UNIT – III

BIO ENERGY

PART – A

1. What is the difference between biomass and biogas?

Biomass is the amount of living matter in a given habitat, expressed either as the weight

of organisms per unit area or as the volume of organisms per unit volume of habitat. Biogas

is any gas fuel derived from the decay of organic matter, as the mixture of methane and

carbon dioxide produced by the bacterial decomposition of sewage, manure, garbage, or

plant crops.

2. What is Pyrolysis ?Pyrolysis is a thermo chemical decomposition of organic material at elevated

temperatures in the absence of oxygen (or any halogen). It involves the simultaneous change

of chemical composition and physical phase, and is irreversible. The word is coined from the

Greek-derived elements pyro "fire" and lysis "separating".

3. State the types of Gasifiers.

Updraught or counter current gasifier

Downdraught or co-current gasifiers3

Cross-draught gasifier

Fluidized bed gasifier

4. Name any five models of biogas plant.A total of seven different types of biogas plant have been officially recognized by the

MNES.

The floating-drum plant with a cylindrical digester (KVIC model),

The fixed-dome plant with a brick reinforced, moulded dome (Janata model)

The floating-drum plant with a hemisphere digester (Pragati model)

The fixed-dome plant with a hemisphere digester (Deenbandhu model)

The floating-drum plant made of angular steel and plastic foil (Ganesh model)

5. Define Gasification.Gasification is a process that converts organic or fossil fuel based carbonaceous materials

into carbon monoxide, hydrogen and carbon dioxide. This is achieved by reacting the

material at high temperatures (>700 °C), without combustion, with a controlled amount of

oxygen and/or steam

.

6. Define Fermentation.Fermentation is a metabolic process that converts sugar to acids, gases or alcohol. It

occurs in yeast and bacteria, but also in oxygen-starved muscle cells, as in the case of lactic

acid fermentation. Fermentation is also used more broadly to refer to the bulk growth of

microorganisms on a growth medium, often with the goal of producing a specific chemical

product.

7. Give any five Biomass resources.Woody source of biomass (Lignocelluloses) such as:Forest residues, Landscaping

residues, Energy wood plantations, Residues from food, Industrial wood residue, Waste

wood residues

Non Woody biomass (Oil, sugar, starch) such as: Energy plants from agriculture, Straw

and other harvesting residues from agriculture, Residues from food industry, Landscaping

residues(grass etc.)

Animal/Men(Fats/Proteins), Farm slurry /excrements, Slaughter waste, Organic waste

from households and industry

8. Define Liquefaction.Liquefaction is a term used in materials sciences to refer to any process which either

generates a liquid from a solid or a gas or generates a non-liquid phase which behaves in

accordance with fluid dynamics.

9. State any five factors affecting the Biogas generation. Sub layer composition; Temperature inside the digester; Retention time; Working pressure of the digester; Fermentation medium pH.

10. What is an Anaerobic digestion?

Anaerobic digestion is a series of biological processes in which microorganisms

break down biodegradable material in the absence of oxygen. One of the end products is

biogas, which is combusted to generate electricity and heat, or can be processed into

renewable natural gas and transportation fuels.

11. Define Hydrolysis.

A chemical reaction in which the interaction of a compound with water results in the

decomposition of that compound.

12. State the types if alternative liquid fuels.biodiesel, bioalcohol (methanol, ethanol, butanol), chemically stored electricity (batteries and fuel cells), hydrogen, non-fossil methane, non-fossil natural gas, vegetable oil, propane, and other biomass sources.

13. What is meant by energy plantation?Eenergy plantation means growing select species of trees and shrubs which are harvestable in a comparably shorter time and are specifically meant for fuel. The fuel wood may be used either directly in wood burning stoves and boilers or processed into methanol, ethanol and producer gas

.14. Give a list of the materials used for biogas generation from agricultural wastes

sugar cane, cassava, corn etc, agricultural residues like rice straw, cassava rhizome, corn cobs.

15. Differentiate Wet fermentation and Dry fermentations