While solar and wind energy hold great promise for the future, the biggest challenge facing the mass commercialization of these technologies is the ability to store the electricity they generate. By gaining the ability to store power from these intermittent sources, one would have access to this power whether night or day, windy or calm.
To address this challenge, flow batteries are on the cutting edge of energy storage and making the promise of solar and wind a reality today. Like any battery, the energy is stored chemically. However, what makes a flow battery significantly different than a standard fixed battery is that the energy storing media, which are typically strong acids, are stored in vats of virtually any size. This allows the battery capacity to only be constrained by the size of the electrolyte vats. This is a huge advantage.
While there are several different flow battery technologies, some of the most promising are based on using strong sulfuric acid as its electrolyte. While the strong acid electrolyte provides more battery capacity than weaker acids, there are challenges in handling these strong acids and protecting the flow battery’s sensitive system. This is especially true as the battery’s electrical stack is in a high purity environment that cannot tolerate corrosion or contamination even at minute levels.
One critical component needed to enable these flow batteries to operate properly is a corrosion resistant heat exchanger. At the heat exchanger, the strong acid electrolytes are most corrosive and need to be cooled. To make these strong sulfuric acid flow batteries commercially viable, a heat exchanger solution was needed that could meet the following criteria:
- Provide a zero corrosion rate, in a range of sulfuric acid concentrations and elevated temperatures.
- The heat exchanger material cannot deteriorate or contaminant sensitive fuel cell components.
- Be compact and have a small footprint.
In order to tackle these challenges, Ultramet CPT’s Ultra-Metal tantalum surfaces were deployed on dozens of corrosion resistant heat exchangers. Working closely with Alfa Laval and their heat exchanger designers, dozens of acid resistant heat exchangers were put into service making the flow battery concept and commercial reality storing hundreds of mega-watts of power.