Renewable Energy

Generation Facility

facility for the production of electricity and/or thermal energy

Co-Generation System

facility that produces electrical and/or mechanical energy as well as forms of useful thermal energy such as heat and steam, which are used for heating and cooling purposes

Hybrid System

any power or energy generation facility that makes use of two or more types of technologies utilizing both conventional and renewable fuel sources

Distributed Generation System

small generation entities directly supplying electricity to distribution grid, not exceeding 100kW in capacity

Distribution Utility

any electric cooperative, private corporation, government owned utility, or existing local government unit which has an exclusive franchise to operate a distribution system

Grid

high-voltage backbone system of interconnected transmission lines, substations, and related facilities.

Net Metering

system for distributed generation in which distribution grid user has a two-way connection to the grid and is only charged for his net electricity consumption and is credited for any overall contribution to the electricity grid

Power Application Facility

renewable energy system or facility that produces electricity.

Non-Power Application Facility

renewable energy facility that produces mechanical energy, combustible products, or any useful form of thermal energy that is not used for electricity generation

Heating Value

energy released per unit mass or volume of the fuel when the fuel is completely burned

Higher Heating Value

condition in which the water is condensed out of the combustion products

Lower Heating Value

condition in which water in the final combustion products remains as vapor or steam

Direct Combustion

burning biomass to produce heat with ash as byproduct

Gasification

biomass (solid fuel) is converted to producer gas (CO, H2, N2, and CH4) in an oxygen-starved environment

Bioethanol

sugar-rich biomass is converted through fermentation of feedstock followed by distillation to separate alcohol from water

Biodiesel

oil derived from processing crops, food wastes are converted through esterification to methyl ester by simply mixing methanol, KOH, and vegetable oil

Biogas

animal wastes are converted to biogas (CH4 , CO2, and H2S) through anaerobic digestion process in the absence of oxygen

Solar Thermal

uses sun’s heat energy captured directly with the use of a solar collector. Efficiency of solar collector is up to 70 - 80%.

Solar Photovoltaic

sunlight is captured and converted into electricity using a solar cell. Voltage and current are obtained by connecting cells either in series or in parallel

Wind Pump

kinetic energy of the wind causes the rotor to rotate producing reciprocating motion that drives a lift pump

Wind Turbine

kinetic energy of wind is used to propel the rotor at a higher speed to produce electricity

Microhydro

uses potential as well as kinetic energy from water to propel a turbine causing it to rotate that drives stationary machine or generator

Hydraulic Ram Pump

uses the force of moving water from a stream to create power that pushes portion of water to a higher level than that of the source.

Water Wheel

kinetic energy of flowing water causes the wheel to rotate producing rotary or reciprocating motion to produce power

Flat-Grate

the grate that holds the fuel is in flat position in the stove. Ashes directly falls into the grate holes to separate from burning fuel.

Step-Grate

grate is inclined at 45 deg position commonly used for rice husk fuel in direct combustion. As the fuel turns to ash, it is discharged at the bottom of the grate using a stick

Center-tube

has a cylindrical holes at the middle of the stove where air is allowed to pass through. A lateral hole is provided at one side for the entry of air and, at the same time, to provide a burning wood stick to sustain combustion of fuel

Conical Grate

grate is in the shape of a cone that surrounds the center of the stove where flame is allowed to hit directly the bottom of the pot

Fire Box

stove component; it is where the combustion of fuel takes place. This should be optimized to accommodate as much fuel with minimal heat loss

Pot hole/ Rim

stove component; is where the pots are positioned on the stove

Chimney

stove component; serves to discharge flue gases and to create suction of air needed for the combustion of fuel in the stove

Baffles

stove component; are obstructions introduced in the flow passage below the second, third, or fourth burner to divert the flow of heat directly to the bottom of the pot

Connecting Tunnel

stove component; passage or duct that connects the different pot holes

Damper

stove component; used to control the flow passage of air supply and power output of the stove

Primary Air

is the air supplied to the stove to support the combustion of fuel. It plays a crucial role in the initial burning process, influencing the efficiency and effectiveness of fuel gasification

