SummaryThe influence of two selenium concentrations (5 and 20 µM) on crop yield, the content of chlorophyll, carotenoids and anthocyanins, as well as accumulation of nickel, selenium and sulphur were studied in the leaves of 50 µM Ni-stressed lettuce plants. Experiments were carried out in water cultures. The obtained results suggest that selenium at concentration of 5 µM in nickel contaminated medium positively affected plants by stimulating their growth, increasing the concentration of assimilation pigments, and thereby at least partially prevented the toxic effect of nickel excess. Moreover, in plants enrichment with selenium a higher increase in content of chlorophyll a than b as well as a higher concentration of carotenoids were found. On the other hand, selenium affected a greater nickel uptake by lettuce plants.

The aim of the paper is to draw attention to both the average annual savings in the costs of consumed fuels and energy, as well as the possibility of obtaining additional funds in the case of implementing projects aimed at improving energy efficiency. On the example of an implemented investment in a cement industry company, the achieved energy savings and obtained economic savings in the form of reduction of fuel and energy costs were analysed. Moreover, it was shown what additional support can be obtained in the form of energy efficiency certificates, the so-called “White certificates”, issued by the President of the Energy Regulatory Office, and the resulting property rights become an exchange commodity and are traded on Towarowa Giełda Energii SA. The purpose of this paper is to estimate how much money will be financed from the certificates.