Abstract
Many households do not use the most efficient bulbs resulting in wasted energy. To fix this issue, households in the U.S must move towards LED lighting. However, LEDs are not the most efficient light source available. Lasers can be used as a viable light source through the use of nanoarchitecture in the form of fog to disperse laser light.
The lightbulb of the future
American households have gradually warmed up to the idea of saving the planet with renewable energy. The public usually thinks of solar, wind, and nuclear power as the future. These are the energy sources of the future, but there is also something else that can be done at the same time. That is making households and businesses more energy-efficient. I do not mean changing the habits of the people, but through seer technological advance in lighting.
In recent years, LEDs have taken over the lighting market. These new bulbs are replacing the halogen bulbs, which replaced the traditional incandescent bulbs. CFLs are also taking a backseat to LEDs due to higher cost and lower life span. Most people are satisfied with these changes as for the first time in decades energy usage in households has dropped mostly to lighting. However, stagnation of progress only leads to the squandering of Earth’s resources. Moving towards highly efficient lasers will help us reach our energy goals faster and on time.
Examination of Current Lighting Fixtures
To understand what determines an efficient light bulb, the term luminous efficacy is used. Luminous efficacy is described as lumens over a watt. Lumens are used to describe the brightness of a bulb and watt is the measure of energy used. Thus, a better bulb will have higher luminous efficacy. There is also luminous efficiency which is used to describe the maximum luminous efficacy in terms of percentages.
Four main types of bulbs are in circulation. The first one is the incandescent bulb first created in the late 1700s and made commercially successful by Thomas Edison. This traditional bulb uses a lot of energy to generate light because most of the energy is going towards heat. This was because the bulb relies on the filament, wires inside the bulb, to produce the light. The bulb also has inert gas within itself to preserve the filament. The bulb does not require regulating, is extremely portable, and cheap to produce. All these factors allowed the incandescent bulb to revolutionize our light industry. The problem is that the luminous efficiency is less than 5 percent. Most of the energy is going towards heat. While this is inefficient for most places, Canada had a unique situation where incandescent bulbs producing heat is better than switching over to more efficient sources. If Canada swapped, then there would be an increase in carbon dioxide emissions because the country uses natural gas to heat housing. In Quebec, it would be approximately 220,000 metric tons of carbon dioxide (Ivanco, 2007). The incandescent bulb fills this unique situation by being a heater that produces some light.
”Incandescent Bulb.” Bulbs.com, Bulbs.com, https://www.bulbs.com/learning/incandescent.aspx. Accessed 5th May 2021.
The second type is Halogen incandescent light bulbs. It has essentially the same build as an incandescent bulb except it uses halogen and tungsten filament. This creates the halogen cycle. This cycle is the halogen reacting with evaporating tungsten allowing the bulb to maintain the same brightness throughout its lifetime. The creation was first patented in 1882 to keep the lamp clean from the evaporated filament. However, it was not until 1953 did General electric made a practical bulb for commercial use. Halogen lamps have around the same luminous inefficiency as normal incandescent; most are between 5 to 10 percent. Even though its luminous efficiency is low the halogen bulb is more efficient energy-wise with 30 percent less and up to three times the normal lifespan of the incandescent bulb.
While the incandescent and its direct descendant are still available most countries are phasing them out by the end of 2021. This is due to more efficient light sources specifically the types of bulbs. CFLs and LEDs became much cheaper to produce and most of the planet now uses them.
Compact Fluorescent lamp (CFL) was first designed by Edmund Germer in 1927. It was General Electric that later created a design that would be commercially viable in 1938. The spiral design that is commonly seen was invented in 1976 was shelved by General Electric at first due to production cost. It was later produced as other companies produced similar products. CFLs were designed to be the successor to the incandescent bulbs. The CFL uses 75 percent less energy compared to incandescent and can last up to ten years. Their luminous efficiency is double of Halogens and is around 20 percent.
CFLs are known to have health and environmental concerns. CFLs release ultraviolet and blue light which may increase the risk of skin cancer and aggravate pre-existing skin conditions. Radiation from CFL bulbs is shown to have little concern as long as the user is 150 centimeters away (around 5 feet away). Most people are usually not more than five ft away from their lamps, so scientists suggest the use of double envelope CFLs to prevent concern of cancer (Nuzum-Keim, 2009). CFLs contain mercury like all fluorescent lamps and disposing of them is difficult. Mercury is dangerous when exposed to touch. Air and water pollution can cause damage to the brain. Many countries and the EU develop special waste disposal methods for CFLs to prevent any pollution.
