As both the human population and living standards grow, so does the worldwide electricity demand. However, the power sector is also one of the biggest environmental polluters. Therefore, options are currently being sought aimed at reducing environmental impacts, one of the potential tools for which concerns the use of life cycle assessment. This study, therefore, focuses on the most commonly used nonrenewable (black coal, lignite, natural gas and nuclear) and renewable sources (wind, hydro and photovoltaic) in the Czech Republic in terms of their construction, operation, and decommissioning periods. Environmental impacts are assessed via the use of selected impact categories by way of product environmental footprint methodology. The results highlight the potential environmental impacts associated with electricity generation for each of the primary energy sources. Black coal and lignite power plants were found to contribute most to the global warming, resource use, energy carriers and respiratory inorganics categories. On the other hand, the impact on water depletion and resource use, mineral and metals categories were found to be most significantly affected by the production of electricity from photovoltaic power plants. Finally, it is proposed that the results be employed to design scenarios for the future energy mix.
The Czech Republic is introducing new technological concepts for mitigation of greenhouse gases (GHG) in coal-based energy industries. One such technology, in power plants, is post combustion CO2 capture from flue gases by activated carbon adsorption. A life cycle assessment (LCA) was used as the assessment tool to determine the environmental impacts of the chosen technology. This article focuses on a comparative LCA case study on the technology of temperature-swing adsorption of CO2 from power plant flue gases, designed for the conditions of the Czech Republic. The LCA study compares the following two alternatives: (1) a reference power unit and (2) a reference power unit with CO2 adsorption. The most significant changes are observed in the categories of climate change potential, terrestrial acidification, and particulate matter formation. The adsorption process shows rather low environmental impacts, however, the extended LCA approach shows an increase in energy demands for the process and fossil depletion as a result of coal-based national energy mix. The feasibility of the study is completed by the preliminary economical calculation of the payback period for a commercial carbon capture unit.
This paper presents experimental results of NO<sub>x</sub> emission measurements for combustion of two kinds of coal in a bubbling fluidized bed combustor. The tested fuels were Czech brown coal (CBC) and German young brown coal (GYC). These fuels have different nitrogen contents. The experiments were performed in the pilot scale BFB experimental unit with power output of 500 kW. The influence of several parameters on NO<sub>x</sub> formation are investigated in this paper. The parameters studied here include the effect of the nitrogen content in the fuel, the effect of the oxygen concentration in the bed, the effect of bed temperature, the effect of air staging, and the effect of fluidization velocity. Significantly different behaviour of the fuels was found. Although GYC has a lower nitrogen content than CBC, it is more reactive and produces higher NO<sub>x</sub> emissions. The biggest dependence of NO<sub>x</sub> production for CBC was found for the effects of air staging and fluidization velocity. As the fluidization velocity increases and the amount of secondary air decreases, there is an increase in NOx emissions. The oxygen concentration in the bed has the strongest effect on the NO<sub>x</sub> production of GYCs. With increasing oxygen concentration, the production of NO<sub>x</sub> also increases. On the basis of the NO<sub>x</sub> measurements, the N-NO conversion factor was calculated and the effect of the operating parameters on this conversion factor was investigated.
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