Secondary Air

air supplied to the stove used to combust combustible volatile matter that is released during the combustion of fuel; excessive amount of secondary air may dilute the air necessary for combustion and reduce heat transfer efficiency

Proximate Analysis

provides information on the percentages of volatile matter, fixed carbon and ash in the fuel. It indicates the flaming and glowing ability of the fuel during combustion

Ash

provides a measure of the incombustible mineral matter in the fuel. The higher it is in the fuel, the lesser is its energy content

Ultimate Analysis

provides information on the chemical composition of fuel in terms of carbon, hydrogen, oxygen, nitrogen, and sulfur as mass percentages of dry and ash-free biomass material. This is essential in estimating air requirements, flue losses and emission of pollutants in the fuel

Calorific Value

quantity of heat in the fuel which is used to meet a given energy requirement or energy demand

Complete Combustion

occurs when all the combustible components of the biomass material are gasified and all the carbon is burned to carbon dioxide, all the hydrogen is converted to water, and all the sulfur to sulfur dioxide

Stoichiometric Air

is the theoretical amount of air required to completely burn the fuel with no dissociation

Excess Air

additional amount of air needed to achieve complete combustion of fuel. It can be determined by the actual amount of air used minus the stoichiometric air. In general, excess air of about 65 to 75% of the theoretical air is needed for complete combustion.

Feeding Mechanism

furnace component; is where the fuel is fed into the combustion chamber.A screw-type feeding mechanism is commonly used for granular fuel while a drag conveyor stoker is adopted for chunks and larger-sized fuel. In the case of fluidized, such as spouted and cyclonic combustor, a pneumatic fuel feeder is used in which the fuel is sprayed at a very high velocity.

Combustion Chamber

furnace component; is where the biomass fuel is completely burned. It is totally enclosed with insulation to minimize heat loss.

Air Supply Unit

furnace component; provides the proper amount and pressure of air required by the fuel. A blower is used in many biomass furnaces where the installation is accessible to the grid

Ash Removal

furnace component; provides uniform discharge of char from the combustion chamber. A screw discharger or a vibratory chute is usually used for biomass furnaces

Heat Exchanger

furnace component; used for biomass furnaces to obtain quality heat without smoke, tars and particulates. Metal pipes or walls separating flue gases from heated air are provided for the furnace to obtain clean hot air

Flue Gas Outlet

furnace component; serves as a discharge outlet for flue gases. Chimney is a commonly used discharge outlet for furnaces

Grate

most commonly used type of combustor. It is suitable for burning a wide range of biomass materials. It is designed to hold biomass fuel in place during combustion and allows the air to circulate freely through it.

Fluidized Bed

type of combustor suited for burning both large and small particulate wood wastes and agricultural residues even with relatively high moisture content. The system basically consists of the combustion chamber containing a sand bed that acts as heat-transfer medium. Particulate biomass is introduced into the hot bed where it undergoes combustion

Cyclonic

type of combustor suitable for burning particulate wood wastes and agricultural residues typically of regular size and shape and of relatively low moisture content

Burning Efficiency

It is the ratio of the actual and the theoretical heating value of burned fuel, expressed in percent.

Furnace Efficiency

It is the ratio of the heat transferred and the heat available in the biomass furnace, expressed in percent

Latent Heat of Vaporization

It is the heat absorbed by a unit mass of material at its boiling point in order to convert the material into gas without changes in temperature

Sensible Heat

It is the heat absorbed or evolved by a substance during a change in temperature that is not accompanied by a change in state.

Heating system Efficiency

It is the ratio of actual and theoretical heat supplied by the fuel to the furnace, expressed in percent

Gasification

limited amount of air is introduced into the burning fuel in the reactor to produce combustible gases. The process takes place with excess carbon which is accomplished in an airsealed, close chamber under slight suction or pressure relative to ambient pressure to convert biomass into carbon- and hydrogen-rich fuel gases such as carbon monoxide, hydrogen, and methane.

Equivalence Ratio

is the ratio of the actual amount of air supplied to the amount of stoichiometric air needed for complete gasification of the fuel. It helps assess the efficiency of the gasification process and the combustion characteristics of the fuel.

