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1. OCH353 – ENERGY TECHNOLOGY Unit 4 – BIOMASS ENERGY R.RAMANATHAN ASSISTANT PROFESSOR/EEE MOUNT ZION COLLEGE OF ENGINEERING AND TECHNOLOGY MZCET/EEE/VII Sem/OCH353_ET/Unit 4

2. Outline 4.1 – Biomass energy resources, thermo-chemical and biochemical methods of biomass conversion 4.2 – combustion, gasification, pyrolysis, biogas production, 4.3 - ethanol, fuel cells, alkaline fuel cell, 4.4 - phosphoric acid fuel cell, molten carbonate fuel cell 4.5 - solid oxide fuel cell, solid polymer electrolyte 4.6 - fuel cell, magneto hydrodynamic power generation 4.7 - energy storage routes like thermal energy storage 4.8 - energy storage routes like chemical 4.9 - energy storage routes like mechanical storage 4.10 - energy storage routes like electrical storage MZCET/EEE/VII Sem/OCH353_ET/Unit 4

3. Course Outcome CO 1: Understand Biomass Basics: Explain the fundamental principles of biomass as a renewable energy source, including its composition, types, and sources. CO 2: Assess Biomass Conversion Technologies: Evaluate different technologies used for biomass conversion into biofuels and bioenergy, such as thermal, chemical, and biochemical processes. CO 3: Analyze Environmental Impacts: Analyze the environmental implications of biomass production and use, including carbon footprint, land use changes, and ecosystem impacts. CO 4: Economic Evaluation: Perform basic economic evaluations of biomass projects, understanding costs, benefits, and financial incentives. CO 5: Design Biomass Energy Systems: Design and propose simple biomass energy systems, taking into account technical feasibility, sustainability, and regulatory compliance. CO 6: Explore Advanced Topics: Explore advanced topics such as bio-refineries, algae biofuels, and waste-to-energy technologies. CO 7: Develop Problem-Solving Skills: Apply critical thinking and problem-solving skills to address challenges in biomass energy production and utilization. CO 8: Understand Policy and Regulatory Frameworks: CO 9: Understand the policy and regulatory frameworks that govern the use of biomass for energy, including international standards and local legislation.. MZCET/EEE/VII Sem/OCH353_ET/Unit 4

4. PREVIOUS SESSION TODAYS SESSION BIO- MASS INTRODUCTION 4.1 – Biomass energy resources, thermo-chemical and biochemical methods of biomass conversion MZCET/EEE/VII Sem/OCH353_ET/Unit 4

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7. Types of Biogas Digesters • Fixed Dome Biogas Plants • Floating Drum Plants • Low-Cost Polyethylene Tube Digester • Balloon Plants • Horizontal Plants • Earth-pit Plants • Ferro-cement Plants MZCET/EEE/VII Sem/OCH353_ET/Unit 4

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10. Fixed Dome Biogas Plants Consists of a digester with a fixed, non-movable gas holder, which sits on top of the digester. • When gas production starts, the slurry is displaced into the compensation tank. • Gas pressure increases with the volume of gas stored and the height difference between the slurry level in the digester and the slurry level in the compensation tank. • The costs of a fixed-dome biogas plant are relatively low. • It is simple as no moving parts exist. MZCET/EEE/VII Sem/OCH353_ET/Unit 4

11. Continues….. No rusting steel parts and hence a long life of the plant (20 years or more) can be expected. • The plant is constructed underground, protecting it from physical damage and saving space. • While the underground digester is protected from low temperatures at night and during cold seasons, sunshine and warm seasons take longer to heat up the digester. • No day/night fluctuations of temperature in the digester positively influence the bacteriological processes MZCET/EEE/VII Sem/OCH353_ET/Unit 4

12. Continues….. • He construction of fixed dome plants is laborintensive , thus creating local employment. • Fixed-dome plants are not easy to build. • They should only be built where construction can be supervised by experienced biogas technicians. MZCET/EEE/VII Sem/OCH353_ET/Unit 4

13. Working of Fixed Dome Biogas Plant A fixed-dome plant comprises of a closed, dome-shaped digester with an immovable, rigid gas-holder and a displacement pit, also named 'compensation tank’. The gas is stored in the upper part of the digester. When gas production commences, the slurry is displaced into the compensating tank. Gas pressure increases with the volume of gas stored i.e. with the height difference between the two slurry levels. If there is little gas in the gas-holder, the gas pressure is low Digesters of fixed-dome plants are usually masonry structures Structures of cement and ferro-cement exist The top part of a fixed-dome plant (the gas space) must be gastight. MZCET/EEE/VII Sem/OCH353_ET/Unit 4

