People often question the need for a new mode of transportation, in this case a, Hyperloop. The most common remark about the Hyperloop is that it is just a train in a de-pressurized tunnel (reducing aerodynamic drag) or a Maglev train (nullifying friction between wheels and rails) which has been running for quite some time now. People do feel the technology already exists and there is no need to spend on something like the Hyperloop.
In very simple terms, yes, the Hyperloop does combine the two remarks to get a highly efficient mode of transportation – running in a de-pressurized tube and levitating. What makes it different is the scope of application of this technology.
The idea behind running the pod in a de-pressurized tube is to decrease air resistance hence reducing drag. There is no use of de-pressurized tube in the first place if your vehicle isn’t optimized for least drag. It doesn’t depend only on the vacuum conditions. If it were so easy, we would have seen a revolution in transportation industry many years ago. Hence, we can’t make our trains run in these tubes because they simply aren’t aerodynamically efficient. The length and shape are the primary reasons why. In the case of the Hyperloop, a single pod is expected to carry 6 to 8 passengers which gives engineers a lot of scope to make the designs of the pod optimized to a high degree for least drag.
Now the Maglev trains first made debut in 1984 and since then have only been running commercially in China, South Korea and Japan. The maglev trains use EMS (Electromagnetic Suspension) system. In layman terms, the track is an electromagnet having metallic coils in the rails and the trains have magnets on the underside. The track is powered by a large electrical power source. The alternating magnetic field in the rails propel the train and levitate the pod to avoid contact friction. Sounds as if we have what we need, but why isn’t it used all over the world?
The concern is the power source. Imagine the energy needed to power an electromagnet which spans the entire length of the route. Maglev requires a dedicated infrastructure including substations and power supplies and cannot be integrated directly into an existing transportation system. To give you a perspective, Japan’s Shinkansen (285.6km long), which runs from Tokyo to Osaka at speeds of up to 505km/h – has also been criticised for being too capital-intensive. The scheme is expected to cost an eye-watering $49bn but could easily end up costing more. It is a lot cheaper to upgrade the tracks for existing route than create a separate infrastructure for the Maglev. This is why Maglev isn’t present all over the world. The method of levitation used isn’t viable for large scale commercial use.
What makes the Hyperloop different is the method of levitation used. The EDS (Electrodynamic Suspension) system is the key for cost savings. In this system, the rail can be an aluminium “I” beam and the hyperloop pod has an array of magnets arranged in a specific orientation. When the pod is propelled along the track and reaches a specific speed, magnetic fields are generated due to relative motion between the track and the magnets on the pod, which repel the pod and it levitates. No power source is required as per the case in Maglev trains saving expenses.
The Hyperloop levitates only after achieving a certain speed; hence it has wheels for low speed conditions while accelerating and braking. As far as propulsion is concerned, the LIM (Linear Induction Motor) is under consideration by Virgin Atlantic and various student project teams working on the Hyperloop. You can imagine it as a normal DC motor but arranged in a linear fashion. The rotors are present on the pod which is magnetically attracted to the stators aligned linearly on the track. The pod is magnetically propelled as it moves over the stators. The stators are nothing but an electromagnet, but the power required is less compared to Maglev trains because the electromagnets are used only for propulsion. Solar panels attached along the tube will power the magnets hence reducing cost again.