Grid Integration of Hydrogen Electrolyzers and Fuel-Cells: Opportunities, Challenges and Future Directions
Written by Lasantha Meegahapola
Hydrogen is gaining momentum as a major energy source in the transition toward low-carbon power systems. Hydrogen can be deployed as a source when used in fuel cells to produce electricity. At the same time, hydrogen production via the electrolysis process (also known as the power to hydrogen (PtH) technology) acts as a load. These two technologies can deliver many benefits to power grids, such as relieving network bottlenecks, maximizing renewable energy penetration, offering system flexibility, and providing system support services (e.g., frequency support services). Although hydrogen can bring many benefits to power grids, many challenges still need to be overcome when integrating hydrogen-based technologies into the power grid. This article discusses the opportunities that can be harnessed from hydrogen-based technologies and the challenges associated with the grid integration of hydrogen-based technologies.
Hydrogen has already begun to make a mark as an alternative fuel technology to replace fossil-fuel-based resources. The hydrogen demand is expected to be doubled by 2030 . Hence, more fossil-fuel-based sectors are likely to deploy hydrogen in the future along with other forms of renewable energy. Electrolyzers and fuel cells are the two main grid integration technologies of hydrogen. Electrolyzers produce hydrogen via the electrolysis process and act as a load in the power grid, while the produced hydrogen is used in fuel cells to generate electricity. According to the forecasts, the global electrolyzer capacity could reach as high as 240 GW by 2030 . Thus, more benefits can be obtained for the electricity sector by integrating hydrogen technologies into the power grid.
Opportunities to Power Grid from Hydrogen-Based Technologies
Hydrogen can bring many opportunities to decarbonize the electricity and transport sectors. The majority of benefits can be gained through green-hydrogen production by co-locating hydrogen infrastructure with renewable energy sources and renewable energy zones (see Figure 1 for the green-hydrogen ecosystem). Hydrogen-based sources would bring the following benefits to electricity and other sectors:
- Ability to relieve the transmission grid bottlenecks and defer transmission network upgrades - With the large-scale integration of converter-based renewable energy sources (e.g. wind and solar-PV farms) into the power grid, existing transmission corridors are increasingly congested, as the existing transmission infrastructure is designed for the conventional synchronous generators. By co-locating hydrogen electrolyzers in renewable-rich regions or renewable energy zones, locally generated renewable energy can be utilized to produce hydrogen. Hence, congested transmission lines can be relieved. Subsequently, costly transmission line upgrades can be deferred for the foreseeable future.
- Increase production of green hydrogen - Based on 2021 statistics, green hydrogen production is less than 1% of the total hydrogen production . In order to effectively reduce greenhouse gases emission, it is essential to produce green hydrogen. Therefore, co-locating hydrogen electrolyzers with renewable energy zones can help increase green hydrogen production, which is an essential step toward lowering carbon emissions in the electricity, transport, and industrial sectors.
- Ability to reduce the losses associated with the transportation of energy and conversion processes - Electricity transmission and energy conversion processes have inherent losses. Hydrogen electrolyzers offer a mechanism to utilize the electricity at the point of energy production and by co-locating them with renewable energy plants. Therefore, electricity transmission to long-distance locations can be avoided to minimize energy losses.
- Reduce the renewable energy curtailment - According to some utility reports, around 1% of the variable renewable energy generation is being curtailed due to various constraints (e.g., stability and network constraints) . This can be avoided by strategically placing hydrogen electrolyzers in the region as they can act as a local load to consume the curtailed energy from variable renewable generators.
- Ability to provide grid-support services and flexibility - With the increasing penetration of converter-interfaced renewable energy sources, power systems require enhanced grid-support services to maintain power grid stability. The hydrogen electrolyzers and fuel cells can provide frequency support services to the power grid . More specifically, Polymer electrolyte membrane (PEM) electrolyzers have a high ramp rate and start-up time, which is ideal for obtaining grid-support services and flexibility . Moreover, the power grid requires more flexibility due to the high variability and intermittency of these renewables and therefore requires new sources to provide system flexibility. Hydrogen electrolyzers can provide such capability by acting as a flexible load (which can increase and decrease the system demand). Also, additional flexibility can be provided by fuel-cell technology. Hydrogen-based gas turbine technology is also emerging, but it is still nascent technology to deploy in power grids .
Figure 1: Green-Hydrogen Ecosystem.
Grid Integration Challenges of Hydrogen-Based Technologies
Infrastructure Barrier – Hydrogen requires special infrastructure for storage and transport from the hydrogen production plants to utilization centers. Specifically, specially designed tankers and pipelines are required for transporting hydrogen under required temperature conditions and specific storage facilities with compression and liquefaction . Although hydrogen electrolyzers can be placed near renewable energy plants, the lack of infrastructure for transporting hydrogen will make this task infeasible. Therefore, the lack of infrastructure is a major barrier to co-locating hydrogen technologies with renewable energy sources.
Placing Hydrogen Electrolyzers – To increase green hydrogen production, it is essential to utilize green energy for hydrogen production. However, placing the hydrogen electrolyzers in renewable-rich areas with the available hydrogen transport infrastructure is challenging. In particular, locating hydrogen electrolyzers to optimize the cost (i.e., minimize the cost) associated with hydrogen storage and transport and maximizing green hydrogen production is a considerable challenge.
Financial Barriers – Electrolyzers and fuel cells are relatively expensive compared with other emerging technologies . Therefore, it is challenging to justify the high investment required for these technologies unless governments subsidize them. Although the capital cost of these technologies is forecasted to be reduced in the future (e.g. 2030), presently, it is challenging to develop large-scale hydrogen infrastructure.
Insights on future directions to overcome the barriers to hydrogen-based technologies.
Insights on Future Directions to Overcome the Barriers to Hydrogen-Based Technologies
The key to maximizing green-hydrogen production is the strategic design of hydrogen infrastructure (e.g., electrolyzers, storage, and transport facilities) with renewable energy zones. This requires a coordinated planning framework for variable renewable resources and hydrogen production. Designing a coordinated planning framework will increase green-hydrogen production and the efficient use of renewable energy and reduce renewable energy curtailment. A coordinated planning framework can be extended with grid constraints, and consequently, potential grid bottlenecks can also be relieved while developing the necessary infrastructure for hydrogen.
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This article was edited by Hossam Gabber.
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He is also an active member of the IEEE PES power system dynamic performance (PSDP) committee task forces on microgrid stability analysis and microgrid dynamic modeling and a working group on voltage stability. He made key contributions toward identifying and classifying stability issues in microgrids. Dr. Meegahapola is also serving as an Associate Editor of the IEEE Transactions on Power Systems, IEEE Power Engineering Letters, IEEE Transactions on Industry Applications, and IET Renewable Power Generation journals.