Energy Efficiency Explained

28 November 2020
Reading through our blogs, articles elsewhere online and in tech news, you’ll see an awful lot mentioned about the “energy efficiency” of certain power production methods.

Reading through our blogs, articles elsewhere online and in tech news, you’ll see an awful lot mentioned about the “energy efficiency” of certain power production methods. Solar panels reached a record high for efficiency in 2014 of 46% and coal-fired power plants range from 33% to 40% efficiency.

If you’ve not come across this term regarding energy production, then you may have come across it when looking at electrical appliances or buying a home.

But what does this mean? 46% of what? Why can it not be 100% efficient? And how is this efficiency calculated?

What Energy Efficiency Means In the Home

The energy efficiency rating of all things is rated in how effectively (and efficiently) the energy input is converted to the output and how much of the energy is lost to other means.

For most domestic applications, the energy to which we refer is electricity.

A washing machine may have an energy efficiency rating of 60% – i.e. 60% of the electricity input is used to meet the means of the device. Where does the other 40% go? The remaining energy is lost as other forms of energy as a by-product of the process. 20% of the electricity input may be converted into sound energy through the electric motor, water pump, sound of water splashing etc. Another 20% of the energy may be converted into heat, lost into the air from the motor and heating elements.

This is why companies spend millions on Research & Development to product quieter electric motors. Energy wasted making noise or heating something up unnecessarily, is energy that could be saved or used in the function of the device. The more inputted energy that goes towards the desired function of the device, the more energy efficient it is.

What does this mean in energy production?

As mentioned above, efficiency is measured in how much of the inputted energy is used for the device’s purpose, not necessarily electricity.

The energy input of a solar panel is the sun. The record breaking solar panel with an energy efficiency of 46% converts 46% of the sun’s solar energy into electricity. That is 46% of the energy that hits the surface of the panel, not 46% of the sun’s energy.

The rest of the energy is converted into another form of energy in the same way as it is in a domestic appliance. In the case of solar panels, the bi-product is predominantly heat.

In Waste to Energy Incinerators – learn more about these here – their efficiency can be up to 28%. The waste is turned into heat energy and this heat is used to produce steam and turn turbines. The other 72% is lost to the environment as heat and sound. Or is it? That’s a lot of heat to just let escape into the atmosphere when there are people out there that pay to heat their homes. This is where ‘cogeneration plants’ come in. Instead of wasting this heat, it’s piped into nearby businesses and homes. By harnessing this heat and using it for a productive purpose, the energy efficiency of a WtE Plant is raised up to 80%. The only losses being the sound of the incinerators and heat lost when piping it to where it needs to go.

Instead of the waste going to landfill and the stored energy being used by microorganisms to produce harmful methane, it’s burnt to produce electricity.

Why does energy efficiency matter?

You might think that energy efficiency is not the most important thing to pay attention to. Does it matter that one solar panel is 21% efficient and the other 30% efficient? The energy is free from the sun!

Energy efficiency matters – even when the input energy is free from the sun – because of money. Electricity generators cost money to install, with the hopes that someday money earned from electricity generation provides profit on the initial outlay of installation.

The more efficient energy production becomes, the sooner the investment sees a return. Combine this with the fact that the wind/sun/tide is free or people’s waste is plentiful and otherwise useless, the return should come to companies much sooner than with fossil fuels which cost increasingly more money.

This is precisely why efficient, clean energy is skyrocketing in popularity and fossil fuels energy production is beginning to show a decline.