Role of Hydrogen in Microgrid

What is Microgrid?

As defined by the International Council on Large Electric Systems, a Microgrid is an "Electricity distribution system containing loads and distributed energy resources (such as distributed generators, storage devices, or controllable loads) that can be operated in a controlled, coordinated way either while connected to the main power network or while islanded."

Imagine a bustling village with its own set of resources, such as farms, water wells, and food storage barns. This village can thrive independently, providing its residents with food, water, and shelter. When the nearby town’s market is open and bustling, the village can trade and share resources. But if a storm hits and the town’s market shuts down, the village can close its gates and rely on its supplies to keep everyone safe and well-fed.

Like this village, a microgrid has its local energy sources and storage, allowing it to function independently when the main power grid is down and reconnect when the grid is up and running again.

Think of it like a neighborhood that's powered by its little energy park, filled with solar panels, wind turbines, and energy storage in the form of batteries and hydrogen gas through electrolyzers and hydrogen fuel cells.

Why Microgrid?

Technological Shifts and Market Opportunities

Traditional electrification methods typically involve creating large, isolated power plants and building extensive networks for power transmission and distribution. However, this centralized/top-down approach is often costly and time-consuming.

Recent technological advancements and cost reductions in generation technologies, such as solar panels and wind turbines, along with innovations in energy efficiency and load management, present new sustainable alternatives.

Microgrids are essential for several key reasons, such as:

Variable Power Generation

A significant gap exists between the installed capacity and actual generation of renewables (Figures 2a, 2b). For instance, solar and wind have substantial capacities (82.64 GW and 46.16 GW, respectively), but their generation contributions are relatively lower (11.33 GW for solar and 4.54 GW for wind). This highlights the need for improved efficiency and better utilization of renewable resources. To effectively manage this variable power generation, a balance between installed capacity and the actual generation of microgrids is essential.

This grid variability and gap in installed capacity vs. . generation will further increase as the global renewable energy share is expected to increase from 12.5% in 2021 to 18.3% in 2030. (Figure 3a,3b)

Energy Security for all

Microgrids are increasingly being recognized for their critical role in global electrification efforts and in overcoming barriers to large-scale renewable energy deployment. Their ability to enhance electrification, particularly in growing economies, and their contribution to reducing global CO2 emissions make them an essential component of the future energy landscape.

The International Energy Agency (IEA) forecasts that 60% of future electrification needed to reach the goal of energy for all by 2030 will be enabled through microgrids and other small stand-alone systems. This includes providing electricity to the 1.2 billion people worldwide who currently lack access to reliable power.

In summary, the recent technological advancements and price reductions in generation technologies (such as photovoltaics and wind power), along with new energy efficiency and load management technologies, offer new sustainable alternatives to the traditional approach. These technologies enable the development of decentralized energy systems, including microgrids, which can complement centralized grids by providing localized and resilient power solutions.

Philosophy of Microgrid

"Spend energy that you are generating" is a supply-driven grid operation where, in most cases, surplus power is generated more than is required, if not less.

Importance of Hydrogen in Microgrid

As indicated in Figure 1, the microgrid management system prioritizes energy sources as follows: solar and wind power (1st priority) directly power the load when available. Surplus power is then managed by charging batteries (2nd priority) or generating hydrogen (3rd priority) using electrolyzers. When sufficient renewable power is not available and batteries are fully charged, power is generated using stored hydrogen in fuel cells.

Hydrogen plays a pivotal role in microgrids, particularly in enhancing energy storage, stability, and sustainability. Here’s an overview of its role:

Hydrogen Production via Electrolyzers

Electrolyzers are crucial for producing green hydrogen, which is essential for sustainable microgrids. They use electricity to split water into hydrogen and oxygen. Modern electrolyzers typically operate with an efficiency of 60–80% and offer fast response times. Recent developments have led to reductions in both CAPEX and OPEX, making them more economically viable.

Energy Storage and Backup

Hydrogen serves as a long-term energy storage solution by storing excess energy generated from renewable sources, such as wind or solar, and converting it back into electricity when needed. With a high energy density by weight (33.6 kWh/kg), hydrogen outperforms batteries and conventional diesel generators (12 kWh/kg) for large-scale storage. The overall efficiency of hydrogen energy storage is influenced by the efficiency of electrolysis (60–80%) and fuel cells (40–60%).

Power Generation

In fuel cells, hydrogen is used to generate electricity cleanly and efficiently with zero emissions. Hydrogen fuel cells can achieve electrical efficiencies of around 40–60%, and combined heat and power systems can reach efficiencies of up to 85%. The power output of hydrogen fuel cells can range from a few kilowatts to several megawatts, depending on the scale and application.

Microgrid Stability and Reliability

Hydrogen contributes to grid stability by balancing supply and demand, especially when integrating intermittent renewable sources. Hydrogen systems can rapidly respond to changes in electricity demand, with response times often in the range of seconds to minutes. Effective integration requires careful management of pressure, storage, and safety systems, with storage pressures typically ranging from 350 to 700 bar.

Hydrogen Vs. Batteries in Microgrid

Higher Energy Density

• Hydrogen: 33.6 kWh/kg.
• Batteries: Typically around 0.1–0.2 kWh/kg for current lithium-ion batteries.
• Advantage: Hydrogen's higher energy density allows for more compact and lighter storage solutions, especially beneficial for large-scale energy storage.

Long-Term Storage

• Hydrogen: Can be stored for long periods with minimal energy loss.
• Batteries: Typically have limited shelf life and can degrade over time, leading to capacity loss.
• Advantage: Hydrogen is suitable for seasonal storage and long-term backup.

Scalability

• Hydrogen: Scalable from small to large applications with modular systems.
• Batteries: Scalability is limited by physical size and capacity constraints.
• Advantage: Hydrogen systems can be scaled up to meet large energy storage needs.

Infrastructure and Costs

• Hydrogen: Requires infrastructure for production, storage, and distribution, which can be costly.
• Batteries: Generally have established infrastructure and lower initial costs.
• Disadvantage: Hydrogen’s infrastructure requirements and higher initial costs can be a barrier.

Efficiency

• Hydrogen: Efficiency losses occur at multiple stages—electrolysis, storage, and fuel cell conversion.
• Batteries: Typically offer higher round-trip efficiencies (80–90%).
• Disadvantage: Hydrogen systems generally have lower overall efficiency compared to batteries.

Storage and Handling

• Hydrogen: Requires high-pressure storage or liquefaction, which involves complex handling and safety considerations.
• Batteries: Easier to handle and store in ambient conditions.
• Disadvantage: Hydrogen storage requirements pose additional engineering challenges and safety concerns.

Technology Maturity

• Hydrogen: Still evolving with higher costs and less mature technology compared to batteries.
• Batteries: Well-established with a wide range of mature technologies and applications.
• Disadvantage: Hydrogen technology is less mature and more costly compared to established battery technologies

While the advantages of coupling hydrogen infrastructure with micro-grids are obvious, it is still an evolving technology, much like batteries 10–20 years ago. Petrochemical refineries and green steel are proven use cases for green hydrogen. As the electrolyzer technology scales in such established industries, the spillover is definitely going to benefit adjacent sectors. The next few decades will be an exciting space for green hydrogen in terms of a myriad of new technology applications, such as microgrids and mobility.

Author: Bhavik Modi , Senior Automation and Instrumentation Engineer.