Indoor farms, especially in Japan, have been using LED lights for a while. Red/blue combos, in the pink/purple range, seem to work best.[1] The big advantage of LED lighting is not the reduced power consumption, but the reduced heat. The lamps can be closer to the plants without cooking them, which means the trays can be stacked closer and the density of the operation goes up. For most non-druggie applications, the plants aren't that tall. So small, distributed lighting units are used, instead of huge ceiling lamps.
Some plants can be overclocked. They do need a light/dark cycle, but it can be shorter than 24 hours. The life cycle of the plant is then sped up.
There are two reasons the light is the size that it is. First temperature. We have a passive heat sink with fins and a plastic remote phosphor sheet. Both have to stay relatively cool and more surface area makes this possible.
Its funny, the first fixture we built and sampled to growers was about 25x smaller. We used an active heat sink and a glass phosphor sheet. A common complaint was "why is this so small?" I want my lights to be "big and strong". We took this feedback and decided to move to passive design.
Our original logic was that smaller is better, especially in a greenhouse. The most efficient light is one that is off and the less shading of sunlight the better.
I think small lights could be a really good market for you, for all the urbanites like me, living in condos. Make a tiny kit that can grow herbs or lettuce at an accelerated rate using little power because of LEDs, and I'd buy it in a second.
As it stands, I think a 1m strand of TL-RL20 will be a purchase for me soon, and I'll build the kit myself.
Trancend’s bulbs differ from typical LED lights because they only use blue light. The company has developed a wavelength conversion system that uses phosphorous to convert blue photons, which are the most efficient type of photon, into any other color photon.
Typical LEDs used for illumination are blue LEDs with a phosphor coating to produce white. Transcend is doing essentially the same thing, but the goal is to produce wavelengths optimal for plant growth instead of a broad spectrum for illumination. The biggest difference in implementation looks to be that Transcend is separating the phosphor from the emitter while most LEDs used for illumination bond the phosphor directly to the emitter.
There are a lot of vegetables and fruits that I do not buy due to the air miles. For instance those nice peas in pods from Kenya. Those things don't get here (the UK) by boat whereas bananas from the Caribbean do get here by boat. Boat is acceptable to me, good for trade and enough arrives by boat for a decent meal to be made.
In theory these lights change everything, why grow peas in Kenya, put them on a plane and send them 1/4 the way around the world when a greenhouse in the Home Counties will do nicely?
The cannabis angle is pretty good too. As things stand growing those plants takes a stupendous amount of energy with all the problems of ventilation, mould growth, noise from the ventilation and the need to 'not get caught'. With this technology those that can hold down a job can get growing their own without having to have the huge 'leccy bill or having to be friends with dealers.
I like the lateral thinking of tuning the light to suit photosynthesis by using phosphors, I am surprised that has not been possible before. One day this will seem so obvious yet it wasn't until this product came along.
You are worried about air miles, but are willing to accept artificial light?
Do you just want to feel like you are being environmentally friendly, or do you actually want to be environmentally friendly?
I've been surprised at how many people only want to feel that way, but don't actually care about being environmentally friendly. (A good example of this is locavores.)
> of tuning the light to suit photosynthesis by using phosphors, I am surprised that has not been possible before.
It has been thought of before, people have been doing it for decades. This is just an incremental improvement.
Wrong. There are distance and repetition factors you are failing to consider.
With a single trip 100m trip, the LEDs lose. With 10^7 100km trips, the LEDs win. The question is where the line is, and the answer is that it's going down all the time.
Hu? You are planning on shipping a single tomato 621 million miles? That's enough to ship it to Mars and then back.
Why in the world would you do that? Wouldn't it spoil?
You know you have to pay to power the LED, right? It's not just equipment cost? It takes less energy to grow a tomato in the sun, then fly it somewhere then it does it grow it indoors with artificial light.
And no, LED efficiency is not going up all that much anymore - there are physical limits to that.
