Earth Hour is an event held every year sometime around March for an hour from 8:30 p.m. to 9:30 p.m by switching off lights around the globe. This is supposed to be a feel good symbolic environmentalism to reduce the carbon emissions at least for an hour at a global scale. Unfortunately, the event that is supposed to reduce emissions ends up increasing emissions!! The reason? The Science behind Earth Hour is wrong.
Understanding How Power Grids Operate
A Power Grid has to maintain its output in line with the current demand. Usually, a power grid knows its average demand at the point of the day and is adjusted to maintain a steady average output according to that demand at the point of the day. Also, a power grid can perform optimally only when it covers an area as large as possible. This will keep the average demand a constant.
Think if a Grid supplies power to just a couple of streets, and if they all switch off or switch on electric equipment at the same time, then the sudden decrease or increase in demand will be drastic. On the other hand if the grid is serving a very large area, then the average increase or decrease swill smooth out, and remains nearly constant and predictable throughout the day and over different seasons.
Sudden Increase or Decrease in Demand is Harmful to the Grid
If the average demand suddenly increases or decreases the power grid has to accordingly adjust its output. Why? Because the power grid outputs power according to current demand, and if the demand suddenly increases a lot, then the average power received at your home will suddenly decrease.
Remember, the bulb becoming dimmer? The voltage drops. So, in case of sudden increase in power demand, the grid has to increase its power output accordingly and immediately. Else, all those equipment that require minimum constant power supply will fail. A classic example is computers that will get restarted if there is a sudden drop in supply voltage.
Similarly if the average demand suddenly decreases a lot, then the power grid has to accordingly reduce its output at the earliest. Else, individual houses will end up receiving more than normal voltage which may cause electrical equipment to break. Have you heard about or experienced electrical equipment like televisions damaged or SMPS units in computers burnt out due to sudden voltage increase? This happens when grid output is way above its demand.
In other words, sudden decrease in demand will cause sudden voltage increase that can damage electrical equipment because the voltage is beyond the maximum threshold it can handle.
On the other hand, sudden increase in demand will sudden voltage decrease that can again switch off electric equipment due to lower voltage than the minimum threshold required for the equipment to operate.
Load Shedding
Load Shedding is what happens when there is sudden increase in demand, and not possible to generate additional power. Some part of the grid is then shut down so that the remaining part continues to receive a steady voltage. This is the reason parts of the world with restricted power generation impose load shedding during peak demand times to divert power to important and essential areas like industries causing black out in other areas like residential areas.
Load Excess
When there is a sudden decrease in demand, the additional voltage it causes has to be absorbed to prevent equipment failure due to high voltage. The unused power in a power grid is not returned back to the grid as many people think. The traditional way has been to use heat sinks that will convert this unused energy into heat! In other words, the unused energy is wasted! What else to do with it?
That is the reason power grids always have to maintain their energy production to match the current energy demand. Any unused energy in this output is a waste. And in addition to this there is also the energy lost during transmission called the transmission loss. So the total power output of a power grid should always be as follows
Total Power Output = Current Demand + Transmission Loss
Any additional power generated will be a waste. So power grids have to constantly adjust to match current demand as much as possible. If there is sudden decrease in demand, then the heat sinks that are supposed to release unused energy as heat might get overheated and burn out causing grid failure!
Many power grids have started using Fly Wheels where this additional unused energy is stored as rotational energy which can later be extracted back. But then again, even here there is a maximum storage capacity, or maximum rotation speed beyond which the system will break.
Earth Hour causes more emission than it saves
Now, you see that during Earth Hour there is this sudden decrease in demand when the earth hour starts. Then there is a sudden increase in demand when the Earth Hour ends.
So the Power Grid initially will be losing all the additional energy generated when the demand drops suddenly. There is only so much additional capacity available to store unused energy, and not all power grids have that either. Most unused energy ends up as heat and is lost!!
Then when the energy demand increases suddenly at the end of Earth Hour when we switch on all the lights, the Grid has to again drastically increase its power output and this causes an additional energy to be used to ramp up the power output.
