Storing renewable energy in hydrogen is primarily achieved by using excess renewable electricity to produce hydrogen through a process called electrolysis.
Hydrogen as an Energy Storage Solution
Renewable energy sources like solar and wind are intermittent, meaning they don't always produce electricity when it's needed. To ensure a reliable energy supply and make full use of generated renewable power, storing this energy is crucial. Hydrogen acts as an excellent energy carrier for large-scale and long-duration storage.
The Process: Power-to-Hydrogen (Electrolysis)
The core method for storing renewable electricity in hydrogen is electrolysis. This process uses electricity to split water (H₂O) into its components: hydrogen (H₂) and oxygen (O₂). When the grid has more renewable power available than consumers need (excess electricity), this surplus energy can be directed to an electrolyzer.
Here's a simplified look at the process:
- Renewable Generation: Electricity is generated from sources like solar panels or wind turbines.
- Excess Electricity: When generation exceeds demand, this extra power is available.
- Electrolysis: The excess electricity is sent to an electrolyzer.
- Water Splitting: Inside the electrolyzer, water molecules are split into hydrogen and oxygen gas.
- Hydrogen Capture: The hydrogen gas is collected.
- Storage: The hydrogen is then stored, typically as a compressed gas in tanks, as a liquid at very low temperatures, or chemically within other materials.
This effectively converts electrical energy into chemical energy stored within the hydrogen molecule.
Why Store Renewable Energy in Hydrogen?
Unlike batteries, which are often better suited for shorter-duration storage, hydrogen offers potential for storing very large quantities of energy for extended periods. This makes it valuable for balancing energy grids over days, weeks, or even seasons.
Applications of Stored Renewable Hydrogen
Once stored, this "green" hydrogen (produced using renewable electricity) can be used in various applications, effectively deploying the renewable energy that was originally captured.
As highlighted by the reference, by storing excess renewable electricity in large quantities in hydrogen, renewable energy can be effectively used for road transportation, grid balancing and fuel cell material handling vehicles.
Specific uses include:
- Road Transportation: Hydrogen can fuel vehicles equipped with fuel cells, producing only water vapor as emissions.
- Grid Balancing: Stored hydrogen can be converted back into electricity using fuel cells or turbines during times of high demand or low renewable generation, helping to stabilize the power grid.
- Fuel Cell Vehicles (e.g., Material Handling): Used in forklifts and other industrial vehicles powered by fuel cells.
- Industrial Feedstock: Hydrogen is used in various industrial processes, such as ammonia production or refining.
- Heating: It can potentially be blended with natural gas or used directly for heating.
By converting surplus renewable electricity into hydrogen, energy generated during peak production times (like windy nights or sunny afternoons) can be stored and utilized later for diverse purposes, increasing the overall effectiveness and reliability of renewable energy systems.
