Primus Power: Light Bearer of Flow Battery Technologies

Primus Power: Light Bearer of Flow Battery Technologies

Tom Stepien, CEO, Primus PowerTom Stepien, CEO
When it comes to the energy sector, cities are betting upon the decentralized, bi-directional distribution capabilities of smart grids to tap energy from both conventional and non-conventional resources. However, intermittencies in the availability of clean energy from sources such as wind and solar, call for efficient means of energy storage. On the other hand, there are large consumer entities, such as factories and plants exploring ways to relieve themselves of peak-load pricing. Batteries have the potential to curb these pain points single-handedly, and the industry has widely acknowledged that it is more economical to serve peak loads with a distributed battery asset than building new substations, which is not only an expensive challenge but is also time consuming. Technological developments and the adoption of batteries were slow paced until recently. Today, the potential of batteries as key elements for efficient energy utilization is becoming more apparent. As such, California-based Primus Power has positioned itself as the light bearer of battery technologies for the smart grid.

The company provides stable zinc bromine flow batteries which are a lesser-known gem in the battery space. Unlike its rather popular counterpart, the Li-ion batteries—that find their best use for applications in electric vehicles—flow batteries are cutout to work best on the grid and are nontoxic with zero fire risks. “Consider flow battery as the marathoner and Li-ion batteries as the sprinter. Flow batteries are best suited for longer duration energy intense applications and Li Ion’s sweet spot are shorter-power applications,” says Tom Stepien, the CEO of Primus Power. The company holds more than forty patents worldwide issued by eleven countries and has redefined the design of flow batteries to make them truly long-lasting.

Flow batteries are best suited for longer duration energy intensive applications

Breaking away from conventional flow battery designs that consist of two tanks, Primus’ second generation of flow battery, the EnergyPod 2, leverages density differences of the electrolytes to work with just a single tank. This drastically reduces the battery size and design complexities. Generally, the separator within a battery, owing to its role as an ionic filter, degrades over time—in about five to six years over 4,000-5,000 cycles. EnergyPods address this predicament by resorting to ‘ion-separation by flow-control,’ thereby eliminating the need for separators at all. Furthermore, as opposed to graphite electrodes, Primus deploys titanium, as it is more conductive, does not change composition over time, can be made thinner than graphite, and more importantly, has a lower cost on the important dollar per kWh metric. With all its innovative makeover, Primus’ flow batteries can last for up to 20 years with routine maintenance.

Another big novelty of Primus Power’s EnergyPod is its size, given the fact that conventional flow batteries occupy the area of a forty-foot container and may not prove ideal for smaller industrial facilities. Each unit of EnergyPod, which roughly covers an area of ten square feet, can be stacked together. The company has thus imbibed a high degree of flexibility, in terms of installation, which any mid-size consumer can leverage. “Peak demand charges can account for up to 40-50 percent of an industrial’s customer electric bill. By putting a battery into the equation, one can reduce those demand charges and the cost of installing the battery can also be easily recovered in four to five years,” explains Stepien.

Owing to a multitude of unique advantages, even the United States Department of Defense is a client of Primus Power. Having crossed nine years since the inception of the company, Stepien recalls the early years wherein the team strived to build efficient flow batteries based on research, regular customer feedback sessions and multitudes of trials. The company has raised about $100 million of equity funding, $20 million from the Department of Energy and has recently received a grant from the US Trade and Development Agency, which will further help Primus Power in delivering revolutionary energy storage system.

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Primus Power


Tom Stepien, CEO

Breaking away from conventional flow battery design, Primus’ flow batteries can last for up to 20 years with minimal maintenance