Overview of Technologies for Converting Waste Agricultural Biomass into Energy

1. Overview of Technologies for Converting Waste Agricultural Biomass into Energy Training on Technologies for Converting Waste Agricultural Biomass into Energy Organized by United Nations Environment Programme (UNEP DTIE IETC) 23-25 September, 2013 San Jose, Costa Rica Surya Prakash Chandak Senior Programme Officer International environmental Technology Centre Division of Technology, Industry and Economics Osaka, Japan

2. CONTENT Technology Classification Direct Combustion Densification Thermo-chemical Conversion Biological Conversion Liquid Biofuels Environmental Characteristics Technology Selection Technologies in Practice

3. TECHNOLOGY CLASSIFICATION Direct combustion of raw biomass is the simplest method of extracting energy with lowest cost Therefore is the most common method of conversion. However, such a use faces the worst features of biomass - bulk and inconvenience. Therefore, before bio-energy is used for end-use activities, it may have to be converted from its primary form into a form that is more convenient for transport and use. This may involve simple physical processing before combustion or upgrading to a variety of convenient secondary fuels (solid, liquid or gas) by means of certain conversion processes.

4. TECHNOLOGY CLASSIFICATION Methods of utilizing waste agricultural biomass as a source of energy WAB Resources Heat Engines Direct Combustion / Gasification Heat Biomass Fuels Conversion Processes Generator Electricity Intermediate Fuels Mechanical Power RESOURCE TECHNOLOGY APPLICATION

5. TECHNOLOGY CLASSIFICATION Different processes and technologies are available for converting biomass to energy. Could be categorized as: Direct combustion of the raw biomass Combustion after simple physical processing, sorting, chipping, compressing, air-drying (beneficiation) Thermo-chemical processing Processes in this category include pyrolysis, gasification or liquefaction; Biological processing Natural processes such as anaerobic digestion and fermentation encouraged by the provision of suitable conditions giving useful secondary fuel (gaseous or liquid); Extraction Trans-esterification to produce biodiesel.

6. TECHNOLOGY CLASSIFICATION Methods of using WAB for Energy

7. TECHNOLOGY CLASSIFICATION Thermo-chemical conversion routes

8. TECHNOLOGY CLASSIFICATION BENEFICIATION Drying Dewatering Sizing Densification Separation Torrefaction Baling Pelletization Briquetting Methods of using WAB for Energy

9. DIRECT COMBUSTION Combustion of biomass has been widely used in the past to generate heat At present, it is making a comeback in many industrial applications including generation of electricity, Straightforward conversion of thermal energy into mechanical or electric power results in considerable losses It is not possible to raise the ratio of thermal to mechanical power above 60%. However, if the low temperature waste heat can be used productively, for instance for drying or heating purposes, much higher overall efficiencies can be obtained.

10. DIRECT COMBUSTION Fuels and Combustion Biomass combustion Convective Heat to Surrounding Heat Energy Hot Flue Gas Combustion Products Air and Fuel Light Flame Front Radiation to Surrounding Volatile Matter Radiation to Wood Wood Entrained Air Conduction to Wood Burning Char Ash Combustion Unit

11. DIRECT COMBUSTION Biomass combustion - Processes and temperatures in a burning piece of wood

12. DIRECT COMBUSTION • Properties of Fuels • Solid. • Density • Moisture Content • Volatile Matter and Fixed Carbon • Sulfur Content • Ash • Calorific Value

13. DENSIFICATION Densification (briquetting or pelleting) is used to improve characteristics of materials (especially low density biomass) Productive transport, Improved fuel characteristics. Raw materials used include sawdust, loose crop residues, and charcoal fines. The material is compacted under pressure Depending on the material, the pressure, and the speed of densification, additional binders may be needed to bind the material

14. DENSIFICATION There are two main briquetting technologies Piston press Screw press. In the piston press the material is punched into a die by a ram with a high pressure. In the screw press, the material is compacted continuously by a screw. With the screw press generally briquettes of higher quality can be produced.

15. THERMOCHEMICAL CONVERSION In thermochemical conversion, biomass is subjected to appropriate temperatures and pressures and normally a restricted supply of oxygen Pyrolysis is the basic thermochemical process to convert biomass into more valuable or more convenient products In fact, it is the oldest method of processing one fuel in order produce better one Conventional pyrolysis involves heating the original material in the near-absence of air, typically at 300 - 500C, until the volatile matters has been driven off.

16. THERMOCHEMICAL CONVERSION The residue is then the char (more commonly known as charcoal) Char has about twice the energy density of the original fuel and burns at a much higher temperature For many centuries, and in much of the world still today, charcoal is produced by pyrolysis of wood. Depending on the moisture content and the efficiency of process, 4 - 10 kg of wood are required to produce one kg of charcoal

17. THERMOCHEMICAL CONVERSION With more sophisticated pyrolysis techniques, the volatile matters can be collected Careful choice of the temperature at which the process takes place allows the control of the composition. The products formed are normally a gas, an oil-like liquid and charcoal The distribution of these products is dependent on the feedstock, temperature and pressure of reaction, the time spent in the reaction zone and the heating rate. High temperature pyrolysis (1000C) maximizes the production of gas (gasification) while lower temperature pyrolysis processes (<600C) have been used for the production of charcoal (carbonization). Another approach to produce liquid fuels and chemicals from biomass is direct catalytic liquefaction

18. BIOLOGICAL CONVERSION Biological conversion consists of exposing biomass to certain microorganisms. The secondary fuels produced are the result of metabolic activity of the microorganisms. Production of Ethanol and biogas are the two most common biological conversion processes. Ethanol fermentation from carbohydrates is probably one of the oldest processes known to man. Today, it is widely regarded as an important potential alternative source of liquid fuels for the transport sector.

19. LIQUID BIOFUELS Definition The term biofuels generally refers to liquid fuels made from biological sources, which include pure plant oil (PPO), bioethanol and biodiesel. Global biofuel production from year 2000 to 2011

20. LIQUID BIOFUELS Production and uses of liquid biofuels

21. LIQUID BIOFUELS Production and uses of liquid biofuels

22. LIQUID BIOFUELS Production and uses of liquid biofuels

23. LIQUID BIOFUELS First, second and third generation biofuels

24. ENVIRONMENTAL PERFORMANCES Impacts of emissions from biomass combustion

25. ENVIRONMENTAL PERFORMANCES Impacts of emissions from biomass combustion

26. ENVIRONMENTAL PERFORMANCES Impacts of emissions from biomass combustion

27. ENVIRONMENTAL PERFORMANCES Carbon emissions

28. TECHNOLOGY SELECTION Analysis of the Options SAT Methodology Level of use Household energy Briquetting Carbonization Combustion Anaerobic Digestion Research Pilot Demonstration Commercial Gasification Pyrolysis Biofuel applications Bio-chemicals TECHNOLOGY RESOURCE APPLICATION