Fixed bed

type of gasifier; is an old, simple technology used for small-scale applications. It requires large, dense, uniformly-sized fuels, and agri-residues often need costly densification

Updraft

suitable for various biomass fuels and can gasify wet fuel without needing specific fuel sizes. It has higher efficiency, as the gas flows parallel to the fire zone and exits at a low temperature. However, it generates a large amount of tar and requires a very large unit.

Downdraft

has a gas stream flowing opposite to the fire zone, which burns off tars before they exit the reactor. It requires properly sized fuel and a special device, and is limited to outputs under 200 kW. This design generates minimal tar, can be very compact, and is suitable for small gas outputs.

Cross draft

the gas stream flows across the fuel bed and the fire zone. It's highly compact and ideal for small power outputs and varying loads, but it is limited to specially-prepared, dry fuels—typically charcoal. It cannot gasify wet fuel.

Fluidized Bed

type of gasifier; achieves the highest gasification rate per square meter of grate area and is ideal for small fuel particles under 20 mm. Although it produces tar, the technology is not yet well-developed and is specifically suited for finer fuels. This rapid heating and violent stirring create a uniform temperature and composition in the fuel bed, ensuring consistent gasification throughout.

Moving Bed

gasifies biomass fuel as it gradually moves down the reactor, making it suitable for loose materials like rice husks. Biomass is fed into the reactor while char is discharged. Compared to a fixed-bed gasifier of the same diameter, it has a lower power output due to limited operational capacity but allows for longer operational times

Bubbling bed

type where solid particles behave like a boiling fluid without being transported by the air stream. This allows for efficient gasification while maintaining a stable bed of materials.

Circulating bed

operates at higher gas velocities, causing some bed material to leave the reactor vessel. This material is then transported back to the reactor via a cyclone and return pipe, enhancing efficiency and maintaining consistent gasification conditions

First-Generation

are edible and virgin biomass, such as vegetable oils and fresh crops, used in food industries. The main concern with using these feedstocks as energy sources is the competition between the energy and food industries

Second-Generation

consist of non-edible plant resources and waste biomass, including food waste, waste vegetable oils, and lignocellulosic materials. These feedstocks are used to produce biofuels such as producer gas, biodiesel, bioethanol, biogas, and bio-oil

Third-Generation

include algae and microorganisms, recognized as fuel sources due to their rapid growth rates, small area requirements, and easily controllable growth conditions

Pyrolysis

thermal decomposition of biomass in the absence of air or oxygen, producing solid char, liquid bio-oil, tar, or gas. Operating between 400° to 650°C (or higher), it can be slow, fast, or ultra-fast (flash). The process can be self-sustaining, as combustion of pyrolysis gas and some bio-oil or bio-char supplies the energy needed for the reaction. It is a promising method for biomass valorization, yielding up to 78% bio-oil from dry biomass.

Slow pyrolysis

method of biomass pyrolysis where biomass is slowly heated (0.1-1°C/s or 5-7°C/min) to temperatures above 400°C, typically around 500-600°C, in the absence of oxygen. This slow heating maximizes char production with minimal liquid and gas outputs. Main products include char, bio-oil, and gases.

Fast pyrolysis

method of biomass pyrolysis where it rapidly heats biomass (10-200°C/s) to around 500°C, producing up to 75% liquid bio-oil, 15-20% char, and 10-12% gases. By using small, dry biomass particles, this method quickly converts biomass into liquids, minimizing char formation.

Flash pyrolysis

method of biomass pyrolysis operating at more than 800°C at a very short retention time of less than 0.5 sec.Operates at extremely high heating rates (>1000°C/s) and reaction times of just a few seconds. This rapid process requires smaller biomass particles and is optimized for high liquid output in minimal time.

Bio-oil

liquid produced from biomass via fast pyrolysis. It contains 35-40% oxygen, which must be removed to produce hydrocarbons suitable for fuel.

Biochar

high-carbon charcoal made by slow pyrolysis, used as a soil amendment to improve water retention, support microbial life, and enhance crop yields. It provides long-term carbon sequestration by storing carbon in soil for thousands of years, reducing atmospheric carbon.