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15. Floating Drum Biogas Plant Om 1956, Jashu Bhai J Patel from India designed the first floating drum biogas plant, popularly called Gobar gas plant. Floating-drum plants consist of an underground digester (cylindrical or dome-shaped) and a moving gas-holder. The gas-holder floats either directly on the fermentation slurry or in a water jacket of its own. The gas is collected in the gas drum, which rises or moves down, according to the amount of gas stored. The gas drum is prevented from tilting by a guiding frame. MZCET/EEE/VII Sem/OCH353_ET/Unit 4

16. CONTINUES…… • When biogas is produced, the drum moves up and when it is consumed, the drum goes down. • If the drum floats in a water jacket, it cannot get stuck, even in substrate with high solid content. • After the introduction of cheap Fixed-dome Chinese model, the floating drum plants became obsolete as they have high investment and maintenance cost along with other design weakness MZCET/EEE/VII Sem/OCH353_ET/Unit 4

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18. Biogas for Cooking Biogas production for domestic cooking depends on an affordable appropriate digester at a suitable scale for domestic use. In any digester, the waste is mixed with water to create the right environment for the bacteria to decompose the biomass. As this is an anaerobic process, this has to happen without the presence of oxygen in an airtight tank. The biogas accumulates at the top of the tank where it is collected and taken by pipe to the user. The slurry has to be removed regularly from the tank. It can be used further, e.g. as agricultural fertilizer MZCET/EEE/VII Sem/OCH353_ET/Unit 4

19. Component of Household Digester Collection space: raw, liquid, slurry, semi-solid and solid animal, human or agricultural waste Anaerobic digester Slurry storage Gas handling: piping; gas pump or blower; gas meter; pressure regulator; and condensate drain(s). End-use device: cooker, boiler or lighting equipment MZCET/EEE/VII Sem/OCH353_ET/Unit 4

20. Continues….. For transporting biogas from the digester to the cooking place a tube is needed. Stoves for this system contain a valve to premix the biogas with the right amount of oxygen. Also a burner to combust the mixture and a structure to hold a cook-pot. Stoves and ovens for biogas application are similar to those of conventional appliances. Most of these conventional appliances can be adapted for the use with biogas by modification of the burners MZCET/EEE/VII Sem/OCH353_ET/Unit 4

21. Advantages of Using Bio-gas Biogas burns very cleanly, and produces fewer pollutants during cooking than any other fuel except electricity. Biogas provides instant heat upon ignition, no pre-heating or waiting time is required. Most biogas burners are able to regulate the flow-rate to turn down fire-power from high heat to small low heat for simmering. Biogas can be used for lighting as well. The by-product (slurry) from the digester can be used as fertilizer. Biogas is a renewable fuel that is ‘carbon negative’: unless there are leakages in the system. Burning biogas in a cook stove releases less greenhouse gases than if the dung was left on the ground to decompose naturally. MZCET/EEE/VII Sem/OCH353_ET/Unit 4

22. Disadvantages of Using Bio-gas High investment costs for the digester, tubes, gas stove, and pots. Biogas can increase the workload of women as it is often made their task to run the digester. It is quite a physical burden to move all the biomass feedstock and water to feed the digester. Slurry must be removed and taken to the field. It is not viable for elderly or sick people to run a biogas plant on their own, if they don’t have labor to assist them in the maintenance of the digester. Installations (depending on material and location) must be protected against theft and damages MZCET/EEE/VII Sem/OCH353_ET/Unit 4

23. Continues…… • Especially metal tubes are a valuable good and often prone to theft. • Cultural rules might limit the acceptance of handling dung or feces and their use as fuel for cooking. • Cooking with biogas requires the change of cooking habits, which might prevent the adoption. • Biogas is difficult to store and to transport to other consumers. MZCET/EEE/VII Sem/OCH353_ET/Unit 4

24. Biogas – Fuel for I.C. Engines Biogas contains 50% to 70% of CH₄, 5-10 % of H₂ and up to 30 -40 % of CO₂. After being cleaned of carbon dioxide, this gas becomes a fairly homogeneous fuel. It contains up to 80 % of methane. The calorific capacity of over 25 MJ/m³. The most important component of biogas, from the calorific point of view, is methane. The other components are not involved in combustion process, and rather absorb energy from combustion of CH₄ . They leave the process at higher temperature than the one they had before the process. MZCET/EEE/VII Sem/OCH353_ET/Unit 4

25. Limitations - Biogas in I.C. Engines High CO₂ content reduces the power output, making it uneconomical as a transport fuel. It is possible to remove the CO₂ by washing the gas with water. The solution produced from washing out the CO₂ is acidic and needs careful disposal. H₂S is acidic and if not removed can cause corrosion of engine parts within a matter of hours. High residual moisture which can cause starting problems. The gas can vary in quality and pressure. MZCET/EEE/VII Sem/OCH353_ET/Unit 4

