Energy from space transmitted wirelessly to Earth: 'It will be affordable'

California. The Caltech SSPD-1 mission concluded by demonstrating the ability to wirelessly transmit solar energy from space to Earth.

SSPD-1 (Space Solar Power Demonstrator) was launched on January 3, 2023 to demonstrate and test three technological innovations needed to make space solar power a reality.

Over the course of ten months, this “test bed” demonstrated the ability to transmit power wirelessly into space; Measure the efficiency, lifetime and operation of a number of different types of solar cells in space; The California Institute of Technology said in a statement that it has tested and tested the design of a lightweight, deployable structure to connect and support solar cells and energy transmitters.

The mission cut off communications with Earth on November 11. The Vigoride-5 spacecraft, which hosted SSPD-1, will remain in orbit to continue testing and demonstrating the vehicle's microwave thermoelectric engines, which use distilled water as propellant. Eventually, it will leave orbit and disintegrate in Earth's atmosphere.

Now that the SSPD-1 space mission has ended, engineers on Earth are celebrating test successes and learning important lessons that will help shape the future of space solar energy.

“Affordable solar energy beamed from space to light up the world remains a future possibility,” said Thomas Rosenbaum, president of the California Institute of Technology and professor of physics. “But this critical mission has proven that this is an achievable future.”

Other projects are related to energy transfer from space
Space-based solar facilities that deliver vast amounts of clean, renewable energy to Earth via microwaves were first created more than 50 years ago, and scientists have noted that these setups are not limited to cloud cover or the sun's cycle.

Last year, Japanese space agency JAXA announced plans to build a commercial-scale solar power station in space by 2025, while the European Space Agency (ESA) is also aiming for a development project through its Solaris programme.

The Japan Aerospace Exploration Agency was first able to transmit solar energy via microwaves in 2015, transmitting 1.8 kilowatts of power to a receiver 55 meters away, roughly the same amount of electricity needed to power a kettle.

Last year, scientists at the University of Pennsylvania discovered how to double the efficiency of a lightweight solar cell that could be used in space solar power plants.

In addition, researchers at the University of Sydney in Australia have created a type of self-healing solar panel capable of regaining 100% of its original efficiency after being damaged by space radiation.

NASA criticism
Proponents of space solar energy criticize a NASA report that provides a skeptical assessment of the technology's ability to provide low-cost green energy.

The report, released on January 10 by NASA's Office of Technology, Policy and Strategy (OTPS), examined two previously published projects to generate electrical power in space and transmit it to Earth via microwaves, known as space-based solar power (SBSP). The report calculated the life cycle costs of these systems and the greenhouse emissions that their development would produce.

The report concluded that one of the two plants would produce electricity at a cost of $0.61 per kilowatt-hour, while the other would produce electricity at a cost of $1.59 per kilowatt-hour. In contrast, terrestrial renewable energy systems, such as wind, hydroelectric, and solar plants, produce energy at a cost of between $0.02 and $0.05 per kilowatt hour.

The report also found that the greenhouse gas “emission intensity” of SBSP systems, or the amount of greenhouse gases generated by building and releasing the systems, is much lower than the current U.S. power grid average, but similar to a terrestrial renewable energy grid. Systems.

“We've found that these space solar projects are very expensive. They're about 12 to 80 times more expensive than Ground Renewable Energy System”. Report.

However, SBSP supporters have criticized NASA's assessment of costs, especially the assumptions used. The Space Frontier Foundation said the report shows that the US government and companies should take this technology seriously, despite the basic model's conclusions. “This report dispels fears that space solar energy is just science fiction, and shows that NASA and the US government recognize the economic and climate-friendly benefits of global leadership in this new energy system,” said Sean Mahoney, the organization's executive director.

The idea of ​​the California Institute of Technology
Like most solar space projects around the world, Caltech's is based on the idea of ​​deriving power not from a few giant solar panels, but from thousands of small panels tightly connected to form a larger structure. In Caltech's case, each micropanel would consist of 16 “tiles,” each containing all the circuitry needed to convert sunlight that reaches one side of the tile into microwave energy that travels from the other side to the Earth's surface.

Microwave radiation, just one type of radio energy, is the beam of choice for space solar projects. This is because, unlike most other forms of energy, such as lasers, microwave rays can pass through clouds, moisture and other obstacles in the Earth's atmosphere, ensuring that most of the energy reaches the Earth. Furthermore, microwave rays can carry the necessary energy at safe levels: the rays will be much less intense than those from a home microwave oven, equivalent to about a quarter of the typical intensity of sunlight reaching Earth. There is no risk of “frying” anything.

The mission consists of three main experiments, each testing a different technology:

– DOLCE (Deployable Lightweight On-Orbit Vehicle Experiment): a 1.8m x 1.8m structure demonstrating the new technical structure, packaging system and deployment mechanisms for the modular, scalable spacecraft that will eventually form a kilometer-sized constellation that will serve as a power plant.

– ALBA: A series of 32 different types of photovoltaic cells to enable the evaluation of cell types capable of withstanding the harshest space environments.

– MAPLE (Microwave Array for Low Orbit Energy Transmission Experiment): A set of lightweight and flexible microwave energy transmitters, based on custom integrated circuits with precise timing control to selectively focus energy on two different receivers, in order to demonstrate wireless communication remotely. Energy transfer in space.