So the energy that is lost due to this sudden decrease and sudden increase in power demand at the Grid level, which is of course significant and outside the average range, will end up costing more power than what is “supposedly” saved during this Earth Hour.
Can’t the grid be automated to adjust output based on demand?
This is a very valid question. But the problem lies in the way the power is generated in the first place. How is energy generated by Power Plants?
Turbines generate Power
All commercial scale electricity in the world is generated using Turbines. These are giant wheels that rotate and thereby convert that rotational mechanical energy into electrical energy. How do these turbines rotate?
Steam Turbines
More than 80% of turbines are steam turbines. They are powered by steam whose heat energy is used to rotate the turbines. Where does the heat energy come from?
Steam Turbines operate by burning fossil fuels like coal or natural gas (Thermal Power Plants), or via nuclear reactions (nuclear power plants). The water heated by this process is used to produce the required steam.
Even large scale Solar Power Plants operate by using solar energy to heat the water and produce steam.
Renewable Energy Turbines
These turbines are powered by natural sources of energy like falling water (Hydro-Electric Power Plants), wind (Wind Mills). Here the water or wind is used to rotate the turbine.
Adjusting the output of Power Grid
The output of power grid can be adjusted by reducing or increasing the speed of the Turbines. Imagine the huge amount of rotational energy of the turbines for them to produce large scale electricity. Now imagine the amount of additional energy that would be required to stop (or slow down) or start (or speed up) these giant machines! That is the additional energy lost at the beginning and end of every earth hour event. That additional energy is much more than the energy saved by switching off lights for an hour.
On top of this, look at the source of the steam. In case of steam engines, the burning fuel amount has to be controlled according to the demand. Then you have the additional energy lost during storing and retrieval, even if any excess energy is stored in temporary batteries or flywheels.
In other words, the efficiency of the power grid always depends on an uniform load. Any sudden increase of decrease in load requires lot of additional energy to be spent to adjust the output in line with increased or decreased demand.
In modern times we do have smart grids that can adjust automatically and efficiently. But the point is, all this requires additional energy that is wasted. Of course, energy is wasted every day when power consumption drops in the night and increases in the evening. But Earth Hour adds an additional cycle to this every year. It is like having an additional night.
Candles – More CO2 produced than reduced
Most people who take part in Earth Hour use candles as an alternate source of light during this period. Guess what? Candles are obviously lot less efficient than the modern light bulbs.
So, due to the Carbon dioxide produced by burning candles you end up creating more pollution in the name of reducing pollution!! Even more disturbing is the fact that Candles are Petroleum based! More demand for candles is even more pollution.
Do light bulbs really matter?
One might as well argue that given the high efficiency of modern light bulbs like CFL, there is very little decrease in power demand during Earth Hour and it has little or no impact on power grid. Point taken.
But again doesn’t that itself mock the very purpose of Earth Hour. By switching off light bulbs for an hour you are not saving any electricity – the little decrease in total demand will probably end up as wasted heat at the heat sinks of power grid.
Even if fly wheels are used, the little power means nothing compared to the transmission loss in saving and retrieving this power. The candles will in addition increase pollution. So we are back to square one. Earth Hour causes more pollution than usual!
Summary – Say No to Earth Hour
To summarize, the additional energy required by power grids to cope up with the sudden decrease and increase in power during Earth hour, combined with the additional CO2 released by burning candles. This only means, Earth Hour causes more pollution. So please, this is symbolism that adversely effects its very purpose.
Symbolism is fine. It is required to create awareness and educate people. But it should not go against its own purpose. Earth Hour is symbolism gone wrong.
And it also sends the wrong message. We cannot reduce the usage of electricity. As human population increases and as technological innovations increase, as we add more and more industries and machines – we need more electricity.
What we need to do is focus our time and energy on generating reliable non-polluting means of electricity. Switching off all the lights is not an answer.
Instead of switching off lights and getting that useless feel good factor which means nothing – get a solar panel to power your energy needs to whatever extent possible. Walk to nearby grocery instead of taking your vehicle out.
See if you can use wind or water sources in or around your house. Come up with more innovative ways of saving energy – like more fuel efficient engines, and more efficient batteries.
Contribute to practically solve the problem. Everything else is wasted time and energy.
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