Debouncing in Arduino

Button bouncing is another common problem that everyone faces when designing electronic circuits. This phenomenon is caused due to mechanical properties of buttons.In here I am concerned with the push button which is a type of button used often in electronic projects.

When we push (close) a switch it sends an electrical current to a microcontroller input pin. Then it is identified by that microcontroller and responds accordingly. When we push a push button it sends a sort of a pulse signal to the microcontroller as given below.

An Ideal pulse from a push button.

However, although switching on or off a switch may seem instant, real switches, buttons take some time to make the contact. so the real case is quite different from the ideal case. since a real push button is consists of a few mechanical contacts, when you press a button these metal contacts will touch several times before it settles down to a stable position (on or off). The following figure shows what happens when you push the button and releases it.

An oscilloscope graph of pushing a push button

As you can see there are several spikes before the switch or button settles to an “on” position. Although this whole thing occurs within few milliseconds, it is a quite a large time period with respect to a microcontroller. The result will be that the microcontroller will count these spikes as button presses (false positives). for example, if you program your Arduino to count the number of button presses, the program will output an incorrect result due to button bouncing.

There are mainly two methods which can be utilised to prevent button bouncing. They are,

• Hardware debouncing
• Software debouncing

This article deals with hardware debouncing methods. I highly recommend you to read it as it will give you a complete understanding. In this article, I would like to focus on software debouncing as it feels the easiest way to overcome bouncing.

As I have mentioned earlier, bouncing occurs due to button contacts making several contacts before it reaches to its desired position (state). So all we need to do is to tell the microcontroller to ignore the signals coming from the button for a certain amount of time. since we know these bounces take less than 1ms, we can program the controller to start accepting input signals after about 5ms. In this way, the microcontroller will not see those undesired spikes hence it will give us correct readings.

In this project, I am using my push button in 3 different ways.

• Toggle a LED using a push button.
•  Count the number of button presses to control a LED.
• Measuring time between pushing and releasing a push button.

All these have a practical aspect since we use these functionalities in actual designs. For examples, we often use the same button to switch on/off electronic devices.Moreover, the same button reacts differently depending on the duration it was pressed. All these are possible due to the correct implementation of button debouncing techniques.

Toggle a LED using a push button

In this exercise, a push button is used to turn on and turn off a LED. although the task is simple, implementing correct functionality is difficult due to button bouncing. As a result, I used a software debounce technique to eliminate button bouncing.

The following picture shows the circuit I used to do the exercise.

The circuit to demonstrate button debouncing

 

Circuit Schematic

I was able to perform all three exercise just using this circuit.

Initialization of the circuit was done as follows.

Initialization of program and board

In this piece of code the variables, “lastbtnstate” and “currentbtnstate” are used to store the status of LED at the moment and one before. “LEDstate” is used to toggle the LED (turn it on or off).

Button debounce Function

In this function, it returns a boolean value as the state of the button. Firstly, it records the current state of the button (btnstatenow). Secondly, it compares the current state of the button with the previous state (previous) to identify whether it is being pressed or released. if those states are not the same, then the function enters to a delay. This delay avoids button debouncing which would last for about 1ms.You can play with delay interval but I recommend using something like 5-10 ms will do the job. After that delay, the function once again reads the button state and returns its value.

The code I used for loop() is as follows,

 

Main function that controls the LED

In this function, it passes the previous state of the button to button debounce function and stores the current state of the button (High or Low) in the currentbtnstate variable. After that, I used if condition to detect the button press. If statement toggles the variable (LEDstate) that controls the state of LED (on or off). Finally, the button status is updated.

 

Count the number of button presses to control a LED.

Next task is to count the number of button presses that can be used to trigger something else. In this exercise, I light up a LED for 1 second and turn it off after the program detects 10 button counts.

In this, the main goal is to count the correct number of button presses. It is impossible to do this without using debouncing as the microcontroller counts unwanted button bounces as legit button presses hence turning on the LED at a random point.

Initialization is done as follows,

Initialization of the program

In this program, the variable count is used to store the number of button presses. You can use the same function that was used in the previous exercise to debounce button presses. So I just copy and pasted it to this program.