26. Purification of Biogas for I.C. Engines CO₂ is high corrosive when wet and it has no combustion value so its removal is must to improve the biogas quality. a) Caustic solution NAOH- 40% NAOH + CO₂ = NAHCO₃ b) Refined process K₂CO₃ - 30 % K₂CO₃ + CO₂ = 2KCO₃ CO₂ removal from biogas can be done by using chemical solvents like mono-ethanolamine (MEA), diethanolamine and tri- ethanolamine or aqueous solution of alkaline salts MZCET/EEE/VII Sem/OCH353_ET/Unit 4

27. Purification of Biogas for I.C. Engines Biogas bubbled through 10% aqueous solution of MEA can reduce the CO₂ content from 40 to 0.5- 1.0% by volume. Chemical agents like NaOH, Ca(OH)₂, and KOH can be used for CO₂ scrubbing from biogas. In alkaline solution the CO₂ absorption is assisted by agitation. NaOH solution having a rapid CO₂ absorption of 2.5- 3.0% and the rate of absorption is affected by the concentration of solution MZCET/EEE/VII Sem/OCH353_ET/Unit 4

28. Biogas in I.C. Engine applications Biogas can be used in both heavy duty and light duty vehicles. Light duty vehicles can normally run on biogas without any modifications. Heavy duty vehicles without closed loop control may have to be adjusted, if they run on biogas. Biogas provides a clean fuel for both SI (petrol) and CI (diesel) engines. Diesel engines require combination of biogas and diesel Petrol engines run fully on biogas MZCET/EEE/VII Sem/OCH353_ET/Unit 4

29. Continues… Biogas cannot be directly used in automobiles as it contains some other gases like CO₂, H₂S and water vapor. For use of biogas as a vehicle fuel, it is first upgraded by removing impurities like CO₂, H₂S and water vapor. After removal of impurities it is compressed in a three or four stage compressor up to a pressure of 20 MPa and stored in a gas cascade. If the biogas is not compressed than the volume of gas contained in the cylinder MZCET/EEE/VII Sem/OCH353_ET/Unit 4

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31. Gasification Gasification is a process that converts biomass- or fossil fuelbased carbonaceous materials into carbon monoxide, hydrogen and carbon dioxide. Reacting the material at high temperatures (>700 °C), without combustion, with a controlled amount of oxygen and/or steam. Resulting gas mixture is called syngas(from synthesis gas) or producer gas. Power derived from gasification and combustion of the resultant gas is considered to be a source of renewable energy(When the source used is biomass) MZCET/EEE/VII Sem/OCH353_ET/Unit 4

32. Gasification MZCET/EEE/VII Sem/OCH353_ET/Unit 4

33. Gasification Lignocellulosic feedstocks such as wood and forest products are broken down to synthesis gas. Primarily carbon monoxide and hydrogen, using heat. The feedstock is then partially oxidized, or reformed with a gasifying agent (air, oxygen, or steam). Synthesis gas (syngas) is produced. The makeup of syngas will vary due to the different types of feedstocks, their moisture content, the type of gasifier used. The gasification agent, and the temperature and pressure in the gasifier MZCET/EEE/VII Sem/OCH353_ET/Unit 4

34. Advantages – Gasification Potentially more efficient than direct combustion of the original fuel. Can be combusted at higher temperatures or even in fuel cells. Can be burned directly in gas engines MZCET/EEE/VII Sem/OCH353_ET/Unit 4

35. Pyrolysis Pyrolysis is the thermal decomposition of materials at elevated temperatures in an inert atmosphere. It involves a change of chemical composition. The word is coined from the Greek-derived elements pyro "fire" and lysis "separating“. Pyrolysis is most commonly used in the treatment of organic materials. It is one of the processes involved in charring wood. Pyrolysis of organic substances produces volatile products and leaves a solid residue enriched in carbon, char MZCET/EEE/VII Sem/OCH353_ET/Unit 4

36. Continues……. Extreme pyrolysis, which leaves mostly carbon as the residue, is called carbonization. Pyrolysis is the first step in the processes of gasification or combustion. The process is used heavily in the chemical industry. Used in the Methane Pyrolysis conversion of natural gas(methane) into non-polluting hydrogen gas. MZCET/EEE/VII Sem/OCH353_ET/Unit 4

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38. Summary Pyrolysis is the thermal decomposition of biomass occurring in the absence of oxygen. Fundamental chemical reaction that is the precursor of both the combustion and gasification processes. Occurs naturally in the first two seconds. The products of biomass pyrolysis include biochar, bio-oil and gases including methane, hydrogen, carbon monoxide, and carbon dioxide Depending on the thermal environment and the final temperature, pyrolysis will yield mainly biochar at low temperatures, less than 450o C MZCET/EEE/VII Sem/OCH353_ET/Unit 4

