BYARTHUR DANIEL DADZIE

MORGAN JESSE ASAREESTIBALIZ BOSIO DORO

A Presentation on Bioenergy

Content

Introduction Resources of biomass Energy Conversion Processes thermal conversion chemical conversion biological or biochemical conversion Biogas Forms of Bioenergy Environmental and economic impact of bioenergy

and biomass

introduction

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 produce biofuels.

Examples of biofuels include methane gas, liquid ethanol, methyl esters, oils and solid charcoal.

The term Bioenergy is sometimes used to cover biomass and biofuels together.

Biomass Resources

Forest and mill residuesAgricultural crops and wasteWood wastesAnimal wasteLivestock operation residuesAquatic plantsFast growing trees and plantsMunicipal and industrial waste

Biomass Resources

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 Chemical processes Thermal processes.

Thermal conversion

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 temperature).

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 gasification.

Combustion

The oldest and most common method of harnessing energy from biomass.

It is simply the oxidation of wood/plant material to produce heat.

The heat produced can be used directly and it can also be used for generating electricity. (CHP)

Gasification

A process that converts organic materials into carbon monoxide, hydrogen and carbon dioxide and other combustible gas.

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 synthetic fuel.

Gasification

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 down biomass.

In most cases micro-organisms are used to perform the conversion process: anaerobic digestion, fermentation and composting.

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

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 digestion.

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 animal waste.

The three principal products of anaerobic digestion are biogas, digestate, and water

Anaerobic digestion

Summary of conversion processes

Biological conversion:- Anaerobic Digestion

Fermentation

Thermal conversion:- Combustion Gasification Pyrolysis

Chemical conversion:- Bio-refining.

Forms of Bioenergy

Bioenergy may exist in different forms. These are mainly;

BiopowerHeatBiofuelsCombined heat and power (co-generation)

Biopower

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 electric generators.

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

Heat

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 fossil fuels.

Biofuels

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.

Environmental impact

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 traditional fuels.

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

Economic impact

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 development;

Economic growth through business expansion (earnings) or employment

Import substitution; andEfficiency improvement

Pricing of biomass against production

BENEFITS

The biomass material acquisition is comparatively cheaper.

Biomass is environmentally friendly compared to fossil fuels

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

Conclusion

Biomass provides low CO2 emissions, heat and power.

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.

References

www.bioenergyconsult.com/tag/biomass-combustion-process/

http//en.wikipedia.org/wiki/gasifierhttp//en.wikipedia.org/wiki/biomasshttp://www.biomassenergycentre.org.ukhttp//en.wikipedia.org/wiki/anaerobic digestion.http//www.wgbn.wisc.edu/http//en.wikipedia.org/wikihttp//en.wikipedia.org/Biomass_heating_system