Development of a Common Waste Combustion System for Generating Electricity at Remote Area

Malaysia’s daily amount of municipal solid waste (MSW) has rapidly increased. This causes the landfills number to increase due to inadequate waste management systems. Apart from that, Malaysia depends on non-renewable resources for electricity generation which could have a significant effect on the environment. Therefore, this study proposed to reduce landfills in Malaysia in a proper way and supply electricity using municipal solid waste as a renewable resource. In this study, the combustion of municipal solid waste (MSW) produces steam, which will rotate a turbine that is connected to a dynamo. Then, the energized dynamo will supply electricity to appliances including a direct current motor. The motor shaft then rotates the dynamo shaft in the pulley system which causes the electricity to flow in a closed loop. In this system, a pressurized container is crucial to produce sufficient steam. Based on the experimental setup, it was observed that continuous electricity was successfully achieved by looping the system using a pulley on the dynamo and motor.


Introduction
Municipal solid waste (MSW) is daily human waste products, including paper, glass, cloth, food waste, appliances, technological devices, and others.Malaysia's daily MSW grew from 33150 tonnes in 2012 to 38699 tonnes in 2021.By 2022, the increase will reach 39936 tonnes per day [1].Population growth, lifestyle changes, and fast urbanisation and development have increased.Unfortunately, Malaysia lacks technology, trained manpower, and waste treatment facilities.14 of 162 Malaysian landfills are hygienic in 2021 [1].Sanitary landfills use engineering to limit garbage to the smallest possible space without harming the environment or public health [2].Landfills destroy biodiversity by removing natural habitats, producing harmful leachate, and contaminating streams, ponds, and lakes.Soil fertility also suffers.Poisonous chemicals and decomposing organic materials can harm soil fertility and plant life [3].Thus, a common waste combustion system that generates electricity reduces landfill in Malaysia and provides an alternate electricity source.This steam turbine project generates electricity from waste.Waste combustion heats a water tank, producing steam.The steam rotates the turbine and powers a DC motor.Because trash is limited, combustion is not intended to run continuously.This technology requires electricity looping.SDG 7-affordable and clean energy-makes this project sustainable.

Research
Renewable resources produce less pollution and greenhouse gas emissions compared to the nonrenewable sources [4].This resource includes municipal solid waste (MSW), which is produced daily and can fuel thermal power plants [5].MSW can be utilised to generate power in Malaysia because it relies significantly on non-renewable resources and waste generation is poorly controlled [6].Based on generators of electricity, a waste-to-energy (WtE) plant is the best way to dispose of municipal solid waste (MSW) because it uses renewable resources and is cost-effective and environmentally friendly.WtE facilities reduce landfill trash and its environmental impact.WtE plants reduce greenhouse gas emissions by lowering fossil fuel use to generate energy [5].Waste-to-energy technology mentioned incineration.Monitoring high-temperature combustion involves burning waste in a furnace at 750-1100°C.This method decomposes organic compounds in municipal solid waste (MSW) in oxygen to reduce its total mass and volume for heat and electricity conversion.Solid waste can be decreased by 80-85% by recovering metals from ash [7].

