4. Introduction
What is Gasification?
A process that converts organic or fossil fuel based
carbonaceous materials into CO, H2 and CO2
By reacting the material at high temperatures (>700 °C)
With controlled amount of oxygen and/or steam
5. Introduction
What is hydrogen fuel?
Zero-emission fuel when burned with oxygen
Hydrogen (H2) reacts with oxygen (O2) to form
water (H2O) and releases energy.
2H2(g) + O2(g) → 2H2O(g)
6. Introduction
Why we need hydrogen fuel?
Renewable energy
Clean energy
Environment friendly
Fuel efficient
11. Methodology
Source: Cuiping et al. (2004). Biomass and bioenergy, 27(2), 119-130.
Elemental characteristics of biomass
12. Methodology
Reference: Higman & Burgt (2008). Gasification (2nd edition), Gulf Professional Publishing
1. C + ½ O2 → CO (-111 MJ/kmol)
2. CO + ½ O2 → CO2 (-283 MJ/kmol)
3. H2 + ½ O2 → H2O (-242 MJ/kmol)
Major chemical reactions within gasification process:
13. Methodology
Reference: Higman & Burgt (2008). Gasification (2nd edition), Gulf Professional Publishing
7. CO + H2O ↔ CO2 + H2 "Water-Gas-Shift Reaction"
(-41 MJ/kmol)
8. CH4 + H2O ↔ CO2 + 3 H2 "Steam-Methane-Reforming Reaction"
(+206 MJ/kmol)
4. C + H2O ↔ CO + H2 "the Water-Gas Reaction"
(+131 MJ/kmol)
5. C + CO2 ↔ 2CO "the Boudouard Reaction"
(+172 MJ/kmol)
6. C + 2H2 ↔ CH4 "the Methanation Reaction"
(-75 MJ/kmol)
15. Result & Discussion
Feedstock Reactor Catalyst used Hydrogen production (vol%) References
Sawdust Unknown Na2CO3 48.32 at 700 °C
55.40 at 800 °C
59.80 at 900 °C
Yongje et al.(1996) Acta Energiae Sol
aris Sinica
Sawdust Circulating fluidized bed Not used 10.5 at 810 °C Chuangzhi et al. (1997) Acta
Energiae Solaris Sinica
Wood Fixed bed Not used 7.7 at 550 °C Xia et al. (2000) ) Acta Energiae
Solaris Sinica
Sawdust Fluidized bed Unknown 57.4 at 800 °C Turn et al. (1998) Int. Jour. of Hydrog
en Energy
Sawdust Fluidized bed Ni
K2CO3
CaO
Na2CO3
62.10 at 830 °C
11.27 at 964 °C
13.32 at 1008 °C
14.77 at 1012 °C
Rapagna et al. (1998) Int. Jour. of
Hydrogen Energy
Chun et al.(2001) Chemistry and Ind
ustry of Forest Product
Pine sawdust Fluidized bed Unknown 26-42 at 700-800 °C Zhewei et al. (2002) Jour. Of Fuel Ch
emistry and Technology
Bagasse Fluidized bed Unknown 29-38 at 700-800 °C Same as above
Cotton stem Fluidized bed Unknown 27-38 at 700-800 °C Same as above
Sewage sludge Downdraft Unknown 10-11 at 700-800 °C Midilli et al. (2002) Int. Jour. of
Hydrogen Energy
Almond shell Fluidized bed La-Ni-Fe
Perovskite
62.8 at 800 °C
63.7 at 900 °C
Rapagna et al. (2002) Biomass & Bio
energy
Switchgrass Moving bed Cu-Zn-Al 27.1 Brown (2003) National Renewable en
ergy Laboratory
16. Factors that influence hydrogen production
Temperature
Type of reactor
Feeding materials
Catalysts
17. Cost Estimation
Source: Bowen et al. (2003) National Renewable Energy Lab, USA
Feedstock Moisture
Content
Test Run
(tonnes/day)
Bagasse 20% 500,1000,2000
Switchgrass 12% 500,1000,2000
Nutshell 12.5% 500
Fig. Process flow diagram
Cost estimation
Detailed breakdown of capital cost
Including labour, construction and installation
19. Cost Estimation
Source: Bowen et al. (2003) National Renewable Energy Lab, USA
Results of economical analysis for gasification of three biomass feedstocks
20. Future Trend
Hydrogen Production by Reaction Integrated Novel Gasification (HyPr-RING) process
Source: Lin et al. (2002) Energy Conversion and Management
21. Future Trend
Concept of Hydrogen Production by Reaction Integrated Novel Gasification (HyPr-RING) process
Source: Lin et al. (2002) Energy Conversion and Management
23. Conclusion
It is possible to achieve hydrogen production about 60 vol.% using a fluidized
bed gasifier along with suitable catalyst. Such high conversion efficiency makes
biomass gasification an attractive hydrogen production alternative.
The cost of hydrogen production by biomass gasification is competitive with
natural gas reforming
Based on both economical and environmental consideration hydrogen
production from biomass gasification should be a promising option.