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Caltech Just Demonstrated The Ultimate Clean Energy Is Possible
Their SSPD-1 satellite has achieved a world first.
Scientists and engineers are in a frantic rush to develop, launch and scale ultra-low carbon and environmentally friendly energy solutions to stave off the apocalyptic effects of human-driven climate change. While wind and solar are doing a sterling job of fighting back against the climate change-driving fossil fuel industry, they aren’t perfect. Their power output fluctuates wildly, they cause habitat loss, and they aren’t applicable for every location on Earth. However, there is a technology that promises to solve all of these problems and become the ultimate clean energy, orbiting solar power. But thanks to Caltech, this Sci-Fi-like power source just took a massive leap forward. Their microsatellite SSPD-1 was recently the first to wirelessly beam energy in space, showing the core technology of orbiting solar can work! But how? And what does this mean for this burgeoning technology?
As always, let’s start at the beginning. What is orbiting solar?
Orbiting solar power, also known as space-based solar power, takes our current terrestrial solar technology, and makes it dramatically better. Down here on Earth, the weather and nighttime cause the power output of solar panels to dip and fluctuate. What’s more, the atmosphere filters out the most powerful rays of light, reducing how much energy a panel can produce. But in space, there is nothing to filter the light, and the Sun always shines. All orbiting solar does is place our solar panels in orbit, to take advantage of how good the conditions in space are for them, and them beam this energy down to Earth to be used. Now, low orbiting satellites do experience a lot of nighttime, as they orbit close to the Earth. But Geostationary satellites (which you would want to use for orbiting solar to ensure you can power a single location 24/7) only experience 14 minutes of nighttime each day.
So, what makes orbiting solar such a prefect clean energy?
Well, thanks to the near 24/7 access to unfiltered light, orbiting solar makes 40 times more power than terrestrial solar power over the course of a year per metre squared of area. As solar panel manufacturing is the main source of carbon emissions for solar power, this means orbiting solar has the potential for incredibly low emissions per kWh, that is if the rocket used to launch them uses carbon-neutral fuel (which is possible with SpaceX Starship). Because you get fully power nearly 24/7, you don’t need utterly giant grid batteries to ensure supply meets demand. These batteries are damn expensive, and have a sizeable environmental impact, so not using them is a massive positive. This also means that orbiting solar is far easier to integrate into current energy grids, as no charge management has to take place. As the Earth-bound energy receivers are compact, orbiting solar will create virtually no habitat loss, and can be deployed almost anywhere on Earth. This also makes orbiting solar incredibly flexible, as you can move the energy receiver to where the power is needed, rather than having to build an entirely new solar farm.
The concept of orbiting solar power is decades old, but there have been some gargantuan hurdles in the way of bringing it to fruition. Firstly, launch cost. The Saturn V cost $8,714 per kg to LEO, and the Space Shuttle cost an astonishing $54,500 per kg to LEO! Launching an MW worth of solar panels into space would cost billions, making orbiting solar completely unviable. This is being solved by SpaceX, as their Starship is slated to have a cost of just $66 per launch once fully developed. So, as long as Elon can actually get this behemoth off the ground, then this will no longer be a problem. The second issue is solar panel energy density. If you can make super light solar panels, then you can pack far more “power” into each launch, which will bring the price per kWh down to near commercial levels. Luckily, such panels have recently been developed, which I covered in a previous article. The final and biggest hurdle is energy transition. It’s all good getting these solar panels into space, but how do we get the energy back to Earth efficiently, and without being impacted by the weather?
Well, this is where Caltech’s SSPD-1 comes in.
You see, the go-to technology for this energy transition is microwaves. As your home-cooking gadget demonstrates, they can transmit a lot of power, and most importantly, they can pass through cloud cover with little impedance. So, simply place a powerful microwave array on the solar power satellite, and place a receiver on Earth, and badabing, you have yourself a wireless energy transmition system!
Sadly, it isn’t this simple. The inhospitable conditions of space can render these arrays useless, and the distances we are referring to are vast! A geostationary satellite orbits 35,786 km (22,236 miles) above Earth’s surface. As such, we need to take baby steps, and develop a microwave energy transmition system capable of withstanding these mad demands.
Well, one of the experiments on SSPD-1 is MAPLE, which stands for Microwave Array for Power-Transfer Low-Orbit Experiment. MAPLE consists of two parts, the first is a series of flexible, lightweight microwave power transmitters. These can be bent with precise timing control to focus the power to different locations. The lack of moving parts and simplicity makes it both lightweight, and robust enough to survive space. On the other side of the satellite, within line of sight of the microwave array, is a small receiver. The idea is that solar power collected by the satellite will power the microwave array, and the nearby receiver will validate that it works, and how well it works.
In a recent announcement, Ali Hajimiri, Bren Professor of Electrical Engineering and Medical Engineering and co-director of SSPP said, “Through the experiments we have run so far, we received confirmation that MAPLE can transmit power successfully to receivers in space.” This is huge news, as it means Caltech is the first to prove such technology can work in space. But it gets better, he went onto to say, “we have also been able to program the array to direct its energy toward Earth, which we detected here at Caltech.”
While this isn’t full-blown energy transmition to Earth’s surface, it proves that Caltech’s technology is able to direct its beam towards a specific area of Earth, and be picked up. If MAPLE was more powerful, then Caltech could have easily been the first to successfully beam usable energy back down to Earth from space.
Now, there is still a question of efficiency. But what Caltech has done provides us with a stepping stone to develop MAPLE’s technology to be both more powerful, and more efficient. In other words, they haven’t unlocked orbiting solar, instead they have demonstrated the basic technology needed to enable it is possible. As such, we may only be a few years away from seeing the first fully functional prototypes of orbiting solar, and it may take less than a decade for it to go into commercial use. Let’s hope this is just in time to help save the world from ourselves.
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