The Following figure shows the main function of the program.

Main function for task 2

Similar in task 1, at the beginning the previous button state is passed to button debouncing function and the current button state is stored. Then it is used to detect a button press using if condition. if the program detects a button press, it increases the counter variable by one and toggles the button state. then another if condition detects the button release and assign Low state to current button state. If the counter hits 10, then the program turns on LED for 1 second and turns it off and resets the counter to 0. Using debouncing guarantees only legitimate button presses are being detected.

Measuring time between pushing and releasing a push button

This functionality is another useful thing about push buttons as it allows us to execute different things depending on the duration of a push button being pressed. In order to do this, I used a built-in function in Arduino called millis(). This returns the number of milliseconds since the board started to run the program.

The concept is very simple. First I programmed the microcontroller to store a time measurement when the button is pressed. This is our starting time. Then I store another time measurement inside another variable when the button is released. Finally, I take the difference in these two measurements and divide it by 1000 to convert it into seconds.

The following picture shows the initialization code.

Initialization of the program

As usual, you can use the same button debouncing function in this instance as well.

The following picture shows the main function in this program.

Main function

You can download all three exercises using this link.Feel free to use them and change them.

I hope to see you all soon with another project.

Facts about FACTS

 

 

(Image of a variable Shunt reactor used in a transmission grid  http://www.bpress.cn/list/di/pic/62/49762.jpg)

In this blog post I would like to talk about Flexible AC transmission Devices (FACTS). I have being studying how these devices are being used in controlling the load flow in electrical grids, therefore I thought to share what I have come across with you.  In past few decades as the power consumption of population increased in   exponential way power industry had to expand their ability to service people by constructing new power lines, transformers and power plants. At the same industry observed that there is reduction in rate of power consumption. This was due to increase in efficiency in power equipment, economic recessions. Because of this expanding and constructing new infrastructure was not a good solution economically. And also due to control schemes used in controlling grid and handle faults were not fast enough as they consisted of mechanically controlled circuit breakers. The long switching periods and discrete operation make them difficult to handle frequently changed loads smoothly and damp out the transient oscillations quickly. In order to compensate these drawbacks, large operational margins and redundancies in equipment used were maintained. These reasons caused electrical utility companies to have higher cost of ownership and longer payback periods for their investments. In order to overcome these problems, a utilization of assets was preferred. FACTS devices were introduced as a result of this.

The development of FACTS was a by-product of development in Power Electronics. Power electronics combines the advantages of semiconductor devices and the high power rating requirements in electrical power engineering. High speed switching, reliability and accuracy were some of the qualities FACTS obtained from using power semiconductor devices such as Thyristor. Due to advancements in Power Electronic technology and advanced control technology, FACTS has become the preferred choice to control Voltage, active and reactive power flow, transient and steady state stabilization that improves the operation and functionality of existing grid assets. FACTS devices increase the efficiency of in terms of both technical and economical ways by allowing operators to distribute generated power through less congested paths to consumer hence reducing overall generation capacity. This will reduce the operation costs in electrical utility.

Before the discussion about FACTS it’s better to have some knowledge in theory behind how power flow in a line being controlled and what are the parameters to be considered.

 

Simplified electrical system with two buses

 

 

 

 

 

The above diagram shows the schematic of a transmission line. Although in reality there is a resistance in the line that causes real power losses it can be neglected as this value is very small one compared to the reactance of the line (typically 10 times smaller). The next figure shows the vector diagram for the power line. In most cases the two buses have the same voltage magnitude (V₁=V₂) but different angles. This angle difference is used to control the power flow direction. There are two main equations used to model the power flow.

 

Equation 1- Active Power Flow and                       Equation 2- Reactive Power flow

 

 

 

 

 

These equations model the active and reactive power flow at bus 2. In here. These two equations shows the power flow will depend on the voltage magnitudes, the phase angles and the impedance of the transmission lines. By controlling those 3 parameters electrical utilities can control the power flow in a transmission line.

