Move Over Lithium-Ion: Vanadium-Flow Batteries Gain Commercial Traction

Early this year, California became the first state in the U.S. to start making use of advanced, distributed energy storage systems. The list of  factors motivating the passage of California's energy storage mandate – AB2514 – is substantial. It encompasses integrating the fast-growing amount of renewable energy generation capacity coming online, enhancing grid reliability and resiliency, neutralizing the high and volatile costs of fossil fuels, and addressing the growing costs of climate change adaptation and degradation of ecosystems and natural resources.

Making billion-dollar investments in solar photovoltaic (PV) and lithium-ion (Li-ion) battery manufacturing, Elon Musk-led SolarCity and Tesla are gambling on their ability to dramatically lower the costs of solar PV and Li-ion battery storage technologies to cover all these bases. On Nov. 5, Southern California Edison (SCE) made its own foray into advanced energy storage, making U.S. power industry history when it awarded local capacity procurement contracts for over 260 megawatts of storage capacity across its Western Los Angeles Basin service territory.

Li-ion batteries lie at the core of most of these planned energy storage investments and deployments. But there are other alternatives that may be better suited when it comes to building an economically and environmentally sustainable energy infrastructure for the 21st century. Having closed its first sales contracts here in the U.S., Imergy Power Systems' vanadium-flow battery systems offer distinct advantages as compared to their Li-ion counterparts, company President Tim Hennessy told 3p. For those unfamiliar with vanadium, it is a soft element, found in about 65 different minerals, that naturally resists corrosion.

Putting flow into the battery storage landscape

Some 200 of Imergy's vanadium-flow batteries are up and running in countries around the world, storing energy for home and property owners; remote, off-grid commercial users; and across institutional microgrids. The majority are operating in India, where Imergy anticipates having 100 units installed by the end of 2014. The Fremont, California-based company's vanadium-flow batteries are also up and running in Kenya, Nigeria and South Africa, as well as in Europe (Slovenia).

On Nov. 5, Imergy announced its first sales in the U.S.: a purchase order for four of its 5-kilowatt/30-kilowatt-hour ESP5 vanadium-flow battery systems by Hawaii's Energy Research Systems.

Two of the ESP5s will be used by residential customers in Hawaii who intend to install the vanadium-flow batteries in conjunction with off-grid solar power systems. Another will be used to assess a variety of clean energy technologies, such as solar, hydrogen production and advanced energy storage, as elements of a microgrid.

The fourth installation in Hawaii will involve installing an Imergy ESP5 vanadium-flow battery in conjunction with a solar PV system at a technical school's science center. Having already earned LEED Platinum and Living Building Challenge certifications, the undisclosed technical school science center aims to take its entire campus off-grid using renewable energy and energy storage technologies.

On Dec. 1, Imergy announced it had won a second order for its vanadium-flow batteries here in the U.S. Three Imergy ESP30 vanadium-flow batteries are to be installed as part of a Smart Microgrid Project sponsored by the California Energy Commission and hosted by the U.S. Navy at its Mobile Utilities Support Equipment facility at Port Hueneme.

Sponsored by the California Energy Commission (CEC), Imergy's vanadium-flow batteries will serve as a core element of a smart microgrid test and evaluation. The Smart Microgrid project will focus on developing applications and use-case scenarios to optimize power consumption at military bases, college campuses, industrial parks and other institutions, according to the companies.

With Foresight Renewable Solutions the lead project developer, a 100kW/400kWh instance of Imergy's vanadium-flow battery technology will be put through its paces. The system will be rigorously assessed from summer 2015 to the end of the year in concert with up to 150-kW of solar PV capacity and the GELI (Growing Energy Labs, Inc.) Energy Operating System (EOS).

Four attributes will serve as the criteria for evaluation of the CEC-Navy smart microgrid's performance:

• Demand charge management: The project will demonstrate how well the system can release short bursts of energy when demand peaks occur, enabling users to reduce their electricity bills by lowering their utility demand charges;


• Load shifting: The project will prove how well the system can shift load from higher-cost times of day to lower cost times of day, enabling users to reduce their electricity bills by shifting load to times when electricity prices are lower;


• Solar firming and ramp rate control: The project will show how well batteries can smooth out the jagged nature of solar power production, helping solar power systems provide more consistent power throughout the day;


• Island mode: The project will demonstrate how well a photovoltaic solar system and battery storage, disconnected from the grid, can provide energy for a user’s critical loads during a given time period. This has potential to enable secure deployment of similar systems at remote, mission-critical facilities.

The unique chemistry of vanadium-flow batteries

Imergy's ability to take full advantage of vanadium's chemical properties makes its ESP series unique in the world of battery storage and ideally suited across the full range of advanced energy storage applications and project scales, CEO Tim Hennessy told 3p in an interview.

The batteries can can ramp up or down and pass through full charge/discharge cycles in a matter of milliseconds as compared to minutes for natural gas “peaker” plants. This enables the batteries to deliver electricity at utility-scale over periods of four, six and even eight hours. Rapid response and smooth ramp-up and ramp-down translate into a more efficient delivery of electricity at lower cost.

That also makes them very well-suited – and better matched than Li-ion battery storage systems – when it comes to integrating solar, wind and other intermittent renewable energy resources into power grids. These attributes are also of critical importance when it comes to recovering from grid outages and failures, which enhances the resiliency and reliability of electricity supply, Hennessy contends.

Longer discharge duration and greater scalability are other key differentiating factors of vanadium-flow batteries, Hennessy continued, making Imergy's ESP30s better suited for grid-scale applications. Furthermore, the electrolytes used never need to be replaced, they're nontoxic and non-flammable.

The key to success for advanced energy storage solutions is duration, Hennessy said. “You need storage that's low in cost on a levelized basis, over the entire lifecycle. [Battery storage] won't work if the batteries will only last for 300 or 400 charge/discharge cycles. You need something that lasts the equivalent of 15 to 20 years – the average life of PV systems.”

Imergy's vanadim-flow batteries fit the bill, Hennessy continued. Separating the energy conversion from energy storage elements of battery storage, “you only need to add more electrolyte[s] to add more hours of storage capacity. The incremetal cost of that is very low. Besides which, our vanadium-flow batteries are basically 'plug-and-play' with PV and even micro-wind systems."

The environmental benefits of energy storage

Whether vanadium-flow, Li-ion, pumped hydro, thermal, compressed air or flywheel, today's advanced energy storage solutions offer a big advantage to conventional use of fossil fuel-based grid storage and distribution assets: zero, or near-zero, greenhouse gas emissions and small environmental footprints.

Imergy uses recycled vanadium from environmental waste in manufacturing its advanced battery storage systems, adding to the CEC-Navy smart microgrid's advantages as compared to conventional alternatives.

Lower energy costs

Deploying solar PV and other renewable energy resources in combination with vanadium-flow batteries makes eminent sense in places where grid power has proven uneconomic or otherwise inaccessible.

Imergy's vanadium-flow batteries are already lowering energy costs, greenhouse gas emissions and environmental pollution in places like India, Kenya, Nigeria and South Africa. Imergy sees loads of prospects – pardon the pun – across the Caribbean, Central and South America, as well as Hawaii, California, New York and other U.S. states.

“Anywhere where diesel is being used to generate electricity, consumers are going to be paying anywhere from 40 to 80 cents/kWh for that energy,” Hennessy said. “If you correctly include a flow battery, you can improve operational and maintenance costs. And if you add solar, you can bring costs down to the 30- to 25-cent range. That sort of spread is obviously significant per kWh, and there's your payback.”

*Image credits: 1) Eos Energy Storage; 2), 3) Imergy Power Systems