Lithium-ion batteries are where it all begins. They’re small, efficient, and quick to react—ideal for homes with solar on the roof. Systems such as the Tesla Powerwall and LG RESU have made it more convenient than ever before to store solar energy throughout the day and consume it during the night.

Lithium-ion batteries are generally around 90 to 95 percent efficient. So, most of the energy we put away can be utilized. They work well for short-term applications—several hours’ worth of consumption—and are fairly straightforward to install. However, they do have some negative aspects. Their efficiency can diminish over time, particularly in Australia’s high-temperature environment, and are not the best for long-term storage. Nonetheless, for day-to-day household applications, they have been found to be a convenient and functional option.

Looking Beyond: Flow Batteries

When we must store energy for longer times—such as through a series of cloudy days or peak demand—flow batteries can provide an improved alternative. These systems utilize tanks of liquid electrolytes to hold energy, and they can be scaled up at will. Need more storage? Simply add larger tanks.

Flow batteries are ideal for commercial or off-grid use where reliability is important and room can be afforded. They have long lifetimes and do not degrade rapidly, so while they are more expensive to purchase upfront, they prove cost-effective in the long term. In remote Australia where long-term reliability is paramount—off-grid farms, mines, or remote communities—flow batteries are already delivering their worth.

Pumped Hydro: Utilizing the Topography

Australia enjoys a natural advantage as far as pumped hydro energy storage is concerned. The system employs surplus energy to pump water from a lower reservoir to an upper one. Subsequently, when one requires electricity, the water is let flow down through turbines to produce electricity.

It’s a simple concept, but it can do something big. Schemes like Snowy 2.0 are intended to supply firm, long-duration storage to back the increasing proportion of renewables in our national supply. Pumped hydro is very efficient and can run for decades. It does need huge initial investment and suitable geography, but Australia’s terrain is ideally suited to such an answer.

Compressed-Air Storage Is Getting Noticed

Compressed air energy storage is another technique that’s beginning to pick up steam. It stores energy by compressing air in tanks or below ground spaces. When we require power, that air is allowed out, is heated up, and used to drive turbines.

While it’s not yet widely adopted in Australia, the potential is there—especially in areas with suitable geological formations. It offers multi-hour storage, making it a great complement to wind and solar farms that don’t always generate on schedule. We’ll likely see more of this technology in the years to come.

Flywheels Offer Fast Response and Reliability

Flywheel storage systems differ. Rather than storing electricity thermally or chemically, they store it mechanically. A massive rotor is spun quickly, and energy is reclaimed by decelerating it.

These systems are optimum for use in applications requiring brief periods of power or quick response times, such as frequency regulation or voltage stabilizing. They’re also extremely long-lasting—years with little maintenance. For remote industries or mission-critical infrastructure that can’t risk interruptions, flywheels are an intelligent and dependable choice.

Storing Energy as Heat

Another method that we cannot ignore is thermal energy storage. In this method, energy is stored as heat using materials such as molten salt or water. That heat is then utilized later for the production of steam to generate power or used as heating.

In concentrated solar power facilities, for instance, light is concentrated by mirrors to warm a fluid that’s stored in tanks. Power is then able to be produced even after nightfall. Given our long sunny days and vast country, Australia is well-placed to increase the application of thermal energy storage—particularly in off-grid or hybrid applications.

Lifting for Storage: Gravity-Based Systems

Gravity storage may seem like science fiction, but it is founded upon pretty simple physics. These systems employ electricity to raise a heavy object, and then discharge the object at some future time to create energy as it falls back down.

The attraction of this technology is its simplicity and ruggedness. There are no chemicals used, and the mechanical parts are simple to maintain. Although still in the development phase, gravity systems are scalable and hygienic, and they may be an option for Australia’s regional and industrial areas in the future.

Hydrogen: Storage for the Long Haul

Perhaps the most promising field of development is hydrogen energy storage. We can electrolyze water using excess renewable electricity, separating it into hydrogen and oxygen. We can store that hydrogen for days, weeks, or months, then use it to produce electricity, fuel vehicles, or assist industry.

Hydrogen is particularly attractive for seasonal and long-duration storage. There has already been significant government and industry interest in green hydrogen, with large-scale projects in Western Australia and South Australia. Technology may not be there yet, but hydrogen can become a key component of our national energy strategy—not only as storage, but as a future clean fuel.

Matching the Solution to the Need

So how do we know what energy storage solution to use? It all comes down to what we want to accomplish. If we just want to light our homes at night, a lithium battery may be sufficient. But if we’re powering a solar farm, keeping the grid stable, or providing power to off-grid communities, we’ll require something more heavy-duty.

For the most part, the most intelligent strategy is to hybridize technologies. Short-term requirements could be provided for using batteries or flywheels, and long-term storage might be drawn from pumped hydro, hydrogen, or compressed-air systems. Blending and matching, we can generate stronger, more flexible energy systems.