Yes, I'd still grow just one single tomato and send it on many millions of trips. I'll call it "travel-with-my-tomato.com" (Overnight charges may apply for trips to mars.) /s
Your point was that LEDs don't break even. My point is that there's a threshold at which they would.
If you only ever grew one tomato then you probably could buy a cheap plane ticket to deliver it, for less than the lights. So you'd be right, the LEDs would use more energy (cost to make, ship, and use) vs the delivery charges for the sun-grown (free energy) tomato from farther away - even if shipped expensively.
But if you grew millions of tomatoes from the same LEDs then you'd be wrong - now buying the grow lights is much more efficient than shipping in sun-grown tomatoes from even a few kilometers away.
I haven't had much to do with this in about 10 years, but back then weed growers (at least in Scandinavia) were already testing fluoros and LED's in addition to the traditional metal halide/HPS lights, and wavelength correlation to photosynthesis and flowering was known.
The descriptions on Transcend's website make me feel uneasy. I presume they have a solid product, but it feels like it's being oversold.
Each of our remote phosphor fixtures are rated to last for 96,000 hours to 90% output. That's over 10 years of 24/7 use.
How has this been tested? And if it is true, why is there a 5 year warranty rather than a 10 year? And what level of decline in output is covered by the 5 year warranty?
Efficiency: >2.0 μmoles per watt
Presuming you mean "per joule" rather than "per watt", this is very close to the claimed efficiency of the underlying Royal Blue LED, and (I think) much higher than any white LED. While I can believe there is some benefit from the lower temperature of the remote phosphor, this would be a remarkably high number for a full spectrum light. How has this been measured?
Yes, it has been tested. The industry standar LM-80 lifetime testing of the LED shows an L70 lifetime of ~300,000 hours. We are operating the LEDs at a lower temperature meaning they should theoretically last even longer. This is how we specify the 96,000 hour operating time to 90%
The Royal Blue LEDs we use have a ~55% EQE (external quantum efficiency). This gives a μmoles per joule a fair amount above 2.0. We lose a few photons during the conversion process and that drops us down to about 2.0.
We have a ~30% efficiency improvement over standard white LEDs because the phosphor is remote. The gain is 100% due to to the recycling cavity and omnidirectional nature of phosphors.
I'm still surprised at the level of efficiency, but glad to hear that you can back it up. I wasn't doubting that an underdriven LED would last that long, rather I was surprised that the remote phosphors would last that long without decrease in output. But reading more elsewhere, I now see that the lifespan of the remote phosphors can be excellent: http://www.digikey.com/en/articles/techzone/2014/apr/develop...
For others who are interested, here's another interesting link on the remote phosphor approach:
The exact figure in the last are already somewhat out of date, but if you plug in the specs for the newer LED's, presumably the underlying physics hasn't changed.
Some are, some aren't. I was going by Transcend's web site which says that they are full spectrum: "The fixture emits full-spectrum PAR light for 96,000 hours (10 years of 24/7 use)."
In theory, you can get a significant gain in efficiency by choosing specific wavelengths. In practice, it's difficult figure out exactly what these wavelengths should be, and to match them to existing high efficiency emitters.
Congratulations on launching! We were in a previous YC batch (glowing plant, S14) and grow lots of plants indoors. We are interested in lighting systems which promote early flowering, as this shortens our product development cycle. Can your lights be set to encourage this (ie can you balance vegetative growth vs flowering?)
It is possible. We are coming out with a new LED T5 lamp where we can easily customize the output spectrum. It would be fun to work together to find out the ideal spectrum.
"...blue photons, which are the most efficient type of photon..."
Argh.
Plants require light at 450 nm (blue) and light at 650 nm (red) to experience normal growth, and 730 nm (far-red) is also required to flower normally. (That last one may be important to growers of certain plants valued for their flowers and/or fruits.)
Phytochromes and photropins are the plant pigment-hormones that govern the plant life cycle. They respond to those 3 critical wavelengths of light to allow the plant to guess the time of day and the season of the year. Some plants also need a dark phase to "sleep", but it doesn't have to be as long as an actual night.
