It is well known that the hydro power plants directly influence the habitat and the climate. Still, the hydro power represents a green renewable energy source, not polluting the environment if proper measures are applied. The main objective of the researches in this field is represented by the quality of the water discharged from turbines and especially by the low dissolved oxygen level that may have an unfavorable impact over environment and can endanger the aquatic life. During the summer months, due to the thermal stratification of the dam reservoirs and to the degasification phenomenon resulted when water passes through the turbine, the oxygen level can drop under the minimum limit of 5-6 mg/L, needed for aquatic life. The authors propose the water aeration process optimization, outlining the importance of the aeration "quality" (bubbles dimensions, retention times, pressure drop, geometry and dimensioning of the aeration systems) on the mass transfer process and not the quantity of air injected.

The renewable energy policy strongly encourages the use of all renewable sources of energy. ICPE-CA starts to develop a new hydrokinetic turbine to be implemented in small rivers or water channels with a low investment cost. In a first step, the characterization of a laboratory reduced scale turbine model is performed. The hydrokinetic turbine model is implemented in a free surface water channel. The produced power for many flow rates and rotation speed of the turbine, as well as the detailed flow characterization (PIV measurements) are presented.

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The development of technologies for waste treatment, simultaneously with minimizing greenhouse gas emissions, has become a matter of great concern at global level. Biogas systems can help in the fight against global warming by avoiding to escape methane from organic waste, into the atmosphere. Biogas technology is of great benefit to the end-users and the environment by energy, compost and nutrient recovery. Romania is a country with a huge biomass potential. Implementing of biogas technology could be a proper solution for waste treatment and producing of electricity from renewable energy sources, as stipulated in EU and national legislation. This paper presents an overview on the progress of biogas technologies in Romania since 1980s and the main obstacles that have slow down the development of this technology in the context of the major political and economical changes registered in Romanian industry after 1990. There are mentioned the main benefits which biogas plants could bring to the environment and also some common problems with biogas plants which have been noticed in the developed countries in this field.

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