Rapid recharge stations

With electric cars one of the main problems will be recharging the batteries and that would typically take hours. If an electric vehicle also contained a bank of capacitors (or ultracapacitors) it could be used as a short term storage medium for electrical energy. With an inductive recharger located underneath the vehicle, you might be able to design inductive charging stations in places like car parks, service stations and perhaps even in some special lanes at red lights – so the capacitors could be charged up while the car is stationary in traffic. You could combine a few technologies, like e-Tags with wireless communications, so that a company that managed the inductive recharge systems under the road could recharge the capacitors in the car above that inductive recharger, if the conditions are right. I don’t know if inductive charging would be suitable for this purpose given the distance from the bottom of the car body to the road.

You could have recharge stations at rest spots along highways designed in such a way that a semi-trailer (semi-trailer truck in American English) could park over a series of designated recharge base stations and have capacitor banks and/or batteries charged inductively with a row of charging coils located along the bottom of the heavy trailer. For large transfers of energy you might consider charging coils on  a heavy trailer that could be lowered to be closer to the concrete so that the distance between the charging coils in the ground and the trailer is reduced. The underside of a heavy trailer would have a large area for installing capacitor banks/ultracapacitors/batteries and with regenerative braking much of the energy during starting and stopping could be conserved. A heavy vehicle would also need true braking systems for rapid deceleration. For recharge stations set along highways you could have a number of local renewable energy power stations to generate the energy for the heavy vehicle transportation. The recharge stations would also need energy storage subsystems.

A prime mover in such a transport scheme might not have the storage capacity to complete a long trip by itself when most of the storage capacity is located in heavy trailers, and while the wheels on heavy trailers might have regenerative brakes, the prime mover would need to have the powerful motors to rapidly accelerate the semi-trailer. There might also need to be some fuel powered motors in an electric prime mover to deal with steep and long climbs.

Imagine if you could design a pair of solutions that when combined could power a small motor with a single waste solution that would be stored. What if you could build a subsystem that could separate the waste solution into the two original solutions when you put energy back into that subsystem? Such an energy fuel system could be used when driving up steep inclines and then when the vehicle is travelling down the decline on the other side of the mountain range the energy from the regenerative brakes could be used to separate out the waste solution back into the two active solutions.  The efficiency might be like it is for thermodynamic fuels – not very good – so even if the process is reversible, the reversible fuel system would still expend a lot of energy. The point is that such a system might be able to give an electric semi-trailer the power to make it across mountain ranges with these reversible fuel solutions. The two active fuel and waste solutions would all be stored on the vehicle throughout the trip. All the energy used during the full trip would still be from the electrical energy downloaded at charging stations.

An example of such a reversible fuel system that has two active compounds that can provide energy and a single waste product after the two active compounds have been combined is with oxygen and hydrogen as the active compounds and water as the waste solution. These are not a suitable kind of fuel for this situation because both oxygen and hydrogen are gases at standard temperature and pressure and they are difficult (and dangerous) to handle. This is only used to illustrate the idea of a reversible fuel. But imagine if you had a couple of tanks of oxygen and hydrogen and used these compounds in an engine to do some work while climbing a steep hill. The waste would be water. The water wastes could be (cooled down and) stored and when the vehicle is driving downhill, the electricity from the regenerative brakes could be used to separate the water into hydrogen and oxygen which can be returned to their respective storage tanks. To state this point again – water is not a suitable medium for such a reversible fuel cycle. As mentioned in the paragraph above, such a reversible fuel cycle may be inefficient and it may be wasteful with energy, but the advantage is that such a system could provide the extra power needed to climb a steep hill. Australia has a number of very steep climbs on the east coast through the Great Dividing Range.

Why bother? Because climbing hills is going to take a lot of energy and regenerative braking while descending on the other side of the hill is going to provide a lot of energy in return which would be otherwise wasted. For large hills it may not be appropriate to rely on the storage capacities of batteries and capacitor banks. One advantage of fuels is that they have a high energy density. It’s not really a standard hybrid design idea. The reversible fuel cycle is like a temporary power boost for an electric semi or for when the batteries are flat and the semi needs to be taken to a recharge centre. On-board computers would ideally optimise energy from regenerative braking to separate the waste of the fuel cycle back into the constituent active solutions and to charge up batteries and capacitor banks.

The power boost system wouldn’t need to include a combustion chamber if the compounds used are in solution and there are no phase changes in the process. Rechargeable flow batteries or similar kinds of systems might work for this kind of application.

How cool would it be to be driving down a long hill using regenerative braking and watch the reversible-fuel gauge slowly rise as if you were adding fuel to the vehicle at a service station. It would feel as if you were getting free fuel. It’s a far cry from the way a fuel gauge moves for a disposable-fuel vehicle at any time.