Maria Paula Calderon – Solar Satellites Chapter Summaries
Solar Satellites: Chapters 1, 2, and 8
Considering our imminent depletion of natural resources and the increasing need of a steady and reliable clean energy source, the development and launch of solar satellites, specifically those of the Sunsat variety, is crucial to the conservation of our planet. The principal purpose of these satellites is to be positioned around Earth’s atmosphere in strategic positions to directly capture the Sun’s energy and then send it back to Earth. This alternative source of energy would be a vital source of “base load power”, as the electrical power generated as a result would be able to be accessed and delivered anywhere in the world. However, in order to reach such a prosperous outcome, there are still several factors that must be further developed. Firstly, larger and more sophisticated space platforms, arrays, and power transmission systems must be developed. More robots and reliable transportation systems to deliver materials must also be done, along with more specialized large-scale receivers, converters, storage and distribution systems on Earth. In-orbit position allocations must also be granted, along with a radio frequency spectrum for the transmission of the energy from Earth’s atmosphere. Finally, an effective operational arrangement and management system would also be crucial for this project to be carried out, as it would ensure that all the components work in a safe and efficient manner.
Chapter 1: What is a Solar Power Satellite?
A solar power satellite is a vehicle located in space whose main function consists of collecting sunlight directly from the Sun and delivering it back to Earth in the form of electrical power through antennas on the ground, which would be plugged into electrical power grids. In order to provide such enormous amounts of energy, the Sun’s energy would be converted into low-density radio or light frequency waves, which would provide “many times more electrical power than we use today” (4). In order to do so, and increase efficiency, large-scale reflectors would be used to concentrate the Sun’s photons. This would result in the PV cells perceiving more energy from the Sun than would usually be the normal.
Currently, there are no solar powers operating yet, but the pressing need for clean, abundant, and instant energy is paving way for the development of such satellites. These satellites would also have functions such as communication (to broadcast audio and video, enable mobile telephony, broadband data, and Internet), remote sensing (to keep a check on weather, environmental surveillance, and mapping), navigation and geo-positioning. The difference between the newly envisioned Sunsats and the current in-orbit satellites pertains to their qualities in terms of the space segment, the Earth segment, and the transport segment.
The Space Segment
New solar power satellites would include several features that are already present in communications platforms, such as a satellite bus, solar arrays, onboard processing, telemetry control, and wireless transmission systems. However, solar power satellites would be specifically made for the purpose of relaying energy back to earth to be converted into electricity, unlike the current comsats that only gather smaller proportions of energy from the Sun simply to power their own spacecraft. With the current advances on thinner, lighter, and cheaper photovoltaic cells, Sunsats would benefit greatly as they would not only be more productive, but also less expensive. However, there is still a great need for bigger, more efficient solar panels in order for such an ambitious goal as that of using Sunsats to replace current energy resources to be achieved.
The Launch Segment
For the successful launching of vehicles or objects out of Earth’s atmosphere, launch systems are crucial. Various reusable launch vehicles (RLV) are used in order to do so, which are of various types, including the “vertical takeoff vertical landing”, and even “single stage to orbit” or “two-stage to orbit” types. At first, Sunsats would use private, commercial, government rockets to get into space, similar to normal communications satellites. Another future possibility is to assemble the solar satellites from components lifted by rockets into a low-Earth orbit. A final alternative would also be to use more powerful thrusters to have the same effect. In terms of its maintenance, the Sunsat would be constructed and maintained tele-robotically by operators on the ground.
The Ground Segment
Similar to radio and TV receivers, rectifying antennas would receive the signals sent by the solar satellites and convert them into electricity. However, these receivers would be larger and would be more spread out to enable a lower density of energy, as passing radio frequency beams with highly concentrated transmissions could potentially harm airline passengers passing by and could even interfere with other communication satellites. These rectifying antennas would also be networked into power distribution centers. Another advantage of these sites is that they could potentially hold agricultural crops or fish farms.
