Light Emitting Diodes (LEDs) – lighting our way to a cleaner, greener future.

The electronics revolution has opened up massive opportunities through the internet and communication technology. It has also made our lives far more energy efficient, particularly through improvements to interior lighting. The latest kid on the block of lighting are light emitting diodes (LEDs) which are quietly revolutionising how we light our lives, in just about every way.

In a few decades we will recall our use of old fashioned, inefficient incandescent light bulbs as strangely as we now view our grandparents using coal-fired stoves to cook on.

There are presently three main varieties of light bulbs available for home use. The old-fashioned incandescent light bulb works by passing power through a coil of tungsten wire enclosed in a vacuum, making it glow white hot. Most of the energy is wasted as heat. The bulbs last only a short time, around 1200 hours on average. Energy efficiency is generally less than 5%.

Incandescent bulbs include the familiar normal round light bulbs, as well as reflective spotlights and the slightly more sophisticated halogen light bulbs normally used as recessed down-lighters. The sheer electrical inefficiency of incandescent light bulbs is rapidly making them obsolescent.

Most people are now aware of the new energy efficient compact fluorescent lights (CFL) which are essentially a miniaturised version of the long, old fashioned fluorescent tubes one still finds in schools, factories and other large open spaces. Miniaturised electronics have enabled manufacturers to reduce the size of CFLs to approach those of incandescent light bulbs.

CFLs are far more efficient and long lasting than the incandescent lights they replace, operating at around 15 to 20% efficiency, about four times that of incandescent lights. They last between 6000 and 10 000 hours, around 5 to 8 times longer than incandescent lights. They emit far less heat, yet do become warm.

Finally there are light emitting diodes or LED lights. LEDs are semi-conductors, just as transistors or computer chips are. It has only recently become technically feasible to manufacture LEDs that emit sufficient amounts of light in similar parts of the colour spectrum to incandescent and CFL bulbs.

Some LEDs still tend to be a bit colder, meaning whiter or bluer, than we are accustomed to. This problem is rapidly being solved with the latest generation of LEDs emitting a more yellow, warmer light spectrum, almost identical to incandescent lights.

However the most important advantage of LED lights is their sheer efficiency. Most LEDs operate at around 35% efficiency and continue to improve in efficiency. Consequently they use far less power and remain cool to the touch.

Then there is the important matter of life span and durability. An LED light bulb lasts between 20 000 and 50 000 hours, 2 to 8 times that of a CFL light and up to 50 times longer than a comparable halogen or incandescent bulb. This is an important consideration as LED lights remain quite expensive, primarily due to the fact that the technology is still developing.

LED efficiency is improving at a similar rate to computing power, doubling every year or so. As the technology improves, the cost will continue to fall.

Fluorescent and incandescent lights emit light differently to LEDs. Both of the former types of lights emit light equally in all directions. LEDs provide a far more focussed beam, most easily compared to a spotlight.

Because of these characteristics it is best to use each of these lights for specific purposes. For instance I have five LED down-lighters in my ceiling that draw only 2 watts each, collectively consuming less power than a single CFL bulb! Because LED light is focussed, they are ideally suited to down-lighters, replacing halogen lights.

They are also far safer because they run cooler. Halogen down-lighters are one of the primary causes of house fires because of the immense heat they emit, combined with the often dusty conditions in which they are installed.

LEDs are also superior for reading due to the fact that they have far less flicker than fluorescent bulbs. The generally whiter light of LEDs is also easier on the eye when reading text on paper. They are also increasingly used in torches, car lights and headlights, with vastly improved battery life and of course bulb life.

There are some individuals who have become sensitive to electromagnetic radiation (EMR), typically emitted by cell phones, wi-fi, cellphone and wi-max masts, who are also often sensitive to the radiation emitted by the circuitry of CFLs. The reality is that CFLs can be a trigger for EMR sensitivity because we are so close to the source of emssions. This, combined with the flicker of fluorescents, remain major reasons for their unpopularity. LEDs do not have this problem, nor do they have a lag after being switched on, common to many CFLs.

However CFLs can be an efficient source of space lighting in situations where conventional incandescent bulbs have traditionally been used. Given their low cost compared to LED lights they presently remain a competitive option when used for this sort of application. I do predict that LED lighting will overcome this shortcoming through design innovations.

It is also important to know that CFL lights contain mercury, in the bulb, to make it work. Therefore broken CFL lights – in fact all fluorescent lights – should not be vacuumed up but should be carefully swept up and safely disposed of. Although the amount of mercury in each lamp is low, the toxicity of this element must be considered when disposing them at the end of their life.

CFLs should never be disposed of in general waste streams or thrown in the bin. Instead they should be returned to the shops where they were purchased, who are obliged, by law, to provide recycling options in South Africa. Many other countries have recycling programmes in place. The CFL light industry is presently finalising a comprehensive recycling scheme which will make the disposal of these bulbs easier.

LEDs on the other hand are completely inert with any toxic material – which may be present in tiny amounts – completely integrated into the solid state lamp. Because of this solid state nature, LED lights are also more shockproof and can usually be dropped without any significant damage, an advantage for clumsy do-it-yourselfers!

So while LEDs presently remain an expensive option they will repay their cost in two ways. Firstly through their efficiency and low wattage saving significant power costs, and then secondly through their longevity.

I have a LED red nightlight for my youngest child that is 11 years old. It is sometimes inadvertently left on but I worry far less about this than if it were an incandescent bulb as it draws less than 1 watt! I remember replacing the old night light bulbs for the younger children almost monthly.

The reality is that LED lights are already far cheaper in the long run, even if they remain expensive to purchase. This is clearly shown in the table below, where LEDs cost about one third of a CFL and more than 12 times cheaper than old fashioned incandescent bulbs.

Even if left on for 24 hours a day a LED light should remain bright enough for around 3 to 5 years; I am not saying that you should leave it on though! They do not blow like other lights but simply fade away when they get older. The cost of the bulbs is constantly coming down and has dropped by almost 50% over the past three years (2011-2014).

LEDs are safer, more environmentally friendly, less polluting in manufacture, use and disposal. They are rapidly becoming more efficient while costs fall. The future is here and it is LED!

 

light comparison table

Table: Cost/Efficiency comparison of incandescent, CFL and LED light bulbs. Ashton 2011.

This article was originally published in the magazine “Natural Medicine” in South Africa in 2011. It has been rewritten and the table was updated to 2014 prices.

South African Journal of Natural Medicine

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