Pyrolysis gas

mainly composed of hydrogen (H₂) and carbon monoxide (CO), along with other components like C₂H₄, CH₄, and tar, depending on the biomass feedstock and pyrolysis conditions, yielding about 10-35%. It serves as a renewable fuel for combustion processes and internal combustion engines, with higher yields achievable in flash pyrolysis, especially at elevated temperatures or using catalysts like dolomite

Torrefaction

a method for altering the properties of biomass by slowly heating it to a maximum temperature of 300°C, under atmospheric pressure and in the absence of oxygen. This process separates water from volatile matter and hemicellulose in woody biomass, resulting in a charcoal-like carbonaceous residue, with low heating rates and residence times of 30 to 120 minutes.

Densification

process of reducing the bulk volume of the material by mechanical means for easy handling, transportation, and storage

Baling

densification method; traditional densification method for harvested crops, utilizing a machine known as a baler to compress chopped materials into compact bales. This process enhances storage and transport efficiency by reducing the volume of the biomass.

Pelleting

densification method; biomass densification process for solid fuel applications that uses high-pressure compaction, known as binderless technologies, to increase the density of biomass from 40-200 kg/m³ to 600-1200 kg/m³, improving storage and transport efficiency

Extrusion

densification method; process that involves pressing biomass material through a die using either a screw or a piston to shape it into a specific form

Briquetting

densification method; a process similar to pelleting but produces larger-sized products instead of pellets

Durability Index

ability of densified materials to remain intact during handling, storage, and transport. It encompasses the physical strength and resistance to fragmentation, which are critically influenced by the bonding performance of the particles during the densification process

Fines content

refers to the presence of undesirable dust particles in densified materials, particularly when used for co-firing with other fuels. Fines are generated during transport and storage due to the breakdown of densified products

Steam Conditioning

process where steam is added to the biomass to make natural binder, like lignin, more available during densification

Steam Explosion

process in which high-pressure saturated steam (approximately 200°C) is applied to biomass in a reactor for 2 to 10 minutes. The rapid release of pressure causes the water within the biomass to vaporize and expand, leading to disintegration which enhances lignin availability for binding during pelletization

Ammonia Fiber Explosion

utilizes aqueous ammonia at elevated temperatures and pressures to enhance hydrolysis yields for various herbaceous feedstocks. This process reduces lignin, removes some hemicellulose, and decrystallizes cellulose while minimizing biomass degradation

Piston press

densification equipment; high-pressure machine used for producing large-sized densified materials. Shape either circular or blocks, depending on the die. Material is pushed into a die by means of punching

Screw Press

densification equipment; highpressure densifying machine that operates by means of screwing the material in to a known shape die

Pelleting Mill

densification equipment; machine that uses sets of roller that pushes the material into a several tapered slots of known size and the densified material is scraped off by means of a stationary blade to cut densified material according to the desired length

Roller Press

densification equipment; material passes in between the two rotating rollers as it is pushed towards a die

Manual Press

densification equipment; low-pressure, hand-operated press for molding briquettes into known shapes

Bioethanol

alcohol made by fermentation, mostly from carbohydrates produced in sugar or starch crops, such as corn or sugarcane.

Starch- and Sugar-Based Feedstock

sugars in these feedstock are easy to extract and ferment, making large-scale ethanol production affordable

Cellulosic Feedstock

non-food-based feedstock that include crop residues, wood residues, dedicated energy crops, as well as industrial and other wastes. These feedstock are composed of cellulose, hemicellulose, and lignin (typically extracted to provide process steam for production)

Fermentation

process of cultivating yeast under a certain condition (35°-40°C) to produce alcohol. Saccharomyces cerevisiae is used to metabolize sugar to produce ethanol and carbon dioxide. The toxicity of ethanol to yeast limits the ethanol concentration. The most tolerant strain of yeast can survive up to approximately 15% ethanol by volume.

Distillation

process of purification of compounds based on their volatility. It is a physical method of assorting mixtures depending upon the difference in the boiling point of the component substances.

Simple Distillation

distillation method; practiced for a mixture in which the boiling point of the components differ by at least 70°C

Multiple Distillation

distillation method; process of repeating distillation on the collected liquid to enhance and achieve the purity desired for the separated compounds