Blue light is likely most efficient at forcing the increase in green plant mass. That is, it makes bigger leaves and longer stems. That isn't always what you want for indoor farming.
The ideal indoor grow light would have a programmable, timed output of those three critical wavelengths of light, with a different ideal program for each type of plant. You may wish to start with red light, to germinate the seeds, go to blue light for rapid growth, then manipulate the plant into flowering out of season by switching between the two reds.
Transcend also needs a smaller, programmable 650/730nm light to offer a complete indoor farming solution, particularly for plants that do not get natural sunlight. It wouldn't need to use nearly as much energy, as it is being used primarily for hormonal signaling rather than photosynthesis.
Most efficient to produce not most efficient for plant growth.
Context: "The company has developed a wavelength conversion system that uses phosphorous to convert blue photons, which are the most efficient type of photon, into any other color photon."
If you're using phosphors, you do want to make blue or UV. It's far easier to step a photon down in energy than to absorb multiple lower energy photons and emit one at higher energy.
But the highest efficiency color for LEDs to produce largely depends on what Cree and Nichia are doing this year. Unfortunately, most of the readily available numbers tout luminous efficiency rather than raw light power. That's fine if you're looking for a reading light, but chlorophyll does not have the same absorption spectrum as the opsins in the human eye. You have to look for "wall-plug efficiency", which is less commonly reported.
So with respect to photons emitted per watt, I'm not sure which LED chemistry takes the prize. It depends on the temperature and input power, too. You can achieve 200% wall-plug efficiency, but only if you're converting picowatts of electricity into picowatts of photons in a hot LED. This is not possible (economically) for grow lights.
The benchmark for grow lights is the low-pressure sodium lamp, at about 38% efficiency. LEDs maybe get 30-65%, considering transformers, internal resistance, quantum efficiency, reflective losses at the die-capsule interface, etc. Higher efficiency comes from more expensive components.
As for chemistry, InGaN efficiency drops at longer wavelengths, and AlInGaP efficiency drops at shorter wavelengths, leaving a big efficiency trough in the green range. (Fortunately for this, plants don't need green.) I suspect that AlInGaP LEDs in the orange range are more efficient than visible blue InGaN LEDs, but this is hard to show with a lazy web search.
So when you say "most efficient" you really have to be very explicit about the application. That was my implied complaint about that sentence in the article.
Don't you lose a lot of usable energy by not having any optics to shape the radiation? The phosphor surfaces will just diffusely glow. Of course, with an emitting area that big, you also need huge optics to control it properly
Phosphors are interesting in that they emit in 360 degrees. We have a "recycling cavity" behind the phosphor plates that reflects "backward" emitting photons. The design of this cavity is key to an efficient remote phosphor system.
As far as forward throw, the plate is a lambertian emitter. This means ~80% of the light is in a 60 degree beam angle and nearly >95% within 70 degrees.
If you already have a light-recycling setup for the phosphor - maybe you could additionally use brightness-enhancement films to use for light recycling in angular space. Just like in liquid crystal screens, BEFs could refract light rays with high exit angles back towards the phosphor, giving you a collimation of about 45° for rectangular, linear prism films.
But of course, conservation of optical étendue ('optical entropy' so to say) can't be cheated and absorption and scattering losses will be the trade-off for better collimation.
Etendue shouldn't be too much of a concern because we are emitting onto a relatively large space. We hadn't considered using a BEF but will certainly look into it.
Someone else mentioned using a holographic printed film for the same purpose of a BEF. Have you every used something like this?
Not personally - I've read about holographic films but they were rather for screen backlighting - you won't need that precision, I think. There are some advanced materials that are basically very advanced diffusers with a defined scattering distribution.
But BEFs are dirt cheap and do a very good job for this, your run-of the mill backlighting setup for screens is a very simple, effective system. Also: Using two linear BEFs (rotated relative to each other at a right angle) is more efficient than one pyramidal film.