“Compact Fluorescent Lamp” Bulbs.com, Bulbs.com, https://www.bulbs.com/learning/cfl.aspx. Accessed 5th May 2021.
LED
LEDs are the most efficient light source commercially accessible today. LED stands for light-emitting diode. LEDs are semiconductors that emit light when electrons flow through them. The electron travel from one side to another side with a lack of electrons creating photons when they reach electron holes (lack of electron at one position). LEDs produce light by moving electrons around to produce photons that produce visible light. Normal bulbs use a filament that heats up to produce light. This makes LEDs much more efficient since it does not rely on heat to produce light making it cooler and having a longer lifespan.
LEDs come from the concept of electroluminescence, which is that materials emit light when a strong current or electric field moves around them. Oleg Losev was the person credited for the creation of LEDs in 1927. Throughout the century more improvements were made on although none were commercially viable. I would say it was not even until 1993 when Nakamura, Amano, Akasaki developed high-powered blue lasers. This led to the creation of Blu-ray and gave these three men the Nobel Prize in Physics in 2014. What followed the breakthrough of highly efficient blue LEDs was the creation of white LED. Initially, it was expensive and highly inefficient until today where white LEDs are the preferred light source.
LEDs have a luminous efficiency of 40 to 50 percent which is more than double that of CFLs. They also use up to 85 percent less energy than incandescent and can last up to 25 years of usage. LED prices dropped to around one to two dollars per bulb. I manage to get four bulbs for five dollars from a local store. The bigger bulbs that are used in living rooms are around ten dollars each. Energy star estimates $2.11 saved per year. To put this into a better perspective this also ignores the lifespan. LED also saves on the cost per bulb; for every LED that you replace, there would be 30 incandescent and 5 CFL bulbs. If every household in the U.S swapped one inferior bulb to LED, it would be taking 800,000 cars off the road or planting 400 million trees (“Benefits of LED lighting //Bulbs.com”, 2014).
“Four bulbs.” NY.Times, Nadja Popovich, The New York Times, March 8th 2019, https://www.nytimes.com/interactive/2019/03/08/climate/light-bulb-efficiency.html. Accessed 5th May 2021.
“theoretical maximum luminous efficacy of different spectra as determined mathematically by DIAL.” Dail, Dail.de, 15th June 2016, https://www.dial.de/en/blog/article/efficiency-of-leds-the-highest-luminous-efficacy-of-a-white-led/. Accessed 5th May 2021.
Understanding Energy Cost in New York
New York on average uses more energy compared to the rest of the country. This is due to New York being colder, so more energy is used in heating. Due to this, New York consumes less electricity compared to the rest of the country. However, New Yorkers still pay around the same amount in electricity due to high prices in New York.
“All Energy average per household (excl. transportation)” U.S Energy Information Agency, EIA, https://www.eia.gov/consumption/residential/reports/2009/state_briefs/pdf/NY.pdf. Accessed 15th May 2021.
“Electricity Only average per household” U.S Energy Information Agency, EIA, https://www.eia.gov/consumption/residential/reports/2009/state_briefs/pdf/NY.pdf. Accessed 15th May 2021.
The average New York house spends 26 percent of its energy on electricity which amounts to around $1200. Around 77% of the electricity cost goes towards lighting. This means the average household uses around $923 on lighting. Switching to LEDs would drop to 20% of the cost or around 185$. This number does not seem to add up for people living in the city, but the average household has around 30-40 lightbulbs in their house. However, this also does not take in the fact that modern appliances such as smartphones and computers are taking up a lot of electricity as well.
The trend for LEDs has already started and we have seen a trend of decreased electricity consumption all over the U.S. For the last eight years, the usage of electricity has declined. For the past decades from 1970 to 2000 families have essentially doubled their electricity consumption. This trend is believed to be because of new efficient lighting with people switching out their incandescent for CFLs and now to LEDs (Nadja, 2019).
“Energy Use is Down in American Homes. Lighting Is a Big Part of the Story.” NY.Times, Nadja Popovich, The New York Times, March 8th 2019, https://www.nytimes.com/interactive/2019/03/08/climate/light-bulb-efficiency.html. Accessed 5th May 2021.
Lasers
Lasers are the next step in reaching new heights of lighting. Lasers stand for “light amplification by stimulated emission of radiation.” Lasers shoot out coherent light by using excited atoms. These atoms reach new energy levels when excited and when a photon hits the atom the atom goes down to a lower energy level and emits photons. These photons are between mirrors bouncing around until they leave through a hole to generate a beam of light. Lasers can travel a huge distance without dispersing because the waveform and frequency of the light are the same.
