*a) Present situation*

the temperature is in a position that corresponds to the interval mode must have been between maximum and minimum measured values. Unfortunately, can not say with certainty whether the value was closer to the maximum, minimum or mean value. For the bale zero position we

adopted the position of the combustion zone.

78 Sustainable Energy - Recent Studies

**Figure 25.** CO and NO concentration in dry flue gas on the outlet

**Figure 26.** Measurement temperature profiles inside the soybean straw bale

**4.4. Small scale plant for combined heat and power generation**

The best way for utilizing residual agricultural biomass for energy production in industrial or district heating is to be used close to place of its gathering - in large agricultural companies. That is the optimal solution, from energy, as well as economy point of view. One of the most effi‐ cient ways, recommended by many institutions worldwide, is the combined heat and power Agricultural Corporation "Belgrade" - PKB is the largest agricultural enterprise in Serbia (≈ 22.000 ha of arable land), with agriculture and livestock as main domain of work. Crops (≈ 25.000 t/year of corn, wheat, barley, ≈ 5.760 t/year of soya, rapeseed and sugar beet), milk and vegetables are the main products. Each year after the harvest, a huge amount of soy straw (≈ 3.000 t/year) and corn stack (10-15.000 t/year) remain on the fields. The thermal fa‐ cility with 1.5 MW power built for heating 1 ha greenhouses, has been working for five years already, using soy straw as main fuel. In the boiler, an original cigarette type combus‐ tion technology has been applied.

The energy efficiency of the straw utilization cycle is mainly affected by process of its prepa‐ ration (balling, chopping, bundling), thus, the most justifiable is to use it close to the place of growing and gathering, and in form in which it is collected from fields. To utilize the re‐ maining balled straw and meet thermal needs of surrounding objects, it is desirable to build a new boiler facility with an efficient and environmentally considerate combustion technolo‐ gy. The most efficient way is a combined heat and power (CHP) plant [30-32].

The planned facility would heat several objects: two greenhouses, the greenhouse office building, a school, and a hospital. An overview of the objects, their installed or required thermal capacity and current heating modus are given in Table 8.


**Table 8.** Heating in Padinska Skela - present situation