The losses I mentioned are because of the light-recycling: You get lots more back reflections into the system - every ray that doesn't have the right exit angle gets reflected/refracted back into the system, the phosphor will absorb/re-emit/scatter, randomizing the ray's direction again and the ray 'retries' to get out of the system with a different angle.
These processes naturally induce losses (non-radiative decay in the phosphor, Fresnel losses at one of the BEFs, no perfect reflection on the back mirror). Even if you only lose a fraction of a percent, you lose that fraction lots of times before a ray may make it out of the system. It adds up - still, the collimation is very good for such a simple system (i.e. slap two films for a few dollars per sqm over your emitting area) it should be very easy to test.
Edit: You'll get the best collimation for 90°-angle prism films - there are other BEF types that'll smooth the angular distribution of the light recycling for wide viewing-angle displays.
Yes, we lose there is energy losses from Stokes shift. For example, when we shift from a high energy blue photon to a lower energy red photon we lose the difference in photon energy as heat. Blue LEDs are approx 55% efficient and red LEDs 35% efficient. Even with Stokes shift losses our fixtures end up being more efficient.
If, however, blue LEDs and red LED emitted at similar efficiencies our technology wouldn't work. We'd lose too much energy in the conversion. Luckily (for us) blue LED efficiency is projected to increase more quickly over the next few years than other colors (more R&D dollars behind them).
The rope lights are especially cool for indoor hydro pole installations. Still, $1000 + 1$/day in electricity, it could grow let's say 100 kg of strawberries / year with that much light (that's an optimistic estimate), which would cost say 500$ to buy in a supermarket. That's not counting the cost of the rest of the installation, fertilizer etc. Could make sense at huge scale, but not for home sized installations, I think.
Yeah, the numbers are funny. They claim they will pay for themselves in energy savings in a year, but that seems to be against some unnamed alternative in their "up to 70% more efficient" claim.
High pressure sodium lamps (apparently the norm for indoor commercial food growing) look to be about 1.8µmoles/watt, compared against the ">2 µmoles/watt" of these lights, well, its going to take a long time to save $1000 in energy on a 250 watt lamp.
Lamp lifetime may tip the scales in favor of these LED lamps. Lamp size may also help, I used a 600 watt high pressure sodium lamp in my calculation against the 250 watt LED.
(µmoles are new units to me. I think I got through the lumens-lux-µmoles calculation correctly, but maybe not.)
The numbers are heavily influenced by cost of electricity and time of use. Payback ranges from 1-5 years with an average user seeing payback in about 3.
Average 600W HPS lamps are 1.0-1.3 µmoles/watt. A complete fixture consumes 660 watts with ballast losses. They generally lose about 20% of their light due to reflectors (omni-directional lamp in a directional application).
This means that our 2.0 µmoles/watt fixture at 230 watt consumption can replace a 660 watt HPS fixture, provide the same amount of light, and have a nice payback.
Here's what I didn't get from your website: there are typically two wavelengths you're interested in for growing plants, depending on the phenological stage: a red and a blue (I can't remember the exact numbers, but the band is quite narrow). How can it be that your lamps have higher efficiency despite providing a complete spectrum? I don't know anything about light physics, hence my question; intuitively, I'd say you could have higher 'yield' by focusing all energy you put in to one wavelength (or at least, a narrow band).
It turns out that plants use more than just red/blue for photosynthesis. They do indeed absorb narrow bands of red/blue more strongly than other colors like green (this is why plants are green) but only absorb about 10% more efficiently.
The green light not absorbed is reflected. This gives the opportunity for green photons to reflect their way down to the bottom leaves for a more distributed growth.
We have built a number of lights with "focused" spectrum but haven't seen a benefit. In many plants, like "red" lettuces the leaves only turn red with a full spectrum (I have no idea why, a botanist might know the answer...)