There are two methods used in power flow controlling,

• Series compensation
• Shunt compensation

 

Series compensation

According to equation1 the active power flow will depend upon V₁, V2, Sin δ and X_L. In series compensation power flow control is done by controlling X_L, the impedance in line. This is the overall line impedance not just the actual line impedance due to the reactance in line. A series connected capacitor or a reactor can inject a voltage causing this reactance to change hence changing the power flow in that particular line.

Series compensation

 

If a capacitor is added. This V_C is called quadrature voltage since it’s shifted by 90 degrees. This effect will add a voltage drop which will oppose the voltage drop in line. The power flow will be increased as a result of this

If a series reactor is added  . This V_L  will add a voltage drop which will cause power flow to be reduced.

Shunt compensation

Shunt compensation is used utility to regulate the voltage profiles of buses. Shunt connected reactors can reduce line over voltages by consuming reactive power and Shunt connected capacitors can inject reactive power to bus to increase the voltage. These methods help to maintain the voltage at a busbar closer to it’s rated value (1pu).

FACTS devices usually employees one or two of these methods to control the Voltage, phase angles or line reactance .

There are many FACTS techniques are being used at present but all can be categorized into 4 categories.

• Series Controllers
• Shunt Controllers
• Combined series-series controllers
• Combined series-shunt controllers

Series Control FACTS

Series connected FACTS could be a variable impedance such as a reactor or a capacitor or power electronics based variable source of main frequency. All series reactors inject a voltage in a series with the line. As long as the injected voltage is in phase quadrature with the line current, the series controller supply or consume reactive power. If the phase difference is different than this it will handle active power as well.

Shunt control FACTS

A shunt controller could be a variable impedance or a viable source or a combination of both. Shunt connected controllers inject current at the point of confection. Although it may seem like impedance devices are not capable of doing this they can create a variable current flow using varying impedance hence it in a way controls the current in line. The injected current is in phase quadrature with line voltage. Therefore it will only consume or deliver reactive power. Any other phase difference will cause it to handle real power as well.

Combined Series-Series FACTS

Combined Series-Series controllers can be used to control both active and reactive power in transmission lines. This method is often used in multiline transmission systems. These types of controllers can be operated in two methods.

• Combination of separate series controllers which are operated in a coordinated manner in order to realise power flow control.
• Unified controllers, several series controllers provide independent series reactive compensation for each line but also has the ability to transfer real power among transmission lines using power link. The real power transfer capability of unified series-series controller maximize the utilization of transmission systems by giving better control over both active and reactive power.

Combined Series-Shunt FACTS

Combined Series-Shunt can be used to control both active and reactive power in transmission lines. There are two types FACTS technologies to achieve this.

• Combination of series and shunt which are controlled in a coordinated manner in order to realise power flow control.
• Unified Power flow controller which contain both series and shunt components, in theory combined shunt and series controllers inject current into the system with the shunt part and voltage in series in the line with the series part. When the shunt and series parts are combined there can be a real power transfer between these two via power link.

Although both series and shunt FACTS have the same objective, Achieving better control over power flow in grid, these the effectiveness of these are different in different scenarios. Therefore it’s better to have a look into some of the advantages and disadvantages in both technologies.

• Series controllers are more effective in controlling the current/power flow and damp oscillations than shunt controllers if both have same MVA ratings.
• Shunt controllers are a good solution to control voltage at a point of connection and around that area. Therefore shunt controllers are often used to control the voltage level at substation bus as it serves the bus node independent of the individual lines connected to it.
• One disadvantage of series controllers are that they have to be designed to handle dynamic and contingency overloading as they are connected in series with power lines.

Advantages of FACTS devices

• Improving Power Transfer Capability.
• Confining Power Flow to designated routes.
• Transient and dynamic stability improvements.
• Ability regulate voltage hence avoiding cascading power outages.
• Damping of power system oscillations.
• Ability use transmission lines close to their thermal limits.
• Improving system reliability.

Drawbacks in FACTS

• Very expensive to design and implement.

•  Device complexity in design and implementation. These devices are often rated in MVar power range and rated voltages are the voltages equals to the system voltage they are connected to. In power transmission this could be high as 132 kV and above.

•  Since the high power requirements, the power electronic devices used have to withstand high power and voltages causing high costs in construction.

