Energy storage can balance supply and demand. (PHOTO: VCG)

By QI Liming

In the transformation of traditional fossil fuels to renewables, the issue of new energy storage is one of major concern—where do we get our energy from when the wind is not blowing and the sun is not shining?

A dive into the current situation and future development of new energy storage reveals understanding, innovation and new technology going forward.

Why does renewable energy need to be stored?

According to UK magazine Impakter and UK National Grid, as the world moves towards a more renewable and decentralized energy system, energy storage is becoming increasingly important.

Energy storage technologies allow us to store energy when it's available and release it when it's needed, providing a range of benefits for the grid, businesses, and households.

Efficient energy storage is crucial for the green transition. One of the primary reasons is the need to manage variable energy supply. Renewable energy sources like wind and solar are intermittent and don't provide a consistent energy supply. Energy storage can help smooth out these fluctuations by storing excess energy when it's available and releasing it when needed.

As many renewable energy sources are becoming cheaper, storing them and using them later can be very cost-efficient for society.

Energy storage can also provide backup power during emergencies and help reduce peak demand, which occurs when many people use electricity simultaneously.

By storing excess energy during off-peak hours and releasing it during peak hours, energy storage can help prevent blackouts and reduce the need for expensive infrastructure upgrades or reliance on fossil fuels.

Improving energy storage infrastructure and overcoming the issues posed by the intermittent renewable energy supply is essential to achieve decarbonization targets and drastically help eliminate our fossil fuel dependence.

How is renewable energy stored?

When asking how to store renewable energy efficiently, one concept needs particular attention, this is long duration energy storage (LDES).

According to Financial Times, LDES generally refers to any form of technology that can store energy for multiple hours, days, even weeks or months, and then provide that energy when and if needed. It is an essential technology if the world is to increase the proportion of renewable energy.

Various technologies are being worked on, with varying degrees of success, but the benchmark is pumped hydro storage, partly because of its high round-trip efficiency: the proportion of the energy stored in this way that can later be extracted is around 80 percent.

It is technology that has been around for more than a century, involving the movement of water between lower and higher reservoirs to store and generate energy. However, it remains the most used storage method globally, with around 160GW of power capacity installed as of 2021. A further 130GW is planned or under construction, with China accounting for around 60 percent of the new plans.

According to South China Morning Post, compared with pumped hydro storage, electricity storage processes that use emerging technologies such as compressed air, flywheels and electrochemical are the trends to follow.

Electricity storage process is more flexible when it comes to site selection, and has other advantages, including short construction periods, faster and flexible response and more diverse functions.

What are the most promising energy storage technologies?

 Frank Wouters, co-president of the LDES Council, said that LDES remains a nascent market without an established business model. Both regulators and industry players are still trying to figure out what the right business model is, he added.

According to research blog StartUs Insights, energy storage is undergoing a rapid transformation wherein research is underway to develop efficient long-lasting solutions.

Currently, the energy storage sector is focusing on improving energy consumption capacities to ensure stable and economic power system operations. Broadly, trends in energy storage solutions can be categorized into three concepts:

    ● Moving away from the traditional lithium-ion batteries toward innovative battery chemistries that offer greater stability, density, and shelf life.

    ● Developing storage solutions that store intermittent renewable energy efficiently and also scale it up to power large geographical areas.

    ● Transitioning from centralized energy storage to a more flexible and portable distributed form of energy storage.

Meanwhile, Greentech Media evaluated the five most promising long-duration storage technologies left standing: pumped hydro,  stacked blocks, liquid air, underground compressed air, and  flow batteries, while Impakter's list is a little bit different: thermal energy storage, pumped hydroelectric storage, green hydrogen, and gravity batteries.