The German energy company RWE has begun testing a new battery technology originally developed by NASA for the International Space Station (ISS). These batteries are now being implemented in the company’s wind and solar energy projects.
As part of a pilot project in Milwaukee, Wisconsin (USA), RWE is evaluating the potential of nickel-hydrogen batteries known as Energy Storage Vessels (ESV). Manufactured by EnerVenue, a company specializing in advanced metal hydride technology, these batteries can withstand more than 30,000 charge and discharge cycles, making them a leader in commercial solutions for long-term energy storage.
What Are Nickel-Hydrogen Batteries?
With the global transition to renewable energy sources, the need for innovative storage technologies is becoming increasingly urgent. Conventional lithium-ion batteries are often expensive and carry risks of thermal runaway, requiring additional cooling, ventilation, and fire suppression systems to ensure safe operation. Nickel-hydrogen batteries present an alternative approach.
These batteries function similarly to traditional rechargeable batteries, with sets of electrodes enclosed in hermetically sealed gas tanks. Hydrogen is used at the anode and nickel hydroxide at the cathode. During charging, hydrogen gas is formed, which is then oxidized during discharge, converting back into water. The internal gas pressure is only 5% of that found in hydrogen fuel cells, enhancing safety. In the event of overpressure, hydrogen reverts to water, eliminating accident risks.
The Evolution of the Technology
NASA started using nickel-hydrogen batteries in the 1970s for ISS systems. However, the high cost of platinum catalysts limited their commercial application for decades. In 2020, Stanford materials science professor Yi Cui proposed an alternative alloy of nickel, molybdenum, and cobalt, which significantly reduced costs. This breakthrough led to the creation of EnerVenue.
EnerVenue’s batteries are exceptionally durable, designed to last through 30,000 cycles, equivalent to 30 years of use. Even after such an extended operation, they retain up to 86% of their capacity. Additionally, they function efficiently across a wide temperature range, from -40°C to +60°C.
While they offer many advantages, nickel-hydrogen batteries also have drawbacks. Their lower energy density means more batteries are required to achieve the same power output as other technologies. They are also more expensive to produce than lithium-ion counterparts. Nevertheless, their durability and ability to withstand extreme conditions make them a compelling option for long-term energy storage.
Testing in the U.S.
RWE’s pilot project aims to evaluate the batteries’ performance, temperature stability, operational longevity, charge-discharge characteristics, and resilience to cyclical changes. The findings will help refine the technology and prepare it for broader integration into the company’s energy projects.
Manufacturers emphasize that ESVs offer flexibility and safety, eliminating the risks of thermal runaway associated with lithium-ion batteries. Moreover, they are easier to recycle, making the technology environmentally friendly.
RWE is actively developing energy storage systems in the U.S., Europe, and Australia. The company’s current battery capacity is 0.7 GW, with another 1.4 GW under construction. As part of its “Growing Green” strategy, RWE plans to increase this capacity to 6 GW by 2030.