•  All conventional FACTS devices used are lumped in nature. Generally these are designed to withstand the load growth in next 30 years. This approach causes poor return of investment to grid owner which is a major drawback.

•  FACTS devices are custom designed according to the requirements of the clients. This results in longer design and construction cycles. This will add additional costs to the devices.

•  Shut down or failure of one of these FACTS have a significant impact on grid as the number of devices used in a particular electricity grid are limited.

References

• Understanding FACTS : concepts and technology of flexible AC transmission systems By  Narain G. Hingorani and Laszlo Gyugyi.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

How Electricity comes to you

Have you ever wondered how the electricity being generated and transmitted to your home? It might be easier to switch on a light bulb and at that instance the bulb light up like the energy required to light up the bulb has always being there  in some sort of a storage. But there is a good chance that the amount of energy that required to light up that bulb was generated by a power plant hundreds of kilometres away from your house and it got transmitted to you by electricity lines spans for hundreds of kilometres unless you have some sort of generating method like solar, wind or natural gas installed at your home premises. Electrical utility has become one of the most sophisticated and critical industries in the world due to the ever increasing demand for energy and the exponential growth in use of electronic devices in day to day activities. In my post today I am hoping to give you a little insight about the concepts used in electrical power engineering.

I’m pretty sure all of you have heard of things like voltage, current, Power, AC, DC, resistance and impedance. Most of us learn these at school and unless you peruse a career related to electrical engineering you might not have more complete idea about these concepts. Therefore I would like to talk about some of these in this post.

Electricity is basically the flow of charged particles. It can be positive or negative but due to the atomic structure of matter electrons are the ones that contributes to electricity most of the time. An electrical circuit is a closed loop that electrons flow from a higher voltage to a lower voltage doing work (releasing energy) on it’s way. This is not always the case but as long as there is a voltage potential difference between two points in space there is a possibility that a current will flow.

Voltage (V)

Voltage can be described as the potential difference between two points in an electric field. An electric field is similar to a gravitational field that occurs due to a presence of a mass. An electrical filed is caused by a charged particle. Voltage is just how we measure the amount of work being done when another charged particle being moved from one point in space to another point in space where there is a difference in electric filed. Although this explanation gives an insight on voltage this definition is not very useful when we are dealing with practical electrical engineering. In electrical engineering voltage is considered as an electromotive force that exists due to a voltage source like a battery or a generator.

There is one equation in electrical power engineering that is being used more often than any other equation. It is . In here P stands for the power being consumed/transmitted to an equipment. V stands for voltage at it’s terminal and I stands for current. If we want to transfer more power there are two ways to do so, by increasing voltage or current. If the power is kept at a constant value, the product of V and I is a constant. Therefore when voltage is raised current will go down and opposite is also true.

In Power transmission high voltages are preferred since using high voltages reduce the losses in occur in transmission lines. In Western Australia 132kV and 330kV voltage levels are used in transmission. But in HDVC transmission (High voltage DC) 800kV is also used. But when high voltages are being used safety becomes a major issue. But using higher voltages allows network operators to transfer more power over longer distances while minimising losses. Minimising losses in transmission is a major concern in power engineering. The power transfer happens in mega Watt scale (MW) therefore losses occur in transmission lines are also in MW scale. Engineers carefully design transmission lines, transformers and other equipment used in power transfer in order to mitigate this. The following diagram shows the different voltage levels that are being used to supply power from power plants to consumers. These voltage level could vary in different countries.

Image retrieved from https://anjungsainssmkss.files.wordpress.com/2011/07/electric_grid.gif

Current (I)

Current in a conductor is the amount of charged particles passing through a surface which is perpendicular to the direction of the flow measured in unit time. It can be expressed mathematically as I=Q/t  where Q is amount of charged particles and t is time interval. You might think that when you plug an electrical apparatus to a port and switched on, the electrons that are in one end of the circuit will suddenly travel to the other end but what actually happens is that electrons are being pushed towards the positive end of the circuit under the influence of voltage. It’s much more like a traffic congestion where each vehicle will move very slowly but overall the traffic keeps going. The speed of an electron in a conductor is very small. This is called drift velocity of an electron (particle) caused by an electric field (difference in voltage).

