More and more people are installing solar panels on their homes in an attempt to reduce their carbon footprint, and indeed, many people believe that solar power is the wave of the future. After all, solar power is clean, sustainable, and can actually save people money, but what is the effect when this type of power is used to power other items – such as airplanes? Despite what you might think, there have been successes, solar airplanes are not always what you think they are.
The Basics of Solar Power
When people choose solar panels for their home, there are two basic components: the panels themselves and a battery that soaks up the sun’s power so that power can be harnessed during times when the sun is down. Between these two components, the home is provided with the power it needs to operate like it normally does 24 hours a day, seven days a week.
Not surprisingly, solar powered planes work essentially the same way. They have a battery and panels, and it is possible to operate the plane for long periods of time because the sun comes out almost every day. Because the battery soaks up so much power during the day, many of them can power the home or plane for a certain length of time even if there is no sun for a while – usually up to roughly 14 days. The number of days may vary, but this is how solar power works in general.
Getting Started with Solar Powered Planes
In the summer of 2018, an Airbus airplane flew just minutes short of 26 days using solar power only. The Zephyr S HAPS (high altitude pseudo-satellite) took off from Arizona and enjoyed an unmanned nearly one-month-long flight. It used lithium-ion batteries and flew at a height of 70,000 feet in the air.
Before that, the longest solar flight was only 14 days long. It took place in 2016 and took 17 separate legs to complete. This plane was called the Solar Impulse 2 and was a manned flight that actually circumnavigated the globe without using a drop of fuel. So as you can see, solar powered flights, although not common, are not exactly science fiction anymore.
Are These Planes the Wave of the Future?
Everybody from scientists to investors are curious about the future of solar powered planes, but before you start looking forward to your own flight on one of these planes, there are a few things you should know. First of all, there are some considerations that need to be looked into by the experts, because after all, fossil fuels and solar energy use two completely different types of power.
To determine if solar power can successfully be used on commercial flights in large numbers, the experts will have to consider aspects such as:
- Scalability: solar power was possible on the Airbus and Impulse because they were both lightweight and had large wingspans. By comparison, a 747 filled with people would be much heavier than that, and it wouldn’t be possible to load that many solar panel cells on its wings because they couldn’t accommodate them. More efficient panels wouldn’t help either because it still would not add enough power to make it work.
- Speed: this is perhaps the biggest problem with solar airplanes, because not only do these planes have larger wings and lighter weights than standard airplanes, they also fly at much slower speeds. One of them, the Impulse, flew at only 30 to 40 miles per hour. Increasing their speed causes problems with drag, which means the flight will be far too expensive for most people to afford flying on it.
- Range: Another thing to examine is the maximum distance the plane would be able to travel without recharging or refueling. Some may think that bigger is better when it comes to a plane’s range, but that is an incorrect assumption. The reason is because they are heavier and thus end up using fuel or energy faster.
In other words, to fly commercial planes with solar power would be too slow and too expensive, and it would likely take the same amount of time to fly people somewhere on a solar powered plane than it would to put them on a bus or even a car. This makes solar power a near impossibility for commercial use, at least for the time being.
Problems with the Batteries
Solar panels on a home operate by a battery that soaks up power from the sun, which is used whenever it’s dark outside, but for solar powered planes, this is likely a very impractical solution. Simply put, the fact that airplanes that use solar power have limited capability to fly at night, and this is partly because of the batteries they use.
Again, the Impulse used a lithium-ion battery, which is not as energy-dense as it would need to be to accommodate commercial flights. Even today, the most dense battery available is the zinc-air battery, but it does not compare with the ones used successfully on a solar powered flight. In fact, the zinc-air battery would only be able to fly at night for around 1,000 kilometers, or roughly 620 miles, which is not a very far distance. This is one of the reasons the Solar Impulse had to take so many legs to complete its trip.
Does This Mean the Task Is Impossible?
So, does all this mean that we should just give up on using solar power to fly airplanes? Not necessarily. Scientists work on new energy solutions all the time, so this goal is not exactly impossible. That being said, it isn’t likely to happen anytime soon, so for now, most experts agree we should concentrate instead on other methods of flying planes that will at least be a little greener than they are now.
Of the suggestions that have been tossed around so far, the electric plane and a plane that runs on power to liquid (PtL), which is more eco-friendly than bio-fuels, are the two most popular. PtL is essentially synthetic kerosene made from electrolyzed water with added CO2. Unfortunately, most experts agree that it will be a minimum of two decades before either of these options is feasible, so in the meantime, society will have to make do with other less-green forms of energy for airplanes.
While solar planes are not a feasible option currently, there are some promising results so far. They continue to innovate and as technology continues to advance in this field, the closer we will be towards having solar powered planes. In the meantime, we can take advantage of other ways to use solar energy. Check out my articles on solar powered cars and my beginner’s guides to solar power.