ABSTRACT
The expression “hydrogen economy” is used to indicate the role of hydrogen in the future energy scenario. Interest in hydrogen, as an energy carrier, has been growing in the recent years due to heightening of air pollution in the world. Hydrogen is a clean and flexible energy carrier that can be used to provide both power and heat across all end-use sectors. Vehicles and stationary power generation fed by hydrogen are local zero emission technologies. Hydrogen can be produced from both traditional fossil fuel and carbonfree energy sources, which are used to store energy and to provide response management to electricity grid. Today, only 4% of hydrogen is produced from electrolysis; other lower-cost methods are preferred, such as steam reforming of natural gas or refinery gas. However, in the next future, the renewable energy sources (RES) will take up an important portion of electric energy produced. In this context, the energy storage is expected to play a key role in the future as “Smart Grid.” The future energy storage technologies should be more flexible and able to balance the grid, ensuring stability and security. Large-scale deployment of variable renewable source (primary wind and solar energy) will be required to store energy to avoid the RES curtailment. Electrolysis is considered as the cleanest way to produce hydrogen using RES and has (along with other storage technologies) the potential
as “energy storage” in this sector. In particular, bulk energy storage technologies are expected to have a key role for the integration of large amount of electricity produced from RES. This sector is dominated by pumped hydro as energy storage (PHES) in the world due to its large unit sizes and history. Anyway, long construction times and high uncertainty of future electricity price developments make PHES systems risky investments. Furthermore, constructions of PHES systems are strongly dependent on certain geographic requirements and topographical conditions.