Losses in a transmission line are caused by movement of electrons. The losses in a conductor can be modelled mathematically by P(losses)= (I*I)*R  . I is the current flows through the conductor and R is the resistance of the conductor. So it obvious that if the current gets doubled in a line the losses will be increased by 4 times. This loss of electrical power will be dissipated as heat and will cause more troubles if it’s going to exceed the thermal capabilities of that line. Therefore network operators do their best to keep the amount of current being sent in a line at minimum. According to  the current required to deliver the same amount of power will get increased if the voltage gets dropped. Therefore it’s very important to maintain the voltage levels at desired level. Uncontrolled voltage drops in an electricity networks can lead to a blackout which will have very bad outcomes.

Power(W)

When electrical engineers think about power it’s a bit different than the conventional power that most of us are familiar with. Most of us are familiar with Active Power which will be converted into other forms of energy like mechanical, heat or light. In electrical power engineering we use apparent power in almost all calculations. Apparent power consists of active power and reactive power. As I mentioned active power is the type which will be converted into useful energy. Reactive power is the power consumed by the network itself in order to keep it running. The following figure shows the relationship between Apparent, active and reactive power.

 

 

Image retrieved from http://solarprofessional.com/articles/design-installation/reactive-power-primer

The ratio between Reactive Power and Real Power is called true Power Factor of a system. Power factor angle is normally defined as the ratio between Apparent Power and Active Power. Cos(θ)=P/S

The power factor of an equipment will determine how much active power it will consume. For industrial loads power factor must be close to 1 (about 0.9) and utilities penalise the customers who don’t correct their power factor according to the specifications since less power factor means utilities have to supply more reactive power to deliver the same amount of active power. This cause lines to get overloaded.

Although Reactive Power may look like a by-product of generation actually it’s very important to keep the amount of reactive power in the network at a desired level. Voltage at a busbar is dependent on amount of reactive power available and failure to keep it at constant level will cause voltage instability problems in network. If the voltage levels get too low this will has a cascading effect over the network and will cause a blackout. Reactive Power is used to change the magnetic or electric fields of electrical equipment in network. Motors need reactive power to produce magnetic fields inside their stators. Reactive power is generated due to the phase difference between voltage and current in an equipment.   S=√3*V*I Gives you the apparent power consumed or produced. All these quantities are vectors therefore they have both a magnitude and a direction. The following graphic demonstrate how apparent power being used in power transmission.

Image retrieved from http://electrical-engineering-portal.com/reactive-power-and-compensation-calculation-basics

It’s obvious in order to transfer more active power using the same line utilities have to reduce the amount of reactive power being transferred. Building new infrastructures like transmission lines is a capital cost to network provider and that is not their first option. Instead of building more lines to transfer power, a technique called reactive power compensation being used nowadays. This method is a very cost-effective, practicable way to supply reactive power. Capacitor banks are used to generate reactive power closer to where it’s being consumed. This approach will reduce amount of reactive power being transferred to site and reactive losses in network overall. Therefore network operator can deliver more active power to customer. And also reactive power compensation helps to mitigate line overloading. Capacitor banks are used in in compensation. Capacitors are capable of supplying reactive power to network.

Image retrieved from http//:electrical-engineering-portal.com

As shown in the diagram a portion of reactive power will be supplied by grid and the rest of the reactive power will be supplied by shunt capacitor.  Qc=P(tanφ1-tanφ2) Equation gives the capacity of the capacitor required.

Image retrieved from http://electrical-engineering-portal.com

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Challenges to the Power quality of modern electricity grids

It’s been a long time since my last post due to a busy semester in  university and my recently started internship but I am looking forward to write more posts in upcoming months since I have some free time due to summer vacation of university. Sharing the knowledge I got from my studies always help me appreciate what I learnt and I think it’s my duty to share them as much as possible because in university I realised how important to share knowledge. In almost every unit we used world wide web to learn more often we use textbook. So I think by doing somebody might find it useful.
Today I am going to present you few points about power system quality. This is not a detailed post but rather an entry point to upcoming posts under this topic. I will talk about each and every topic in this post in upcoming posts.

