Climate Action Planning for Ports Act of 2021 This bill authorizes the Environmental Protection Agency to award grants for developing climate action plans to reduce greenhouse gas emissions or other air pollutants at ports or port facilities or implementing plans to reduce greenhouse gas emissions at one or more ports or port facilities. Climate action plans must demonstrate that the measures proposed to be implemented through the grants will do at least two of the following: improve energy efficiency at ports or port facilities, deploy technology or processes that reduce idling of vehicles at ports or port facilities, or reduce the direct emissions of greenhouse gases and other air pollutants with a goal of achieving zero emissions.