Solar Power Stations in Space - Science Fiction or a Future Reality?

                  Image credit: solarspacetechnologies.com.au

Solar power stations in space or the so-called space-based solar power (SBSP) concept means capturing solar power in outer space and distributing it to Earth. In 1941, science fiction writer Isaac Asimov first wrote about space-based solar power stations in the short story “Reason”. Later, American aerospace engineer Peter Glaser wrote the first technical article on the concept – Power From The Sun: Its Future, and it was published in the journal “Science” (1968). 

Generating solar power in space has many advantages. As we know, the Earth’s atmosphere absorbs and reflects some of the Sun’s light. A considerable fraction of incoming solar energy (55–60%) is lost on its way through the Earth's atmosphere. So, solar cells above the atmosphere will receive more sunlight and produce more power as the Sun always shines in space. An orbital solar power station will be an inexhaustible source of clean energy.

One of the major challenges will be getting the power transmitted back to Earth. The idea is to convert electricity from the solar cells into microwaves or lasers and transfer them down to an antenna on the Earth’s surface. The antenna would then convert the waves back into electricity. 

Recently, the UK government reveals an ambitious new plan for a space-based solar power station that could collect solar energy and beam it down to the UK. According to it, giant solar power satellites in orbit could harvest solar power and transmitting it as high-frequency radio waves to ground-based receivers connected to the electrical power grid.

The big question is how to launch such large structures into space. One possible solution is to develop many smaller satellites that could easily connect in space to form a single solar power station. In 2017, researchers at the California Institute of Technology created a prototype for a modular power station, using thousands of ultralight solar cell tiles. 

Another related news is that researchers at the University of Liverpool are working on a project to design and manufacture low-cost, ‘origami’ deployable structures consisting of thin-film photovoltaic cells incorporated onto a sail. A swarm of photovoltaic solar sails could be configured in-space to provide large-scale and versatile Space Solar Power (SSP) energy generation. 

Also, the Australian-based company Solar Space Technologies, working in partnership with US-based Mankins Space Technologies, Inc. (MSTI), is planning to develop, manufacture, deploy and operate a solar power satellite (called SPS - ALPHA) into geostationary orbit to supply baseload energy to the Australian grid by 2027. SPS-ALPHA was first-examined under a NASA Innovative Advanced Concepts (NIAC) project (2011-2012). The newly proposed solar power satellite has been re-designed to be made up of many repeatable building blocks that can be assembled in space instead of manufacturing one, expensive, single large system. This approach makes the cost of building the platform much lower than if traditional satellite building approaches were. SPS- ALPHA platforms are sized to deliver 2.1 GW each at a levelized cost of electricity (LCOE) of 5¢ per kilowatt-hour ($, US) over a 30-year nominal lifetime. 

Researches in Japan led by the Japan Aerospace Exploration Agency have been working on a project to build a space solar power station for a long time. They have already developed designs and demonstrated solar power satellite of sandwich type.

In my post “Solar energy interesting facts” I have mentioned that China has designed a space solar power system, which they aim to have operational by 2050. This system should be capable of supplying 2GW of power into Earth’s grid at peak performance. 

It seems that scientists are already much closer to construct solar power stations in space. Currently, we are reliant on materials from Earth to build power stations but maybe one day we can use resources from space for manufacturing, such as materials found on the Moon.

The concept for constructing a space solar power station has fantastical origins but it is now being researched by several nations and many scientists around the world are working on it. Thanks to rapid advances in lightweight solar cell tiles and wireless power transmission technology it may become a future reality sooner than we could imagine.

Sources: wikipedia.org, bbc.com, imeche.org, solarspacetechnologies.com.au

Photovoltaics and the Space Industry

The International Space Station in December, 2001. Credit: the crew of STS-108, NASA

Starting in the 1950s and 60s, the space industry was the first market for photovoltaics. Photovoltaics were light and the "fuel" is both weightless and free for the taking. The high costs were never an issue since money was never a problem with the space industry.

In 1954 Bell Laboratories built the first photovoltaic module. It was billed as a solar battery and was mostly just a curiosity as it was too expensive to gain widespread use. Bell Labs used a new process called the Czochralski process to develop the first crystalline silicon photovoltaic cell with an efficiency of about 4 percent. The new technology got the first major commercial push when NASA integrated it into its new space program.

In 1955, the preparation on satellite energy supply by solar cells began. Western Electric put for sale commercial licenses for solar cells production. Hoffman Electronics - Semiconductor Division introduced a commercial photovoltaic product with 2 % efficiency for US$ 25 per cell with 14 mW peak power. The energy cost was US$ 1,785 per W.

In 1957, Hoffman Electronics introduced a solar cell with 8 % efficiency. A year later, in 1958, the same company introduced a solar cell with 9 % efficiency. The first radiation proof silicon solar cell was produced for the purposes of space technology. On 17th March 1958, the first satellite powered by solar cells, Vanguard I, was launched. The system ran continuously for 8 years. Two other satellites, Explorer III and Vanguard II, were launched by Americans, and Sputnik III by Russians.

In 1959, Hoffman Electronics introduced commercially available solar cells with 10 % efficiency. Americans launched the satellites Explorer VI with photovoltaic field of 9,600 cells and Explorer VII.

In 1962, Bell solar cells powered Telstar, the world's first communications satellite.

1964 - NASA launches the first Nimbus spacecraft - a satellite powered by a 470-watt photovoltaic array.

In 1965, the Japanese scientific programme for Japanese satellite launch commenced. The following year, in 1966, NASA launches the first Orbiting Astronomical Observatory, powered by a 1-kilowatt photovoltaic array, to provide astronomical data in the ultraviolet and X-ray wavelengths filtered out by the earth’s atmosphere.

Today, the space industry is still a significant user of photovoltaics since they play an important role in space, providing electrical power to satellites in an orbit around the Earth. Solar cells power virtually all satellites, including those used for communications, defence, and scientific research. More than 600,000 flight-proven solar cells are powering over 60 satellites.

The International Space Station uses multiple solar arrays to power all the equipment on board. The success of the space and planetary exploration missions often depends on their on-board PV power sources — providing power for experiments and for getting the data back to Earth. The three Mars rovers - Pathfinder rover Sojourner, Spirit and Opportunity, completed their missions successfully, powered by PV.

See also: http://www.aerospaceweb.org/question/spacecraft/q0298b.shtml and http://mars.jpl.nasa.gov/MPF/roverpwr/power.html)