Background
As the world is moving towards clean energy, countries are setting up ambitious clean energy targets. Declining costs of wind and solar energy-based power generation projects are facilitating higher penetration of renewable energy into the generation mix. This has generated the need for an energy storage solution to manage the intermittency of renewable energy sources. Grid balancing remains the key challenge in the integration of renewable energy into the grid. Energy storage plays a role in balancing the grid as well as can act as an alternative for inefficient peak power gas plants that are deployed to provide flexibility. Though Li-ion batteries have captured the market, certain limitations associated with these batteries create the need for alternative technologies. Li-ion batteries are not cost-effective when considered for a longer duration of storage hours. Multiple fire incidents have raised the issue of safety around these batteries. Further, the shorter life cycle of Li-ion batteries is yet another concern. This makes a case for long-duration, safe, and durable energy storage technologies.
These alternative battery technologies are targeted for the off-grid energy storage market as well. Renewables, combined with long-duration energy storage, delivers the perfect power solution for isolated lands or areas with low power supply reliability. Commercial and industrial customers are also getting benefited by these technologies.
Battery Technologies – Alternatives to Li-ion Batteries
A lot of efforts are being put in to find a technology that overcomes the limitations associated with Li-ion batteries and is yet cost-competitive. Many companies have entered the market with battery technologies that can be an alternative to Li-ion battery technology. Some of these technologies are discussed below.
Aqueous Air Battery by Form Energy
Form Energy, a Massachusetts-based start-up founded in 2017, has developed Aqueous Air Battery, which can store
energy for up to 150 hours. The start-up claims that this battery is extremely cost-competitive with lithium-ion batteries on a dollar-per-kilowatt basis. The battery is low-cost, safe, scalable, and uses some of the safest, cheapest, most abundant materials. In May 2020, Form Energy announced a pilot project with Great River Energy to deploy its super-long-duration energy storage technology. The pilot project is planned to support the integration of 1,100 megawatts of new wind capacity. The project size is 1 MW and it’s the first utility deal of Form Energy. The start-up received $40 million in Series B funding and $9 million in Series A funding. The company has developed software that offers efficiency and cost-saving benefits modeling of using Form’s long-duration storage. The software also identifies the value of the entire electricity ecosystem.
Zinc Air Battery by Zinc8
Zinc8, a Canada-based start-up founded in 2012, has developed an innovative battery technology that uses zinc and 
air as fuel. The company claims to provide the lowest cost of storage in the market for long-duration applications. The technology completely decouples the linkage between power and energy. Scaling Zinc8’s battery system requires increasing the size of the fuel tank and quantity of recharged zinc fuel, unlike lithium-ion technology, which requires new stacks to scale. The battery is durable with zero capacity fade over an extended lifetime and is robust in performance till the end of the life cycle. The non-flammable and non-toxic technology is safe and offers a lower cost per kWh. The battery system also has the advantage of established stable supply chains for mass manufacturing. Zinc8 system finds its application in utility-scale projects, remote microgrids, and behind-the-meter energy storage for commercial & industrial customers. The company announced its first private sector deployment agreement with Digital Energy Corp in March 2020. The project is of size 100kW/1.5MWh and is to be installed in Brooklyn, New York. The project cost is C$2.5 million and is being financed by the New York State Energy Research and Development Authority (NYSERDA).
Vanadium Flow Battery by Invinity Energy Systems
Leading UK & North American flow battery firms – redT and Avalon have merged in March 2020 to form Invinity 
Energy Systems. The new company aims to create global leadership in Vanadium Flow Batteries. The company claims that the aqueous solution used to store energy in its vanadium redox flow battery never degrades, even under continuous maximum power and depth of discharge cycling. The safe and stable chemistry of the vanadium electrolyte offers non-flammable operation. The battery is economical with 20,000+ deep discharge cycles over the lifespan and very little maintenance. Modular design architecture offers system resilience as there is no single point of failure. The battery is scalable and can store energy for 2-12 hours. Invinity Flow Battery finds its application at commercial and industrial sites, in storage systems to facilitate renewable energy integration, ancillary services, and trading, and in stand-alone or renewable energy coupled off-grid storage projects. The company has installed its vanadium flow batteries at more than 40 sites across Europe, North America, Africa, Asia, and Australasia.
Iron flow battery by ESS
ESS has developed an iron flow battery that is safe, clean, sustainable, scalable, and can provide long-duration 
energy storage for a low cost. The battery uses iron, salt, and water for the electrolyte, making it non-toxic, non-hazardous, and completely recyclable. It can provide over 20,000 cycles of power with minimal maintenance. The battery chemistry remains stable without any degradation for an unlimited number of deep-cycle charge and discharge cycles. The battery offers efficient energy management through energy flow and the rate of storage control. ESS claims that its technology leads to the Levelized cost of storage. The battery can store energy for 4-12 hours and has an operating life of around 25 years. ESS energy storage system is suitable for utility-scale applications, off-grid & microgrid applications, and commercial & industrial customers. ESS has partnered with multiple stakeholders to accelerate the deployment of its battery. It raised $30 million in October 2019 and $13 million in December 2017.
Going Forward
The need for long-duration and safe energy storage technology is being underlined on the backdrop of ambitious clean energy targets. The alternative battery technologies are emerging as a result of continuous efforts to develop suitable technology for large-scale clean energy integration. Though these technologies are cost-competitive with Li-ion batteries and claim to overcome the limitations of Li-ion batteries, it will take some time for these technologies to prove their effectiveness for grid-scale, off-grid and behind-the-meter applications. Many of these technologies are in the phase of being deployed in pilot projects and are not yet fully commercialized. These technologies are set to witness accelerated deployments once those demonstrate effectiveness in early-stage deployments.
ESS has developed an iron flow battery that is safe, clean, sustainable, scalable, and can provide long-duration energy storage for a low cost. The battery uses iron, salt, and water for the electrolyte, making it non-toxic, non-hazardous, and completely recyclable. It can provide over 20,000 cycles of power with minimal maintenance. The battery chemistry remains stable without any degradation for an unlimited number of deep-cycle charge and discharge cycles. The battery offers efficient energy management through energy flow and the rate of storage control. ESS claims that its technology leads to the Levelized cost of storage. The battery can store energy for 4-12 hours and has an operating life of around 25 years. ESS energy storage system is suitable for utility-scale applications, off-grid & microgrid applications, and commercial & industrial customers. ESS has partnered with multiple stakeholders to accelerate the deployment of its battery. It raised $30 million in October 2019 and $13 million in December 2017.
Going Forward
The need for long-duration and safe energy storage technology is being underlined on the backdrop of ambitious clean energy targets. The alternative battery technologies are emerging as a result of continuous efforts to develop suitable technology for large-scale clean energy integration. Though these technologies are cost-competitive with Li-ion batteries and claim to overcome the limitations of Li-ion batteries, it will take some time for these technologies to prove their effectiveness for grid-scale, off-grid and behind-the-meter applications. Many of these technologies are in the phase of being deployed in pilot projects and are not yet fully commercialized. These technologies are set to witness accelerated deployments once those demonstrate effectiveness in early-stage deployments.
