The general press urges the public to conserve energy on a regular basis – but in the push to better inform the public about the importance of energy conservation, a few energy myths have slipped through the cracks.

The press generally provides a multitude of reasons to be mindful of energy consumption, including the cost of energy, energy scarcity, its short- and long-term effects on the environment and lastly, that it is plainly the right thing to do.

Currently, the issue of stable availability of electrical energy is paramount in most conversations and forms an integral part of most strategic decisions in South Africa. Therefore, I want to address a couple of well-intended comments that I encounter daily that are, in actual fact, myths about energy, with the intention to stimulate readers with some lateral thoughts on what energy is and what we really understand about energy and energy cost.

There are at least three pillars required to create the foundation for an economy to grow and they must all be available: energy, transport and communication. An economy’s growth potential is severely constrained if anyone is missing or lacking. We are also aware that the weakest link in a chain is the ultimate critical factor determining the strength of the chain. 

Surrounding these pillars is, of course, a conducive regulatory framework in which to conduct business, normally provided by the Government. Although the availability of cost-effective energy plays a critical role, alone it is insufficient to establish the necessary conducive environment to enable economic growth.  Energy enables the production of goods, which cannot reach the market in good quality and time without transport and cannot be traded on the market without communication.

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Strictly speaking, electricity is not really a form of energy – it acts only as a transporter of energy. Energy is converted from the heat of combustion (mostly coal in South Africa) through a turbine and generator into orderly moving electrons, so-called organised energy of high quality. As the moving electrons cannot do work in themselves, they must then be converted again into a useful form, either heat or mechanical energy through a rotating shaft from an electric motor. 

The fact that electrical current cannot be used directly but needs to be converted can be used to state that electricity only acts as a transporter/taxi of energy from one point to another. This also implies that when the user receives the energy (only about 27% of the 100% of energy imbedded in the original coal) at his/her transformer, only from that point onwards can the user manage certain aspects of the electrical energy conversion into useful work. However, the generation of electricity, transmission and distribution will still continue if the user “waste” the received energy with the resulting impact and consequences to the environment and to society as a whole.

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Energy cannot be conserved as it cannot be created nor destroyed. Energy conservation is a vague term and is thus scientifically “incorrect” terminology. We need to consider the amount of practically useful energy which is available to convert to useful work. The engineering term is exergy and means we consider the theoretically useful available energy, but decide to focus only on the part which is practically available to be converted into useful output.

Energy Management is thus concerned with how much of the practically available energy (exergy) is actually converted into useful energy.  Any part not converted into useful energy goes to waste (becomes non-useful energy, called entropy) while we have paid for it, but we waste it! The real savings lay in minimising this waste, in engineering trams depleting the maximum amount of exergy through any process. This will also affect the environmental and societal impacts directly through lower the need for generated electricity.  Further inclusion of energy conversion into the circular economy concept can flow directly from this approach to consider exergy.

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The most energy saving happens when you switch off the equipment using energy.  While LED lighting is known to provide us with one of the highest light outputs (in lumen) to rate of energy use (watt) ratios, called efficacy, it will not save anything if it is switched on when not needed.  Lighting savings are achieved by taking the characteristics of the entire luminaire (Fixture, lamp, reflector, and diffusion media) with high appropriateness and high efficacy and then matching it to the least appropriate operation time in hours. 

Energy savings in lighting are linked to control, control, control. New layering strategies, which include timer controls, use of connected occupancy sensors, use of vacancy sensors and daylight harvesting sensors, provide many opportunities with additional substantial savings in energy and cost. Even though you use the optimum type luminaire, the actual hours of being switched on provide numerous opportunities for substantial savings.

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Consider the recent trend toward human-centric lighting where the new tuneable white light LED technology adjusts the LED light’s spectral power distribution (SPD) to influence your circadian rhythm.  With different spectral distributions now possible with the push of a button or programmed into the control system for continuous variation of SPD, lights can now stimulate the natural secretion of melatonin to promote sleep, stimulate people when required (like in an exam), provide better visual acuity and, through stimulation, secrete natural ghrelin that we use to manage our feelings of hunger! It can also assist in resetting the circadian rhythm of your body clock, which runs on 24 hours and 20 minutes, back to the 24-hour cycle on our clocks.

To summarise, the more I delve into energy and energy conversion, the more I uncover numerous opportunities for us working in the energy efficiency sphere to enable energy efficiency gains, lower impact on the environment and the society, lower energy cost and even better alignment with our minds and bodies! ESI

Louis Lagrange is the Head of the Department of Engineering Sciences at the University of the Free State.

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