VDM Energija d.o.o. - Viljevo

The 1 MWh biogas power plant is located in the municipality of Viljevo in Osijek-Baranja County. In a rural area such as the village of Viljevo, the construction of a biogas power plant is an appropriate system for the closure of the production and processing agricultural process, as it enables heat and electricity to be obtained as well as for the provision of excellent fertilizer represented by the processed kosopstrat. The construction of a biogas power plant began in July 2016 with the help of bank loan financing. The 2-3 month trial with obtaining the Operating License took place in mid-2018, and the full operation began at the end of 2018.

The biogas plant is designed as a continuous charge and operates in the medium or mesophilic temperature range, in the anaerobic environment, that is, the environment without the presence of oxygen.

The energy value of the biogas thus obtained is from 5.2 to 6.5 kWh / m3 of biogas. From this, 83.8% of usable energy is produced in the co-production or cogeneration process, while the rest is conversion losses. This energy produces approximately 42.1% of electricity and 41.7% of heat.

The generated electricity is transmitted to the grid, while the heat produced is used for the processing of feedstock for biogas production.

Figure 2: Proposed scheme of a two-stage biogas plant

Input material (biomass)

Raw materials for biogas production are divided into two main groups:

substrates:
Fertilizers: bovine and pig manure and manure, poultry manure;
Vegetable biomass: maize, sorghum, cereal and grass silage, fresh grass clippings, forage residues, products;
Coppice or waste of the food processing industry:
Animal by-products including food residues, fat, waste fruits and vegetables, compost, protein and carbohydrate-rich industrial waste water, fat breakdown waste.

In order to produce electricity from biogas, it is necessary to ensure stable and sufficient quantities of waste of biological origin, which is the raw material in production. The second component of bio-waste consists of slurry (liquid cow dung), which will be delivered by livestock farmers and farmers from the region with which purchase agreements have already been signed for a period of 15-20 years. Slurry is a problem for livestock farmers due to the legally prescribed method of disposal (in accordance with the European Union nitrate directive) and will be transported and provided free of charge to the biogas plant. The process of biogas production – anaerobic digestion, requires, in addition to the abovementioned primary feedstock, the use of substrates. Different types of biomass can serve as a substrate for biogas production. Due to its favorable characteristics and proximity to suppliers, corn silage is used as a substrate for biogas production within the biogas plant.

For the purchase of electricity, a 14-year contract is signed with the Croatian Energy Market Operator (HROTE) at a preferential feed-in tariff, which is adjusted annually for inflation and rising energy prices.