A presentation that highlights how to harness energy from waste materials
A R T H U R D A N I E L D A D Z I E
M O R G A N J E S S E A S A R E
E S T I B A L I Z B O S I O D O R O
A Presentation on Bioenergy
Resources of biomass
Energy Conversion Processes
biological or biochemical conversion
Forms of Bioenergy
Environmental and economic impact of bioenergy and
The material of plants and animals, including their wastes
and residues, is called biomass. It is organic, carbon-based,
material that reacts with oxygen in combustion and natural
metabolic processes to release heat.
Such heat, especially if at very high temperatures, may be
used to generate work and electricity. The initial material
may be transformed by chemical and biological processes to
Examples of biofuels include methane gas, liquid ethanol,
methyl esters, oils and solid charcoal.
The term Bioenergy is sometimes used to cover biomass and
Forest and mill residues
Agricultural crops and waste
Livestock operation residues
Fast growing trees and plants
Municipal and industrial waste
Biomass Conversion Processes
Biomass conversion methods can be classified based on;
• Conversion Technologies and
• The End products.
• Conversion Technologies can be said to be through either
Biological or biochemical processes
Thermal conversion processes use heat as the dominant
mechanism to convert biomass into another chemical form.
The basic alternatives are combustion, torrefaction,
pyrolysis, and gasification.
Direct combustion for immediate heat. Dry homogeneous
input is preferred.
They are differentiated principally by the extent to which the
chemical reactions involved are allowed to proceed (mainly
controlled by the availability of oxygen and conversion
Thermal conversion processes cont’d
The output depends on temperature, type of input material
and treatment process.
In some processes the presence of water is necessary and
therefore the material need not be dry. If output of
combustible gas is the main product, the process is called
The oldest and most common method of harnessing
energy from biomass.
It is simply the oxidation of wood/plant material to
The heat produced can be used directly and it can
also be used for generating electricity. (CHP)
A process that converts organic materials into carbon
monoxide, hydrogen and carbon dioxide and other
Achieved by reacting the material at high temperatures
(>700°C), without combustion, with a controlled amount
of oxygen and/or steam.
The resulting gas mixture is called syngas (from
synthesis gas or synthetic gas) or producer gas and is
itself a fuel.
Syngas may be burned directly in gas engines, used to
produce methanol and hydrogen, or converted into
Chemical conversion processes
A range of chemical processes may be used to convert
biomass into other forms, such as to produce a fuel that is
more conveniently used, transported or stored, or to exploit
some property of the process itself.
Biorefining is the process of "refining" multiple products
from biomass as a feedstock or raw material much like a
petroleum refinery that is currently in use.
A biorefinery is a facility like a petroleum refinery that
comprises the various unit operations and related
equipment to produce various bioproducts including fuels,
power, materials and chemicals from biomass.
Chemical conversion process cont’d
By producing multiple products, a biorefinery takes
advantage of the various components in biomass and their
intermediates therefore maximizing the value derived from
the biomass feedstock. Inset is a biorefinery.
Biochemical conversion processes
Biochemical or biological conversion makes use of the
enzymes of bacteria and other micro-organisms to break
In most cases micro-organisms are used to perform the
conversion process: anaerobic digestion, fermentation and
Another chemical process used in converting straight and
waste vegetable oils into biodiesel is transesterification.
Another way of breaking down biomass is by breaking
down the carbohydrates and simple sugars to make alcohol.
Anaerobic digestion is a series of processes in which
microorganisms break down biodegradable material in the
absence of oxygen.
It is used for industrial or domestic purposes to manage
waste and/or to release energy.
Much of the fermentation used industrially to produce food
and drink products, as well as home fermentation, uses
anaerobic digestion. Silage is produced by anaerobic
Anaerobic digestion cont’d
Many microorganisms are involved in the process of
anaerobic digestion. These organisms feed upon the initial
feedstock, which undergoes a number of different
processes, converting it to intermediate molecules,
including sugars, hydrogen, and acetic acid, before finally
being converted to biogas.
Feedstocks can include biodegradable waste materials, such
as waste paper, grass clippings, leftover food, sewage, and
The three principal products of anaerobic digestion are
biogas, digestate, and water
Forms of Bioenergy
Bioenergy may exist in different forms. These are mainly;
Combined heat and power (co-generation)
Biopower is electricity generated from combustion of
biomass, either alone or in combination with coal,
natural gas or other fuel (termed co-firing).
Most biopower plants are direct-fired systems. That is,
biomass feedstock are burned in a boiler to produce
high-pressure steam which runs turbines connected to
The electricity produced can be distributed for industrial,
residential or commercial use.
The steam generated from combustion of biomass
feedstock can also be used directly power mechanical
processes in industrial settings
Processes like combustion, pyrolysis and gasification
produce heat in large quantities which is harnessed.
Gasifiers offer a flexible option for thermal applications, as
they can be retrofitted into existing gas fueled devices such
as ovens, furnaces, boilers, etc., where syngas may replace
Biofuel is liquid, gas and solid fuels produced from two
types of biomass materials – plant sugars and starches
(e.g., grains), and lignocellulosic materials (e.g., leaves,
stems and stalks).
Liquid and gas biofuels are produced through fermentation,
gasification, pyrolysis, torrefaction, and transesterification
conversion technologies. The primary use of liquid and gas
biofuels is transportation
They include ethanol, biodiesel, syngas, biogas, methanol,
char and bio-coal and bioethers.
Combined heat and power.
Combined heat and power (CHP), also known as co-
generation, is the simultaneous production of electricity
and heat from a single fuel source, including biomass.
In a gas turbine CHP plant, hot exhaust gases from the
combustion process are captured in a heat recovery unit
and used to heat steam which is then used in heating and
cooling of various indoor environments.
In steam boiler CHP plants steam is produced that runs
electric generators and for heating/cooling.
Using biomass as a fuel produces air pollution in the form of
carbon monoxide, carbon dioxide, NOx (nitrogen oxides),
VOCs (volatile organic compounds), particulates and other
pollutants, in some cases at levels above those from
Biomass systems can reduce waste energy from 66% to 25%
compared to traditional fossil fuels, meaning a significantly
smaller amount of input material (biomass) is used,
therefore having a positive effect on the global environment
and use of fuel.
Environmental impact cont’d
Modern biomass systems use filters. These filters capture
carbon and other pollutants before they enter the
atmosphere. Thus in the biomass lifecycle, the pollutants
are captured by trees and crops, they are burnt, pollutants
are captured and less are released back into the
environment. Any pollutants released are then reabsorbed
by trees and plants
In combination with a significant energy efficiency effort,
there is almost nothing better for the local economy than
increased reliance on biomass fuels. From a
macroeconomic perspective, there are three different
engines that can be applied to drive local economic
Economic growth through business expansion (earnings) or
Import substitution; and
The biomass material acquisition is comparatively cheaper.
Biomass is environmentally friendly compared to fossil
Biomass can be sourced locally.
The use of biomass fuel provides an economic incentive to
manage woodland which improves biodiversity.
In rural economic development and stability: we spend
billions of dollars each year importing oil, biomass could
replace half of this and direct the rest to other sectors
Biomass provides low CO2 emissions, heat and
like other renewable energy sources, good planning
and managing will give higher efficiency.
Systems for it use are still under-development and
improved utilisation of biomass is expected.
Considering the benefits mentioned above; biomass
is a promising source of renewable energy and
developing it should be a key issue.