There are several environmental issues in urban areas that are caused by the unintentional consequences of past activities. One of these issues is the wide application of asbestos cement in roofing materials in the 2 nd half of the 1900s. In this study, our goal was to identify different roof types and to determine those with asbestos components using high-ground (1 m) and spectral (126 bands) resolution airborne hyperspectral imagery (AISA Eagle II) and several classification approaches. In addition, we aimed to identify those wavelengths that play a significant role in distinguishing the different roof types. In the image analysis, the SAM, MLC and SVM classification methods were used to evaluate the different types of roofs. These methods resulted in accurate maps of the roof types, and asbestos cement roofs were identified with over 85% accuracy.

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In our study, we examined the annual carbon footprint and energy balance of a Hungarian biogas power plant with a power output of 0.637 MW in 2013, with reference to the complete life cycle of the biogas production. The life cycle analysis (LCA) considered the emissions of greenhouse gases (GHG) during the production of feedstock and its transportation into the power plant, during the operation of the factory and during the process of rendering the discarded waste materials harmless. We established that the highest GHG emissions related to the feedstock production in which both the use of machines and N 2 O release from the use of artificial fertilizers played an important role. In 2013, the power plant produced 4347.21 MWh electric power and 4607.89 MWh thermal energy. The carbon footprint of the complete energy production life cycle was 208173 kg CO 2 equivalents (CO 2 e). If the regular Hungarian energy structure produced such a quantity of energy, GHG emissions would be 15 times higher. Therefore, the energy balance of the power plant is positive; in contrast to its 8955.10 MWh energy production, its energy requirements were merely 2720.26 MWh, of which 1520.60 MWh as thermal energy served to heat the digesters. Unfortunately, more than 50% of the produced thermal energy is currently wasted; therefore, in the future, it is important to find a solution for the proper utilization of this valuable energy.

The aim of our report is to refer on the actual state of small biogas power plants in Hungary summarising the increase in their number and capacity and their effects on climatic change. The above is based on the CO 2 emission of the energetic utilization of biogas and the calculation of its ecological footprint that were compared to the environmental effects of natural gas energetic utilization. The aim of this paper does not include the complete life cycle analysis therefore the environmental benefi ts of the energetic utilization of biogas produced from various raw material are presented via only the direct CO 2 emission of the production process.