Long-duration energy storage holds the key to solar and wind power dominating the energy sector. This is because solar and wind energies are produced intermittently throughout the year, thus raising the need for complementary energy storage solutions to solve the intermittency conundrum. The most obvious energy storage systems to use would be the lithium-ion batteries since they are currently the main suppliers of new storage capacity. However, producing long-duration lithium-ion batteries would be so expensive that using them as wind and solar energy reservoirs would be counterproductive. For an energy storage solution to play the long-duration role, production must be achievable within an acceptable price point and development cycle. For a long time, there hadn’t been a viable contender for long-duration storage because companies that attempted production didn’t succeed in selling their products and over time, they went under due to bankruptcy. Thankfully, things are beginning to look up now that Southeast Asia is heavily invested in deploying floating energy storage systems (ESS). This new innovation is the perfect solution for the land scarcity issue power producers in this region have been facing. The successful deployment of floating ESS will enable grid operators in Singapore, the Philippines and other Asian countries to supply affordable energy to consumers. Such emerging innovations create the long-awaited push for long-duration storage solutions in Asia and other parts of the world that register a high concentration of wind and solar farms. Governments and private companies are investing heavily in renewables and long-duration storage technologies with the hopes that green energy will eventually replace carbon fuels.

In light of the new developments in the energy sector, here are the surviving long-duration contenders you should know about.

1.    Pumped Hydro

Pumped hydro is a mid-century technology that generates power using the principle of gravity. Ideally, water is stored in a reservoir lifted off the ground so that power is produced when the water descends. Pumped Hydro has been around for years, and it’s still greatly relied upon for electricity generation across the globe. Water reservoirs are invaluable assets in the energy industry due to their massive capacities. The amount of energy they can hold surpasses the capacity of most energy batteries in the world. Modern pumped hydro constructions are focusing on building advanced water reservoirs that don’t interfere with the flow of water bodies. Quite a number of pumped hydro construction projects are inching forward, and hopefully, the industry will deliver reliable plant additions.

2.    Stacked Blocks

What if, instead of relying on batteries, the global energy industry found a way to use robots to store excess power? This is the idea behind using stacked blocks as a long-duration storage technology. An automated robot would stack together energy blocks in a tower that dropped an energy block every time power needed to be released. This long-duration storage technology would borrow from Pumped Hydro’s gravity principle. Stacked Blocks would leverage the planet’s geographical diversity to remain operational into the future. With today’s advancing robotics technologies, private energy companies can build robotic cranes to serve as labor in stacking up the blocks.

In 2019, Energy Vault, the company behind this gravity storage idea, secured $110 million in funding from SoftBank. This alone is proof that this is a vision that can be actualized. While Energy Vault hasn’t yet communicated if this gravity storage solution is up and running, big players in the energy sector are positive that this idea will be brought to fruition. Meanwhile, it’s a concept that will take the general public to warm up to, especially now that the energy sector is exploring technologies that slightly deviate from standard operating practices. Energy Vault would have to find the most suitable way to launch stacked blocks to avoid spooking customers.

3.    Liquid Air

Liquid Air is yet another long-duration contender that’s set to be introduced by a UK-based startup that has been running pilots for over a decade. After refining its technology, Highview Power is hoping to start developing large-scale power plants. The mechanism behind Liquid Air is storing cooled and pressurized air in off-ground tanks. Highview Power hopes to use advanced supply chains to provide grid operators with reliable storage. For proof of concept, Highview Power will self-finance early projects to show potential investors that it’s a project worth giving a chance.

4.    Underground Compressed Air

Storing energy underground isn’t a new concept, but pioneering projects for underground energy storage failed to kick off. Private energy companies have been trying to improve on the initial concept for years with no success. The idea is to leverage surplus electric energy to drive pressurized air into an underground storage tank. Automation would then be used to release the compressed air and re-generate electricity. Hydrostor, a Canadian-based energy company, figured out how to use underground compressed air as a long-duration energy storage solution. The company intends to leverage abandoned caves to store pressurized air and use water to suppress the pressure. To generate electric power, reservoir operators would use the cave’s natural cavities to control the amount of air released. At the moment, Hydrostor is in the process of demonstrating to qualified investors that this idea can work.

Flow Batteries

Last but not least is Flow Batteries that have been considered viable options ever since the long-duration conversation began. However, this technology hasn’t had much success in the marketplace, even though several battery scientists swear by it. The principle behind flow batteries is applying redox reaction to charge and discharge energy generated from liquid electrolytes in circulation. Interested energy companies are currently working on value-scale projects to test the viability of this technology. Flow batteries’ main selling point is cheap large-scale production because the project requires an abundantly available raw material.

Wrapping Up

The ultimate goal with long-duration storage technologies is to achieve 100% carbon-free power around the globe. While production of different long-duration energy solutions are still in their infancy, just the fact that production is underway is a great step in the right direction. Successful launching of long-duration storage solutions will ensure grid operators no longer have to rely on gas plants to fill the gap of renewables’ ups and downs.

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