For example, turning off unnecessary lights and machinery when not in use and replacing an old high-power motor with lower power and efficient one is a great way to reduce costs. There are many industries which use old motors, which need to be replaced. Suppose a motor with an efficiency of 83% having an electric cost per year of around $3923 when replaced with a motor having a high efficiency of 87.5%, will consume electric power worth $3734 and annual savings of $189 can be achieved. In this blog, we will be discussing more ways in which an industrial, commercial, or residential consumer may reduce their electricity consumption.
Power saving or conserving energy has become important nowadays due to the following reasons:
So to reduce pollution, mitigate losses, and reduce the cost of electricity, power-saving has become essential.
Energy policy is a document or set of regulations that include strategies and steps to be taken for energy saving. There are several standards based on which energy policies are made.
For example, ISO 50001, a standard made for energy management purposes has the following features:
A regular energy audit helps in finding out the power losses due to different equipment, also the areas where most of the power is consumed and what steps are required to be taken in order to reduce power consumption without affecting the production.
Energy audit consist of the following steps:
The use of renewable energy is becoming common nowadays as it is a free source of energy and has almost negligible carbon emission. Renewable energy includes the use of wind energy, solar energy, biomass energy, and many more. These energies are utilized for supplying to load through the combination of power system equipment besides power electronic devices. The use of renewable energy in industrial facilities can also be a source of cost-saving and reducing demand on the utility company. For example: On industrial scale installing solar panels and shifting lighting load to it can help in reducing the burden of power generation greatly.
The use of electronic ballast in tube lights instead of using an old electromagnet blast can also reduce energy consumption.
Replacing fluorescent and incandescent with low power led lights is a fine approach to saving energy. For example: on replacing a 40 Watt and 500 lumens incandescent bulb with a 7 Watt led bulb providing the same lumens (brightness), then about 33 Watts (40 minus 7) can be saved per luminaire.
Sensors based light in washrooms and other areas can save a lot of energy. for example, an office has a working hour of about 10 hours and washroom lights remain on during the complete hour. Instead of turning on the light throughout the office hour, ultraviolet sensor-based light can be used in the washroom which turns on only when it senses any physical thing moving around it, this will reduce the waste of energy.
The power factor shows the ratio of what amount of power is utilize for doing useful work from the power that is supplied. As most of the motor present in industries is induction motor. The power supplied to an induction motor is used for two purpose
It is preferred that reactive power should be minimum. An increase in reactive power reduces the power factor and low-power factors cause penalties on the industry.
For example, two industries are supplied by a grid having the following data:
|DATA||INDUSTRY A||INDUSTRY B|
|Power utilized||1 MW||1 MW|
|Power factor (P.F)||0.5||0.8|
|Power required (MW/P.F)||2 MVA||1.25 MVA|
The given data shows that both industries may have the same amount of motors utilizing 1 MW for doing useful work but due to the difference in power factor the power supplied by the grid changes. Industry A will have to pay a high bill as the grid has to supply more power.
So in order to compensate reactive power requirement, synchronous condensers , STATCOM, and capacitor banks are used.
Due to overloading, voltage fluctuation, and insulation damage, motors winding temperature increases and starts to get damage. The rise in temperature leads to increased losses. It is said that motor life gets halved at every 10-degree rise in its temperature.
For this purpose, we send motors for rewinding. But if rewinding is performed with a lack of care and precautions then every rewinding could cause a 1% decrease in efficiency which ultimately results in increasing the cost of electricity.
Following points should be under consideration while deciding for motor rewinding:
At the time when the motor starts, it consumes almost three times as much power than its rated power. So for industries have numerous motors, it is recommended that each motor should be started one by one after some delay. This will reduce the overall burden on electricity generation end thus reduce the fuel cost.
An industry consists of three motors each of 10 KW and having a starting power of 30 KW for a few seconds. If all the motors are started in one go, then the surge of 90KW will appear at generation end. Instead of this if the motors our started one at the time then the surge will be much less.
Control Systems in Motor:
Motors can be used at high efficiency using power electronics devices. For example:
| At the time of starting, the motor draws a large amount of current than the rated current. Eventually the requirement of power increases.||A 'soft starter' reduces the starting current for high HP motors. For low HP motors, star-delta starter and DOL (Direct On-Line) starter can also be used.|
|A motor works better at its rated speed when it is provided the full load. As the load decreases the motor will provide the remaining power to cater to the losses, resulting in less efficiency.||A 'Variable Speed Drive (VSD)' proportionally changes speed as load varies.|
Proper scheduled maintenance and monitoring of loads in industries could increase the life span of equipment and also help in controlling the losses or failure.
As motors run continuously in certain industries, this can result in increased motor temperature. More overexposure to a rough environment also leads to body damage and insulation failures. A proper maintenance schedule for regular maintenance, inspection, and cleaning is a good option for motor protection from environmental adverse effect.
Cogeneration means using exhaust heat for the purpose of heating or cooling. There are many industries out there that have a heating or cooling process so instead of wasting the heat of exhaust they can reuse it to generate electricity or provide heating somewhere else. Gas turbine and Gas engine generators also produce exhaust heat having high temperatures. This heat energy can be utilized instead of being released to the environment. The hot exhaust gases can be directed towards the HRSG (Heat recovery steam generator) which then produces steam which can be utilized for electricity generation using steam turbines or any other heating purpose. This is known as the combine cycle. These combined cycle plants are highly efficient and greatly reduce energy losses saving fuel costs.
HVAC (Heating Ventilation and Air Condition) are used in almost all process industries, commercial buildings, and homes. The following steps can be taken for making efficient use of HVAC.
Due to changes in shifts, variations in weather, and different production times, demand never remains the same. Such variation in load causes an increase in the number of generators which proportionally increases the maintenance and control system requirement and thus cost increases.
Proper load management like reducing unnecessary loads like lights, motors, and economic dispatch of power improves our energy savings in such cases.
Another method that can be employed to reduce peak is using control systems or 'Smart Grid' that is the supply from certain loads automatically cuts off or an alarm starts to ring whenever it reaches a certain peak.
Peak shaving can also be done through a distributed generation that is having supply from both grid and self-generation. Here self-generation means that having a gas, diesel generators, or UPS (uninterruptable power supply) present at your facility can be used as a backup supply or for peak demand-supply.
Even with the many energy-saving methods, it is still not easy for industries to properly follow these steps because it may affect their production. Sometimes the cost of taking these measures is higher than the investment or they might not have a good payback or return. Also, it is not easy to convince employees and the public to follow these methods. However, it is our responsibility to create energy literacy among people we know, we should also lead by example and promote energy saving in our society.
About The Author
Abdur Rehman is a professional electrical engineer with more than eight years of experience working with equipment from 208V to 115kV in both the Utility and Industrial & Commercial space. He has a particular focus on Power Systems Protection & Engineering Studies.