Biomass to biofuel

Biomass to biofuel

1. Biomass to Biofuels S K Singh Centre for Energy Studies IIT Delhi

2. Contents Definition of biomass and biofuels Conversion of biomass to solid biofuels Drying Sizing Densification Slow Pyrolysis Conversion of biomass to liquid biofuels Fast Pyrolysis Liquefaction Conversion of biomass to gaseous biofuels Gasification Anaerobic Digestion References

3. Biomass Biomass So all the organic matter is called biomass. Examples - “Bio” - Life “Mass” - Matter Any living matter or matter derived from living organisms Vegetation Animals Agricultural waste

4. Biofuel Biofuel - Biomass used for energy production. Energy produced is called Bio Energy. May or may not require any conversion. Examples - Firewood Charcoal Biodiesel

5. Classification of Biofuel on the basis of state Biofuel Solid Biofuel Liquid Biofuel Gaseous Biofuel

6. Biomass to Solid Biofuels

7. Unprocessed Solid Biofuels Do not require any processing. Can be directly burnt for heat production. Examples - Firewood Dry Agricultural Residue Cow Dung Cakes

8. Processed Solid Biomass

9. Drying A part of combustion heat goes into evaporating the water content of the biomass. Lesser the moisture in biofuel, more energy will be available for our use. It leads to increased flame temperature which leads to More complete combustion Lesser carbon monoxide and fly ash production Becomes an important step before any further processing.

10. Drying Requirements for drying Heating Source Method for Removing evaporated water Introduction of new material Dryers can be divided into two broad categories - Direct Dryers Indirect Dryers

11. Dryers Direct Dryers Material get heat from direct contact with the fluid. The fluid is either hot air or hot steam.

12. Dryers Indirect Dryers Material is separated from the heat source by a heat exchange surface.

13. Sizing The combustion process depends on the surface area of the fuel. More the surface faster is the combustion. Breaking up solid biofuel increases overall surface area Sizing also makes drying easier. Size is reduced by shredding, chopping, crushing, milling, grinding etc. Wood chunks Wood chips

14. Sizing

15. Densification The low density of biomass poses a challenge for handling, storage and transportation. The densification process advantages - Reduced transportation cost due to increased energy density. Simplified mechanical handling and feeding. Simplified storage and handling infrastructure. Reduced possibility of spontaneous combustion in storage.

16. Densification Process Done using hydraulic or mechanical piston drive.

17. Densification Pellets Cubes

18. Carbonisation Conversion of organic material into carbon or carbon containing residue through pyrolysis.

19. Pyrolysis Thermal decomposition of biomass in the absence of oxygen. Pyrolysis can be categorized as - Slow Pyrolysis Fast Pyrolysis Slow Pyrolysis Slow heating of organic matter in the absence of oxygen. The volatiles from organic material evaporate and charcoal as solid product remains. Charcoal contains large part, normally 80% of the carbon. Slow pyrolysis is also called carbonisation, and it emphasizes charcoal as main product. Fast Pyrolysis in contrast emphasizes the liquid product.

20. Slow Pyrolysis The thermal decomposition starts between 260-300 o C The cellulose, hemicellulose and lignin components of the wood break down and volatiles are released. The volatiles consist of CO, CO 2 , CH 4 , H 2 and tars.

21. Slow Pyrolysis The main product of slow pyrolysis is charcoal.

22. Charcoal Briquettes The components of charcoal briquettes are - Charcoal Main component of charcoal briquette

23. Charcoal Briquettes Accelerant To accelerate the combustion process.

24. Charcoal Briquettes White Ash By observing the degree of turning white we can judge the degree up to which the briquette has burnt.

25. Charcoal Briquettes Briquette binder To bind the mixture together Popular briquette binder is arabic gum or acacia gum.

26. Biomass to Liquid Biofuels Fast Pyrolysis Liquefaction

27. Fast Pyrolysis Pyrolysis of biomass at high temperature decomposes it into charcoal and volatile matter. The temperature ranges from 650-1000 o C. The volatile matter comprises of Condensable vapours at room temperature called pyrolysis oil(also called bio-oil or biocrude) And non condensable gases CO, CO 2 , H 2 , CH 4 . This mixture is also called biogas. This process is primarily used to produce bio-oil and biogas. It yields 60% bio-oil, 20% biochar, 20% biogas.

28. Fast Pyrolysis

29. Bio-Oil

30. Liquefaction Thermochemical conversion of organic matter into bio-oil and co-products At moderate temperature(300-400 o C) and Pressure(10-20 MPa) with CO or H 2 as reducing agents. The biomass used is wet(high water content) - Food processing waste, animal manure. Process - The long carbon chain are thermally broken down Oxygen is removed as H 2 O (dehydration) and CO 2 (decarboxylation) Recombination of reactive fragments Results in high H/C ratio bio-oil.

31. Liquefaction

32. Biomass to gaseous biofuels Gasification Anaerobic digestion

33. Gasification Converts organic matter at high temperatures(>700 o C), without combustion, with controlled amount of oxygen and steam into CO, CO 2 and H 2 . The CO reacts with H 2 O to give more CO 2 and H 2 . Adsorbers or special membranes can be used to separate the H 2 from the gaseous mixture. A simple example of reaction C 6 H 12 O 6 + O 2 + H 2 O CO + CO 2 + H 2 + Other products CO + H 2 O CO 2 + H 2 + Heat

34. Anaerobic Digestion Biomass is broken down by microorganisms in the absence of air. The microorganisms digest the biomass and release methane gas which can be used for power generation. The four key stages of anaerobic digestion involve hydrolysis, acidogenesis, acetogenesis and methanogenesis. The overall process can be described by the chemical reaction, where organic material such as glucose is biochemically digested into carbon dioxide and methane by anaerobic bacteria.

35. Anaerobic Digestion

36. We have looked at various processes used to produce solid, liquid, gaseous biofuels from biomass.

37. References https://energypedia.info/images/1/1b/Solid_biomass_fuels_for_cooking_-_beyond_firewood_and_charcoal._GIZ_2017.pdf https://www.nrel.gov/docs/fy99osti/25885.pdf http://northwestchptap.org/nwchpdocs/biomassdryinganddewateringforcleanheatandpower.pdf http://ecoursesonline.iasri.res.in/mod/page/view.php?id=1255 http://www.omafra.gov.on.ca/english/engineer/facts/11-035.htm#:~:text=The%20low%20density%20of%20biomass,properties%20than%20the%20raw%20biomass. https://www.intechopen.com/books/pyrolysis/pyrolysis-a-sustainable-way-to-generate-energy-from-waste https://www.uaex.edu/publications/PDF/FSA-1052.pdf http://www.esru.strath.ac.uk/EandE/Web_sites/03-04/biomass/background%20info8.html http://pyrowiki.pyroknown.eu/index.php/Slow_pyrolysis#:~:text=Slow%20pyrolysis%20is%20the%20slow,normally%2080%25)%20of%20carbon.

38. References https://www.ftmmachinery.com/blog/composition-and-processing-of-charcoal-briquette.html#:~:text=Charcoal%20briquette%20is%20a%20kind,smoke%20and%20odor%20during%20combustion. https://en.wikipedia.org/wiki/Hydrothermal_liquefaction