Lithium battery schematic. All batteries work on the same general principles.

Critics of renewable energy used to complain about the cost. Now that it is cost competitive with fossil fuels, they complain that it is intermittent. The recent emergence of energy storage should finally silence the skeptics.

Energy storage offers a way to integrate unlimited solar and wind power into the grid. It also offers a more economical way to manage the daily variations in demand for electricity than fossil fuels.  Fossil fuels do so by starting and stopping expensive and inefficient peaking plants.

Lithium batteries have provided the impetus for the recent dramatic surge of interest in energy storage. They are not a viable long-term solution. The future belongs to flow batteries, and probably vanadium flow batteries.

Lithium energy storage

Tesla Motors introduced its first electric car to the public in 2008. Traditional automakers have since introduced their own electric models.  In 2015, Tesla introduced the Power Wall to provide energy storage for residential solar panels. Renewable energy and electric vehicles have become an irreversible trend. Electric vehicles can even help utilities integrate renewable energy into the grid.

So far, lithium ion batteries dominate both storage and transportation. The growing demand for lithium batteries means growing demand for lithium. In 2018, the largest manufacturers of lithium batteries worldwide took steps to meet it.

Both residential and utility-scale storage grew dramatically in 2018. In North America, the residential storage market is expected to triple by the end of 2019 from 15,000 installations in 2018.

Puerto Rico has begun to include batteries in new solar installations as part of the efforts to recover both from hurricanes and the incompetence of the island’s electric utility. In California, utilities expect to add storage parks that will add up to 2.2GWh of capacity.

Asia, Australia, and Europe, at least, expect similar expansion of lithium storage systems.

It’s not only large, rich countries where energy storage is growing. Megapower, a company in Barbados, has sold and serviced electric vehicles throughout Caribbean countries since 2013. In addition, it offers a variety of renewable energy services.

Batteries for electric vehicles eventually outlive their usefulness for transportation, Megapower can repurpose them to provide storage for solar installations. Taking back batteries can reduce the replacement cost for its customers.

And using battery storage has enabled the company to go off grid entirely. Its cars, lights, air conditioning, refrigerators, and office equipment all rely on solar power stored by old batteries.

The weaknesses of lithium

Portland General Electric lithium ion battery system

So far, most energy storage applications rely on lithium. The future appears to lie with vanadium, at least for utility-scale storage. Lithium will remain the predominant technology both for residential storage and electric vehicles for the foreseeable future.

Lithium batteries may be flat like a hearing aid battery or cylindrical like a flashlight battery. They are small. Grid-scale storage requires hundreds of thousands of them. They get hot and can explode. Their efficiency varies with temperature and the age of the battery. Sooner or later, they wear out.

Another environmental consideration: lithium comes from mines. Plenty of other applications, including medicine, compete for the same supply. Lithium batteries require rare earth metals and other mined materials, too. It is so far not economical to recycle any of the metals a lithium battery. So lithium has all the same environmental impacts of mining operations plus a disposal problem.

Why the future of energy storage is vanadium

Vanadium flow battery–likely alternative to lithium ion battery system–Schweitzer Engineering Laboratories, Pullman, Washington

Conventional batteries store energy as the electrode material. Flow batteries store it as the electrolyte. Most commonly, they use two different liquid energy sources separated by a membrane. The electrolyte flows from a tank through the system and then returns to the same tank.

Flow batteries can be quickly recharged. Their power and energy ratings are independent of each other. Therefore, each can be separately optimized as required by different applications.

Other kinds of flow batteries may play a role in energy storage. Most research and commercial development, however, focus on vanadium flow batteries. Vanadium batteries range from large (the size of a fish tank) to huge.

That makes them more easily scalable. Scaling up a lithium system means installing more batteries. Scaling a vanadium system means only building a larger tank. And so vanadium flow batteries cost less to build than utility-grade lithium systems. They cannot overheat or explode and can perform much longer without significant deterioration of capacity.

Vanadium batteries are less efficient than lithium. Although they have lower energy-related costs than lithium, they have higher power-related costs. That may explain in part why a technology known to be commercially suitable for energy storage since 1980 has not yet captured a larger part of the market.

Virgin vanadium must also be mined, but vanadium for batteries can come from mine tailings, depleted oil wells, and other wastes. It is not necessary to replace the vanadium in a flow battery, so recycling is not an issue. Vanadium flow batteries can help solve environmental problems lithium causes.

Related posts:

Energy storage has arrived (2015)
Electric cars and an emerging breakthrough in grid stability (2017)
Energy storage gains momentum from record quarter (2017)

Sources:
The electric vehicle revolution is alive in Barbados / James Ellsmoor, Forbes. December 20, 2018
Energy storage outlook for 2019: e-mobility, clean energy technologies and lithium batteries / Livio Filice, Renewable Energy World. January 15, 2019
Lithium or vanadium: in energy storage, it’s no contest / Bill Watkins, Renewable Energy World. July 10, 2014
Vanadium redox flow battery (VRFB) for solar storage / Barry Tonkin, Sun Power Source. December 31, 2018

Photo credits:
Lithium battery schematic. Public domain from Wikimedia Commons
Portland General Electric lithium system. Some rights reserved by Portland General Electric
Photo by UniEnergy Technologies. Public domain from Wikimedia Commons