**4. The features of application of the lighting systems in greenhouses**

The advent of the energy-efficient light sources on the basis of the electrodeless sulfur lamps with microwave excitation having a wide spectrum of radiation in visible region of electromagnetic spectrum (from 0.38 to 0.78 μm) allows to extend practical application of artificial light sources. In particular, the greatest interest is an application of such lighting sources in modern greenhouse and cattle-breeding farms for raising the level of crop yield and cost saving. On the one hand, the portion of the sectorial electricity consumption in the technological processes of the greenhouse farms using optical radiation is 10–15%, and the losses in them reach to ∼40%. To reduce electricity consumption, it is necessary to modernize lighting systems with energyintensive light sources to modern energy-efficient and economical ones. On the other hand, choosing artificial light sources that must have a certain spectral characteristic, the influence of optical radiation on the efficiency of the main photochemical processes of the plant is first of all taken into account. This is because each pigment has its own individual absorption spectrum and, thereafter, its own spectral characteristic of the light activity of the exciting radiation.

The most important and energy-intensive process is the process of photosynthesis. As shown, an investigation of the spectrum efficiency of the photosynthesis, that was carried out in [10, 11], the leaves of different systematic groups had approximately the same spectra of photosynthesis activity. An average curve of the spectrum of photosynthesis activity of the green leaf is shown in **Figure 10**.

All parts of the solar spectrum are important for the normal outgrowth of plants. More detailed information about results of an impact of the optical radiation having spectrum close to the solar spectrum is shown in **Table 2**.

**Figure 10.** Averaged curve of the spectrum of photosynthesis activity of green leaf.

As shown in **Figure 9**, the spectral characteristic of the electrodeless sulfur lamp has a continuous quasisolar spectrum of optical radiation and is very close to the solar spectrum in its visible region. The second advantage of this lamp worth noting is its durability, which is

**Gas discharge xenon lamp OSRAM XBO 10000**

**Sulfur lamp Plasma-i** 

**AS1300**

**Table 1** demonstrates the comparison of the lamps' characteristics that are most widely used in SSRs, as well as the parameters of the electrodeless sulfur lamp with microwave excitation. Analyzing the characteristics of the electrodeless sulfur lamp with microwave excitation and comparing them with other light sources that applied in the SSRs, we can say that this lamp can also be successfully used in SSRs enabling to produce not only high-precise measurements of the characteristics of the photovoltaic convertors and solar cells of space application, but also to provide correct modeling of various modes of their operation under laboratory

**4. The features of application of the lighting systems in greenhouses**

The advent of the energy-efficient light sources on the basis of the electrodeless sulfur lamps with microwave excitation having a wide spectrum of radiation in visible region of electromagnetic spectrum (from 0.38 to 0.78 μm) allows to extend practical application of artificial light sources. In particular, the greatest interest is an application of such lighting sources in modern greenhouse and cattle-breeding farms for raising the level of crop yield and cost saving. On the one hand, the portion of the sectorial electricity consumption in the technological processes of the greenhouse farms using optical radiation is 10–15%, and the losses in them reach to ∼40%. To reduce electricity consumption, it is necessary to modernize lighting systems with energyintensive light sources to modern energy-efficient and economical ones. On the other hand, choosing artificial light sources that must have a certain spectral characteristic, the influence of optical radiation on the efficiency of the main photochemical processes of the plant is first of all taken into account. This is because each pigment has its own individual absorption spectrum and, thereafter, its own spectral characteristic of the light activity of the exciting radiation.

The most important and energy-intensive process is the process of photosynthesis. As shown, an investigation of the spectrum efficiency of the photosynthesis, that was carried

important for its application in the SSRs [9].

**Characteristic Halogen lamp** 

**Table 1.** Characteristics of lamps.

**KG-220-10000**

Power consumption (kW) 10 10 1.3 Light output (lm/W) 26 50 140 Luminous flux (lm) 260,000 500,000 163,000 Color temperature (K) 3200 6000 6000 Operating time (h) 2000 500 50,000

84 Emerging Microwave Technologies in Industrial, Agricultural, Medical and Food Processing

conditions.


**Table 2.** Effect of the spectrum of optical radiation on plants.

The part of the solar radiation reaching the plants and used for the process of photosynthesis is called photosynthetically active radiation (PAR). PAR is the density of the photosynthetic photon flux, that is, the total number of photons emitted per second in the wavelength range from 400 to 700 nm (μmol m−2 s−1⋅). Different plant species, as well as the identical species at different age stages, may have different requirements for the PAR spectrum. To obtain fullfledged plants when growing under artificial light conditions, a certain ratio of energy over the spectrum in used lamps is required: 20–25%—in the blue area (380–490 nm); 20–25%—in the green one (490–600 nm) and 60–50%—in the red one (600–700 nm).

contain mercury and do not require disposal). However, there are a number of differences

Microwave Energy and Light Energy Transformation: Methods, Schemes and Designs

http://dx.doi.org/10.5772/intechopen.73755

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The LED lamps are low power and effective when the light flux is about ∼100 lm, so they can be used for small rooms. Besides, the LED lamps have a narrow band of optical radiation. In order to obtain the entire range of the visible spectrum, it is necessary to use LEDs with different spectral characteristics, the overall spectrum of which can cover the entire region (380–700 nm). This complicates the technology of manufacturing the LED lamp, since the cor-