We do see a benefit to skew the spectrum for many flowering/fruiting plants in later growth cycles and have a plan to come out with a "fruiting spectrum" in the future. This will part of our August Indiegogo campaign.
Interesting. I do admit that much of what I know comes from books written for growing marijuana, since until a few years ago those were almost the only (large scale) applications of indoor growing, and that most of that knowledge isn't very scientific (for example until a few years ago the mainstream technique to force bloom on mj plants was to vary the light cycle only). Research is frantic in the field, a fascinating development.
One last question if you don't mind: do you see a market for this in small scale operations, or do market pressures force your customers to grow always bigger like in the rest of agriculture? It seems that the only (sustainable) way to make a profit on growing food (plants and animals) is by scaling up.
(OK I lied, I have another question actually: with the pressure on lighting system vendors in Europe to screen their customers for illegal operations, and increasing pressure to hold vendors accountable for such use, are you experiencing that American vendors actually have a market advantage on this? Do you export to Europe? (meta: who would have thought just 10 years ago that in 2015 the US would become the world's leader on high tech marijuana production!) also sorry for focusing on mj, your industry suffers from its association with it, I know - it's just that that market was the only non-academic source of knowledge on it for so long)
It will be interesting to see how the market scales. There are certainly advantages to large commercial greenhouses etc... but there is a quickly growing trend for small local producers that grow a few hundred or couple thousands plants at a time. They might service a grocery or a few restaurants. There is also a trend for people to grow at home, grove labs was already mentioned in this thread as an example. My guess, ultra-efficient, nearly fully automated indoor production facilities will be a major player. Labor and energy are the two biggest costs to production and there are emerging technologies to address both of these.
Regarding Europe, it hasn't been a primary focus for us but we have exported a few orders to the UK, Germany and Netherlands. I hadn't heard of pressure on vendors to screen their customers. I'll have to look into this.
Our orders so far have split about 50:50 between veggies and marijuana. The marijuana side of the business does certainly seem to overshadow the veggie side as far as general public interest goes!
But are they common with the light yields and spectrum width of the GP? If so, can you cite where they're for sale? No hydro growth shops can source any at significantly better prices than the one in GP, and with higher energy use to boot. You cannot just go to IKEA, get a couple of meters of their bottom-price LEDs and start your indoor grow operation with that. Believe me, 1000's of people have tried and failed; forums are full of reports. (Mostly from people growing marijuana of course, but also chili peppers, which is my use case).
I actually have a grow shop around the corner from where I live who have chili peppers in their display grow boxes (because they can't grow marijuana there for legal reasons), and they use MH lamps still; if there would be a cheaper way to grow, they'd switch in a heartbeat, because indoor growing is about squeezing every last drop of efficiency from your setup (although it's been a while since I've been there to be honest, and I did see them advertise a LED grow light a few weeks ago, but still not at prices much lower than GP).
It doesn't matter so much now with legalisation, but I cannot help but wonder what impact these high efficiency LED lights would have had on the illegal weed business. A lot of police forces did things like use infrared cameras and electricity usage to find people growing such things, but with these LEDs they could remain more undetected for longer.
But on a more broad note: Indoor farming has real potential, in particular for certain types of crops. Not only do indoor farms use less water (which takes energy to produce and transport), but requires less or no pesticides, can be grown out of season, and you're less subject of good/bad weather patterns.
I don't think we'll see this type of thing for inexpensive crops that use up a lot of land (e.g. corn) but we might be more expensive crops that are fairly land efficient (e.g. nuts, fruits, etc).
A guy is setting up a large-scale LED vegetable farm in Alaska, where getting fresh produce in the winter is quite expensive, since of course it has to be shipped in by a fairly fast (= costly) method. See:
I actually built an experimental LED grow light for a friend several years ago, back before legalization. She was not particularly worried about getting busted, but reducing the cost of electricity was a really big deal, since power and rent defined the cost of business. The system was a few years ahead of its time, as LED emitters were not yet powerful enough to replace her high-pressure sodium lamps, but it worked well for getting her new clones started. Beyond the simple efficiency of LEDs as light producers, the fact that we didn't have to waste any power generating yellow-green light meant the power requirement was something like 10% of what it had been with HPS. Clorophyll absorption peaks are at 430nm and 662nm, so we used LEDs with peak wavelengths near those values, and while the light appeared dim and purple to human eyes, the plants loved it.
