The U.S. Naval Research Laboratory (NRL) is developing technologies designed to capture solar power in space, directly by an orbiting satellite, and beaming that captured power back to Earth. One of those technologies is the Photovoltaic RF Antenna Module (PRAM) satellite launched in May 2020 aboard the U.S. Air Force’s experimental orbital aircraft, the X-37B. Power beaming uses different light frequencies to wirelessly transmit power to a receiver. NRL previously tested a land-based system using an infrared laser whose 400 watts of direct current was wirelessly captured by photovoltaic cells tuned to the laser’s wavelengths over a distance of 325 meters. The collected satellite data will be also be compared to existing data from the land-based experiment.
The PRAM satellite does not currently have the capability to capture or transmit power back to Earth – for example, its’ solar panels are black. However, it is the first satellite in orbit that converts solar energy to microwaves. Two primary research questions still to be addressed are: How efficient is the conversion of solar energy to microwaves and how effective is the satellite’s thermal management system? Conversion efficiency and thermal management directly affect power density—too much power will burn whatever the satellite is pointed at; too little and not enough electricity will be generated.
If successful systems are created, commercially and/or for the military, power beaming has the potential to deliver power anywhere on Earth. Receptors, whether fixed or mobile, land, sea, or aerial, could directly capture power beams, eliminating intermediate infrastructure, such as transmission towers/wires from a power generation plant. Local distribution could be installed anywhere. For contingency operations and emergency response, power beaming could quickly provide sources of electricity where no local sources exist or are inadequate for the mission.
Dr. Marc Kodack is Senior Fellow at the Center for Climate and Security and former Sustainability and Water Program Manager in the Office of the Deputy Assistant Secretary of the Army for Energy and Sustainability.
* This post is part of the Council on Strategic Risks’ “Responsibility to Prepare and Prevent” Blog Series, designed to increase the tempo and scale of relevant and useful analysis during a time of crisis