The electrodeless sulfur lamp with microwave excitation, on the contrary, is a powerful light source having a quasisolar emission spectrum with reduced intensity in the region of ultraviolet and infrared radiation (**Figure 11**), and providing light fluxes of ~140 klm, which is three orders of magnitude higher than that of the LEDs as well as color temperature of ~6400 K. Also, the electrodeless sulfur lamp with microwave excitation has the ability to con-

Thus, the modern lighting system under conditions of protected soil (greenhouses) has to economically reduce electricity costs, as well as raise the quantity and quality of the crop yields. The promising sources of artificial lighting are LED and electrodeless sulfur lamps with microwave excitation. The LED lamps are most successfully used in small greenhouses,

trol the radiation power, which allows imitating the modes of sunrise and sunset.

while the sulfur lamps are suitable for larger greenhouse complexes.

**Figure 11.** Spectral and color characteristics of electrodeless sulfur lamp with microwave excitation.

between these lamps that allow them to occupy different fields of application.

responding currents have to be selected for each LED.

The use of the sources of artificial light in crop production is diverse, but not all of them are effective and safe. The characteristics of widely used lamps in the lighting systems of greenhouses are presented in **Table 3**.

As can be seen, the most perspective lamps for practical application as a modern source of visible radiation are light-emitting diode (LED) lamps and electrodeless sulfur lamps with microwave excitation [12–14]. The LED and sulfur lamps are durable, economical, have a high PAR efficiency (LED: 30–45%, sulfur lamp: 70–80%), are environmentally friendly (do not


**Table 3.** Characteristics of radiation sources.

contain mercury and do not require disposal). However, there are a number of differences between these lamps that allow them to occupy different fields of application.

The part of the solar radiation reaching the plants and used for the process of photosynthesis is called photosynthetically active radiation (PAR). PAR is the density of the photosynthetic photon flux, that is, the total number of photons emitted per second in the wavelength range from 400 to 700 nm (μmol m−2 s−1⋅). Different plant species, as well as the identical species at different age stages, may have different requirements for the PAR spectrum. To obtain fullfledged plants when growing under artificial light conditions, a certain ratio of energy over the spectrum in used lamps is required: 20–25%—in the blue area (380–490 nm); 20–25%—in

The use of the sources of artificial light in crop production is diverse, but not all of them are effective and safe. The characteristics of widely used lamps in the lighting systems of green-

As can be seen, the most perspective lamps for practical application as a modern source of visible radiation are light-emitting diode (LED) lamps and electrodeless sulfur lamps with microwave excitation [12–14]. The LED and sulfur lamps are durable, economical, have a high PAR efficiency (LED: 30–45%, sulfur lamp: 70–80%), are environmentally friendly (do not

**Lamp type Source of radiation P, kW** *τ***, thousand hours Efficiency PAR, %**

Osram Fluora 0.018 10 20–22

DRF-1000-04 1.0 2 —

DNaZ-400 0.4 12 26 DNaZ-600 0.6 18 30 Sylvania Grolux SHP-TS 0.25 24 26–28 Sylvania Grolux SHP-TS 0.4 24 26–28 MASTER GreenPower 0.6 10 26–28 PLANTASTAR 0.6 12 35

DRI 2000–6 2.0 2 26

DKSTV 6000 6.0 <1 —

AGRO-24 0.024 50 30–35

0.4 17 28

Fluorescent lamps FL-40 0.04 12 22

High-pressure mercury lamps DRLF-400 0.4 1 11

Metal halide lamps Growmaster HIT 0.25 10 25

Xenon lamps DKSTL 10000 10.0 <1 12–16

LED lamps LED GLOW-Е27 0.135 50 20–35

Sulfur lamp PLS-PSH07 0.73 60 70–80

the green one (490–600 nm) and 60–50%—in the red one (600–700 nm).

86 Emerging Microwave Technologies in Industrial, Agricultural, Medical and Food Processing

houses are presented in **Table 3**.

High-pressure sodium lamps MASTER SON-T PIA

**Table 3.** Characteristics of radiation sources.

Agro-400

The LED lamps are low power and effective when the light flux is about ∼100 lm, so they can be used for small rooms. Besides, the LED lamps have a narrow band of optical radiation. In order to obtain the entire range of the visible spectrum, it is necessary to use LEDs with different spectral characteristics, the overall spectrum of which can cover the entire region (380–700 nm). This complicates the technology of manufacturing the LED lamp, since the corresponding currents have to be selected for each LED.

The electrodeless sulfur lamp with microwave excitation, on the contrary, is a powerful light source having a quasisolar emission spectrum with reduced intensity in the region of ultraviolet and infrared radiation (**Figure 11**), and providing light fluxes of ~140 klm, which is three orders of magnitude higher than that of the LEDs as well as color temperature of ~6400 K. Also, the electrodeless sulfur lamp with microwave excitation has the ability to control the radiation power, which allows imitating the modes of sunrise and sunset.

Thus, the modern lighting system under conditions of protected soil (greenhouses) has to economically reduce electricity costs, as well as raise the quantity and quality of the crop yields. The promising sources of artificial lighting are LED and electrodeless sulfur lamps with microwave excitation. The LED lamps are most successfully used in small greenhouses, while the sulfur lamps are suitable for larger greenhouse complexes.

**Figure 11.** Spectral and color characteristics of electrodeless sulfur lamp with microwave excitation.
