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Are You Ready for 4G Acceleration?

(An abridged version is found in the April 2011 issue of Maximum Yield.)

Spectral Halo Brings LEDs Up to Speed!

Brian Chiang and Josh Puckett

LED advancement is moving forward at lightning speeds. As people announce LED light output records being broken in rapid succession, it's no wonder that LEDs are swiftly taking over traditional methods of lighting across industries. In fact, LEDs are projected to become the primary illumination source for most lighting applications.

What is the history of the LED movement and where is it heading? More importantly, what does this mean for the indoor gardening industry?

Moore's Law and Haitz's law

The LED lighting revolution is often compared to the digital revolution that started in the late '60s. Intel's co-founder Gordon Moore predicted in 1965 that integrated circuits (i.e. computer CPUs) would double in complexity about every two years. This predication later became Moore's Law. 45 years later, this remains the standard that manufacturers in the semi–conductor industry strive for. Consumers are enjoying the benefits of the ever–increasing digital processing power on their desktop PCs, their laptops, and now their numerous mobile devices such as smart phones, and miniscule digital music and video players.

Dr. Roland Haitz, a scientist from Agilent Technologies, has made a similar prediction for LEDs. He proposed in 2000 that LED light output efficiency would double roughly every two years. Known by people in the LED industry as "Haitz's Law," this prediction is closely watched by insiders.

Haitz's Law has held up in the past decade, and countless companies have rushed into the LED field for a chance to stake out this new frontier. The energy crisis, in addition to other environmental concerns, has caused governments worldwide to invest in the LED "gold rush." Governments are setting policies and allocating research funds to aid the acceleration of this advanced technology.

The fusion of four important factors—technology potential, enormous market opportunity, massive private sector investment, and public incentive programs—has propelled unprecedented explosive growth by the LED industry. With better, brighter, and more cost-efficient LED lighting products, consumers everywhere are able to reap the fruits of this movement.

LED Grow Lights for Indoor Gardening

LED lighting can roughly be divided into four different levels of applications: decorative lighting (Christmas lights), general lighting (white light), professional–level lighting (stage and theatrical lights), and spectrum–specific lighting (bio and machine vision applications). Each level has its own set of requirements, and every level up often poses more than one new technical challenge. For decorative lighting, light output is not as much of an issue as cost. When considering general lighting, LED efficiency is a main concern. In professional–level lighting, uniformly mixed colors from different LED chips is a must. And finally, for spectrum–specific lighting, specific requirements get right down to the precision of each wavelength of light.

LED grow lights are at the top end of spectrum–specific LED lights. Not only does wavelength mix matter, light intensity is also critical. On top of that, the usage environment may not be the most ideal. There are many engineering considerations that are taken when designing an LED lighting product for the indoor gardening industry.

Great Expectations

Most indoor gardeners are passionate about growing efficiently with the resources they have. This group drastically optimized hydroponic growing methods in the past 30 years, and they continue to fine-tune various parameters to advance indoor growing. When LED grow lights first appeared on the market a few years ago, this is the group of people that quickly and bravely embraced this new innovation, because of their strong desire to see improvement.

Unfortunately, many LED grow light sellers understood this mentality and took full advantage of it by making outrageous claims about LED grow light performance. Some vendors promoted marketing slogans that boasted, "Replace a 1000W HID with a 90W LED!" Many growers jumped on board with these expectations, but after the LEDs did not perform as promised, they were left severely broken hearted. Not only did these LEDs not save on energy, many were poorly made, causing them to break down quickly instead of lasting the expected thousands of hours.

Growers who participated in this first wave of LED grow lights were left with such a bad taste in their mouths that many swore never again to use another LED grow light. Hydroponics storeowners started to call LED salespeople "snake oil salesmen," because LEDs could not live up to their hype. While there may perhaps be a few "snake oil salesmen" out there, the industry is undergoing rapid transformation with better companies and better products now joining this ever–changing field.

What's next? From Christmas Lights to 4G Spectral Halo

The personal computer (PC) revolution of the '80s went through many stages. Intel © came out with countless generations of processors: x286, x386, x486, Pentium, Pentium II, and so on. Each new CPU is another upgrade in computing power and requires a new set of hardware (motherboard, memory chip, etc.) to work with. The same holds true for wireless communication. From the little pager/beeper of the '90s, we now have a fully integrated smart phone that can run HD videos on the next generation 4G network.