Overall process of the system
Figure 1 shows the process flow of the proposed system.First, high-calorific MSW is used to boil water at high temperatures to maximise steam output and pressure to rotate the turbine.Strong pressurised steam then turns the turbine blades and causes the dynamo to rotate.The dynamo generates electricity from mechanical energy.Pulse frequency modulation (PFM) buck voltage requires dynamo voltage greater than 1V.With 0.9V input, it boosts 5V.TP4056 is activated to charge a 3.7V Li-ION battery.This battery stabilises power as the dynamo cannot.After charging, the battery will power the second PFM buck voltage.Then, the buck voltage creates 5V for the USB cable boost converter to step up to 12V.The system generated 12V DC voltage.
MB102 breadboard power supply and DC motor will receive 12V next.MB102 supplies 3.3V to appliances.The breadboard powers 5 LEDs, 1 DC lamp, and 2 DC fans on the appliances board via MB102.If the user wants to stop using electricity, they can turn off the MB102.Thus, appliances can be powered and used.Since the motor and dynamo shafts are connected by a pulley system, the motor shaft starts rotating when 12V is applied.Dynamo pulleys are smaller than motor pulleys because dynamos need more RPM to power appliances.Next, the pulley system rotates the dynamo to generate voltage and current, repeating the process.This is a closed-loop system because power flows continually.Due to MSW shortages expectation, this project is closed-loop.The pulley system can generate electricity even without combustion but to maximise charging, steam turbines must be used.Pulleys alone cannot charge it efficiently.Finally, if the battery does not need charging, closed-loop electricity can end MSW incineration.If the user stops using electricity, the system can be turned off.Flowchart ends.

Prototype development
The development consists of three main system which are combustion system, turbine system and pulley system.Dynamo is also included because the power obtained indicates the project purpose.

Combustion system
Wood and paper municipal solid waste (MSW) are burned to generate steam to turn the turbine.Wood and paper are used for their high calorific value.A fuel's calorific value is the thermal energy generated when it is completely burned under standard conditions and constant pressure [8].Paper has 3226kCal/kg and wood 3441kCal/kg [9].This high calorific value allows MSW combustion to generate pressurised steam for turbine rotation.Maximum steam production requires a pressurised boiling tank.This project generates steam with a pressure cooker.This pressure cooker heats quickly at 121°C and 70kPa.

Turbine system
Tin was chosen as the container material for the turbine system because it can withstand extremely high temperatures and pressures.This material can smooth the passage of steam.Only one turbine is utilised to attain maximum turbine speed.The blade of the turbine is made from zinc plate with a 0° tilt angle.To maximise the turbine's RPM, the steam passage must be perpendicular to the blades.Zinc is the material of choice for turbines because it can withstand temperatures up to 415°C [10].This design has been tested, and the turbine rotates extremely quickly using steam from a pressure cooker.Thus, objective 1 can be attained: to generate pressurised steam from the combustion of waste to power the turbine.

Dynamo utilisation
The 5.5V DC dynamo was selected due to its high-power output.This dynamo transforms mechanical energy into electrical energy.The dynamo is powered by the rotation of the turbine and/or pulley system.Then, it will generate voltage and current for the system's use.For objective 2, it is possible to generate DC voltage from the combustion system.

Pulley system
The selected gear has 2mm gear teeth (2GT), which denotes the distance between teeth.To facilitate the looping of electricity once municipal solid waste has been depleted, the pulley system needs two gears.In the presence of this pulley system, electricity can flow in a closed loop by default.The gear on the motor is the driver pulley, while the gear on the dynamo is the driven pulley.In response to this pulley system, the dynamo can still power the entire system even in the absence of steam.Since the motor's speed is 217RPM and the dynamo's speed is 1278RPM, the gear ratio should be 1:5.21 to ensure compatibility and optimal performance.So, the selected gears for the motor and dynamo are 2GT 80T B5 and 2GT 16T B5, respectively.T represents the number of gear teeth, while B represents the gear's bore measurement in millimetres.This pulley system employs a 300mm 2GT timing belt made of rubber.By looping the system, it is possible to meet objective 3, which is to develop continuous, independent electricity.

Block diagram
The block diagram that was developed based on the flowchart, the process flow, and every component that was used in this project can be seen in figure 2.

Result and Discussion
This section will describe the project's analysis, output, and result.The findings are based on data collected from actual experiments and analyses conducted during the development of the project.The paper will provide an analysis of calorific Value of MSW, heatsink utilisation, turbine blade angle, dynamo's performance, gear ratio and lastly effect of loads on the system.The results were observed in term of voltage, current, power, revolutions per minute (RPM) and others.

