Electricity generation through food waste and garden waste of SIBAU

With the increasing rate of energy demand, the world is facing Environmental problems, for instance Global Warming, Pollution and Waste. The project is about energy generation to fulfil the demand considering the environmental problems. Presently, we are dependent on conventional methods of

Project Title

Electricity generation through food waste and garden waste of SIBAU

Project Area of Specialization

Electrical/Electronic Engineering

Project Summary

With the increasing rate of energy demand, the world is facing Environmental problems, for instance Global Warming, Pollution and Waste. The project is about energy generation to fulfil the demand considering the environmental problems. Presently, we are dependent on conventional methods of energy generation which pose a threat for the environment. Our project is related to energy generation using waste material (food waste, yard trimmings) as fuel. 

In order to fulfil the energy requirement, Pakistan imports crude oil worth 1400 million US dollars that was just 530 million US dollar in 1996, which has a negative impact on economic growth. Pakistan spent approximately 20 percent of foreign exchange on the imports of fossil fuels and almost 14.5 billion US dollars for conventional energy resources that is 40 percent of the country's total import. Pakistan produces electricity using natural gas, oil, coal, hydel and nuclear energy. Where the generation from renewable resources is 3%-5% which is a very small amount in the energy share.

These techniques will make the plant efficient to produce bio-gas from organic waste. Additionally, this project is environmentally friendly. Success of the project will be the success of environmental drive globally.  

In the field of energy generation and power systems, the world is going toward Smart Grid and Micro Grids. These projects can be interconnected to these Grid for efficient energy utilisation and Distribution.

By the process of anaerobic digestion, we’re going to treat the municipal waste in the absence of oxygen in an anaerobic digester, and as a product we will be getting methane gas that can be ultimately used for cooking purposes and as an input fuel to run the generators.

We know that the different waste materials have different composition and hence different amounts of methane and other gases. So we have analysed the different set of parameters that can be varied to attain the maximum yield. We have many parameters that can be considered while working with anaerobic digestion, for instance:

1. Effect of Temperature?

2. Effect of Hydraulic Retention Time (HRT)?

3. Effect of Organic Loading Rate?

4. Effect of pH?

5. Effect of particle size

When the feed is loaded into the digester, that feed goes through four different phases to give us biogas, that are: Hydrolysis, Acidogenesis, Acetogenesis, Methanogenesis.

And after the methanogenesis, we get biogas which is further filtered to attain pure methane gas.

Project Objectives

The aim of this project is the design of an anaerobic digester to fulfil the daily electrical load needs of an average family. Which is around 4.98 kWh as per our survey conducted.

Along with that, using electrical and mechanical approach to maintain the anaerobic process and control parameters to improve efficiency which has low HRT (Hydraulic Retention Time), less time period of biogas extraction from organic waste and pure more filtered form of the methane.

The major objective of this project is to reduce garbage that increases by food waste, yard trimmings, sludge etc and converting those organic waste to energy using anaerobic digestion method. This will not only fulfil our daily needs but also contributes to the rehabilitation of our planet by reducing the waste that ends up in landfills.

Project Implementation Method

The aim of the research is to develop a methodology for analysing the energy demand in biogas plants at a detailed level. In the methodology, the energy carriers are allocated to. The phase includes the steps to come up with the physical structure of the project.

We will work on the following points in this chapter. .

1. Assumption of waste Quantity

2. Calculate the digester dimension

3. Water addition to manure

4. Biogas production and composition

Bio-digestion is a biological process. The process is called anaerobic digestion which means absence of oxygen. Anaerobic digestion is a multi-stage process and parallel reactions where different types of bacteria degrade organic matter successively. Large bacterial populations are identified, which are developed catalysing three consecutive processes. In some literature, the process is defined in four steps. The steps are as under.

HYDROLYSIS:

Hydrolysis is a type of decomposition reaction where one of the reactants is water, and typically, water is used to break chemical bonds in the other reactant.

The general formula of a hydrolysis reaction is:

AB+H2O?AH+BOH

ACIDOGENESIS:

Acidogenesis is the second stage in the four stages of anaerobic digestion. A biological reaction where simple monomers are converted into volatile fatty acids. 

ACETO-GENESIS:

Aceto-genesis is a process through which acetate is produced by anaerobic bacteria from a variety of energy and carbon sources. It is a biological reaction where volatile fatty acids are converted into acetic acid, carbon dioxide, and hydrogen. The different bacterial species that are capable of aceto-genesis are collectively termed acetogens. 

METHANOGENESIS: 

A biological reaction where acetates are converted into methane and carbon dioxide, while hydrogen is consumed.

MATHEMATICAL MODELLING:

The main parameters affecting biogas production and digester structure are also important for mathematically modelling of the system. In this section, we are modelling the system mathematically. The modelling includes the digester infrastructure, volume of the feedstock to add, bio-gas production and composition (Methane, Carbon, Nitrogen).

PHYSICAL MODELLING:

The physical modelling of the project is divided into sub-phases. After the digestion process, the biogas is passed by the treatment process by means of a gas outlet pipe. While the slurry is taken out to an open environment for drying, which is used as fertiliser.

Benefits of the Project

1. It is a net energy-producing process that generates biogas, which is a renewable energy source.

2. It sanitises the feedstock/waste that passes through it as long as the temperature is above a set point for a set amount of time (pasteurised).

3. It decreases stench to levels below that of unprocessed trash. Consider the difference between spreading manure and spreading the same material after anaerobic digestion, which is known as "digestate."

4. It is far less likely to pollute the environment than dumping untreated organic waste on land.

5. Provides for efficient resource recovery and nonrenewable energy source conservation.

6. When compared to an aerobic system applied to the same contaminant concentration and flow, a primary water treatment approach produces less sludge mass.

7. The fertiliser's effect lasts longer than that of untreated organic waste.

8. It can be converted to "biomethane," which has numerous advantages over raw biogas (it can be filtered to practically pure methane). Not least, when pressed to become bioLNG, it is one of the few options for decarbonizing the transportation industry.

9. In addition to methane, the process creates carbon dioxide, which can be refined and sold as a valuable product.

Technical Details of Final Deliverable

Biogas Composition Biogas is generally used as fuel. Therefore, its value is determined by combustible components, i.e. methane. Good quality biogas mainly consists of methane at around 55-70% followed by carbon dioxide around 3045%. It was revealed that the biogas consisted of fairly high methane content (41.73 to 57.23 %) so that it was well burnt and can be used for fuel. The table shows that methane content decreases by increasing loading rate with the highest value (57.23%) is given by biogas collected from digester with OLR of 1.33 g VS/L/d). Increasing loading rate means shortening HRT that leads to incomplete decomposition of organic matter.

Final Deliverable of the Project

Hardware System

Core Industry

Energy

Other Industries

Food

Core Technology

Others

Other Technologies

Clean Tech

Sustainable Development Goals

Affordable and Clean Energy, Climate Action

Required Resources

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