What truly separates lasers and LEDs is the fact that lasers can handle higher amounts of power while still being dense. Thus, to be able to light up a larger area while still being efficient in cost per lumen laser diodes must be used. Currently, state-of-the-art laser diodes rely on the properties of the phosphor to produce white light. The process can be described as a blue laser going through a yellow-light emitting phosphor. Their efficiency of this method can be described by the stokes shift and photoluminescence quantum yield. These two mechanisms have an 80% and 90% efficiency, respectively.
This is not the most effective way to use a laser as a lighting system. A way to use the laser up to 99% percent is by using an “artificial fog.” This fog is a nanoarchitecture that is highly porous and non-absorbing. This “fog” will scatter the light waves over a huge area without conversion loss in terms of energy. A red, green, and blue light will shine onto the fog to generate white light before bouncing off (Schutt, 2020).
“Schematics of laser-based lighting concepts.” Nature.com, Schütt, Nature communications, 18th March 2020, https://www.nature.com/articles/s41467-020-14875-z#citeas. Accessed 16th May 2021.
The figures above show that using a remote phosphor to convert to white light has conversion losses. Using the artificial fog with RGB laser will generate white light with negligible losses.
Cost
For this product to be commercially viable a bulb will have to be around 5 dollars for the cost to be worth it. I determine this through the fact that LEDs currently have a maximum efficiency of less than 50% and a LED bulb cost around 1-2$. Since a LED bulb saves two dollars in saving in a year and since the laser will have an efficiency nearing 100% the laser should save around four dollars. The LED bulb practically pays for itself and I wish for the laser to achieve this. One thing that was not considered is the lifespan of the laser. If the laser can last much longer than the LED bulb then a price difference is acceptable. I don’t see this happening for a long-time considering LED just hit commercial viability. If 99% is achieved the amount of energy used worldwide can be expected to decrease to an amount that is insane. Humanity effectively can save the environment every year just by being efficient in lighting. This is only because people do not start using lighting everywhere just because it is more efficient.
Conclusion
If everyone in the world swapped their incandescent bulbs for LEDs, we can expect a 16% decrease in energy consumption. We are still far away from reaching the goal of moving everyone towards more efficient lighting sources. Many poor countries still use oil lamps that are considered health hazards by medical experts. To reach our goal of a sustainable Earth, more efficient sources of energy must be used along with renewable ones. We cannot expect solar and wind energy to replace all electric energy consumption unless the average household helps meet that goal by using less energy. Laser lighting that is almost perfectly efficient provides a helping hand towards the cause of a green Earth.
Sources
Popovich, Nadja. “America’s Light Bulb Revolution.” The New York Times, The New York Times, 8 Mar. 2019, www.nytimes.com/interactive/2019/03/08/climate/light-bulb-efficiency.html.
GmbH, DIAL. “Efficiency of LEDs: The Highest Luminous Efficacy of a White LED.” – DIAL, 28 Apr. 2021, www.dial.de/en/blog/article/efficiency-of-leds-the-highest-luminous-efficacy-of-a-white-led/.
M. Ivanco, B. W. Karney and K. J. Waher, “To Switch, or Not to Switch: A Critical Analysis of Canada’s Ban on Incandescent Light Bulbs,” 2007 IEEE Canada Electrical Power Conference, 2007, pp. 550-555, doi: 10.1109/EPC.2007.4520391.
Nuzum-Keim AD, Sontheimer RD. Ultraviolet light output of compact fluorescent lamps: comparison to conventional incandescent and halogen residential lighting sources. Lupus. 2009 May;18(6):556-60. doi: 10.1177/0961203309103052. PMID: 19395458.
YouTube. (2014). Benefits of Led Lighting // Bulbs.com. YouTube. https://www.youtube.com/watch?v=9iUfCHzDUzY&list=WL&index=16.
Schütt, F., Zapf, M., Signetti, S. et al. Conversionless efficient and broadband laser light diffusers for high brightness illumination applications. Nat Commun 11, 1437 (2020). https://doi.org/10.1038/s41467-020-14875-z
su, Chandrajit, Meinhardt-Wollweber, Merve and Roth, Bernhard. “Lighting with laser diodes” Advanced Optical Technologies, vol. 2, no. 4, 2013, pp. 313-321. https://doi.org/10.1515/aot-2013-0031