39. Types of Pyrolysis Methane pyrolysis – In the presence of catalytic molten metals for the direct conversion of methane to non-polluting hydrogen fuel. Hydrous pyrolysis - In the presence of superheated water or steam, producing hydrogen and also substantial atmospheric carbon dioxide. Dry distillation - In the original production of sulfuric acid from sulfates Destructive distillation - In the manufacture of charcoal, coke and activated carbon Charcoal burning - The production of charcoal MZCET/EEE/VII Sem/OCH353_ET/Unit 4

40. Hydrolysis Hydrolysis is a chemical process in which a molecule of water is added to a substance. This addition causes both substance and water molecule to split into two parts. One fragment of the target molecule (or parent molecule) gains a hydrogen ion. It breaks a chemical bond in the compound. Common kind of hydrolysis occurs when a salt of a weak acid or weak base (or both) is dissolved in water. Water spontaneously ionizes into hydroxide anions and hydronium cations. The salt also dissociates into its constituent anions and cations. MZCET/EEE/VII Sem/OCH353_ET/Unit 4

41. HYDROLYSIS MZCET/EEE/VII Sem/OCH353_ET/Unit 4

42. Hydrogenation Treatment of substances with molecular hydrogen (H2 ), adding pairs of hydrogen atoms to compounds. Requires a catalyst for the reaction to occur under normal conditions of temperature and pressure. Most hydrogenation reactions use gaseous hydrogen as the hydrogen source. The reverse of hydrogenation, where hydrogen is removed from the compounds, is known as dehydrogenation. Hydrogenation differs from protonation or hydride addition because in hydrogenation the products have the same charge as the reactants. MZCET/EEE/VII Sem/OCH353_ET/Unit 4

43. Hydrogenation MZCET/EEE/VII Sem/OCH353_ET/Unit 4

44. Hydrogenation Hydrogenation reactions generally require three components: the substrate, the hydrogen source, and a catalyst. The reaction is carried out at varying temperatures and pressures depending on the catalyst and substrate used. The hydrogenation of an alkene produces an alkane. Platinum, palladium, rhodium, and ruthenium are known to be active catalysts which can operate at lower temperatures and pressures. MZCET/EEE/VII Sem/OCH353_ET/Unit 4

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46. Biomass Gasification Biofuels are fuels produced directly or indirectly from organic material or biomass. It includes plant materials and animal and human waste. Production of electrical energy using biomass as a fuel involves accessing the hydrocarbon portion of the biomass that can be converted into heat. Biofuels are considered renewable as they use energy from sunlight to recycle the carbon in the atmosphere in the form of carbon dioxide. MZCET/EEE/VII Sem/OCH353_ET/Unit 4

47. Gasification Definition A thermal process which converts organic carbonaceous materials (such as wood waste, shells, pellets, agricultural waste, energy crops) into a combustible gas comprised of carbon monoxide (CO), hydrogen (H) and carbon dioxide (CO2) MZCET/EEE/VII Sem/OCH353_ET/Unit 4

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49. Biodiesel Production Produced from vegetable oils, yellow grease, used cooking oils, or animal fats Produced by transesterification—a process that converts fats and oils into biodiesel and glycerin (a byproduct) Approximately 100 pounds of oil or fat are reacted with 10 pounds of a short-chain alcohol (usually methanol) in the presence of a catalyst (usually sodium hydroxide [NaOH] or potassium hydroxide [KOH]) 100 pounds of biodiesel and 10 pounds of glycerin (or glycerol) will be produced. Glycerin, a co-product, is a sugar commonly used in the manufacture of pharmaceuticals and cosmetics. MZCET/EEE/VII Sem/OCH353_ET/Unit 4

50. Summary Biomass energy refers to the use of organic materials—such as plant and animal waste, wood, and agricultural residues—as a source of energy. This energy can be harnessed through various methods, including burning, microbial digestion, and conversion into biofuels like ethanol and biodiesel. Biomass is considered a renewable resource because it relies on the natural cycle of growth and decay. When managed sustainably, it can reduce reliance on fossil fuels, lower greenhouse gas emissions, and provide energy security. However, its environmental impact can vary based on factors like land use changes and resource management practices. MZCET/EEE/VII Sem/OCH353_ET/Unit 4

51. REFERENCE https://www.hsmukunda.in/files/books/2011_Wiley_Biomass_book.pdf https://link.springer.com/book/10.1007/978-3-319-07641-6 https://nap.nationalacademies.org/read/9714/chapter/8 https://ledsgp.org/app/uploads/2015/10/biomass-energy-data-book.pdf https://www.sciencedirect.com/book/9780124109506/biomass-for-renewable-energy-fuels-and-chemicals https://tedb.ornl.gov/wp-content/uploads/2019/04/Biomass_Energy_Data_Book_Edition_4.pdf MZCET/EEE/VII Sem/OCH353_ET/Unit 4