Calorific value of MSW
In order to boil water in the pressure cooker, MSW was burned in an open area using dry wood sticks and papers with calorific values of 3441kCal/kg and 3226kCal/kg respectively [9].After 15 minutes of combustion, the water began to boil and generate steam.The turbine connected to the dynamo's shaft was then rotated at 713RPM.The dynamo then produced 2.37V of voltage and 0.24mA of current.The RPM result was measured with a digital tachometer, while the voltage and current results were measured with a multi meter.The calculated power of 0.57mW was sufficient for the operation of the system.Therefore, the calorific value utilized in this analysis is appropriate for steam production.Figure 3 depicts the combustion of MSW to produce electricity.The calculated power was done using formula (1) where voltage unit is V, current unit is milliampere (mA) and power unit is milliwatt (mW).

Heatsink usage
Combustion of MSW generates heat up to 121°C, affecting motors and dynamos due to their proximity to fire.Electricity production heats step-up transformers and charger modules.Heat loss also heated components.Components that generate too much heat will fail or shut off automatically.So, heatsinks utilization are essential.
Five components-motor, dynamo, two step-up voltage, and charger module-were pasted on heatsinks to minimize heat and assure proper operation.Aluminium heatsinks were glued with heatsink paste for equal heat absorption.Airflow through heatsink fins reduces heat.Before heatsinks were applied, the motor was warm after 15 minutes of operation and PFM step-up transformer was so hot it had to be powered down after several minutes.Thus, heatsinks were placed on components to reduce heat and extend their lifespan.Thermoreceptors felt the heat since there was no digital thermometer.

Turbine blade angle
Two prototype turbines were created with a tilt angle between 30-40 degrees and the other one was 0 degrees or perpendicular to steam flow.Since the pressure cooker had only one steam output, one turbine was used to rotate the dynamo shaft to reduce weight and increase efficiency.Two turbines with 30° and 0° angles were evaluated for RPM.Turbine efficiency increases with RPM.Table 1 shows the results.The table shows that turbines with 0 degrees had higher RPM because steam was perpendicular to the blade, making it rotate quicker.The 0° turbine had a little larger diameter than the 30°-40° turbine, hence its surface area was larger and exposed to steam flow.The 0° turbine produced more power than the 30° -40° turbine because its RPM was higher and the dynamo produced more voltage and current.0° turbine data was used to calculate the power using equation (1).Because this project produced very little current and power, mA and mW were used as units.Thus, 0° turbines are superior to 30°-40° turbines.

Dynamo's performance on pressure
The pressure cooker's pressure was adjusted to monitor the dynamo's voltage, current and RPM.To determine the pressure-dynamo performance relationship, current and voltage values were used to derive power in milliwatts.Steam from the pressure cooker rotates the turbine, which turns the dynamo shaft.
A digital tachometer measured RPM, while a multi meter measured voltage and current.A stove is used to generate stable heat.Pressure cookers can sustain 70kPa.Thus, the stove fire maxed out at 70kPa.The knob was turned to max, half, and half again.Both the knob and pressure were halved.The pressure was 70kPa during maximum fire, 35kPa at medium fire, and 17.5kPa at low fire.Table 2 shows the data.
To see the trend, power data was graphed against varying pressure in figure 4. From the graph, it can be said that the dynamo's RPM, voltage, current, and power rise with pressure.Turning the stove knob to a maximum fire creates 70kPa pressure, which maximizes dynamo power.

