The Sun(129786)

Nowadays, renewable power is popular: many people install solar panels on the roofs of their houses. It’s actually quite idealistic, trying to help nature by consuming less fossil fuels and polluting less. But what real difference does it make for nature? The power solar panels provide isn’t enough to be completely independent of fossil fuels. But it’s a start.

Solar energy can be very useful. Well, under certain circumstances that is. The energy of the sun shining for an hour on Earth is enough to power up our planet for over a year.[6996] Too bad we can’t capture this energy just like that. The Earth’s atmosphere consisting of air, moisture, pollution and other small particles blocks more than 90% of the solar energy that reaches our planet.

The solution: go higher into space, where the atmosphere isn’t as impeding as on Earth.

Solar Panels in Space

Beaming Solar Energy to Earth

Even in 1968, when mankind was just discovering space travel, Peter Glaser, consultant for Arthur D. Little in Massachusetts, get the idea to build a satellite to use solar energy. His plan was to build the satellite on Earth and then bring it to space. There, the satellite would generate energy which could be beamed to Earth with microwaves.

He thought of panels of a size of 50 square kilometers (almost 20 square miles), shot into space with reusable rockets. Hundreds of astronauts would be staying in space to assemble the project. He calculated the sender dish would have a cross-cut of around 1 kilometer (0.62 miles) to beam the microwaves to Earth. And the receiver on Earth would need to be even bigger.

Too bad for Glaser, NASA didn’t think the project was achievable: bear in mind that we’re talking about 1968. Neil Armstrong hadn’t even set foot on the Moon yet. The launching of the satellites would cost billions of dollars.

The Present

John Mankins, now President of the Space Power Association, readopted the idea of Glaser. He’s been lobbying at NASA to promote Space Solar Powerstations (SSPs), and says the idea of Glaser is perfectly feasible now.[6997]

One reason he’s confident SSPs are possible, is that the power output these solar panels have has increased significantly since the seventies. Solar panels the size of 10,000 soccer fields won’t be necessary anymore to achieve the same results. There’s also been made a lot of scientific progress with microwaves: the size of the sender en receiver dish could be reduced. And the main argument NASA didn’t want to start the project could also be invalidated: making use of robots for the assembling of the panels could bring down project costs and especially risks significantly.

The SunTower

Mankins is getting more concrete about his plans as his SunTower SSP is the most promising. The SunTower resembles a giant sunflower, due to his form and due to the fact that it rotates with the Sun. The SunTower will consist of many modules (like the ISS is): solar panels with a diameter of 50 to 60 meters (165-195 ft) and a “spine”. This spine sends the generated energy to a klystron.

A klystron is a device that generates and/or amplifies micro waves. Those micro waves are used to transmit the power to Earth, using an antenna dish with a diameter of 260 meter (850 ft). It’s clearly a lot smaller than Glaser’s dish. However, the receiving dish would have a diameter of 4 kilometer (2.5 miles). Back on the ground the dish transforms the power back into usable electricity and adds it to the power grid.

At first, many ground stations are needed, since the receiving dish turns around with Earth, while the transmitting dish stays with the Sun. A receiving power plant of a few hundred megawatts will cost 8 to 15 billion dollar. When this proves successful, more SSPs can be brought into space, and receiving dishes can be used in turns.

Waves from Space

The reason these proposed space stations use micro waves to transport their generated energy back to Earth is they’re highly efficient. Microwave Power Transmission (MPT) is 90% efficient. Theoretically, high power can be transported with this technology. Practically, it’s unclear what would happen with passing birds or planes that could fly in this “beam” of micro waves being sent to Earth. The method wouldn’t get a lot of supporters if the area around the antenna would be littered with dead birds and crashed planes.

Japanse in Space

Japanese in Space

Since the eighties, Japan has also been exploring the idea of SSPs. Masahiro Mori, president of the Mukta Research Institute, has an ambitious plan for his country. Financial support of the Japanese space organization JAXA and the industry makes it possible to think seriously about solar energy from space.  It can reduce CO2, is stable and is clean.

Japan intends to make this happen by trying to push down the price to build the equipment. For only a billion dollars, Mori wants to build an installation that can generate up to one gigawatt. Because of the reduced costs, the resulting electricity can be sold cheaply. A way of reducing the costs is making robots do most of the work. 


Still, many people aren’t convinced yet that experimental space projects like these are feasible. Some say with the money to build an SSP, many solar panels on the ground could be built, much cheaper. Others say that the projects are too risky for that kind of money. But then again, sometimes risks should be taken for the sake of science.

By coremelter on