FUEL CELLS FOR STORAGE OF ELECTRIC ENERGY GAINED FROM WIND POWER PLANTS

Goal of this article is to present possibilities of accumulation of redundant electric energy which has been produced by unconventional sources of electric energy and their use at the time of increased load of electric supply system. This work deals with different ways of design systems of accumulation of electric energy in parks of wind power plants. There were described these five options of accumulation of electricity in parks of wind power plants: Supply of Peak Energy, Minimal Supply, Prediction of Supply of Power, Cover of Own Consumption and Overdesign of Accumulation. Analysis of these five variants related to specific wind power plant pointed to that there are necessary large accumulation capacities to supply reliable wind energy (variants Supply of Peak Energy and Minimal Supply). In case of options Prediction of Supply of Power and Cover of Own Consumption can be used any size of accumulation. Option Prediction of Supply of Power looks like the most economical one of these five variants. There are also mentioned fuel cells their advantages and disadvantages. Fuel cells use clean hydrogen (or hydrogen containing fuel) and oxygen to produce electricity during electrochemical process. Fuel cell consists of two electrodes - negative anode and positive cathode which surround electrolyte. Anode is supplied by hydrogen and cathode is supplied by oxygen. Hydrogen atoms are then activated by catalyst and divide into protons and electrons. Electrons go throw external electric circuit producing electricity while protons go throw the electrolyte to the cathode where they join up with oxygen and electrons producing water and heat. Advantage is that fuel cells (PEM type) use only clean hydrogen. They work without polluting matters. They have high efficiency. Fuel cells are suitable for cogeneration because as it was mentioned they produce also heat and water. Their overall efficiency rise when they are use in cogeneration. Fuel cells don't require charging up. If fuel is supplied they work consecutively. Main disadvantage is that the hydrogen is difficult to produce and to storage and is often made from fossil fuels. His energy density is low. Fuel cells are very sensitive to impurities in fuel which can damage expensive catalyst. Fuel cells were compared with other sources of electric energy - batteries and internal combustion engines in terms of efficiency and number of energy conversion. In case of appliance fuel cells as electricity generators they demand less energy conversion than heat engine. There is presumption that this work will be developed with purpose of choose an optimal storage system with the help of multicriterial analysis method.