Commercially available LED grow lights have also undergone significant generation changes. The first generation (1G) of LED grow lights in the market offered little more than decoration. A mom–and–pop company put together some red and blue LEDs together while citing NASA's LED grow light experiment and proclaiming a new, energy–efficient way of growing. Growers who experimented with this 1G light were extremely disappointed with the poor results.

When 1W high-brightness LEDs started to appear on the market, a few more companies joined in. The second generation (2G) LED grow lights offered better light output; however, higher wattage LEDs give off more heat. Many of the poorly designed grow lights did not take this into consideration and would burn out quickly, often in a few months. Growers who used the 2G lights were able to see some benefits of these lights, but were frequently discouraged by their unreliability.

Through field trials and grow experiments, LED grow light suppliers have accumulated better understanding of spectrum as a concept. Together with technology improvements, the third generation (3G) grow light made a drastic leap. Changes were seen in two key areas: larger companies brought in higher wattage LEDs with active fan cooling, and the concept of spectrum instead of color alone became the focus of the light. In this generation, dense matrix LED technology emerged on the market and presented an option for growers who required light with high intensity. Growers also started to pay attention to LED grow lights, noting positive results especially during the vegetative phase.

With more reputable companies in the market, growers are also able to distinguish the good apples from the bad ones. The shift to LEDs started in this third generation and is happening right now. Many are asking, what is after 3G? Is something new coming out? What will a 4G LED grow light bring?

A new dense matrix LED platform is now here. In the 4G LED grow light, a much higher powered dense matrix LED will deliver significantly greater light output and penetration. To manage this high power device, a brand new cooling system is introduced and integrated into the grow light. A specially designed vapor–cooling chamber quickly removes excess heat away from the LED core to achieve maximum thermal efficiency. Just like a turbo engine in a car requires an advanced cooling system, the thermal design in the 4G LED grow light is extremely sophisticated. In addition to this technology advancement, the spectrum in 4G is further refined with more optimized spectrums for different stages of plant growth.

4G LED Grow Light Experiment

We did several experiments using 80W 4G LED grow lights with Husky Red Cherry Tomatoes as well as other crop types. Featuring the special vapor cooling technology to draw heat away, this light puts out more than 2.5X the light intensity compared with the grow lights we used previously. For this lab study, we grew the Husky Red Cherry Tomatoes and collected data during both the vegetative and reproductive phases of growth. Experiments were conducted in standard 4' x 4' grow tents, and conditions were monitored on a daily basis.

Using the 4G grow light, a Deep Purple spectrum was created for the vegetative phase. This spectrum has higher emphasis on blue wavelengths to promote vegetative performance. We used four Deep Purple LED grow lights and compared the results against conventional lighting systems of higher wattage use.

Plants grown beneath these LED units displayed larger stem widths, higher rates of branching, higher vegetative biomass, and reduced plant height due to internode shortening. This all equates to denser vegetative growth. By emitting PAR specific wavelengths, which cater to chlorophyll production, plants growing beneath these units exhibit a healthier, darker green than usual.

For the reproductive tests, we selected 4G LED grow lights using an optimized Magenta spectrum. In the performance comparison against conventional lighting systems of more than twice the wattage use, results under 4G LED grow lights showed increased flower production, higher rates of fruit onset, and came ahead in overall yields. In some cases fruit ripening occurred at a faster rate in crops growing under the 4G LED grow lights; in another experiment, the production of larger sized fruit was observed.

The results from growing under 4G LED are very promising, they are helping to usher in the next generation of LED grow lights!

The Spectral Revolution

We've written quite a few articles on LEDs in the past 12 months. Some readers might be wondering, are you guys done? Not only we are not done, we're just at the beginning. Take hydroponic growing—after 30 years from its inception, manufacturers still come out with new nutrients every year. Growers everywhere continue to refine and produce new growing methods. In the same way, there are infinite possibilities with the wavelength-tuning ability of LEDs. LED light output efficiency will continue to increase, and new spectrum combinations will continue to be discovered and implemented.

So what are you waiting for? Get on board and join the spectral revolution!