Wind energy is defined as the kinetic energy of the wind converted into mechanical work. This mechanical work can be used to drive an electrical generator for the production of electricity. A machine that performs this conversion is called a Wind Turbine Generator (WTG).
The stochastic nature of wind is responsible for the intermittent operation of the wind energy systems; an effect that unpredictable operating and high maintenance costs. To solve those problems, any appropriate energy storage technique associated with the unstable performance of wind energy systems was proposed.
Producing hydrogen as energy storage by the electrolysis of water, where the main power input is electrical power produces from the conversion of wind energy, is a very promising way. It is because (i) the existing experience regarding the handling of hydrogen is already high; and (ii) hydrogen is well adapted for seasonal energy storage without energy loss over time.
The water electrolysis process consists of electrochemically splitting water into its constitutents, namely hydrogen and oxygen. According to the electrolyte used for electricity conduction in the process, 4 types of water electrolysis may be found. There are (i) Acid electrolyte, (ii) Polymer electrolyte, (iii) Steam electrolysis, and (iv) Alkaline electrolyte.
There are no electrolyzers developed specifically for operation with wind turbines. However, the rapid response of electrochemical systems to power variations makes them suitable "loads" for wind turbines. For example: Advanced alkaline electrolyzers may be subject to input power variations in the range 15-120% of their nominal power within 1 s and this feature makes them attractive for coupling with the wind turbines.
Hydrogen production from electrolysis of water powered from a wind energy system is installed on some sites. A very important issues related to the performance of the whole wind-hydrogen system are:
- Reliability of the power electronics used for the AC/DC conversion
- The cooling system of the electrolyzer
- The compressor of the gaseous hydrogen
- The purification units of water and hydrogen
The combination of hydrogen and wind energy systems may contribute to the further growth of both technologies while one serves the other for different reasons. From the time that hydrogen becomes the primary energy carrier for transportation and other mobile applications, this method will be considered as one of the most competitive investments.
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