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Danish LED greenhouse system lights path to energy savings



A LED system producing photosynthetic wavelengths of light could result in dramatic energy savings for plant growers. The concept was developed in the University of Southern Denmark.

Designed for use in greenhouses, the LED system emits light at the specific photosynthetic wavelengths that target the plants’ needs. Cutting out the production of redundant elements of the spectrum results in significant energy savings without compromising plant growth.

The approach was conceived in 2005 by Professor John Erland Østergaard in the Institute of Sensors, Signals and Electrotechnics at the University of Southern Denmark. Using his background in optics and LED systems, Prof. Østergaard formulated the idea of applying LEDs to greenhouse lighting in an effort to find new uses for the technology. The system is now being developed by Fionia Lighting, founded in 2008 as a spin-out from the University of Southern Denmark and located in Odense in the heart of Denmark's pot-plant industry.

Current high pressure horticultural lamps emit orange light and do not cater for the specific needs of individual plants. “We have spent a long time learning about the wavelengths of light that plants can use – and there are differences,” says Thomas Rubæk of Fionia Lighting. “For example, tomatoes have completely different needs to roses.”

By ‘tuning’ the LED lights to the precise photosynthetic wavelength of the plants concerned, the energy that would ordinarily been used to create unnecessary wavelengths of light is saved. It is estimated that this system could result in energy savings of between 50 and 80%.

Moreover, the LED lights have other advantages over traditional systems. Not only do they offer longer life – ten years in comparison with the one-year lifespan of ordinary bulbs – but also installation costs are lower. In addition, the spectral composition of the lights can be fine-tuned to compensate for seasonal changes in light levels, as well as the impact of cloud cover.

During the three years of testing, 12 people including consultants have been involved in the project at various stages. “We are close to the commercialisation stage,” says Rubæk. “We have already built functioning prototypes, and the first full-scale system is expected to be finished this autumn.”

The programme received funding from the Danish government for the initial stage of development; and will be supported by private funding as it moves towards commercialisation. The company has already received an award for this energy-saving technology from the Danish Ministry of Climate and Energy.

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