Powering the world from space

The demand for energy has never been greater. Traditional sources of energy, such as coal, oil and natural gas, cannot keep up – and are also not environmentally friendly. We need new, more sustainable options for generating power.

The solution may lie in a surprising innovation: space solar power systems.  

Solar power is clean, inexhaustible, and readily available, with its practical applications becoming increasingly compelling. It’s a pollution-free energy source that serves to reduce our collective reliance on electricity, oils, and fossil fuels.

Space solar power systems operate satellite orbits 36,000 km above the ground. They harvest the energy of the sun, efficiently converting sunlight into lasers or microwaves. The satellites then wirelessly transmit beams to the ground without being affected by atmospheric fluctuations and efficiently convert high-intensity rays into electric power.

It’s especially effective because a satellite in geostationary orbit can receive energy from the sun almost 24 hours a day, 365 days a year, receiving about ten times more energy per unit area than on the ground.

And space solar technology has uses beyond energy transmission. It can be used as a power distribution system for mobile devices such as drones and automobiles, and as a power distribution system using microgrids and power supply for remote islands and evacuation centers in the event of a disaster.

Overcoming the challenges of transmitting wireless power from space

NTT is conducting research and development into new ways of harnessing wireless power transmission from space. Since the wavelength of lasers is about three to four orders of magnitude shorter than microwaves, the company is exploring how to use lasers to transmit over long distances efficiently without being affected by diffraction.

Leveraging its emerging all-photonics network (APN) and photoelectric conversion technologies, NTT is close to achieving high-efficiency, ultra-long-distance wireless power transmission in the very near future.

Three main technologies that generate space solar power

Space solar power is generated using three types of technologies:

1. Efficiently converting sunlight into a laser on a satellite in geostationary orbit. NTT is conducting research on a system that executes laser oscillation highly efficiently by directly irradiating a special crystal with sunlight to excite a laser – unlike the conventional method of laser oscillation using power generated from solar cells.
2. Propagating a laser beam accurately to a target on the ground. Although a laser can be more easily transmitted over a long distance than a microwave, the effects of diffraction are inevitable in the propagation as long as 36,000 km. The effects of atmospheric turbulence must also be removed, so NTT is conducting research on optical systems with deep focal depths to avoid diffraction and eliminate fluctuations in light propagating through the atmosphere. In addition, direction control accuracy is required to shine a laser beam from a satellite in a geostationary orbit.
3. Converting lasers into energy with high efficiency. Laser light is a single wavelength, unlike sunlight which has light comprising various mixed wavelengths. So NTT is researching solar cells with high conversion efficiency at specific wavelengths. When a laser is converted into electric power using a solar cell, about half the energy becomes heat; NTT is studying methods of storing energy in different forms such as hydrogen and ammonia using thermochemical reactions instead of converting lasers directly into electricity.

Innovating for a sustainable future

NTT is innovating the future by researching technologies like space solar power that will enable smart, sustainable energy – and enhance the wellbeing of people and the planet.

Learn more here.