Fruit and nuts are probably not going to see this sort of thing, primarily because the trees take a very long time to come to maturity. With some varieties you might be looking at a decade of care before you actually get any yield from them at all.
Interesting tech, but quite expensive. I'm looking to do some indoor herbs/greens in my office, but these lights look maybe 5x more expensive than the multi-color diode competitors.
I'd be curious to see comparison with PAR spectrum and plant grow results against similar wattage multi-color LED.
The major difference is upfront cost vs. cost of ownership. If you purchase the "cheap" multi-color products you will end up consuming MUCH more energy. The difference is much more than the upfront cost of the lights.
There are some well designed multi-color "pink" lights out there and there cost is similar to ours. A 325watt multi-color design has similar light output to our 230 watt remote phosphor design.
I actually have free electricity at my office, otherwise I'd run the numbers to see the cost savings. 5x longer lifespan ... I'd want an independent review.
Oh wow those are very good prices. If they perform well (or even half of what they promise), then yes these will give the upmarkets ones a run for their money. Of course the same can be said for almost all goods. I'd love to have time to experiment with an indoor aquaponics garden in my basement, and try out various lights.
considering that not all plants need the same spectrums throughout growth, i wonder if they have any plans to allow tuning of such things. if you are trying to grow the best, energy efficiency doesn't matter as much as top quality product at any cost. I think heliospectra lights allows you to change their output via an open API.
with the legalization of marijuana already happening in some states and pending in many others, the lighting industry is full of fluff right now and too many players... will be interesting to see who stands, who falls and who M&A. I think many growers will stick to HIDs until someone can prove LEDs, Plasma or induction not only delivery the same quality product, but can actually do it cycle after cycle, these 50k hour guarantees are suspicious at best.
We don't have spectral tuning functionality at the moment but it's something we are working on. A number of customers growing fruiting/flowering plants have asked for this sort of spectral control. For non-fruiting plants there seems to be less of a demand. We plan on having a next gen remote phosphor design with spectral control within the next 12 months.
i would imagine spectral controls to be less useful for leafy greens. will the spectral controls be remote controllable? ie; an api over some type of wifi connection?
I've been spending some time myself designing remote phosphor lighting and I'm wondering if they've really developed a new remote phosphor technology, or if they're sourcing a custom phosphor blend and substrate from someone like Intematix.
Also curious if they're using a film (like WhiteOptics White97) or having the cavities coated (I forget the product name). None of the coatings were cheap when I was researching them, but a % or two better than the films.
I'd love see the LED driver board on these...
But anyhow:
It's incredibly cool stuff, especially when you show someone the raw blue leds (blindingly bright), then drop a remote phosphor over it.
Kudos for going for it, and good luck. I wish I had your fortitude!
We build our own remote phosphor components and in some cases source components from companies like Intematix. We have a solid "side business" where we formulate and produce custom remote phosphor components for non general lighting applications.
For the recycling cavity we do indeed use WhiteOptics. We used Furakawa in our last design and have had success with both.
Indoor farms, especially in Japan, have been using LED lights for a while. Red/blue combos, in the pink/purple range, seem to work best.[1] The big advantage of LED lighting is not the reduced power consumption, but the reduced heat. The lamps can be closer to the plants without cooking them, which means the trays can be stacked closer and the density of the operation goes up. For most non-druggie applications, the plants aren't that tall. So small, distributed lighting units are used, instead of huge ceiling lamps.
Some plants can be overclocked. They do need a light/dark cycle, but it can be shorter than 24 hours. The life cycle of the plant is then sped up.
[1] http://www.economist.com/news/science-and-technology/2160219...