Food for Thought – Increasing Food Production with LED Lighting

Cary Mitchell, from left, and Celina Gomez harvest tomatoes grown around red and blue LED lights, which use far less energy than traditional high-pressure sodium lamps in greenhouses. (Purdue Agricultural Communication photo/Tom Campbell)

Cary Mitchell, from left, and Celina Gomez harvest tomatoes grown around red and blue LED lights, which use far less energy than traditional high-pressure sodium lamps in greenhouses. (Purdue Agricultural Communication photo/Tom Campbell)

We’ve touched upon innovative uses of LEDs and research into the benefits of LEDs with cows and bees, but there’s news that LED lighting can cost effectively improve the growth of greenhouse tomatoes and a start-up is working on affordable LED lighting to help small farms increase egg production in chickens.

According to the USDA, the U.S. is one of the world’s leading producers of tomatoes, second only to China. Fresh and processed tomatoes account for more than $2 billion annually.  Fresh-market tomatoes (not the ones that are processed) are produced in every state, with commercial-scale production in about 20 States led by California, Florida, Ohio, Virginia, Georgia, and Tennessee. The supply is seasonal depending on the weather.

Many producers grow tomatoes in greenhouses off-season, traditionally lit by very warm high-pressure sodium lamps. Researchers at Purdue University are looking into whether growing tomatoes under LED lights in the winter can significantly reduce greenhouse energy costs without sacrificing yield.

Perdue horticulture professor Cary Mitchell, interviewed in a Purdue newspaper, said the average tomato is shipped about 1,500 miles from warmer climates where they’re grown to cooler climates that cannot produce the fruit cost-effectively in the winter.  According to Mitchell, the journey is costly because tomatoes are picked green and ripen during shipping, decreasing quality and flavor. In addition, the shipping distance adds cost and adds to the industry’s carbon footprint.

Mitchell and doctoral student Celina Gómez experimented with light-emitting diodes, which are cooler and require far less energy than traditional high-pressure sodium lamps used in greenhouses. According to the article, the researchers received the same yield – size and number of fruit – with high-pressure sodium lamps and LED towers, but the LEDs used about 25 percent of the energy of traditional lamps.

The goal of the research is to reduce costs to the point where local growers could compete with the tomatoes that are shipped from far-away places. Local tomatoes could be harvested vine ripe, would taste better and would boost local economies.

“The United States still imports one-third of its tomatoes from Mexico and Canada, as well as other countries,” Mitchell said in an interview with Purdue Agriculture News. “This technology could allow U.S. growers to create local jobs that shrink carbon footprints and produce better-tasting tomatoes.”

Finally, a small group of recent grads from of the University of California, Davis, formed start-up Henlight to develop a solar powered LED light for small scale egg farmers to light chicken enclosures.  Scientific evidence shows that the amount of eggs a chicken will lay is strongly correlated to the amount of sunlight received per day.

Large-scale egg producers already use light to artificially boost egg production.  For example, the spring and summer typically provides between 12-16 hours of sunlight per day giving poultry the necessary amount of light to reproduce (produce eggs).  In the fall, the amount of daylight decreases along with egg production.  This reduces a farmer’s income and access to nutrition from eggs.   Henlight could bring this capability at low cost to small farms around the world .  Henlight’s founders received a $10,000 prize as start-up investment to launch the product.

For Further Reading

Clearlysapphire.com, Benefits of LED Lighting for Cows and Bees, http://blog.clearlysapphire.com/?p=472

NPR Berlin, Increasing Egg Production On Small Farms: A Solution To The International Food Crisis?, http://nprberlin.de/post/increasing-egg-production-small-farms-solution-international-food-crisis

Purdue University, Agriculture News, LEDs reduce costs for greenhouse tomato growers, study shows, http://www.purdue.edu/newsroom/releases/2013/Q2/leds-reduce-costs-for-greenhouse-tomato-growers,-study-shows.html

Sapphire – Quality Matters, Part 2: Transmission Quality

Recently, Novus Light Today published an article by Dr. Jonathan Levine, Director of Technical Business Development at Rubicon Technology, about sapphire quality.  His article shares a thorough review of the measures of sapphire quality for optical-grade applications.  Last week, we looked at the first two metrics, chemical analysis and X-ray rocking curves.  This week, we’ll look at transmission quality.

Levine writes that the quality of a sapphire is determined by how closely the grown crystal matches the ideal structure with respect to the arrangement of atoms within the lattice, dislocations, defects, and stress.  Root causes for these problems often originate from insufficient purity of the starting material and the growth process itself.

Sapphire exhibits excellent transmission in the ultraviolet (UV) to the mid-infrared (IR) range (~200 – 5000 nm).   According to Levine, conditions within the sapphire growth furnace can induce subtle interactions between the molten sapphire and the growth environment.  These interactions can produce bubbles, dislocations and other stresses that could impact optical performance.   Levine says that carefully controlling the growth environment produces sapphire that maintains excellent transmission at 200 nm through the mid-IR wavelengths.  He illustrates the impact of furnace interactions by comparing Rubicon’s ES-2 sapphire with another commercial sapphire maker’s crystal produced using a different growth method in the figure below.  From the image in the post, you can see a sharp absorption peak at 200 nm for sapphire produced by the commercial maker that is absent in sapphire grown by Rubicon.

