Can You Harvest Solar Energy In Space?

Space-based solar power (SBSP) refers to the concept of collecting solar energy in space and transmitting it wirelessly to Earth. SBSP aims to overcome issues with ground-based solar power, like nighttime, clouds, atmospheric absorption and land requirements, by putting solar collectors in orbit. Theoretically, SBSP could provide a constant, consistent power source to any place on Earth.[1]

The basic idea is to place large solar arrays into orbit to collect significantly more solar energy than what is possible on Earth’s surface. The arrays would convert sunlight into microwaves or lasers and beam the energy wirelessly to receivers on Earth. The receivers convert the energy back into electricity and feed it into the electrical grid.[2]

SBSP has the potential to provide massive quantities of renewable energy without producing any greenhouse gases. It could be a gamechanger in mitigating climate change and transitioning the global energy system.[3] However, SBSP still faces enormous economic and technical hurdles before it can become a viable energy source.

[1] https://www.energy.gov/space-based-solar-power

[2] https://en.wikipedia.org/wiki/Space-based_solar_power
[3] https://www.esa.int/Enabling_Support/Space_Engineering_Technology/SOLARIS/Space-Based_Solar_Power_overview

How Space-Based Solar Power Works

The basic concept behind space-based solar power (SBSP) is to collect solar energy in space and transmit it wirelessly to Earth. SBSP takes advantage of the fact that solar intensity in space is significantly higher than on Earth’s surface. Solar arrays mounted on satellites or other space structures could collect sunlight 24/7 and beam it down to receiving stations on Earth using microwave or laser transmission (Department of Energy).

The solar arrays in space would be enormous compared to terrestrial arrays, likely kilometers in size. The arrays would convert the sun’s energy into electrical energy and then into a beam, which is transmitted to Earth. A receiving station on Earth would convert the beam back into electrical energy which is then fed into the existing power grid (European Space Agency).

SBSP takes advantage of several factors: the high intensity of solar energy in space, the 24/7 availability of energy, removal of weather and diffused light effects, and the enormous collecting area available in space compared to terrestrial sites. However, SBSP requires overcoming some substantial technical challenges in order to become economically and technologically feasible.

Advantages Over Ground-Based Solar

One of the biggest advantages of space-based solar power over ground-based solar is the abundant and uninterrupted sunlight available in space. On Earth, solar panels can generate power for only part of the day when the sun is shining. The amount of sunlight that reaches the ground is also reduced by atmospheric absorption and scattering. In space, sunlight is up to 30% stronger and available 99% of the time outside of occasional eclipses (source). This means space-based solar can potentially generate significantly more total energy over time compared to an equally-sized installation on the ground.

Additionally, space-based solar power would not be affected by weather events or seasons that can limit sunlight on Earth. While ground-based solar arrays need to contend with clouds, storms, and winter seasons, space-based arrays could receive constant sunlight year-round. This reliability and predictability of space-based solar makes it attractive for meeting continuous baseline power demands (source).

Past Research and Concept Studies

The concept of space-based solar power has been studied by major space agencies and companies for decades. According to the European Space Agency, the idea dates back to 1923 when Russian theorist Konstantin Tsiolkovsky proposed using space-based mirrors to beam sunlight to Earth. Significant research efforts began in the 1970s at organizations like NASA.

In the late 1970s, NASA conducted an extensive concept study called the Satellite Power System Concept Development and Evaluation Program. This multimillion dollar research project examined the feasibility and potential of large-scale space solar power stations. While the program concluded the concept was technically feasible, NASA did not move forward due to economic factors.

Japan’s space agency JAXA has been studying space-based solar power since the 1990s. In 2021, JAXA successfully transmitted 1.8 kilowatts of power wirelessly between two spacecraft in orbit as part of its technology demonstrations toward developing space solar power generators. The European Space Agency has also conducted multiple reviews and prototype projects related to beaming solar power from space to Earth.

Though major hurdles remain, many experts believe the enormous potential of space-based solar represents a promising clean energy solution for the future.

Technical Challenges

While the concept of space-based solar power has intriguing potential, there are significant technical hurdles that must be overcome before it can become a viable energy solution. Two key challenges involve building and launching the equipment into orbit, and transmitting the power wirelessly back to Earth.

Constructing solar power satellites cheaply enough to offset the high launch costs is difficult. The structures need to be lightweight yet able to unfold into large collection areas once in space. researcher Dr. Sheila Bailey notes that operating and maintaining the satellites in the harsh space environment also poses engineering challenges.

Efficiently beaming gigawatts of power wirelessly over long distances is another major obstacle. While various concepts have been proposed, including using microwaves or lasers, the transportation losses and precision required make this very technically challenging.

