 h
[45]
Hydrogen Microalgae biomass (Chlamydomonas reinhardtii CC124) 1.05 mL·L− 1 h− 1 Medium: sulfur-free TAP
Light intensity: 50 μE·m− 2 s− 1
Anaerobic condition
Reaction time: 120 h
[46]
1.3 mL·L− 1 h− 1 Medium: sulfur-free TAP
Light intensity: 50 μE·m− 2 s− 1
Anaerobic condition
Reaction time: 120 h
Hydrogen Microalgae biomass (Chlamydomonas reinhardtii CC124) 0.60 mL·L− 1 h− 1 Medium: sulfur-free TAP
40 mg·L− 1 nanoparticle
Anaerobic condition
Reaction time:72 h
[47]
Transesterification (Acid/Base Enzyme Catalyst) Biodiesel Triacylglycerols Catalysed by acid or base [48]
Biodiesel Crude oil of Pongamia pinnata, Jatropha curcas, Calophyllum innophylum 90% Esterification:
Temperature: 60 °C
Reaction time: 3 h
Transesterification:
mixture of oil with methanol
Temperature: 60 °C
Reaction time: 2 h
[49]
94% Mixture of methanol and sodium methoxide (base catalyst)
Temperature: 50 °C
Reaction time: 2 h
Stirring: 700 rpm
Biodiesel Recycled cooking oil MgO + CaO: 98.95% Mixture heated to 55 °C for 20 min, added with methanol and warmed to 75 °C, moved to decanter after 4–6 h [50]
Biodiesel Mangifera indica oil MgO: 79.26%
ZnO: 77.14%
SiO2: 94.9%
Optimized conditions:
Methanol-to-oil molar ratio: 15:1
Catalyst: 0.5 wt%
Temperature: 64 °C
Reaction time: 1.5 h
[51]
Biodiesel Refined sunflower oil Yield: 94% Optimized conditions:
Methanol-to-oil molar ratio: 9:1
Catalyst: 0.3 wt%
Temperature: 67 °C
Reaction time: 3 h
[52]
Supercritical fluid Lipid Spent coffee grounds Yield: 98.14% Optimized conditions:
Temperature: 40 °C
Ethanol (18 ml/100 g) as modifier
Pressure: 250 bar
[53]
Biodiesel FAME 100% Optimized conditions:
Methanol-to-oil molar ratio: 40:1
Pressure: 200 bar
Temperature: 350 °C
Reaction time: 10 min
[54]
Lipid Corn 99% Optimized conditions:
Temperature: 60 °C
Pressure: 300 bar
CO2 flow: 3 ml/min
10 min static extraction
150 min dynamic extraction
[55]
MFC Bioelectricity Wastewater Power density: 642 mW·m− 2 MFC equipped with Pt electrode [56]
Bioelectricity MSW Power density: 1817.88 mW·m− 2 Two chamber MSW MFCs with alkali hydrolysis pre-treatment [57]
Bioelectricity Fermentable household waste Power density: 29.6 mW·m− 2 Dual-chamber MFCs [58]