Ultracapacitor manufacturer Ioxus has closed its Series C funding at $21 million. The International Finance Corporation (IFC) provided the final $5 million that closed the round, according to TechCrunch.

The IFC was reportedly interested in helping address climate change by integrating the technology of Ioxus in the hybrid buses of China. Ioxus chief executive officer (CEO) Mark McGough explained that their ultracapacitor could cut bus emissions by 72%. He also disclosed that the firm is already working with an unnamed bus company in China, the report detailed.

McGough said: "95% of car companies use internal combustion engines, and we provide an inexpensive way to improve fuel efficiency."

Ioxus is a company that makes ultracapacitor energy storage systems for industrial, energy, and transportation sectors, the report added. The latest funding brings the firm's total raised capital to $46 million. Aside from the IFC, the Westly Group and Energy Technology Ventures also contributed to the Series C financing, TechCrunch reported.