Energy Storage
For more than ten years, many countries have worked hard to implement renewable energy plants. According to the International Energy Agency (IEA), by 2035, renewable energy sources such as hydroelectric, bioenergy, wind and solar will account for 18% of primary energy. Since 2013, increased grid capacity in renewable energy has outpaced the combination of coal, gas and oil. While these statistics are promising, one of the problems with renewables is that electricity can be intermittent. The energy produced for solar and wind power will vary depending on the season, location, or weather conditions.
In many cases, the areas best suited to producing renewable energy are often far from the most significant demand. In these cases, long-distance or overseas transportation is required. Solar energy has the most critical potential in northern countries during the summer when energy consumption is lowest. Wind conditions change every day and change rapidly. The energy generated by hydroelectric power may not be appropriately used during periods of low consumption.
Countries like Germany have implemented power plants based on renewable energy (wind and solar) with great effort and enthusiasm based on renewable energy (wind and solar). Still, they encountered problems of unstable or unreliable energy. Common power quality problems include voltage drop or surge, flicker, overvoltage, Undervoltage, interruption, transients, distortion, noise, and frequency drift. To solve these network quality and reliability problems, energy storage must provide continuous and uninterrupted power. An effective energy storage system (ESS):
- Will respond to daily, weekly or seasonal fluctuations in power demand.
- Will respond to intermittent problems in the renewable energy system connected to the network.
- Recovery of energy that may be wasted.
This is particularly important for large-scale applications that improve energy security and help balance energy prices.
Traditional fossil fuels have excellent energy storage capabilities, which is why they are so widely used. However, due to (apparent) supply, emissions, and political reasons, we aim to stay away from fossil fuels. There are many types of energy storage solutions, and each type has advantages and disadvantages. There are differences in size, storage time, equipment and energy transport capacity. Many types of fuels can be used for energy storage (oil, natural gas, biofuels). Still, these fuels may not always be suitable for transportation in a particular application due to volume requirements, length of storage or the amount of fuel required. . Non-combustible energy storage, like batteries, has a range of available power (1 kW to 1 MW); However, the energy density of the weight is low and electricity cannot be stored in batteries for a long time. Therefore, different energy storage methods are suitable for other purposes.
Hydrogen Storage
Hydrogen is a flexible energy carrier that can be produced from various energy sources, providing many opportunities for long-term energy storage. Hydrogen can be compressed, liquefied, or stored in solid or liquid form in fuel cells, turbines, or internal combustion engines. The main challenge associated with hydrogen is its production and storage. Approximately 48% of hydrogen is produced from natural gas (NG) through steam methane reforming (SMR), 30% is petroleum refining, 18% comes from coal, and 4% comes from water electrolysis. In the United States, 59% of hydrogen is produced in refineries and ammonia plants, and nearly 36% of hydrogen is a by-product of catalytic reforming in refineries and chlor-alkali plants. In terms of equivalent energy, the annual global demand for hydrogen (172 Mtoe, 60 Mt) is less than 2% of the world’s energy production.
The widespread use of hydrogen in the global economy faces two significant challenges: (1) the cost of producing hydrogen from low-carbon sources is high, and (2) the slow development of hydrogen infrastructure hinders widespread adoption. The cost of building the hydrogen distribution infrastructure and long-distance transportation is the main economic obstacle to the implementation of hydrogen-based technology. In addition, large-scale centralized production will depend on the development of the market capacity to offset capital expenditure for capacity building. In the future, electricity based on renewable energy can be used to produce carbon-neutral hydrogen by electrolyzing water. This distributed production method using an electrolytic cell system is considered an attractive medium-term option for hydrogen supply. The electrolyzer uses electricity to split water into hydrogen and oxygen. The electrolysis of water occurs through an electrochemical reaction that does not require external components or moving parts. It is very reliable. When the power source is renewable energy, it can produce ultra-pure hydrogen (>99.999%) in a pollution-free manner. Electrolysis provides a modular, decentralized approach to energy utilization, delivery, and cost for developing hydrogen-on-demand energy storage systems. Electrolyzers can convert water to hydrogen-rich gas to help store potentially large amounts of electricity that can be used under batch conditions. The hydrogen fuel produced by the electrolyzer is well suited for hydrogen fuel cells. The reaction in the electrolyzer is very similar to the reaction in the fuel cell, except that the reactions at the anode and cathode are opposite. In a fuel cell, the anode is where hydrogen is consumed, while in an electrolyzer, hydrogen is produced at the cathode. The disadvantage of the electrolytic cell is that it requires electrical energy to complete the reaction.
The electricity required for the electrolysis reaction preferably comes from renewable energy sources, such as wind, solar or hydroelectric. Electrolyzers are very useful and ideal when integrated into specific fixed, portable and transportation power systems that convert excess energy into long-term energy storage. Beneficial applications for electrolyzers include grid energy storage, long-term field use, fuel cell-powered vehicles, and portable electronics. Some of the advantages of using an electrolyzer are:
• The hydrogen produced is very pure
• It can be produced directly
• Cheaper than transporting hydrogen in high-pressure cylinders
The global natural resources of solar and wind energy are sufficient to produce all the hydrogen needed for stationary, transport and portable applications. Electrolysis has the potential to meet cost requirements set by many governments around the world.
Conclusion
The use of hydrogen for energy storage is an effective solution to intermittent energy problems related to solar and wind energy. The main challenges associated with the implementation of hydrogen are related to its production and storage. Many hydrogen storage schemes have been proposed, and the feasibility of adopting different strategies according to the needs of the target industries. An ideal energy storage system would include an electrolyzer that runs on excess wind or solar energy and a hydrogen storage system. The fuel cell power generation system will use hydrogen to collect and supply energy when needed.