Modern power transmission and distribution is done by using alternative current (AC).  There are several advantages using AC transmission over DC transmission like ability step down or step up voltage as required, Ability to use high voltages in long distance transmission and almost all generators (Synchronous generators) are AC machine is another reason that AC transmission is used. But in recent years HVDC (High voltage DC) technology proved it’s capability for long distance transmission and to connect grids that use different frequency levels are quite useful. We might see HVDC more in future but at the moment all our grids are used to transmit AC.  In an ideal case these currents (including voltages) would be purely sinusoidal waves which have a frequency of 50 or 60 Hz depending on the country.  But this is impossible to achieve as we all aware.  Since the advancements in electronic devices and large demand for power by numerous types of customers on daily basis the utility companies face numerous challenges to keep their power close to the ideal case mentioned above. There are several problems associated with quality of power.

•         Voltage dips
•          Voltage swells and spikes
•          Over  voltages
•          Harmonics
•          Variations in frequency
•          Voltage fluctuations
•          Voltage unbalance
•          Supply interruptions
•      Transient behaviour 

Voltage dips

Voltage dips are decrease in magnitude of the supply voltage for short time period. Voltage dips can happen due to various reasons such as,

•          Tripping of sensitive protection equipment.
•          Resetting of large computer systems.
•          Inductive loading
•          At the starting of a large inductive motor.

When activating large industrial loads such as large motors, they draw large currents. These are called inrush currents and this happens due to the transient nature of the motor. This causes a sudden voltage drop in line until the load (motor) starts to operate in steady state. This period could be few seconds but during this period other equipment that is connected to same node might not be able to operate. In an industrial site there may be lot of other motor as well that are connected to same node. In order to prevent motors operating under low voltage they can be equipped with under voltage relay protection which isolates the motor if such things happened.

Voltage Swells/Spikes

This is the opposite phenomena of voltage dips. Equipment can be damaged due to failure of insulation, destruction of sensitive electronic devices and electromagnetic interference caused by sudden change in voltage. Voltage spikes are often caused by lightning strikes and during switching operations of circuit breakers.

Voltage abnormalities (Image retrieved from:http://assets.tequipment.net)

Over voltages

Over voltages exceed the nominal voltage of a system over a period of time. They are mainly caused by malfunctioning voltage regulators on generators.

Voltage unbalance

Voltage unbalance occurs due to unbalance loading. Unbalance voltage supply creates zero sequence currents in wires which is responsible of heating the components. This is a serious problem in motor operating. Therefore it’s a common practice to use phase unbalanced relays to detect and unbalance cases and protect the motors against them.

Frequency variations

Frequency variations often happen in isolated networks due to faults and malfunctions of governors in power plants. Frequency variations can cause problems. Motor drives will not work properly, power generation may goes out of synchronism if the frequency has changed a lot from it’s nominal value. This may require isolating generators and reconnect them again. So having the nominal frequency value at all times over the whole network is critical.

Harmonics

A very common problem in power systems is effect of harmonics. The main cause for having harmonics in power systems are power electronic devices such as rectifiers, inverters, uninterruptable power suppliers (UPS) ,variable frequency drives(VFDs) and computers etc… In general any non-linear loads (loads where the voltage waveform is different than current waveform) are responsible for creating harmonics. The effect of harmonics is significant when loads are motors. Harmonics consists of negative sequence voltages which cancel the positive sequence voltages which creates the required flux to operate the torque of the motor. Since a negative sequence component creates a negative flux (which is responsible for creating negative torques) this will reduce the amount of positive torque available to operate the load. Besides negative sequence components, triplet harmonics (3^rd9^th 15^th) which are responsible for creating zero sequence currents in neutral wire causes heating problems and eventually degrades the machine.   

