To be able to function at all, the engine must provide power for valve operation and timing, and oil pumping. These functions are optimally driven directly from the crankshaft, for they are required as soon as the engine starts to rotate.
In addition to the main purpose of providing vehicle propulsion, the engine is required to provide power for secondary functions, which include some or all of the following:-
– coolant pump (required)
– electricity generation (required)
– power-assisted braking (optional)
– power steering (optional)
– air conditioning (optional)
Although secondary functions are traditionally driven from the primary side of the engine using power taken directly from the crankshaft, there is no compelling reason why this should be so. Furthermore, there is no need to couple these requirements, which are more or less constant, to the varying demands of propulsion, and its need for acceleration and deceleration.
Overall fuel efficiency would be significantly improved if the power for the secondary functions is provided from high-temperature exhaust gases, which would otherwise be wast heat. Instead of a turbo-charger, a turbo-generator could be used, and the secondary functions modified to use electrical power. Another type of heat engine may in fact be preferable for this purpose – the Stirling Engine – as it relies on heat flow rather than gas flow, and can be designed to produce electrical power directly.
Similarly, the cooling system could be redesigned to power a second Stirling Engine, thus recovering another large proportion of waste heat.
Finally, surplus electricity could be used to hydrolyse water, the Hydrogen resulting therefrom being mixed back into the fuel intake, further enhancing overall fuel efficiency, or stored for use in a fuel cell.
Recovering waste heat from the braking system is only seen as a useful possibility if the vehicle’s final drive is to electric motors, when regenerative braking could be used.
Note. A total redesign of the Internal Combustion Engine with the objective of using as much waste heat as possible would probably improve overall efficiency even further. It could be possible to do away with water-cooling completely, for example. In the timescales dictated by global warming, however, it seems that the more obvious measures should be tackled first.
Our transport systems use fossil fuels inefficiently. Compared to the solar-powered cars in the World Solar Challenge, with electrical efficiencies of over 90%, (and free fuel), the internal combustion engine using petrol or diesel comes a very poor second at less than 30% efficiency.
Regardless of the efficiency of individual vehicles, all efficiencies drop to less than zero when the vehicle is stuck in a traffic jam. They burn fuel, but don’t travel anywhere. We can no longer afford this.
Utilization patterns are so wasteful that they cry out for modification. A vehicle is typically driven from A to B in the morning, left there all day, driven back to B at night, and left there again overnight. This is predominantly because vehicles are personal property. If vehicles were to be made communal property, the situation could be radically improved.
A) A driver takes the nearest suitable vehicle, inserts his license, and the usage is automatically deducted from his bank account. The driver does not leave a key in the vehicle – all keys are the same, and every qualified driver has one. Without a valid license, the vehicle is inoperative.
B) Fuel purchases in excess of usage are automatically credited to the driver’s bank account.
C) When at the destination, the vehicle is simply left for the next driver.
D) Faults and breakdowns are reported via the inbuilt communication system. The nearest repair shop collects the vehicle, effects the necessary maintenance., and returns it when completed.
E) Staggered working hours not only reduce congestion, but enable the same vehicle to be used by many drivers during the day.
F) Improved utilization reduces the number of vehicles on the road overall, hence congestion, and thus improves overall efficiency.
We have the technology to enable this already. We now need a change in attitude, and Global Warming is the compelling reason for it