Harvesting energy in space
A matter of semantics
A technology of generating electricity from solar energy using satellites and transporting it to the Earth through radio waves.
As a consequence of global energy challenges and technological advance, Energy from Space has been, and currently continues to be, explored by scientists, engineers and entrepreneurs mainly in Japan, the United States and Europe.
What is Energy from Space?
Energy from Space, also known as Space Based Solar Power (SBSP) and Space Solar Power Systems (SSPS) are used interchangeably. They all refer to the same concept. In a nutshell, this concept is based on:
- Space-based solar power plant
- Wireless power transmission to Earth
- On-ground energy conversion
Various versions are designed and all have their advantages and challenges. Just as that not all solar parks on Earth are identical, the same holds for Energy from Space systems.
All full-scale Energy from Space systems are typically designed to deliver 1 GW or more for $0.10/kWh to $0.50/kWh and operate for 30 to 40 years continuously.
Energy from Space systems collect solar energy in space by satellites in geostationary orbit. Here, at 36,000 km altitude, the satellite will always stay above the same location on Earth. For example, a plant above Japan can provide continuous power to many places in Japan. This is the same orbit as where our daily-lives communication satellites are in.
When the solar energy is converted to electric energy, the electricity is then converted into microwaves to transmit the energy to Earth. A typical unit in space with net energy output on-ground of 1GW has a solar panel area of about 4 km². The solar panels are similar to those already used by satellites for more than 40 years.
The area could be reduced when mirrors are used that concentrate the solar rays to a more efficient energy converter. This principle is called concentrated photo-voltaic,
The power beam on Earth is received by a large antenna array. This array consists of many poles supporting simple antenna modules. These modules convert the radio waves into electricity and combined produce 1 GW of power, enough to power 1 to 2 million homes.
The array that is required for a typical Energy from Space system is about 3 km in diameter and will be probably placed offshore or on deserted land areas.
Compared to other energy plants, Energy from Space is an extremely safe and reliable source of power.
The Energy from Space system converts the electricity coming from the solar panels into one or more power beams. The beams consist of radio waves in the microwave frequency and experience almost no obstruction by the atmosphere, irrespective of day or night.
These waves (2.45 GHz or 5,8 GHz) are comparable to those used by mobile phones, wireless internet and even GPS, and are usually harmless to living organisms on ground including humans.
This conversion technique has already been proven more than 50 years ago when the first satellites where launched.
Converting energy on the ground