Electric/Electric

Interesting work on ultra-capacitors, and electric/electric hybrids. This essential PDF file details how the system works.

A zinc-air battery, with high specific energy density, is used as the primary power source- perfect for cruising to a destination, lots of stored energy in a small space. A conventional battery with energy density being no issue, for example of Ni-Cad cells, is used for rapid power requirements, ie. stop/start traffic, and urban driving. This can be rapidly regenerated through braking, and topped up from the zinc-air battery if required. With this system, space is not lost entirely to Ni-Cads, as zinc-air batteries are much smaller for equivalent energy. The low energy density Ni-Cads can therefore be employed in lesser amounts, to fulfill only rapid power requirements that zinc-air cannot meet. This system gives performance comparable to the fossil fuel based system in the vehicle it replaces.

Where it gets interesting, is the idea of ultra-capacitors being perfectly attuned to the rapid energy demands, and zinc-air being perfect for the distance requirements- the two would be amazing as a hybrid system. I really want to put one in a Delorean. It is of course worth remembering that the recharging of zinc-air batteries is a complex process.

Note that there is a proposal for scooters in the PDF, very interesting as far as my own personal transport concepts are concerned.

Edit: I have been running this idea through my head since the above post. Economies of scale appear to support this application in large formats, especially public transport. For a very light commuter vehicle, the purchase costs would be prohibitive when dealing with both zinc-air and ultra-capacitors. A secondary factor is the idea that the very light vehicles with conventional batteries can recharge to replace the energy used in the commute as described below- this would not be possible with a zinc-air cartridge requiring seperate infrastructure.

One compromise would be an electric/electric domestic vehicle closer to a car, seating 5 people. The conventional battery could be big enough to practically last for an entire commute in to work, and thus be recharging over the day for the return, but not have an excess- the actual capacity would require some experimentation. To make up capacity and act as a high-density resevoir while commuting, a small zinc-air battery would be installed with the whole system working in series, the zinc-air batteries topping up energy in the conventional batteries, in concert with regenerative braking. For longer journeys, the system would operate in parallel with the zinc-air running the car directly for extended periods at a constant speed, the conventional batteries supplying rapid energy. Both batteries would be modular, so different combinations would be easily installed depending on the intended nature of the trip, and intended mode (series or parallel). The zinc-air cartridge would then be sent off for recharging when desired. Variables in this idea:

Series: Short trips, a lot of installed conventional battery space is taken up, but less luggage capacity is needed on commute anyway. Most energy can be recharged during parking period, so no complex external infrastructure is required daily. Because overall speeds are slow, external luggage panniers can be fitted without affecting energy consumption adversely.

Parallel: Long trips, less conventional batteries are installed so more luggage space available. Not parking for long periods so no chance to recharge these batteries anyway, apart from regenerative braking and topping up from zinc-air batteries- they are used only for rapid energy requirements. High specific energy storage in a number of zinc-air batteries for long range, but complex external refuelling facilities will be needed at some point in the journey.


2-3 person enclosed vehicles, dedicated commuters - conventional batteries.

4-6 person vehicles - conventional batteries or electric/electric hybrid or fuel cells.

Public transport - electric/electic hybrid or system distributed electricity.

Edit 2: A Norweigian start-up company, ReVolt, has established technology to directly recharge zinc-air cells. So far only small scale applications such as mobile phones are being commerically concentrated on, but could this technology change the above thinking? we need to formulate a system to contact some of these parties, Nilut.