SINGAPORE – As Singapore seeks to harness as much sunshine as it can to maximise its limited renewable energy sources, it needs to improve technologies that can store excess solar energy from the day.

       One such technology is energy storage systems (ESS), which are essentially giant batteries packed in containers that store electricity for later use.

       The Energy Market Authority (EMA) has awarded grants of $7.8 million to two companies to advance ESS technology – from installing ESS underground to free up land, to exploring a different type of battery.

       The Straits Times unpacks how ESS work, and why emerging technologies are crucial.

       Commonly run on lithium ions, ESS store energy during sunny days when solar panels generate more electricity than consumed. At night or when electricity demand peaks, ESS will discharge electricity for use.

       The systems can also serve as a form of backup during power supply disruptions.

       The International Energy Agency has projected that global battery storage capacity is expected to almost triple by 2030.

       By signing up, I accept SPH Media's Terms & Conditions and Privacy Policy as amended from time to time.

       Dr Wesley Zheng, chief executive of Posh Electric, one of the two firms awarded grants, said that ESS are costly due to high upfront capital costs, including raw materials, technological complexity and requirements to integrate with the power grid.

       A one megawatt hour (MWh) system could cost between $450,000 and $800,000, with a payback period of seven to 10 years, he added.

       Yes, there are ESS of various scales deployed here. The largest is on Jurong Island, with more than 800 large-scale battery units across 2ha of land installed by Sembcorp Industries in 2023.

       With a capacity of 285MWh, the storage system can, in a single discharge, meet the electricity needs of around 24,000 four-room HDB households for one day.

       At the Singapore International Energy Week conference on Oct 21, Deputy Prime Minister Gan Kim Yong said EMA and Sembcorp are in discussions to expand the system on Jurong Island.

       At the conference on Oct 23, EMA chairman Richard Lim added that Sembcorp will stack the ESS units and employ units that store twice as much energy as existing ones on Jurong Island.

       VFlowTech – the other company awarded grants for advancing ESS technology – has a storage system on Pulau Ubin that discharges 50 kilowatts of electricity for 24 hours, reducing the island’s reliance on diesel by nearly 100,000 litres per year.

       Instead of using lithium ions for the battery, the company uses another metal called vanadium, which is safer and less susceptible to fires.

       On Oct 22, VFlowTech entered an agreement with fuel and chemical storage company Advario Asia Pacific and JTC Corporation to scale up VFlowTech’s vanadium flow batteries in Advario’s industrial tanks on Jurong Island. The system is expected to be fully deployed by 2024.

       This project repurposes existing oil tanks to store vanadium-ion liquid that comes from recycled industrial waste.

       Doing so would free up more land for other uses, but fire risks, among other safety issues, need to be tackled before the systems can be built underground.

       VFlowTech received a grant to find out if an underground ESS is possible in Singapore. The company will first conduct a feasibility study, which includes looking into fire safety measures for an underground system.

       “Since underground space is often under-utilised and cheaper, deploying energy storage systems in these areas... supports the efficient use of building basements for energy storage,” said Dr Avishek Kumar, VFlowTech’s CEO.

       On top of identifying suitable underground locations and looking into fire safety, the project will study spill control, electrical safety and emergency response measures.

       VFlowTech’s storage system will combine two types of batteries – lithium-ion and vanadium flow – drawing on their respective strengths. The conventional lithium-ion batteries store large amounts of energy in a small space. Vanadium flow batteries are suitable for long-duration storage, and have a reduced fire risk.

       VFlowTech is currently in discussion with local partners to explore potential sites for the underground ESS. If regulatory approvals are obtained, it will build the underground infrastructure and the ESS.

       Posh Electric specialises in developing ESS that run on sodium-ion batteries. With the grant, the company will study the viability of this newer type of battery for energy storage in Singapore.

       Sodium is 1,000 times more abundant on earth compared with lithium, which has to be mined in specific areas, such as briny water and rock ores. Lithium is also highly coveted for electric cars, phones and laptops.

       Because of sodium’s abundance, sodium-ion batteries could potentially be a cheaper alternative to conventional lithium-ion batteries in the future, said EMA.

       “Sodium can be easily sourced from seawater and salt deposits... This abundance reduces the need for intensive underground mining operations that are currently necessary for lithium extraction,” said Posh Electric’s Dr Zheng.

       Lithium is also tied to supply chain risks, price volatility and environmental concerns, he added. Moreover, sodium-ion batteries store slightly smaller amounts of energy compared with their lithium counterpart.

       Posh Electric will test a 1MWh system alongside rooftop solar panels at geotechnical engineering firm Utraco’s facility in Tuas.

       The project will also look at the effectiveness and performance of the ESS in Singapore’s tropical climate.

       Dr Zheng said that while sodium-ion battery projects are being tested in China, their use remains limited elsewhere.

       Correction note: In an earlier version of the story, we quoted EMA’s chief executive instead of EMA’s chairman. This has been corrected.