I suggest the following links might be useful if you need more details.
Harmoincs
In depth details about harmonics and it’s effects
Voltage abnormalities

Electrical power industry trends in Australia and the problems associated with it

Electrical energy is the main energy type we use in our almost every aspect of our lives. It is impossible to imagine a world without it. Although is a very basic need in modern society most people take it for  granted but generating electricity power and distributing it with a good efficiency to the places where it’s been used is a very complex and carefully designed process. I recently read a report by climate council of Australia (“Australia’s electricity sector: ageing inefficient and unprepared”) and as the title implies it focuses on the matters related to Australia electricity industry and propose the solutions for them .So I thought to share some key points I read in that report and share with you. I personally believe that it’s a responsibility of engineering community to educated general public about how science and technology is important for a better future and for a sustainable development. All the facts and data I go thorough in this article were extracted from that report and all the credit should go to the writer and the climate council of Australia.

Globally the energy sector accounts for the largest proportion of greenhouse gas emissions which is the main cause for climate change around the world as scientists speculate. In order to avoid the effects of climate changes countries have agreed to keep the temperature rise below 2 degrees and in order to achieve this goal every country has to reduce their greenhouse gas emissions it needs large scale changes to how countries produce their electricity and other energy methods.

Figure <!–[if supportFields]> SEQ Figure \* ARABIC <![endif]–>1<!–[if supportFields]><![endif]–>-Global energy related CO2 emission

The above graph shows how the energy sector is responsible for the emission of CO₂one of the main component of greenhouse gases has increased over the time. As the graph shows it is an exponential growth. Coal is the main reason for this and as everybody knows coal is one of the main source for conventional electricity production. Australia places as 9th country in the top ten countries that emit greenhouse gases in electricity production. In 2011/2012 about 91% of Australia’s electricity was generated using fossil fuels.75% of the portion was from coal and 25% from natural gas. Australia’s per capita CO₂ emission is the world highest in 2011.So it is obvious that electricity generation in Australia is not ecofriendly as people might think. Australia produces 60% of emissions per MWh than USA. Even Australia is well behind China when reducing the emission of GHG (greenhouse gases) .Over the decade to 2012, China has reduced the GHG emission by electricity up to 16% but Australia was able to reduce that by less than 4%.As a result electricity sector responsible 33% of GHG emissions in Austalia.

Table <!–[if supportFields]> SEQ Table \* ARABIC <![endif]–>1<!–[if supportFields]><![endif]–>-Global Emitters of CO2

The reason behind this is the way electricity is generated in Australia. As mentioned above coal and natural gas are the main sources used to generate electricity .Coal and gas power plants operates in Australia are getting old. Currently the average age of coal power plants in Australia is over 30 years where it is less than 2 years in the global scale and by 2030 over 65% of coal power plants will be over 40 years old. The age of the plant is an important parameter when it comes to it’s efficiency since an old plant operates on technology which is established over decades ago. The technology related with electricity generation is developing rapidly since these plants operates on low efficiency it becomes very expensive to produce electricity it’s and waste of natural resource. Some might see this is not a problem since we have time but building a megawatt scale power station will take at least a decade to plan, finance and build and operate in the required manner. Various much efficient technologies were introduced during the past decades in order to reduce the Carbon emission from plants but the old power plants are unable to adopt to these relatively new technologies since it’s not economically beneficial and those plants are constructed on old technology hence they are locked down to use that instead of moving to more efficient new technologies. One parameter to measure the emissions from a plant is cycle efficiency. It is determined by the steam temperature and the pressure conditions at the limits of a cycle. These efficiency are divided in to 3 categories, Subcritical, Super critical and ultra-critical. Most Australian coal power stations are subcritical hence they have become one of the least inefficient power stations in world.

Figure <!–[if supportFields]> SEQ Figure \* ARABIC <![endif]–>2<!–[if supportFields]><![endif]–>-Fuel usage for electricity generation in Australia 2012-13

Figure <!–[if supportFields]> SEQ Figure \* ARABIC <![endif]–>3<!–[if supportFields]><![endif]–>-Electricity production in Australia

As people realise the negative effects of using fossil fuel based electricity generation the world is slowly moving towards replacing fossil fuel with renewable energy sources like solar, wind, hydro and fuel cell (H₂) technologies. Hydro power is the leading renewable source in the world at the moment. AS it can be seen in above graphs it is the same trend in Australia. In Australia hydro power has supplied 8186MW (16.1% of total capacity) .New South Wales got the biggest portion of hydro power stations (55%). In global scale hydro power has supplied around 15% of electrical energy needs.

