Above the clouds, beyond the horizon, the Sun always shines and warms much more than on Earth. Putting aside the Zen or philosophical suggestions, it is all the truth that is needed to be able to imagine an inexhaustible source of energy, continuous, only, so to speak, to be caught and brought down. The use of energy that our star gives us has existed since life began here with us. The practice of transform it directly into electricity for more than half a century. But to solve the energy crisis, not just the current one, the challenge that awaits us in the coming decades, linked to climate change, solar energy as we are using it is not enough. The idea is therefore a great one: to go and collect the sun’s rays directly in space, where the Sun does not set and is not obscured by clouds, and send it to the ground as a wireless recharge, without wires. It looks like a tale by Asimov or Arthur C. Clarke. Others around the world are planning how (and investing a lot of money). ESA has recently announced its Solaris program, which could provide Europe with 10 to 20 percent of its energy needs.
Solar panels in orbit
The idea is, to put it this way, simple enough to explain. To launch a huge amount of satellites to create a gigantic photovoltaic park. From up there, frequency converters can transform that electrical energy into microwaves to be “shot” towards Earth in directions to power plants that can convert them back into current to be fed into the grid. Space implants will have to be in geostationary orbit, so a about 36,000 kilometers away from our Planet, to orbit without ever disappearing behind the horizon, and constantly aiming at the power station to which they transfer energy.
The European Space Agency released the results of two cost-benefit studies on the “Space based solar power” (Sbsp) commissioned to as many companies: the English Frazer-Nash Consultancy and the German Roland Berger. In summary: it can be done, but it is necessary to do research, invest a lot, and start immediately, because the others (China and the USA in the lead) are several steps forward. ESA’s Solaris program is the first step in deciding, in 2025, to invest to give Europe its space solar. It could finally be one of the solutions to solve the energy demand of the future, even if not so close, enough in time, however, to contribute to the European goal of net-zero 2050.
The main weakness of resources such as renewables, and solar in particular, is their inconstancy. The wind doesn’t always blow. Every day the Sun goes down beyond the horizon, the incidence of the rays changes during the day and the seasons and, obviously, any clouds shield it. In space and in the right position in orbit, instead, the Sun always shines and without the disturbance and dissipation of the energy of the solar rays caused by the atmosphere. The idea for space solar is not new, he expressed it in an article published on Science American aerospace engineer Peter Glaser 54 years ago. But as he himself admitted, there was not yet the necessary and sufficient technology to make it happen. Half a century later, much progress has been made, but the challenge remains titanic.
The largest space building
The technical documents describe colossal works, bordering on science fiction. Frazier and Nash examines Cassiopeia, a helical structure with a diameter of two kilometers with 61 thousand layers of panels that convert the light collected by two equally large mirrors into electricity. All with a weight of two thousand tons. For comparison, the International Space Station, the largest space building ever built, is the size of a football field at 420 tons.
Such a complex project will have to be assembled directly in orbit by robots designed for this purpose (which do not yet exist), it will take hundreds of launches to bring everything up there: “The supply of the number of satellites necessary to satisfy the maximum contribution that the SBBS could giving the energy mix in 2050 would require a 200-fold increase in space transport capacity compared to the current one, ”the report reads. Relying on private providers like SpaceX would not be enough, we should build new spaceports and invest a lot in infrastructure, as well as in research and development. Public money, at least initially, in order to open the way to private individuals. This has always been done in space. Estimated cost: 9.8 billion euros for the first plant, the economy of scale would make it possible to reduce the tenth plant to 7.6 billion. With operating costs of 1.3 billion euros.
Also the project analyzed by Roland Berger, SPS-Alpha of NASA physicist John C. Mankins it is monumental. A reflective structure, made up of mirrors, conveys the light towards a conversion system that transforms it into radio frequencies to be transmitted to the receiving stations on the ground through the antennas. The whole should occupy an area of about 15 square kilometers, with a diameter of around four kilometers. Even for a station of this type, which could, according to the study, have a capacity of 2 Gw, it is necessary to develop an assembly model in orbit with robots as autonomous as possible, and a launch capacity and frequency much higher than those current. For costs, a range that goes is estimated from 8 to 33 billion for the first station alone7.5 to 31 for 30 years of operation, and 2.3-2.5 for development.
The technological challenges
For both systems, the reports highlight that there are still many technological research efforts to be addressed. In particular, to study the components of the structures to be sent into space, energy conversion and transmission (never attempted from such a distance) and to build large ground stations for receiving and feeding into the network. But above all, it will be necessary to design and build space robots capable of taking every brick and placing it in its place. It’s all within our reach, but everything has yet to be made possible, as we are at the dawn of these technologies. Estimates say that in 2040 we could already have the first stations, but we must invest immediately to catch up, analysts warn, from China, the US and the United Kingdom.
How much energy will come from space?
Assuming that everything goes according to plan, the first system, Cassiopeia, could produce “800 Twh per year by 2050”. While in the case of SPS-Alpha, “a system
SBSP with a capacity of 2 GW would produce around 15.78 TWh per year. To meet around 10% of the EU’s gross electricity demand, equal to around 3,500 TWh in 2050 (EU 2020 baseline scenario), 20-25 operational SBSP systems with a total electricity production of 314-390 TWh would be needed ”We read in the Roland Berger study.
In economic terms, however, taking stock is complex because it depends on forecasts on the cost of energy, which also depend on the political will, or not, to implement the ecological transition. So if in the future we continue to use fossil fuels to a large extent or give a definitive boost to renewables and nuclear power. And how markets and economies will react. Considering the investments to build, launch, assemble, maintain and operate the Cassiopeia system (418 billion), the net value of profits would be between “149 billion euro and 262 billion euro with the central case value of 183 billion euros between 2022 and 2070 “.
In short: it is worthwhile. But Europe is not the first to think seriously about it. On the contrary. Much ahead of us is the United States, in fact NASA is working on it, while a year ago the entrepreneur Donald Bren donated 100 million to Caltech for the project of the California University. The UK is already considering investing in a £ 16 billion project and could bring the first prototype into orbit in 2035. While China, which apparently is ahead of them all, has successfully tested a complete model and could bring it into orbit as early as 2028.