High-Temperature Reversible Fuel Cell Overcomes Traditional PEM Limitations
California-based startup HyWatts launched its modular 'Power-Plant-in-a-Box' system in July 2026, integrating an electrolyzer and reversible fuel cell that operates at 160°C—far exceeding the 60°C to 80°C range of conventional proton exchange membrane (PEM) systems. The system employs a phosphoric acid-doped membrane, enabling operation without additional humidification equipment and replacing complex liquid cooling with air cooling to streamline the overall architecture.
In a 2025 white paper, HyWatts highlighted several advantages of high-temperature systems (120°C to 180°C). Since the electrolyzer’s input water is in steam form, it is inherently demineralized, eliminating costly pretreatment processes. Additionally, the system generates heat exceeding 150°C during electrolysis, which can be recycled as pressurized steam to enhance energy efficiency. The company claims that newly developed materials effectively prevent phosphoric acid loss under high temperatures, avoiding declines in proton conductivity and catalyst contamination.
The white paper outlined three key cost-reduction strategies: simplifying the balance of power (BoP) system, optimizing overall efficiency, and integrating the electrolyzer and fuel cell into a single device. BoP systems include peripheral components such as valves, heat exchangers, water treatment, and control systems. Through integrated design, HyWatts asserts it can significantly reduce the number of components, lowering manufacturing and maintenance costs.
Green Hydrogen Applications Expand: Off-Grid Charging and Agricultural Fertilizer Take Center Stage
HyWatts’ 'Power-Plant-in-a-Box' system targets applications such as off-grid electric vehicle (EV) charging stations and data centers, aiming to address gaps in renewable energy supply stability. Green hydrogen technology has gradually been adopted across multiple sectors in recent years. For instance, the electric racing series Extreme E deployed green hydrogen systems for off-grid charging stations several years ago, while Texas A&M University has partnered with entities in Qatar to study green hydrogen charging stations.
In the agricultural sector, Texas-based Talus Ag developed a green hydrogen system for producing green ammonia fertilizer. In March 2026, the company announced a collaboration with wind energy providers in Minnesota to use excess wind power for fertilizer production. By May 2026, Talus Ag had reached an agreement with PepsiCo to expand the technology across Europe, Sub-Saharan Africa, and the Asia-Pacific region. Margaret Henry, PepsiCo’s Vice President of Sustainable and Regenerative Agriculture, stated that decarbonizing fertilizer is critical for climate progress but must align with the practical needs of farmers.
The green hydrogen industry in the United States faces challenges due to shifting policies. Under former President Donald Trump, federal energy policy adjustments led to the cancellation or delay of several large-scale projects under the Regional Clean Hydrogen Hubs program. Despite this, some companies continue to explore opportunities abroad. HyWatts’ technological breakthrough underscores ongoing innovation in the green hydrogen sector, though market adoption still requires overcoming barriers such as cost and infrastructure. Currently, HyWatts has not disclosed system efficiency, durability, or real-world deployment examples, nor has it clarified its funding sources.
Green hydrogen, produced through renewable energy-powered water electrolysis, is seen as a key solution to replace hydrogen derived from fossil fuels. However, the high costs of electrolyzers and fuel cells, along with the lack of large-scale commercialization, remain major challenges for the industry. HyWatts’ high-temperature reversible fuel cell technology offers new possibilities for green hydrogen applications, but its long-term competitiveness awaits market validation.
