AS of 2016, there are already tens of thousands of electric cars on the roads, and that number promises to skyrocket in the coming years, as more and more automobile manufacturers try their hand at this growing industry. The combination of responsible energy use and a move away from fossil fuels, while also delivering a comfortable ride in some of the most high-demand cars on the market, is a good sign for the environment.
This new rise in electric cars has also led many to wonder about other forms of transportation, particularly those that traditionally require huge amounts of fuel. With more than 100,000 airplane flights per day on this planet, that is a whole lot of fuel being used to cart us around in big metal tubes. Although only 87 orbital rocket launches occurred in 2016, the type of fuel required for these launches, and the inevitable rise in rocket launches in the coming years, this is also an area of some interest when it comes to electric power. The question is… are electric rockets and planes even possible?
Short Answer: Yes, but they are severely limited by a number of factors, making their widespread use either unfeasible or impossible, at present.
The Dream of Electric Planes
The idea of electric planes is hardly a new one, the first man-carrying electric-powered flight happening in the early 1970s. However, with the resurgence in interest in electric-powered transportation, and the battery capacity advances in recent years, the idea has come back to the forefront for many aeronautic engineers and entrepreneurs.
Nearly all of the aircraft in the sky today manage to fly with turbines, with engines that suck air in through the front, compress it, and then spray in fuel. The fuel is lit and then essentially blown out the back of the turbine, creating a fiery exhaust and a huge amount of forward thrust. This is how we’re able to span oceans on a single tank of fuel, in conjunction with the physics of flight and incredibly well-designed airplanes.
However, an electric-powered plane would be quite different. Batteries would have to power an engine, which would spin the propellers and create forward thrust. The problem is that the amount of thrust would be significantly less than the type created through chemical combustion, i.e., the burning of fuel. Overall, the process is a more efficient use of fuel than traditional planes, but the maximum speed that an electric-powered aircraft can get is only 10-20% of a fuel-burning aircraft, and even that is on a smaller scale aircraft. So far, no electric plane has surpassed the 200 mph mark, whereas the fastest commercial planes in history have topped 1,500 mph (Tupolev TU 144).
The main problem is the capacity of batteries to generate as much energy as burning fuel. To have a flight powered entirely by batteries, with a full load of passengers, the plane would have to be jam-packed with batteries (which aren’t the lightest things in the world!). For example, a full Boeing 787 Dreamliner can hold over 220,000 pounds of jet fuel. To store an equivalent amount of energy in the form of batteries would weigh over 4,000,000 pounds. As battery technology and capacity continues to improve, spearheaded by visionaries like Elon Musk, we might see a shift towards electric planes, but at present, it is simply not efficient for large-scale, commercial airlines.
For smaller planes and short-duration flights, electric power is definitely a reality, and will continue to grow at a rapid clip as an industry, but for those of use without private planes, we may have to deal with fuel-burning planes a bit longer.
Other people are quick to point to the potential for solar-powered planes, but the problem is even more severe in that case. The amount of solar panels that would need to be loaded on a plane in order for it to fly would be enormous, and the speed would be even less impressive, perhaps lower than 50 mph. Solar energy capture and battery storage remains highly inefficient, so serious advances need to be made before we’re taking energy-independent puddle jumps over the ocean.
Electric Rockets Are the Future?
When we start talking about rockets, it’s important to discuss Newton’s Laws of Motion, specifically #3, which states that for every action, there is an equal and opposite reaction. On land, say, when you’re driving a car, the vehicle pushes backward against the ground, thanks to friction, which allows the car to move forward. In space, however, there is no up, down or ground, so that complicates the situation. In that case, as we’ve done since the beginning of the space program, and ejection of mass must work against the direction of the rocket launch. To simplify this, the exhaust velocity is equal to the rocket’s forward velocity.
We currently have incredibly compressed rocket fuel that is shot out behind a rocket to launch it into orbit – and the release of energy to push that rocket into space is enormous! Consider the same limitations of batteries on airplanes and add a few more orders of magnitude. Once again, we simply don’t have batteries that can generate enough energy in an efficient mass:output ratio to make an electric-powered rocket feasible. The primary problem is getting a rocket from the ground into space. If this issue can be overcome, then the concept of battery-powered space travel is much more viable.
Once a rocket has made it into space, there are many other theories and ideas for propulsion that aren’t so limited by the enormous forces of gravity and the need for thrust. Ion propulsion has been proposed, as well as lightsails and beam-powered propulsion (in which a laser beam from Earth is directed at a spacecraft and the photons act as the propellant. This precise technology is in the development phase; you can read more about it here.
That being said, many of these potential technologies are theoretical, and in the case of solar sails and beam-powered “lightcraft”, the entire structure is very small, and not suitable for manned flight.
As it currently stands, enjoy your electric cars and pat yourself on the back for contributing to the sustainable-energy revolution, but don’t hold your breath for large-scale transitions to electric power for planes and rockets… in reality, we’re still years or decades away from those incredible innovations.
- Electric Aircraft – Wikipedia
- Electrically Powered Spacecraft Propulsion – Wikipedia
- New Project Plans To Send A Spacecraft To Alpha Centuri In 20 Years IFL Science
- 2015 Space Launch Statistics – SpaceFlight101.com