Which is better: batteries or hydrogen storage?

The type of battery storage that might be chosen for different scenarios depends on the requirements of the power source, its location and the consumers that demand it, as well as the application, for example, grid, mobility, and industrial energy needs. Energy storage can deliver benefits in the form of reduced cost, higher efficiency, increased scalability and safety. We’ll take a look at two different types of battery storage: electrochemical and hydrogen.

How each technology works and where it fits

Different applications require different types of batteries, depending on factors such as the urgency of the energy need and the duration for which the energy is required. 

Lithium-ion Batteries

The benefit of lithium-ion batteries is speed. They can store electricity as chemical energy and return it for use again very quickly, with a millisecond response time, which is ideal for fast-response, frequency services where demand requirements are immediate and energy is needed for a short to medium duration. Batteries are a heavy technology to transport, but relatively simple to deploy on site. This simplicity means that lithium-ion is a more developed and widely used, mature technology, which enjoys broad vendor support thanks to successful example applications already in existence. 

Hydrogen Batteries

Hydrogen batteries differ from lithium-ion batteries in that they require energy to operate, as well as to store and dispatch energy. Hydrogen batteries use electricity to split water through a process called electrolysis, before it stores H₂ as a gas or a liquid. When energy is required, it then reconverts via turbines or fuel cells. Hydrogen has high gravimetric energy density but low volumetric density, which means that it requires compression or liquefaction during processing, resulting in a growing but uneven infrastructure. Hydrogen systems respond more slowly compared to lithium-ion batteries, but they can sustain output for longer periods. This type of energy storage is most suited to seasonal or very long-duration.

Cost, efficiency and lifetime comparison

Both types of batteries have their benefits and challenges; we examine how they compare in terms of cost and efficiency. 

Capex and Opex: The wide-reaching research and development of batteries mean that the technology benefits from scale manufacturing, making them a significantly cheaper alternative to hydrogen fuel cells, although costs vary by chemistry and duration. Hydrogen, on the other hand, involves Capex across the board, with significant upfront investment required for electrolysers, storage, and reconversion assets.

Round-trip efficiency: Batteries typically experience a higher level of round-trip efficiency, whereas hydrogen loses energy at various stages, including electrolysis, compression and liquefaction, and reconversion stages, making them less efficient than they would otherwise be. 

Lifetime and cycling: Lithium-ion battery life is tied to depth of discharge and temperature, meaning extreme temperatures can reduce their lifespan. In some ways, hydrogen is more hardy: storage tanks and pipelines can last much longer, though they may require more frequent maintenance of components, such as stack turbine mechanisms. 

Levelised cost of storage (LCOS): The levelised cost of storage (LCOS) measures the cost of one unit of energy from a storage device over its lifetime. The estimated LCOS depends on the purpose for which the batteries are used and their duration, as well as the prevailing power pricing at any given time. Batteries are more effective in high cycling frequency and short duration scenarios. Still, hydrogen improves as a power storage option as the duration of usage extends and when waste heat or by-products such as oxygen have value.

Revenue stacking: Batteries are more revenue-rich from a frequency response perspective, whereas hydrogen tends to add more value when it can be sold for industrial or mobility applications, which diversifies the revenue of the storage systems.

Deployment reality: safety, siting and infrastructure

Storage facilities can be expensive, hazardous, and difficult to integrate into the grid, depending on the type you opt to use. 

Safety: Both storage types require robust standards due to the operating conditions and behaviours of the technology. Batteries, for example, can risk thermal runaway, while hydrogen is flammable with leak and embrittlement risks. To help mitigate the potential for failure, engineering controls are essential for monitoring the health and responding to issues in both technologies.

Siting and permits: Space can be a significant factor when choosing a storage technology. Batteries might be more suitable for urban or suburban sites with small footprints, where space is in short supply.  Hydrogen requires space for compressors, storage vessels, and setback distances, making it more suitable for remote locations with ample space.

Infrastructure readiness: Both technologies are at different levels of grid readiness due to their varying levels of integration. Batteries are more straightforward as they can connect directly to power electronics.  Hydrogen, however, is a little more complex. It requires a water supply, as well as power for electrolysis, storage, and either pipelines or road transport. 

Supply chain constraints: Storage system production can be threatened by shortages of certain materials required for manufacturing. Battery minerals, such as lithium and nickel, have historically been affected by geopolitical bottlenecks. Hydrogen storage sees restrictions more from an equipment and skills perspective. The acquisition of electrolysers, tanks, and valves can sometimes be challenging, as well as the skilled contractors required to operate hydrogen storage facilities.

Use-case matchups: who should choose what?

While both technologies are suitable replacements for their fossil fuel counterparts, it's essential to choose the right storage type for the right situation. For shorter bursts of grid support, batteries are typically preferred for backup electric power, peak shaving, and solar energy after dark. They currently dominate the light-duty and short-haul electric vehicle market; however, when long-duration energy release is needed, for example, in the case of long-range logistical transport, hydrogen’s longer duration capabilities are more suitable as a fossil fuel replacement. Hydrogen also performs well in applications where temperatures are extreme, in harsh and remote environments.