Advancing the Clean Hydrogen Future Act of 2021 This bill requires the Department of Energy (DOE) to establish a research, development, demonstration, and deployment program to improve the efficiency, increase the durability, and reduce the cost of producing hydrogen using electrolyzers. Electrolyzers are systems that produce hydrogen using electrolysis, a process that uses electricity to split water into hydrogen and oxygen. The goal of the program is to reduce the cost of hydrogen produced using electrolyzers to less than $2 per kilogram of hydrogen by 2026. In carrying out the program, DOE must award grants for projects that DOE determines would provide the greatest progress toward achieving the goal. In addition, DOE must fund demonstration projects under the program to (1) demonstrate technologies that produce hydrogen using electrolysis; and (2) validate information on the cost, efficiency, durability, and feasibility of commercial deployment of those technologies.