led lighting - growsave · 1) photoperiodic (night break) lighting leds for photoperiodic lighting...
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•They are highly energy efficient.
• They have a very long service life.
• They have less disposal problems.
• Compatible with different shapes/sizes of luminaire.
• They are easily controlled (rapid on/off or dimming).
“Engineering benefits” of LEDs
LEDs have developed very rapidly- what are the potential advantages for horticulture
1)Photoperiodic lighting using LEDs.
2)Supplementary lighting using LEDs
3)New opportunities for crop lighting from LEDs
What are the uses of LEDs in horticulture?.
1) Photoperiodic (night-break) lighting
Long established approach to regulate flowering.
Traditional lamps have been tungsten so, regardless of energy use, will need new approaches as lamps are withdrawn.
Tungsten lights also some undesirable properties leading to “stretching” in some species.
1) Photoperiodic (night break) lighting
Compact fluorescents (18W) for photoperiodic lighting are available, some can be unsuitable for some crops (wrong balance of wavelengths).
LEDs for photoperiodic lighting (18W) are now becoming available, specifically designed to replace tungsten in E27 fittings
1) Photoperiodic (night break) lighting
LEDs for photoperiodic lighting (18W) are now becoming available, specifically designed to replace tungsten in E27 fittings
It SHOULD be possible to design an LED with the right light output for photoperiod control AND good energy efficiency.
Commercial properties of photoperiod LEDs not clear for UK conditions (at least in the public domain) but on-going HDC
research.
2) Supplementary lighting
Artificial lighting to “make-good” the lack of sunlight during late-Autumn to early-Spring.
Use in the UK largely limited to high value crops, some ornamentals and a few edibles (tomatoes, herbs…).
More widely used elsewhere in Europe.
HIGHLY ENERGY DEMANDING.
2) Supplementary lighting
Artificial lighting to “make-good” the lack of sunlight during late-Autumn to early-Spring.
Use in the UK largely limited to high value crops, some ornamentals and a few edibles (tomatoes, herbs…).
More widely used elsewhere in Europe.
HIGHLY ENERGY DEMANDING.
September
2) Supplementary lighting
High-pressure sodium (HPS) has been the system of choice for many years.
Typically 240v/400W units although some use of 1000W and/or high voltage systems to obtain some energy gains.
Units placed high for
(i) uniform distribution and (ii) to avoid over-heating.
2) Supplementary lighting: new possibilities using LEDs?
1) LEDs as “like-for-like” replacements for HPS
LED-based units placed high above the canopy used in the same way as HPS.
Usually a mixture of different colours to deliver the right balance of wavelengths for the plant.
Sometimes “white” LEDs added for workers etc.
2) Supplementary lighting: new possibilities using LEDs?
What it might say on the tin!
“Integrated LED system for optimum lifetime performance of up to 50 years.”
“Reduced energy consumption and operating costs by up to 80%.”
“Maintenance free operation - lasts up to 10 times longer than conventional lighting.”
“Cool beam – Does not produce Ultra Violet (UV) light or IR...”
2) Supplementary lighting: new possibilities using LEDs?
1) LEDs as “like-for-like” replacements for HPS
In principle could deliver energy benefits BUT
(i) Unit prices remain high
(ii)Little information (yet) on application in commercial use.
(iii) May not be the best way to get the greatest benefits from LEDs.
2) Supplementary lighting: new possibilities using LEDs?
2) “Reaping the benefits of LEDs as LEDs”
The light produced by LEDs is “cool” compared with HPS, although LED units do generate a lot of heat.
LEDs support a wider range of lamp geometries than HPS.
YOU CAN PUT LEDS WHERE THE LIGHT IS REALLY NEEDED
(AT LEAST IN TALL CROPS)
Top of
canopy
Bottom of
canopy
2) Supplementary lighting: new possibilities using LEDs?
2) “Reaping the benefits of LEDs as LEDs”
The greatest BIOLOGICAL efficiency is acheived by adding light where its really needed.
Top of
canopy
Bottom of
canopy
Photosynthesis per unit light =
Photosynthesis per unit energy used
=Yield increase per energy
used
2) Supplementary lighting: new possibilities using LEDs?
2) “Reaping the benefits of LEDs as LEDs”
INTERCANOPY LIGHTING
Even when upper leaves have enough light, lower leaves may contribute nothing to crop growth (or worse).
“Linear” LEDs (mixed colours) placed low in the crop to deliver higher whole canopy photosynthesis.
Top of
canopy
Bottom of
canopy
2) Supplementary lighting: new possibilities using LEDs?
2) “Reaping the benefits of LEDs as LEDs”
INTERCANOPY LIGHTING
Even when upper leaves have enough light, lower leaves may contribute nothing to crop growth (or worse).
“Linear” LEDs (mixed colours) placed low in the crop to deliver higher whole canopy photosynthesis.
2) Supplementary lighting: new possibilities using LEDs?
“We are now also using LED inter-lighting. With this we expect to increase production by a further 15%. Thanks to these excellent figures our payback period is around two and a half years”.
Commercial properties of LED intercanopy lighting is not clear for UK conditions (at
least in the public domain).
Intercanopy lighting is available “off-the-shelf” now.
The approach is solidly placed in theory and (manufacturers) trials indicate good results…
2) Supplementary lighting: new possibilities using LEDs?
2) “Reaping the benefits of LEDs as LEDs”
Intercanopy lighting is NOT applicable to low canopy crops.
Alternative may be similar linear lighting units in tiered growing systems.
Some existing use overseas for specialist production, and a great
deal of interest internationally.
2) Supplementary lighting: new possibilities using LEDs?
LEDs for tiered production might be used in conventional glasshouses (a mix of natural and LED lighting) increasing effective growing area on the same “foot-print”- efficiency?
OR “Warehouse units” with all light from LEDs
Some existing use overseas for specialist production, and a great
deal of interest internationally.
URBAN FARMING....? Commercial properties of LED in tiered production is not clear for UK conditions (at
least in the public domain).
3) New opportunities for crop lighting from LEDs?
The light quality of HPS is fixed, and not ideal for many crops.
LEDs are available in many colours (wavelengths) and might be mixed to deliver improved quality, pest and disease control, etc.
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Probably medium-long term: initial LED units for horticulture are using the most readily available “bulk” LEDs.
3) New opportunities for crop lighting from LEDs?
The biggest benefits, in terms of energy and
beyond, may come from exploiting the
ability to use LEDs in ways that are not
possible with conventional HPS
•They are highly energy efficient.
• They have a very long service life.
• They have less disposal problems.
• Compatible with different shapes/sizes of luminaire.
• They are easily controlled (rapid on/off or dimming).
.....
...
....
?
LED lighting- where is it going?
1) Photoperiodic lighting using LEDs.
2) Supplementary lighting using LEDs
- Interlighting
- Replacement for HPS
3) New opportunities
Sooner
Later
Precise timings will obviously depend on multiple commercial drivers, e.g. fuel price, carbon taxation, viability of imported
produce…
OR
LED lighting- where is it going?
BUT WHAT LEDs AND WHEN?