LOGISTIC ASPECTS OF THE ECOLOGICAL IMPACT INDICATORS OF AN AGRICULTURAL BIOGAS PLANT

Background: Poland must fulfill its obligations regarding increasing the share in the production of energy from renewable sources. By 2020, this share for Poland is to amount to a minimum of 15% of green energy consumption in final gross energy consumption. Poland has significant biomass potential that can be used for biogas production. Biogas can be produced in biogas installations installed in landfills, sewage treatment plants or agricultural biogas plants. Literature sources state that in studies of environmental effects concerning the operation of agricultural biogas plants, it is the logistics of the feedstock load that causes the greatest environmental burdens as well as that the distance to which the feedstock is transported significantly affects the growth of global warming potential. In this publication for the first time for Polish conditions will be presented the results of the analysis of logistics aspects and their impact on the ecological impact indicators of four agricultural biogas plants differing in the way the feedstock is provided.

Methods: The assessment of ecological impact indicators was carried out using the Life Cycle Assessment (LCA) methodology based on ISO 14040-44 and using the LCIA Impact 2002+ method. In this method 15 impact categories are distinguished to which damage categories: Human health, Ecosystem quality, Climate change and Resources are assigned. Primary data obtained in the tested biogas plants and selected secondary data obtained from the Ecoinvent database v. 3.4 were processed using the SimaPro Ph.D. v. 8.3.0 calculation program. All results are analyzed relative to the functional unit defined as producing 1000 MWh of electricity. The analyzed four agricultural biogas plants are representative examples for particular types of agricultural biogas plants.

Results: The results of the calculations show that the greatest environmental effects are related to the stage of providing the raw material in biogas installations, mainly due to the long-distance transport of substrates with the use of heavy transportation equipment. The results of the variant analysis show that transporting slurry with a pipeline would allow for 10-fold reduction of environmental damage in relation to BAU, i.e. transport by means of a farm tractor with a barrel.

Conclusions: The logistics aspects of the operation of selected agricultural biogas plants differing in the way the feedstock is provided are one of the main factors affecting their ecological efficiency. The transport of raw materials, both as to the length of the transport route and the means of transport used, impact on the ecological impact indicators of agricultural biogas plants.

The obtained positive environmental effects from the production of electricity from biogas are often significantly reduced by inadequate transport of raw materials or their transport over long distances.

Further work is required to convince the biogas plants operators on the need of proper logistics solutions. Preferably if based on the results of the presented analyzes, they should consider submitting a logistics management system for the flow of raw materials in a biogas plant, to the certification for example in the ISCC system and REDcert.