Renewable Energy: Biomass Systems

• The document discusses Renewable Energy Engineering focusing on Solar, Wind, and Biomass Energy Systems.
• The module focuses on biomass, its types, and characterization.
• The text refers to both lecture 01 part 1 and lecture 01 part II and mentions lecture 02.

Introduction to Energy

• "Energy" derives from the Greek "en-ergon," meaning 'in-work' or 'work content'.
• An erg equals 10⁻⁷ joules and originates from the CGS system, but it's not an SI unit.
• Energy is essential for work, with output depending on input, serving as basic infrastructure for economic growth.

Energy Timeline

• Before the Industrial Revolution, people relied on manual and animal labor and met energy needs through food.
• Life was simple, environment was clean.
• The steam engine brought the industrial revolution, and coal use began.
• The internal combustion engine led to using fossil fuels like oil and natural gas which allowed for concentrated energy.

Energy Consumption Sectors

• Key sectors consuming energy include agriculture, domestic, industry and transportation.

Classification of Energy Resources

• Classifications are based on the usability of energy, if it is traditional, exhaustibility, commercial use or origin.

Usability of Energy

• Primary resources are the base form of energy
• Intermediate resources are partially converted
• Secondary recourses are fully converted

Traditional Uses of Energy

• Conventional energy resources include fossil fuels, nuclear and hydro resources.
• Non-conventional energy resources include solar, wind, and biomass.

Exhaustibility / Availability of Energy

• Non-renewable resources are static stores of energy underground unless released by human interaction.
• Fossil fuels and uranium are examples of non-renewable energy
• Renewable resources are energy from persistent flows in the immediate environment, that can be replenished.
• Biomass, solar, wind, ocean, geothermal, and hydro are renewable examples of this.

Commercial Application

• Commercial energy resources supply commercial activities.
• Non-commercial energy comes directly from nature and is not sold to consumers.
• Wood, crop residue, and animal dung are examples of non-commercial energy resources

Energy Chain

• Energy chain shows the transformation between primary and secondary energy forms
• Processing primary energy such as coal turns it into electrical energy for the consumer

Common Energy Types

• Mechanical energy comes from the motion of a substance or system.
• Electrical energy is a common, versatile form, easily converted.
• Thermal energy, or heat energy, raises an object's temperature; it exists in high, medium, and low grades.
• Chemical energy, stored in atomic/molecular bonds, releases in exothermic reactions and can convert to electrical/thermal energy.

Importance of Non-Conventional Energy Sources

• Global energy demand is rising due to population and economic growth which the conventional energy sources cannot meet.
• Conventional resources are finite, and their use causes pollution and greenhouse effects.
• Large hydro resources can harm wildlife and cause social issues.
• Fossil fuels, while supplying energy, contribute to the manufacture of organic chemicals.

Biomass Definition

• Biomass is any organic matter used as an energy source, including wood, crops, seaweed, and animal waste.
• It includes plants, animals, and their wastes and residues.
• Biomass includes non-fossilized, biodegradable organic material from plants, animals, and microorganisms and also covers industrial/municipal wastes and liquids from decomposition.

Sustainable and Renewable Aspects of Biomass

• It's a sustainable source, formed from CO2, air, water, soil, and sunlight interacting with plants/animals.
• The carbon in biomass recycles when burned or digested.
• Energy from biomass doesn't increase the Earth's total CO2.

Biomass Characteristics

• Biomass includes live and very recently dead biological matter
• Biomass does not include organic material transformed by geological actions such as coal and petroleum.
• It stems from plants, animals or a combination of the two.

Biomass Formation

• Solar radiation on green plants causes two actions; chemical reaction and the capturing of photosynthesis.

Photosynthesis Detail

• Photosynthesis is the conversion of CO2 in the atmosphere to carbohydrates such as sugars, starches, celluloses and hemicelluloses with chlorophyll and water.

Photosynthesis Expression

• A chemical equation of photosynthesis is expressed as xCO2 + yH2O + sunlight -> Cx(H2O)y + xO2
• A more exact formular can be used 6CO2 + 6H2O + sunlight -> C6H12O6 + 6O2

Solar Radiation

• Net energy absorbed from solar radiation during photosynthesis can be calculated from combustion.
• Net energy, post energy of respiration is about 470 kJ.mol, and 16 MJ/kg of carbohydrate.

Broad Biomass Classification

• Biomass is split into Maiden biomass primary and Waste Biomass.

Maiden Biomass

• This is broken down into Terrestrial biomass and Aquatic biomass.
• Terrestrial includes forests, grasses, energy crops grown, and cultivated crops.

Waste Biomass

• This includes agriculture waste, industrial waste, forestry residue, and municipal waste
• Industrial waste includes demolition, sawdust, and waste oil
• Forestry residue includes bark, leaves and floor residues
• Municipal waste includes mass solid waste and bio solids and sewage

Common Biomass Sources

• Agricultural residues include straw, rice husk, bagasse, corn stalks,seed hulls, and nutshells.
• Forests (natural and cultivated) serve as fuel wood, charcoal, industrial residues utilized at mills
• Urban waste comes in two forms, municipal solid waste or sewage
• Specific cultivated plants are energy crops, such as raw material energy that creates sugar, starch, and oil.