Challenges That Sunsat Face
In order for the Sunsats to be launched, there are still several challenges that are to be faced. Such a project faces challenges in terms of their orbital registration, position, frequency allocations, and levels of power transmission, which would be a further struggle in current times as there are scarce orbital slots. The nation-by-nation approval process that would have to be passed would also be an enduring constraint. The lack of commitment from the government is also a hindrance to the project in general, which is mostly being carried out by the private sector. Finally, some of the technical challenges that this project faces include increasing the efficiency and capacity of solar cells, enabling wireless power transmission and receiver networks, developing energy conversion mechanisms, and further developing the storage and distribution systems.
Chapter 2: What are the principal Sunsat services and markets?
Overall, solar power satellites are crucial solutions to our need for a clean energy resource as they can be strategically placed in orbital sectors where the greatest amount of solar energy can be collected, supply power at all times due to this, and their land receivers can be used for multiple purposes.
As listed by the National Space Society, other advantages of solar powered satellites include:
- No emission of greenhouse gases
- No production of hazardous waste
- High quantity availability at all times
- No requirement of environmentally problematic mining operations
- No potential target for terrorists (unlike nuclear power plants)
Other main uses for the solar satellites pertain to the production of baseload electrical power to support agriculture, desalinate water, disaster relief, military operations, and other uses.
- Power utilities: will provide on-demand electric power that can be repurposed and reutilized and could also potentially replace other, polluting sources of energy.
- Agriculture: could pave way for the creation of a multipurpose greenhouse that would have constant temperatures and light all year round. Not only allows farmers to farm their cash crops but also serves as a supply of electricity.
- Terrestrial purposes: Rectennas would be placed along with other solar power plants, and can be designed to let light pass through, so the same area could be used for the production of electricity through normal solar plants, or could be even used for agriculture.
- Fresh water: the satellite could also provide the power needed to desalinate seawater, a process that would provide freshwater at all times every day.
- Cities: the continuous and non-depleting supply of energy would be crucial in meeting the growing energy needs of cities. As there is no atmospheric nor cloud interference and no night nor seasons, this continuous baseloud resource is vital.
- Disaster sites: these solar powered satellites could also not only provide illumination and a communication means during power outages in disaster sites, but could also provide an alternative means to recover from a power outage through its readily available energy. An extension of this possibility is to create a navigable airship that hovers around the stratosphere to provide help when needed. It would be able to relay up to one billion watts of energy to any surface on Earth that would need it, which could power a million homes during a crisis. It could even potentially run generators and power up an electrical grid, and could contain passive electro-optical and active radar sensors to find people trapped in debris.
Chapter 8: How is Sunsat Development Faring Internationally? *Focusing only on section on China
Given the rapid growth of China accompanied by a growing need of electricity and energy, the country is currently developing space-based solar satellites in its attempt to provide an alternative clean means of meeting the energy demand. Given that by 2050, 85% of the growth in energy demands would feed from fossil fuels, nuclear power, and hydropower, and only 30% of the remaining 15% would be met by alternative renewable energy resources, the situation calls for a pressing, and early, development of solar power satellites. To make matters worse, the Chinese Academy of Engineering reported that oil, coal, and natural gas would be depleted in the next 15, 82, and 46 years respectively. In response, the Chinese Academy of Space Technology (CAST) has stated in its report on “Solar Power Satellites Research in China” the following timeline in terms of its goals related to the development of SPS.
- 2010: finish concept design
- 2020: finish industrial level testing of in-orbit construction and wireless transmissions
- 2025: complete first 100kw SPS demonstration
- 2035: 100mw SPS will have electric generating capacity
- 2050: first commercial level SPS system will be in operation
Amongst the CAST’s priorities in the development process of SPS, sustainable development, a skilled workforce, and a means of disaster prevention and mitigation are included. Four other important areas of development include the launching approach and mechanisms, the in-orbit construction mechanisms, high efficiency solar conversion, and wireless transmission.