Powering electric vehicles in the city

Simple stuff today just to stop my brain seizing up, nothing terribly new.

Grid lock is usually a term often used to describe interlocking traffic jams. But think about a canal lock, used to separate different levels of canal. A grid lock could be used to manage the different levels of stored and kinetic energy within a transport grid, keeping it local as far as possible to avoid transmission losses, and transferring it between different parts of the grid when necessary.

Formula 1 racing cars have energy recovery systems that convert kinetic energy to stored electrical energy during braking – Kinetic Energy Recovery System (KERS). In principle, energy could be shared between members of a race team by transmitting it from one car to another instead of simply storing it on board. For a city-wide system, that makes even more sense. There will always be some vehicles coasting, some braking, some accelerating and some stopped. Storing the energy on board is fine, but requires large capacitor banks or batteries, and that adds very significant cost. If an electrical grid allowed the energy to be moved around between vehicles, each vehicle would only need much smaller storage so costs would fall.

I am very much in favor of powering electric vehicles by using inductive pads on the road surface to transmit energy via coils on the car underside as the vehicles pass over them.  Again, this means that vehicles can manage with small batteries or capacitor banks. Since these are otherwise a large part of the cost, it makes electric transport much more cost-effective. The coils on the road surface could be quite thin, making them unattractive to metal thieves, and perhaps ultimately could be made of graphene once that is cheap to produce.

Moving energy among the many coils only needs conventional electrical grid technology. Peer to peer electrical generation business models are developing too to sell energy between households without the energy companies taking the lion’s share. Electricity can even be packetised by writing an address and header with details of the sender account and the quantity of energy in the following packet. Since overall energy use will fluctuate somewhat, the infrastructure also needs some storage to hold local energy surpluses and feed them back into accelerating vehicles as required, and if demand is too low, to store energy in local batteries. If even that isn’t sufficient capacity, then the grid might open grid locks to overflow larger surpluses onto other regions of the city or onto the main grid. Usually however, there would be an inflow of energy from the main grid to power all the vehicles, so transmission in the reverse direction would be only occasional.

Such a system keeps most energy local, reducing transmission losses and simplifying signalling, whilst allowing local energy producers to be included and enabling storage for renewable energy. As one traffic stream slows, another can recycle that same energy to accelerate. It reduces the environmental demands of running a transport system, so has both cost and environmental benefits.

 

 

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2 responses to “Powering electric vehicles in the city

  1. When shall I be able to personal use on purchase?

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    • Electric cars are already in existence of course, so i guess you mean when will they be able to use such a mechanism for powering. That could roll out from the bus trials to car trials within 5 years, and it could implemented as a commercial solution in 10, widespread in 15.

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