Gear ratio
This pulley system required two gears to loop electricity when MSW ran out.The gear on the motor acted as a driver pulley while the gear on the dynamo acted as a driven pulley.This pulley mechanism allows the dynamo to power the system without steam.The length of the rubber timing belt used was 300mm.The project's best pulley system was selected from 6 gears.The optimal gear ratio was calculated by fixing one driven pulley gear.Thus, only the driver pulley was modified with 6 gear sizes.Because the pulley system had to work with both motor and dynamo, their RPMs had to be considered for the analysis.The best dynamo was 1278RPM and the motor was 217RPM.The calculation of gear ratio was done by using formula (2) where the diameter was measured in unit of milli meter (mm) [11].Also, the calculation of the driven pulley's speed with a unit of RPM was done by using formula (3) [11].
Speed of driven pulley = ( To choose the optimal pulley system, gear size and driven pulley RPM were analyzed in table 3.As noted, the driven gear size was fixed at 9.68mm, which is 16T gear because it has 16 teeth.Gear teeth increase gear size.The experiment also set the motor's driver pulley speed at 217 RPM.For a better explanation, the selected motor produced 217RPM and the selected dynamo produced 1278RPM.To determine the ideal gear ratio, the driven pulley speed must be roughly the same as the dynamo speed.Based on the table below, the best gear ratio was 1 to 5.21 since the driven pulley can reach 1130.57RPM.With a gear ratio of 1:5.21, the dynamo can create 1130.57RPM when the motor produces 217RPM.Since the speed differential was only 147.43 RPM, the dynamo can still perform well.

Loads number
As the number of loads utilised by appliances increases, the system's dynamo power decreases.This was due to increased power consumption, which depleted the system's current and voltage capacity.As more appliances are added to the system, the efficacy of the motor decreases because the RPM of the motor decreases, which in turn affects the RPM of the dynamo due to the pulley system.In this project, 5 LEDs, 1 5V DC lamp, and 2 3-6V DC fans were used as loads.However, in order to observe the motor's performance, the loads were represented by 5 RGB LEDs.In this analysis, motor RPM was measured because it served as the dynamo's driver pulley.In this instance, dynamo RPM is dependent on motor RPM.The relationship between the number of LEDs utilised and the motor's RPM is depicted in table 4. Based on figure 6, it can be concluded that the motor's efficacy in terms of RPM decreases as the number of loads used in the system increases.Therefore, the selection of type and quantity of loads must not exceed the system's capability in terms of producing electricity.

Conclusion
Overall, the waste combustion system for electricity generation in a remote area has been designed and developed.Based on the experimental results, it shows that the tin container was successfully can withstand high temperatures and pressure.Due to the direct and strong flow of pressurized steam striking the turbine's blade, one of four prototypes was managed to rotate the turbine at 1400 RPM.The selection of a single turbine with an angle of 0° resulted in greater RPM, voltage, current, and power output than turbines with an angle of 30-40°.Besides, the combustion was also producing enough steam by using MSW with high calorific value.The dynamo can generate enough power for the system's usage.The gear ratio of 1:5.21 was determined to be the optimal choice, as it allowed the driven pulley to reach 1130.57RPM at 217 RPM motor speed.It can be identified that the heatsinks on the components are effective for dissipating heat and assuring long-term functionality.It should be noted, however, that as the number of devices connected to the system increased, the dynamo's output decreased.Therefore, the number and power requirements of the devices connected to the system should be carefully considered.In conclusion, all three objectives in this project have been achieved where the combustion of MSW producing pressurized steam to move the turbine was successful.Then, the turbine moves the dynamo's shaft and allow it to produce DC voltage to power up DC appliances such as LEDs, lamp and fans.And lastly, continuous electricity was successfully achieved by looping the system using pulley on the dynamo and motor.

Figure 1 .
Figure 1.Process flow for the system

Figure 2 .
Figure 2. Block diagram of the system

Figure 4 .
Figure 4.The effect of pressure on power of dynamo

Figure 5 .
Figure 5. Relationship between gear ratio and dynamo's RPM

Figure 6 .
Figure 6.Affect of number of LED used on motor RPM

Table 1 .
Turbine blades with different angle of tilt

Table 2 .
Dynamo's performance on different steam pressure

Table 3 .
Affect of gear ratio on driven pulley speedAccording to table 3, the gear ratio and driven pulley speed in RPM are illustrated into a graph in figure5.It can be concluded that the greater the gear ratio, the faster the driven pulley speed which represented the dynamo.

Table 4 .
Motor performance on different LED number used