More about Energy Crops

• Sugar plants include sugar cane, sweet sorghum, and sugar beet.
• Starch crops include cassova.
• Oil producing includes Palm, Soybean, Groundnut, and Repeseed.

Water Plants

• Water plants include all aquatic plants, both submerged and emersed
• These species grow faster in water than on land and are a type of energy crop (water hyacinth, sea weed, and algae).
• Biological waste can include both animals and plants in the form of waste and liquid matter.

Biomass type

• To determine what kind of biomass is to be harvested, there are 3 considerations
• Is there some after use for the discarded material other than to be disposed?
• Is what is left, the run off of other mass, woody by products?
  • Yes. Material is feedstock for energy.
  • No. the remaining material discarded as landfill.

Components of Woody Biomass

• Woody biomass comes from extractives, cell wall components, and ash.
• The extracted components can come from solvent from materials composed of vegetable matter, tissue and more.

Biomass Cell Wall

• Leaves and bark usually have more extractives and less cell wall materials than wood
• Cell walls provide support
• This allows plants stand on their own
• Plant structure consists of fibres containing structural carbohydrates and lignin
• Cellulous is generally very strong and what impact structure in fibre

More about Plant Fiber

• Plant fibers vary based on plant type such as conr, soybeans, or potatoes.
• Plant’s fibre has three grades and are made up of high, low, and medium thermal.

Ash

• Ash refers to inorganic material which in small values is critical to cell growth.

Constituents of Biomass Cells

• Three polymers make up the cells walls which are cellulose, hemicellulose, and lignin.

Cellulose

• It's the world’s most common organic biopolymer
• It is a common form of glucose
• It the mains structural component of cell walls
• It has a crystalline structure with glucose molecules
• Makes up about 40 to 45% of Biomass, if you extracted any excess water content
• It is mostly composed of carbon 6 or hexose sugar

Hemicellulose makeup

• It is constructed often with both carbon 5 and carbon 6 based sugars, and is often found within the walls of plant cells Cellulose, conversely, is very rigid.
• Hemicelluloses serves as a structure from for other plant parts, but biomass varies from hemicelluloses to biomass greatly
• Mostly, contains C5 sugar including Xylose
• Also solubale well in dilute forms acids and often are easily disolved under 2 acid base, or dilute conditions.

Contents of hardwood

• The content could be related but may be different depending on the type and the wood used

Hemicellulose is easier to decompose

• It also thermochemically and biochemically decomposes and can be very abundant

Lignin

• Lignin is a important polymer and one of the third most abundant on the planet to date
• It is what is left over from other polymers that is very strong and complex
• Lignin has no carbohydrates unlike the other polymers.
• The other polymer is also a alcohol called coniteryl and sinapyl achohol and the content is what makes it the material

Characteristics of Biomass

• Biomass characterization is essential for understanding how it works as a renewable energy source.
• It helps to understand the chemical and physical properties
• This information is important for designing biomass conversion systems.

Characteristics Affecting Biomass as a Fuel

• Proximate analysis includes bulk density, moisture content, volatile matter, ash, and fixed carbon.
• Ultimate analysis includes elemental composition (carbon, hydrogen, nitrogen, sulfur, oxygen) and HHV value.
• Structure includes the amount of cellulose, hemicellulose, lignin, and extractives.

Density

• Density is design parameters for biomass conversion, processing, and comes in three types in characteristics, the true density, the bulk density, and the apparent density.

More on Density

• Weight per unit of biomass is how this element can be rated, measured by testing and volume
• Apparent, which in effect tested, measures the total external test volume including open pore space
• Bulk denisty is volume measured in the test in space in an encolsed contaitner

Moisture

• Biomass constituents made of moisture are directly related to the content and can impact thermal conversion capabilities like combustion gasification and pyrolysis
• The high moisture, can impact drying conditions and price of the biomass due to transport cost, energy penitilites Low content in these instances can increase operation. And assist processing the energy into new forms

Equations about Moisture Contents

• Basic equations when the materials is considered are shown by $$

  𝑀_{wet}= (weight wet - weight dry)/(weight of wet)

              $$
  

• Basic equations measuring dry mass $$ Mdry= (weught wet - weight dry) / (weight of dry) $$

• Relationally : $$

Mdry=(1-Mwet)/Mwet

$$

Some notes material

• Low moisture materials and plant species make better test material
• Conversion of biochemical samples, such as fermented sugar can lead to herbaceous plants to produce Methane. The fermentation must be anareobic.

Moisture and How the Testing Works.

• Loss of weight occurs as the instrument does its test over the biomass sample. $$

Weight loss % = (Wi - Wt)/(Water I - Water C ) * 100 = A $$

What A stands for is also equivalent to the following

W= the cruicble and cover where

• I = intergral weight
• F = final

The mass then creates volatile material that is tested

• A = weight of (water i / F ) B moisture equals test 871 in these instances.
• For a biomass and sustainable materials, its important that the source, be it low, heat stable, It be a good source of coal, that can give to sustainable energy
• Low ash materials must show low ash during the experiment by under-going oxidation