Optical transmission of sapphire depicting a sharp absorption peak at 200 nm for sapphire produced by a commercial producer that is absent in sapphire grown by Rubicon.  Inset: Optical transmission for Rubicon sapphire from the visible to mid-IR range approaching 90% due to the high quality of the material.

Optical transmission of sapphire depicting a sharp absorption peak at 200 nm for sapphire produced by a commercial producer that is absent in sapphire grown by Rubicon. Inset: Optical transmission for Rubicon sapphire from the visible to mid-IR range approaching 90% due to the high quality of the material.

For Further Reading

Novus Light Today, Optical-Grade Sapphire, Where Quality Matters, http://www.novuslight.com/optical-grade-sapphire-where-quality-matters_N1596.html#sthash.giGipxT1.dpuf

Sapphire Quality Matters: Part 1

Sapphire is an extremely versatile material with a growing list of applications in a wide range of industries.  Sapphire suits optical applications because of its scratch resistance and its transmission characteristics.  You’ll find sapphire components such as lenses and windows in medical equipment, lasers, satellites, aircraft, flame detectors, smart phones, cameras and watches.  Recent advances in sapphire crystal growth technology and fabrication have improved the performance, purity, and availability of sapphire for all types of applications.

Recently, Novus Light Today published an article by Dr. Jonathan Levine, Director of Technical Business Development at Rubicon Technology, about sapphire quality.  His article gives a thorough review of the measures of sapphire quality for optical applications.  Levine writes that the quality of a sapphire is determined by how closely the grown crystal matches the ideal structure with respect to the arrangement of atoms within the lattice, dislocations, defects, and stress.  Root causes for these problems often originate from insufficient purity of the starting material and the growth process itself.

The effects of these variables in the final product are commonly quantified by three metrics: chemical analysis, X-ray rocking curves, and optical transmission.  Additionally, the observance of bubbles in the crystal provides a baseline from which crystal quality is determined because bubbles serve as scattering centers for any light transmitted through a sapphire optic, thus reducing its performance.

This week, we look at the first two metrics, chemical analysis and X-ray rocking curves.

Powdered aluminum oxide

Powdered aluminum oxide

 

 

 

 

 

 

Purity of the crystal is highly important.  According to Levine, the presence of certain elements can vary drastically between suppliers, and sapphire manufacturers must exercise proper quality control.  For example, titanium (Ti) and chromium (Cr) impurities can result in pink crystals.  In nature, these impurities lead to rubies and other variations of sapphire depending on the impurity.  Levine says trace amounts of these elements must be kept below 1 ppm.  Levine includes a graphic about other elements that can cause issues including silicon (Si), potassium (K), chlorine (Cl), iron (Fe), lithium (Li), and sodium (Na).  The data was collected using glow discharge mass spectroscopy (GDMS).

Typically, a company can buy two types of raw material for crystal growth that can have impurities.  Levine says it can be purified alumina powder and/or Verneuil sapphire.  Rubicon has developed a new in-house purification process that converts the raw powder into densified pellets for crystal growth without an increase in cycle time or decrease in crystal yield. This process enables Rubicon to eliminate impurities in the alumina power that they use to make crystal.

Levine includes another useful metric for analyzing sapphire, rocking curve data obtained via X-ray diffraction.  A rocking curve helps measure various stresses in a crystal.  Levine says the width of the resulting peak is highly sensitive to strain and defects within the crystal.  A narrow peak, indicated by its full width at half maximum (FWHM) measured in arcseconds, signifies a high quality crystal free of low-angle grain boundaries and lattice strain.  A standard narrow rocking curve for Rubicon’s ES2 sapphire windows is shown below.

Sample rocking curve data from Rubicon ES2 sapphire.

Sample rocking curve data from Rubicon ES2 sapphire.

 

 

 

 

 

 

 

 

What can introduce a poor rocking curve?  Levine says that high thermal gradients, fast growth rates, and impurities contributed by the surrounding insulation can introduce defects and stress into the crystal that subsequently yield poor results in rocking curve data.  He adds that accurately controlling the temperature gradient and maintaining a stable growth interface throughout the entire process can help make higher quality sapphire.

For Further Reading

Novus Light Today, Optical-Grade Sapphire, Where Quality Matters, http://www.novuslight.com/optical-grade-sapphire-where-quality-matters_N1596.html#sthash.giGipxT1.dpuf

Industrial LED Lighting Gains Momentum

 

LED lighting in an industrial location (source, Greenbiz.com, http://bit.ly/YZFMbE)

IDC Energy Insights reports that the industrial market for LEDs is picking up momentum as companies looking to build new “smart” facilities or retrofit old ones choose energy efficient LED lighting.  Adoption of LEDs for industrial lighting is good news for the commercial sapphire market and others in the LED supply chain. More LED lighting means more demand for sapphire.

