Identification of a coal power plant share at the overall air pollution

The share of particular CEZ coal power plants at the air pollution is evaluated in mathematical models. Even abroad, computation models are routinely used for simulation, of anticipated effects of technical measures at pollution sources on air pollutant quantity changes, and in many cases their use is required.

For an evaluation of a single air pollutant source share at the overall air pollution, a mathematical model is usually the only option available, for a performance of such an analysis. An air pollution computation, in comparison with air pollutant measurements, brings both advantages and disadvantages.

The advantages include the fact, that a computation model may not perfectly describe specifics of a reference point particular location. Additionally, a description of meteorological conditions implemented in such a computation model is a mere generalization, making use of both long-term and short-term information. Consequently, computed average air pollutant concentration values at a specific reference point may often differ from the average air pollutant concentration quantity provided by a measuring station.

The computation model advantages include the fact, that a computed concentration value is a sum of partial concentration values as provided from particular air pollutant sources, which makes possible to identify a share of a particular air pollutant source at the overall air pollution, for a given reference point. Equally, locations and quantity of reference points for the computation may be easily be selected. A collection of such information is significantly less costly, in contrast to the air pollutant measurement itself, where additional problems with its both quality and usability may be encountered.

When the computations are performed each year, however, some of the above mentioned disadvantages change to advantages, because a mutual comparison of computed air pollutant concentration quantities in particular years does not suffer from fluctuations in weather conditions, which in case of a higher occurrence of inversion situations may significantly affect measured concentration quantities.

Into the computation of air pollution in the vicinity of CEZ coal power plants, the following input data were included as the air pollutant sources :

• all the REZZO 1 monitored sources (in particular, large sources and sources of extensive pollution), located on the whole Czech Republic territory,
• REZZO 2 sources (medium size pollution sources) and REZZO 3 (local pollution sources), registered in districts within a distance of 60 km from CEZ, a. s. power plants

The air pollution computations were performed for sulphur dioxide, nitrogen dioxide, and airborne dust. The computation itself was performed as follows: in the vicinity of particular CEZ, a.s. power plants, (evaluated area as a square 60 x 60 km, in the centre of which a particular power plant is situated), computation reference points were selected, in a uniform network of 2 x 2 km density. For these 900 reference points, approximately, air pollutant concentration values were computed. From these data, using dedicated topographic software, isolines of equal concentration, i. e. of equal shares at the total air pollution, were created, and then converted into schematic maps of area being evaluated.

A computation of nitrogen oxide air pollution did not include pollution caused by traffic, which in towns, in particular, is quite significant.

The airborne dust concentration computation did not include secondary-dust effects, occurring with higher wind speed causing turbulences of dust settled on the ground. The airborne dust concentration values computed, therefore, display effects of solid substances (particles) brought to the air by sources, which are active and only active during the evaluated period.

Objective determination of the share of CEZ, a.s. coal power plant operation at the air pollution, through model computations, may only be performed if official data are utilized, as included in the "Air Pollutants & Pollution Sources Registry" (REZZO) national system. The mechanism of processing REZZO data and making them available is such, that official current data for each year are available, as a rule, with a year delay (e. g., air pollutant data for the year 2002 would be available not earlier than in the first year-quarter of the year 2004).

On the web page, computed shares of CEZ, a.s. coal power plants are presented, at the total air pollution, provided for particular years of the 1991 to 2001 period (data for dust concentration since 1992). The data are updated annually, towards the end of the second year-quarter. In June 2004, the presentation of shares shall be updated with data processed in computations for the year 2002.