Volvo Technology Japan Co., Ltd. and Nippon Dengyo tools, aim to commercialize wireless power transmission. It is essential to the spread of environmentally friendly electric trucks and buses. Power from the outside of the vehicle is provided wirelessly. They have built a high efficiency rectenna.
A high efficiency system (84%) could be used to beam power to electric cars and trucks that are parked at stop lights or in parking lots. There would be no need to use plugs and outlets.
The prototype high efficiency rectenna is uses microwaves. It beams power from outside the vehicle and rectifier circuit is mounted on the vehicle side to gather the power. It was previously thought that the development of microwave power beaming would be a long, difficult process and practical efficiency of the rectenna would be low.
Nihon Dengyo Kosaku and Volvo Technology Japan succeeded in wirelessly transmitting more than 10kW of electricity to a distance of 4m or more.
The output power per area is 3.2kW/m^2 or higher, which Dengyo claims is the “world’s highest output.” The frequency of the microwave is 2.45GHz.
The 10 kW rectenna was made by combining eight rectennas the output of which is about 1.3 kW each; overall efficiency of the conversion is about 84%.
Recently there was success with laser power beaming in the USA
Lockheed Martin and LaserMotive, Inc., recently demonstrated the capabilities of an innovative laser power system to extend the Stalker Unmanned Aerial System (UAS) flight time to more than 48 hours. This increase in flight duration represents an improvement of 2,400 percent.
Laser Motive is steadily increasing the power and distance that they can transmit.
Lasers are currently 20% efficient in wireless power transmission (but could reach higher levels). The Microwaves are 84% efficient.
The lasers can tranmit over a far longer range.
The microwave system tranmitted more power, but they combined 8 units.
The lasers have a lighter receiving system.