These issues of scale, cost, construction and wireless transmission present formidable barriers. Significant technology innovations will be required for space-based solar to move beyond conceptual studies and small-scale demonstrations.

Potential Solutions

Some potential solutions for the technical challenges of space-based solar power include using thin-film photovoltaic panels and transmitting the energy via microwave or laser beams.

Thin-film photovoltaic panels are lighter and more flexible than traditional silicon panels, making them well-suited for large arrays in space (Source). They can be rolled out into space instead of requiring heavy deployment mechanisms. Flexible panels are also more resilient than rigid panels against space debris impacts. However, thin-film panels tend to be less efficient at converting sunlight to electricity.

For wireless power transmission, microwaves or lasers could be used to safely beam the energy from the satellite to Earth (Source). Microwaves are an extension of radio wave technology, while lasers provide a highly focused and precise energy beam. Both options need further research to scale up to the levels required for space-based solar power while minimizing transmission losses.

Economic Feasibility

One of the main challenges of space-based solar power is the extremely high upfront costs required. Building and launching the satellites, transmission infrastructure, and ground stations requires massive capital investments estimated in the hundreds of billions of dollars (Space Solar is the Next Energy Market). However, the potential long-term revenues could make the large initial outlays economical in the long run.

According to one concept study, space-based solar could generate electricity at around $0.12/kWh once fully operational, competitive with other renewable energy sources (The Case for Solar Power From Space – NSS). With enough investment and scale, costs are projected to fall even further over time. The continuous sunlight in orbit also allows for very high capacity factors of 70-80%, much greater than ground-based solar.

While still highly theoretical, some analysts project the total market for space-based solar could reach $1 trillion or more per year by 2050 if the technology matures. The revenue opportunities from selling clean electricity worldwide are massive. However, it remains unclear whether private companies or governments will be willing to take on the large upfront costs required to fully demonstrate the concept.

Environmental Impact

Space-based solar power can provide clean, renewable energy without greenhouse gas emissions. However, some environmental impacts from the production and launch of spacecraft must also be considered. According to the National Space Society, the full environmental benefits come from locating most of the system outside Earth’s biosphere https://nss.org/space-solar-power-info/. Materials extraction and manufacturing would take place off-planet, minimizing terrestrial impact. While launch vehicles do emit pollutants, the overall lifecycle emissions are far lower than fossil fuels. As noted by Energy5, space solar avoids any direct environmental impact unlike some ground-based renewables https://energy5.com/space-based-solar-energy-a-game-changer-for-renewable-energy/. With conscientious spacecraft design and launch operations, space-based solar can provide significant clean energy benefits.

Political and Policy Issues

Space-based solar power has some significant political and policy implications that need to be considered. Most notably, there are challenges related to international agreements and space law.

The 1967 Outer Space Treaty declares space to be the “province of all mankind” and forbids any nation from claiming sovereignty over celestial bodies. It also bans weapons of mass destruction in space. Any plans for large-scale space-based solar would need to comply with this treaty (NASA).

The 1979 Moon Treaty goes even further in declaring the Moon and other celestial bodies to be the “common heritage of mankind.” However, only a small number of nations have ratified this treaty. There are disagreements about whether it would prohibit space-based solar power if only a few countries controlled the technology (NASA).

There are also challenges around allocation of orbital slots and wireless power transmission regulations. The International Telecommunication Union coordinates wireless frequencies, but has no specific provisions yet for space-based solar. New international agreements and governance models may be needed (DOE).

Overall, realizing the potential of space-based solar power will require extensive multinational cooperation and new policy frameworks to uphold principles of shared benefit and access.

Outlook and Conclusions

Space-based solar power holds significant promise as a potential sustainable energy source, but still faces major technical and economic obstacles. Key challenges include launching materials into orbit, constructing and operating large solar arrays in space, and safely transmitting the energy back to Earth. However, studies by organizations like NASA and JAXA show it may be technically feasible using wireless power transmission and ultra-thin, lightweight solar cells NASA Space-Based Solar Power Report.

Realizing space-based solar will likely require substantial investments over decades to further develop the necessary technologies. Estimated costs range from several hundred billion to trillions of dollars. The economic viability remains uncertain, but proponents argue the potential benefits of unlimited clean energy could justify the upfront costs. Further concept studies and technology demonstrations will help provide more clarity.

Overall, space-based solar represents an ambitious long-term vision for meeting global energy demands. With continued research and development, it may become economically and technically feasible later this century. The concept aligns with goals to transition to renewable energy and reduce greenhouse gas emissions. If realized, space-based solar could play a major role in supplying clean power worldwide.