Table <!–[if supportFields]> SEQ Table \* ARABIC <![endif]–>2<!–[if supportFields]><![endif]–>-Hydro power generation distribution worldwide

Wind power is also another emerging renewable source since it’s large reductions in costs associates with installation and equipment .Australia got one of the best wind fields in the world and Australia was able to generate over 6000 GWh in 2012/13 at an average capacity factor of 34%.(Capacity factor measures the ability to extract and store energy from wind by a turbine over a period of time).South Australia is the leading state is wind energy production. It is expected that there would be more 8900 MW of wind energy will be available by 2020 but still Australia is well behind most developed countries.

Solar power is another wildly used renewable energy source. It’s becoming more popular than wind because of it’s domestic use. While coal and other fossil fuels are expected to become expensive in future it’s obvious that solar energy will be less expensive than coal in near future because of the rising demand for solar PV. The advantage of solar is it can act as a distributed power source in houses and commercial premises or it can be scaled up to MW size and feed to the grid.

Over 1 157 000 Australian households had installed 3039 MW of solar PV by 2013. South Australia has the largest proportion of power generated by Solar. Although there is a decline in installing new solar PV in houses due to reductions in Feed in tariff rates it is expected that by 2020 the power generated by solar PV could be doubled. Although household solar PV is a popular alternative to grid power, Australia has only few field scale solar power stations. A 10 MW station at Greenough River in WA and 1MW project at Uterne in Northern territory. Besides these existing projects there are several new projects that are under construction. A 20 MW project at Royalla in ACT. A 102 MW project at Nyngan in NSW. A 3 MW project at Brokenhill.

The popularity of PV has caused them to reduce it’s price and more affordable to households. Furthermore many solar markets around the world getting closer to achieving ‘Socket parity’ point, where it is more economical to produce electricity using solar rather than buying it from the grid. Nowadays it’s more economically beneficial if people use electricity generated by solar for their needs rather than feeding into the grid. Because in that way they will reduce the amount of electricity they consume from grid. One of the major drawbacks of solar PV is it is unable to provide power when it is needed most. In generally the maximum solar insolation is received during noon time but the electrical peak arrives during evening times and most of the time solar power is unable to supply the demand. Therefore households have to use more grid generated power during this period. Therefore solution is to use battery system to store excess energy produced during day time and consume it during peak time. The price of the battery systems are relatively high but it’s becoming cheaper because of it’s popularity and with new battery designs like Tesla Power Wall it has become a worthy investment.    

There is no doubt that sooner or later the whole world has to change their way of producing energy therefore earlier is better. It could be cheaper to use fossil fuels at present but in about 20 years it won’t so nations should start planning and implementing renewable energy plants from now. It is a fact that Australia’s existing fossil fuelled plants can’t compete with renewable energy methods in long term because it’s obvious that price of fossil fuel is becoming higher while the cost of renewable energy solution becoming cheaper. According to the studies wind is the most suitable energy source for Australia along with field scale solar PV.

Table <!–[if supportFields]> SEQ Table \* ARABIC <![endif]–>3<!–[if supportFields]><![endif]–>-Cost reduction potential for onshore wind systems

Table <!–[if supportFields]> SEQ Table \* ARABIC <![endif]–>4<!–[if supportFields]><![endif]–>-Cost reduction potential for PV modules and systems

Although Solar, Wind, Hydro and other renewable energy sources are very promising technologies one problem associating with them is they are very sensitive to climate changes. It is very difficult to predict what would be the climate conditions in a region by 10 or 20 years. If the conditions changed dramatically in future the expected output will not be achieved by those plants and the investments done will be wasted. Therefore these aspects has to be taken into account when planning a large scale renewable plants .On the other hand when more renewable sources have been used , governments and other corresponding authorities will be forced to take environment protection more seriously. It will be helpful for a more sustainable and greener development. In conclusion, the fate of future generations in Australia and the rest of the world depends on how we address the energy crisis and take necessary steps to switch to renewable energy. 

References:

Australia’s Electricity Sector: Ageing, Inefficient and Unprepared        

esaa:data and statistics-energy in Australia