Can Hydrogen Store Renewable Energy?
Renewable energy sources like solar and wind are intermittent, meaning they only produce power when the sun is shining or wind is blowing. This intermittency creates a need for energy storage to capture excess renewable energy when it’s generated and discharge it when renewable resources are not available. Energy storage helps balance supply and demand on the electric grid. As electric utilities move toward wind and solar energy to replace power generated by fossil fuels, the importance of energy storage continues to grow.
One potential method for energy storage is using hydrogen. Hydrogen offers unique advantages for storing renewable energy over the long-term. This article will explore how hydrogen can be used to store energy from renewable sources, the benefits and challenges of hydrogen storage, and how it compares to other energy storage technologies.
How Hydrogen Can Store Energy
Hydrogen can be produced through a process called electrolysis, which uses electricity to split water into hydrogen and oxygen. This process can utilize electricity from renewable sources like solar or wind to generate the hydrogen. The key advantage is that unlike the electricity, the hydrogen can be stored until it is needed.
The hydrogen gas can then be kept in storage tanks or underground caverns. When electricity is needed, the hydrogen can be fed into a device called a fuel cell. Inside the fuel cell, the hydrogen reacts with oxygen from the air to generate electricity through a chemical reaction. The electricity is emissions-free because the only byproducts are water and heat. In this way, hydrogen provides a method to capture renewable electricity and save it for later use when the sun isn’t shining or wind isn’t blowing.
Hydrogen energy storage provides a solution to the intermittency issues surrounding renewable power sources. By converting the electricity to hydrogen, it can act as a battery to store the energy long-term until it needs to be used. This helps provide stability and reliability to the electrical grid.
Benefits of Hydrogen Storage
Some of the primary benefits of using hydrogen for energy storage include:
Lightweight: Hydrogen is the lightest element, which makes it easy to transport and store. One kilogram of hydrogen is equivalent to around 30 kWh of energy, so it can store a large amount of energy in a small, dense package. This makes hydrogen storage more space-efficient compared to other energy storage options like batteries (source).
Clean emissions: When hydrogen is used in a fuel cell to produce electricity, the only byproduct is water. There are no carbon dioxide or other greenhouse gas emissions generated in the process. This makes hydrogen an extremely clean way to store and utilize renewable energy (source).
Challenges of Hydrogen Storage
While hydrogen has potential as an energy storage medium, there are some key challenges that need to be addressed:
Hydrogen production requires a significant initial energy input. Most hydrogen today is produced via steam methane reforming of natural gas, which has a large carbon footprint. Using renewable electricity to produce hydrogen via electrolysis is cleaner but less efficient overall [1]. Improving the efficiency of hydrogen production processes is an area of active research.
Storing and transporting hydrogen can also be challenging. As the lightest element, hydrogen has very low volumetric energy density as a gas. It must be greatly compressed, liquefied, or bonded with other elements in order to be stored and transported efficiently. This requires specialized equipment that adds complexity and cost [2].
Fuel cells, which convert hydrogen back into electricity, remain expensive compared to other generation technologies. Bringing down their cost through improvements in materials and manufacturing is another key area being researched [3].
Examples of Hydrogen Storage Projects
There have been several pilot projects and demonstrations for hydrogen energy storage around the world. In California, SoCalGas has worked on multiple projects to test the viability of hydrogen storage. At the University of California Irvine, they converted a 1-megawatt molten carbonate fuel cell power plant into a hydrogen battery capable of storing up to 130 kilowatt-hours of energy.
In Europe, the Underground Sun Storage project in Switzerland is using excess solar electricity to produce hydrogen via electrolysis. The hydrogen is then injected into underground salt caverns for storage and can be withdrawn to generate electricity in fuel cells when needed. This pilot project has a capacity of 2 megawatts.
The HyStock project in Germany is demonstrating hydrogen storage in salt caverns at larger scales. With capacities up to 400 megawatt-hours, this project aims to establish technical rules and standards for hydrogen storage in salt caverns across Europe.
Cost of Hydrogen Storage
The current cost of hydrogen energy storage is one of the biggest challenges to wide-scale adoption. According to a report by Research Nester, the cost of hydrogen storage can be over 10 times more expensive than fossil fuel storage on a per unit energy basis[1]. The high infrastructure costs for transportation, storage facilities and fuel cells also add to the overall expense.
However, costs are expected to come down as the technology scales up. A Globenewswire report predicts the global market for hydrogen energy storage will grow from $1.47 billion in 2021 to over $23 billion by 2028[2]. As more projects demonstrate feasibility, manufacturing ramps up, and infrastructure matures, costs can reach more competitive levels. Research by Shi et al. found the reduction in carbon emissions achieved with hydrogen storage systems helps offset the higher financial costs[3].
Most experts agree that continued investment, research and government incentives are needed to further reduce costs and make hydrogen energy storage cost-competitive with other energy storage methods.