First, let’s start with some background.  Warehouses are particularly fertile ground for LED lighting since instant-on LED lights provide virtually no cycle time compared to traditional industrial lighting sources like HID (high-intensity discharge lamps) along with lower lifetime costs (including maintenance), higher efficacy and local utility incentives among others.

For those who watched the recent Super Bowl in New Orleans, the HID lights may be familiar.   After the electricity loss during the second half, the lengthy delay in the game – more than 20 minutes — was partially due to the cycle time of the HID lighting for the interior of the stadium.  In a warehouse situation, HID cycle time becomes a big issue as no one wants to wait for the lights to cycle and as a result, many warehouses just keep the lights on, running up energy costs.

IDC Energy Insights research analyst Casey Talon commented in her clean energy blog that LED lighting and “smart building” will be the disruptive technology for energy efficiency over the next three years.

Talon highlighted two big announcements in early January 2013 that demonstrate the momentum of smart building with LED lighting.  First, lighting leader Acuity Brands acquired Adura Technologies.  Adura’s Zigbee wireless mesh architecture enables individual fixture controls for cost and energy savings.  Secondly, Digital Lumens, a leader in the industrial lighting solutions market, announced new growth numbers and funding, that demonstrates the viability of the emerging smart building technology segment.  The company secured a new round of $10 million in financing and reported a footprint of 500 ‘large-scale’ installations representing 150% growth.

She notes in the blog that “fundamentally this news demonstrates that end users are increasingly aware of the benefits of energy efficiency to both their bottom lines and corporate goals.  The activity in these markets illustrates a growing acceptance of upfront costs to achieve longer term benefits.”

LED lighting combined with lighting control and management software offers the ability to track and manage the benefits of LED lighting.  Wireless controls and analytics help building managers understand when to have lighting on or off when employees are present, measure “free” ambient light from outside to cut down reliance on lighting, and know when and where to adjust brightness in areas when high precision work is needed.

Using analytics already is paying off.  According to one case study from Digital Lumens, Vector Aerospace Helicopter Services North America, a worldwide leader in helicopter maintenance, repair and overhaul for Sikorsky, Eurocopter, AgustaWestland and Boeing helicopters, saved more than 72% on their annual energy costs with a Digital Lumens retrofit.

According to Talon, “If these early announcements are a signal, then 2013 may mark a tipping point in the smart buildings marketplace as customer awareness and investment begin to converge for broader adoption of intelligent energy management solutions.”

Further Reading

IDC Energy Insights, Illuminating the Smart Building, https://idc-insights-community.com/energy/clean-energy/illuminatingthesmartbuilding

Greenbiz.com, LED lighting gaining traction in commercial retrofits, http://www.greenbiz.com/news/2013/02/05/led-lighting-gaining-traction-commercial-retrofits

LED Lighting Growth Update

This week, LED lighting market research firm Strategies Unlimited announced some very positive research about LED lighting as well as the LED industry as a whole.  Strategies Unlimited measured the LED component revenue for lighting applications and noted that it reached $3.11 billion in 2012, just beating out the large area display backlight segment at $3.06 billion for top LED application.

This is good news for sapphire, as the substrate for more than 80 percent of the world’s LEDs. The more demand for LEDs and LED lighting, the greater demand for sapphire. Examining lighting further, Strategies Unlimited said that the total illumination market for 2012 is estimated at $14.52 billion.  LED lighting, including LED replacement lamps and luminaires, is estimated at $11.72 billion—an increase of 26% between 2011 and 2012—and it is forecast to grow at a CAGR of 12% over 2012-2017.

Another interesting area of growth is the automotive market.  Beyond the Audi A8s with their signature eyebrow LED headlights, LEDs are catching on with other auto makers.  Strategies Unlimited puts the total market for LEDs in the automotive segment at $1.4 billion in 2012 and estimates that it will grow to $2.1 billion in 2017. Where’s the growth?  The firm says the number of cars with LED headlights nearly doubled in 2012.  LED daytime running lights also contributed to the growth.

Here’s a look at how LED applications break out according to Strategies Unlimited:

Strategies Unlimited, Worldwide LED Revenue Forecast by Market Segment (Source: Solid State Technology)

 

 

 

 

 

 

Further Reading

Strategies Unlimited, WORLDWIDE LED COMPONENT MARKET GROWS 9% WITH LIGHTING RANKING FIRST AMONG ALL APPLICATION SEGMENTS,ACCORDING TO STRATEGIES UNLIMITED, http://www.strategies-u.com/articles/2013/02/worldwide-led-component-market-grew-9–to–13-7-billion-with-lig.html

Solid State Technology, Worldwide LED component market grows 9% with lighting, http://www.electroiq.com/articles/sst/2013/02/worldwide-led-component-market-grows-9-percent-with-lighting-.html?cmpid=EnlLedFebruary132013