Estimated impact of different factors on the reduction in emissions of nitric oxide and nitrogen dioxide (NOx) from public electricity and heat production between 1990 and 2007, EEA-32
The top line represents the hypothetical development of emissions that would have occurred due to increasing public heat and electricity production between 1990 and 2006, if the structure of electricity and heat production had remained unchanged from 1990 (i.e. if the shares of input fuels used to produce electricity and heat had remained constant, the efficiency of electricity and heat production also stayed the same and no additional abatement technologies had been introduced). However, there were a number of changes to the structure of electricity and heat production that tended to reduce emissions and the contributions of each of these changes to reducing emissions are shown in each of the bars. The cumulative effect of all these changes was that emissions from electricity and heat production actually followed the trend shown by the black bars. This is a frequently used approach for portraying the primary driving forces of emissions. The explanatory factors should not be seen as fundamental factors in themselves nor should they be seen as independent from each other.