[1]https://www.researchnester.com/reports/hydrogen-energy-storage-market/3811
[2]https://www.globenewswire.com/en/news-release/2022/02/02/2377839/0/en/Hydrogen-Energy-Storage-Market-Surpass-23-103Mn-by-2028-CAGR-6-3-Report-Published-By-Acumen-Research-and-Consulting.html
[3]https://www.sciencedirect.com/science/article/abs/pii/S0960148122007765
Safety Considerations
Hydrogen is a flammable gas that requires careful handling and storage. According to Winsen Technology, hydrogen sensors are critical for detecting leaks and preventing explosions at hydrogen energy storage facilities (https://www.linkedin.com/pulse/winsen-technology-energy-storage-safety-gas-detection-pinckney-cao). The use of hydrogen comes with inherent safety risks due to its wide flammability range. Precautions need to be taken such as adequate ventilation, leak detection, and avoiding ignition sources.
Due to its small molecule size, hydrogen can leak through the smallest openings. Therefore, storage tanks and piping need to be extremely well sealed. Hydrogen detectors should be positioned throughout a facility to immediately identify any hydrogen leaks. Explosion-proof electrical equipment may also be required in hydrogen storage areas. Strict safety protocols need to be established and followed when working with hydrogen systems.
While challenging, the risks of hydrogen can be managed with proper design, equipment, training, and procedures. With adequate safeguards in place, hydrogen energy storage can be accomplished safely (https://www.winsen-sensor.com/knowledge/gas-sensors-for-electrochemical-energy-storage-power-stations.html?searchid=4558). However, hydrogen’s hazards must always be respected.
Regulations for Hydrogen
Hydrogen is still an emerging technology in many parts of the world, so regulations are still evolving. Some key regulations and policies regarding hydrogen storage include:
In the United States, the Department of Energy has programs to advance research and development of hydrogen storage technologies. The DOE has set targets for optimal storage capacity, efficiency, and cost to help drive innovation in this field (https://www.energy.gov/eere/fuelcells/hydrogen-storage).
The European Union has also established a strategic plan to promote the development of hydrogen energy and storage via its Hydrogen Strategy and Horizon 2020 program. This includes over $10 billion in planned funding through 2030 (https://ec.europa.eu/energy/topics/energy-strategy/hydrogen_en).
Japan aims to expand hydrogen usage to 3 million tons annually by 2030, aided by national subsidies, tax breaks, and favorable regulations. This includes exempting hydrogen from Japan’s fuel tax (https://www.energyintel.com/00000186-9ca8-dcca-a9f7-dda962f00000).
Safety standards and building codes are also evolving to allow hydrogen storage and distribution, though further development is needed. Overall, government support and strategic policy will be key drivers enabling hydrogen’s growth as an energy storage medium.
Comparison to Other Storage Methods
Batteries are a common alternative for renewable energy storage compared to hydrogen. Studies have found that batteries tend to be more efficient at storing and discharging electricity than hydrogen storage. For example, one analysis by the National Renewable Energy Laboratory found that lithium-ion batteries can store and discharge electricity with round-trip efficiency of 86-98%, while hydrogen storage using electrolysis and fuel cells has a round trip efficiency of only 25-35% (https://iesr.or.id/en/we-dont-have-a-choice-we-have-to-achieve-carbon-neutrality).
However, hydrogen storage has some advantages compared to batteries. Hydrogen can store larger amounts of energy for longer durations than batteries before discharge. This makes it suitable for seasonal storage and buffering renewable sources like solar and wind which have intermittent production. Hydrogen is also lighter than batteries, making it easier to transport. Refueling hydrogen is faster than recharging batteries in some applications like vehicles. Safety is a concern though, as hydrogen is flammable while batteries carry less fire risk (https://www.federalregister.gov/documents/2010/01/19/2010-864/hydrogen-and-fuel-cell-technical-advisory-committee-htac).
Overall, batteries tend to be better for short-term storage and fast discharge uses. Hydrogen has benefits for large scale, long duration storage, but has efficiency challenges. More research is needed to improve hydrogen storage technologies.
Conclusion
In summary, hydrogen shows significant potential as an effective means of storing renewable energy generated from sources like wind and solar, although more research and development is still needed. When renewable electricity is used to split water into hydrogen and oxygen through a process called electrolysis, the hydrogen can then be stored and later converted back into electricity when needed using a fuel cell. This provides a way to help overcome the intermittent nature of renewable sources.
Some key advantages of hydrogen storage include its high energy density, the ability to store it long-term with little loss, and the fact that it does not produce direct greenhouse gas emissions when converted back to power. Hydrogen can also potentially use much of our existing natural gas infrastructure for storage and transport. However, work is still needed to bring down costs and scale up technology for production, storage and use. Safety regulations will need to be developed to cover risks like flammability. And renewable hydrogen production needs to expand greatly to provide sufficient supply.
Overall, hydrogen energy storage represents one of the most promising options for enabling high levels of renewable energy in the future. But fully realizing its potential will require continued research, policy support, infrastructure investment and technological innovation. If these advancements can be achieved, hydrogen may play a major role in a clean, sustainable energy system.
