Drawbacks of LEDs

Posted by David Jones on

Demand for LEDs is at an all-time high, and they are being promoted as the eco-friendly lighting option. It is prudent to keep its drawbacks in mind, to understand how best one can use them in everyday life or as grow-lights in indoor plant cultivation. 

Lifespan of LEDs

The advertised claims are that LEDs can last up to 35,000 to 50,000 hours. This is significantly longer than its closest rival the eco-friendly compact fluorescent light (CFL), which last 10,000 to 15,000 hours, or the conventional incandescent bulbs which last only 1,000 to 2,000 hours. However, experience has shown, it is best to expect that LEDs only last 50% to 70% of the advertised lifespan (1). 

Even with these lower pragmatic expectations, LEDs outperform all other lighting systems. Moreover, though LEDs do not last the advertised 50,000 hours, unlike incandescent bulbs they do not burn out abruptly but gradually dim over time (2). 

LEDs are Expensive

This is cited as one of the main disadvantages of LEDs in comparison to other types of lights. It is true that currently, the initial capital cost of LEDs is much higher than that of many conventional lights, in terms of ‘price-per-lumen’ (1). 

However, because LEDs are seen as the light of the future, the innovations and development that this technology attracts, is making them increasingly more economical. These days they are offered at prices competitive with CFL (3). 

Moreover, LEDs have a much lower energy consumption compared to other lighting systems and result in considerable energy savings in their life-span. Given their relatively long life-span, they need to be replaced less often and result in lower maintenance costs in terms of material and labor. When all these factors are considered, LEDs are actually cheaper in the long run (2). 

Less Luminescent

LEDs are small, and even though they are highly efficient, each LED produces less number of lumens or brightness. So it is necessary to use many LEDs to get the same brightness as a single incandescent bulb. This is another reason why using LEDs becomes expensive (1, 2). 

LEDs’ ability to provide light without the accompanying heat that other lights do makes them the better option for many uses, compensating for this drawback. Moreover, as grow-lights, smaller light sources can be an advantage in combining different colors to achieve the correct light rendering for growing vegetables and flowers. 

Performance

Contrary to advertisements, LEDs’ performance depends on the ambient temperature of the atmosphere and age. 

Heat: LEDs produce heat at the semiconductor junction within the device, where 60 to 95% of the input power is lost as heat. Therefore, when the ambient temperatures rise, this can become a problem, as the LED characteristics, such as color, can change. In extreme circumstances, the damage can be permanent affecting the lifespan of the LEDs (1, 2). 

This is a factor which must be considered when using them in applications in the automobile, medical and military sectors. This is especially a concern when they have to operate in conditions where there are big differences in temperatures as in automobiles (1). 

This problem can be fixed through correct engineering of the light fixture. A heat sink which is a device with fins that conducts heat away from the LED can be used in a process called heat sinking to keep the LEDs cool (4). 

Age: In addition, LEDs change color due to age, and the perception of white LEDs is also not very consistent. 

Supply of electricity

Energy must be supplied at the correct voltage at a constant flow. This makes LEDs complex electronic devices requiring high levels of technical expertise during preparation. 

During operations, they need a series of resistors to maintain the flow of electricity (1, 2).

LEDs’ Toxicity

Though LEDs do not contain mercury like their conventional counterparts, they do contain many other dangerous heavy metals, such as lead, arsenic, nickel, and copper. Red LEDs are the worst offenders containing eight times the amount of lead allowed by Californian state laws. Lead is well known as a neurotoxin, and a carcinogenic. Arsenic can also lead to cancer and other problems, while nickel causes allergic reactions. Copper can harm aquatic animals and is an environmental threat (5). 

LEDs are at present not considered hazardous material by law. However, in their best interests and to be safe, people who clean up any broken LEDs should use gloves and mask, and treat the LEDs’ waste as well as the materials used for cleaning as hazardous waste. Similarly, in case of car crashes or broken traffic lights, places where they could be a high concentration of LEDs, people should take care by using protective garments and treating the waste as hazardous and dispose of it accordingly (3). 

The scientists who discovered the toxicity, have advised setting safe benchmarks for manufacturers to improve their design with safer materials. They also seek government engagement to motivate recyclers and waste management teams in adopting proper disposal methods for end-of-life LEDs (5).

Blue Light Hazard of LEDs

There is growing concern that cool white and blue LEDs could lead to blue-light-hazard, which is harmful to eyes. Blue light falls in the short wavelength and high energy part of the light spectrum. The human eye cannot filter out blue lights, so excessive exposure to blue light leads to eye strain, and could also lead to macular degeneration (6). 

However, there are many scientists who challenge the claim that LEDs emit enough blue light that could cause eye damage. However, even they advise that it is best not to expose people, especially babies, to cool white or blue lights. Instead, it would be best for people to consider the warm white light for fixtures at home and in buildings (7). 

People who are involved in the indoor cultivation of plants can use suitable eyeglasses, which filter out blue, to avoid any possible harm to their eyes as an occupational hazard (6). Some examples are, - special glare-reducing anti-reflective coatings for lenses. - glasses with photochromic lenses, which offer protection from blue light as well as UV radiation both indoors and outdoors.

It should also be remembered that blue light is not all bad, some of it is actually even beneficial for people. It is when the eyes are excessively exposed to blue light that it could become a problem (6).

In the Balance LEDs are Beneficial

There is growing concern that cool white and blue LEDs could lead to blue-light-hazard, which is harmful to eyes. Blue light falls in the short wavelength and high energy part of the light spectrum. The human eye cannot filter out blue lights, so excessive exposure to blue light leads to eye strain, and could also lead to macular degeneration (6). 

However, there are many scientists who challenge the claim that LEDs emit enough blue light that could cause eye damage. However, even they advise that it is best not to expose people, especially babies, to cool white or blue lights. Instead, it would be best for people to consider the warm white light for fixtures at home and in buildings (7). 

 

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