When it comes to renewables, the big question is: How do we store all that energy for use later on? Because such energy is intermittent in nature, storing it when there is a surplus is key to ensuring a continuous supply—for rainy days (literally), at night, or when the wind doesn’t blow.
Using today’s lithium-ion batteries for long-term grid storage isn’t feasible for a number of reasons. For example, they have fixed charge capacities and don’t hold charge well over extended periods of time.
The solution, some propose, is to store energy chemically—in the form of hydrogen fuel—rather than electrically. This involves using devices called electrolyzers that make use of renewable energy to split water into hydrogen and oxygen gas.