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The Future of Automotive Transportation

Paul Chadwick
May 19, 2009

The future of automotive transportation is a marketing/technical innovation problem, and the company that solves it will come out ahead.

Market factors:

Consumers (not only in USA) prefer to drive larger, safer, more comfortable vehicles.
Consumers like performance and acceleration capability in their vehicles: not necessary all the time, but on demand for safety and fun.
Some consumers require power on demand for towing, cargo-carrying and hill-climbing capacity when needed.
Regardless of fuel price, most consumers will gladly buy a more fuel-efficient vehicle if it satisfies their needs under 1/2/3 above.

Technical factors:

For long-distance highway travel, the amount of engine power actually required is a function of aerodynamics, frictional forces in the vehicle, and rolling resistance of the tires and is much less than peak power required for acceleration, hill-climbing, and towing.
Even in stop & go city traffic, on level streets, the amount of power needed for acceleration is ordinarily much less than the power required for acceleration under open-road conditions.
The amount of engine power required when a vehicle is not moving, e.g., standing in traffic or at a stop light, or decelerating or braking is zero.

[In summary of tech factors 1/2/3: motor vehicles are characterized by dual-power requirements. In many instances, power requirements are small or zero. In others, a much larger amount of engine power is required.]
Conventional internal-combustion-powered vehicles solve the dual-power requirement by having one large engine that runs all the time. This is wasteful and produces less than optimal fuel economy.
Electric vehicles provide a partial solution to the dual-power requirement by having a motor that is lightweight, does not run or draw current when the vehicle is at rest, and can generate some electricity to partially recharge batteries during deceleration. Drawbacks are: limited range, long charging times, cost of batteries, limited battery life, shock/chemical/explosion risk of batteries, weight of batteries, environmental concerns with battery components. Additionally, electric vehicles only reduce CO2 emissions if the power to charge the batteries can be generated by solar, wind, hydro, tidal, nuclear, or biofuels.
Hydrogen fuel-cell powered vehicles are a special case of electric vehicle in which hydrogen gas and the fuel cell generate power on board. The hydrogen tanks and fuel cells add cost and complexity. Also, to reduce CO2 emissions, hydrogen must be generated by power from renewable sources — solar, wind, nuclear, or biofuels. Hydrogen gas is potentially explosive and hydrogen refueling stations would be needed.
Internal-combustion/electric hybrid vehicles provide a solution to the dual-power requirement by having an internal-combustion engine smaller than needed for peak power requirements and an electric motor than provides additional power when needed. Both power sources can shut down when the vehicle is at rest, and the electric motor can generate electricity to partially recharge batteries during deceleration. However, the optimum-size internal combustion engine is larger than required to power the vehicle alone during minimum-power-requirement operation. Sustained operation under high-power-requirement conditions is not possible for long periods of time; when the electric motor discharges the batteries, only the power of the internal-combustion engine is available. Two power sources in the vehicle adds cost and complexity. All the drawbacks of batteries also apply.
Internal-combustion engines typically run on fossil fuels. However, internal combustion engines can be designed for reduced carbon footprint by running on biofuels. In addition, internal combustion engines can be designed to run on hydrogen, which also reduces carbon footprint if generated by power from renewable sources — solar, wind, hydro, tidal, or nuclear.
Modern electronics and microcomputers provide the technology for sophisticated, rapid, responsive control with all types of engines and power transmission systems, including internal combustion engines.
Smaller, simpler internal combustion engines with less moving parts, less frictional resistance, and higher power/weight output have been designed and perfected for reliability and long life. An example is the two-stage 1.3-liter "Renesis" rotary engine sold by Mazda Motors in its RX-8 sport coupe. This engine has 212 HP power output equivalent to a six-cylinder conventional piston engine in a significantly smaller and lighter package. There are no camshafts or valves, which reduces operational friction. Mazda has developed a version that will run on hydrogen. The design is modular, and could easily be expanded to incorporate three or four stages, equivalent to conventional nine- or twelve-cylinder engine for higher power requirements. A much larger vehicle could easily run at speed on a level highway or in city traffic driven by the power of just one rotor of the Renesis engine.
The dual-power requirement could potentially be satisfied by incorporating two internal combustion engines in a vehicle — a smaller engine to provide minimum power for sustained travel on level highways and light acceleration in city traffic, and a larger engine to provide added power for acceleration and hill-climbing as well as sustained power when needed for towing. The power requirements of the vehicle could be monitored either automatically or manually and smooth transition between the two engines managed by advanced microcomputer systems, sensors, and actuators. Alternatively, rather than two separate engines, the dual power levels could be obtained by a single modular multi-stage engine with sections that can be coupled or decoupled from the vehicle drive train under computer control. (This type of action has already been approximated by certain production engines that reduce operation from eight to four cylinders when the additional power is not needed by cutting spark and fuel supply to the unused portion. However, in such engines to date, the entire mechanical component of the complete engine continues to turn, so there is no reduction in frictional forces.) A modular multi-stage engine need not necessarily be restricted to two stages, but could consist of three or four stages, allowing power output to be more precisely calibrated to the needs of the vehicle under various operating conditions. An advantage of a single multi-stage engine would be that certain common components — water pump, oil pump, alternator, starter, transmission components — could serve all stages of operation and not necessarily be duplicated as in the case of two separate engines, reducing weight and complexity. Also, a computer-controlled shut down and rapid restart system could be incorporated to completely shut down the engine when standing traffic or at red lights and during deceleration. The Mazda Renesis engine might serve as the ideal model for such a modular multi-stage engine. Its modular design with direct in-line coupling among the rotor modules by a single power shaft could lend itself to a simple rapid coupling and decoupling system, and there are no camshafts or valves to complicate coordinating operation between the various stages, meaning only the angle of coupling on the power shaft and timing of spark and fuel injections would need to be managed. If properly developed, the power transition between single-stage and multi-stage operation could probably be accomplished smoothly and with delay of less than a second or so. Also. for times of sustained power requirement the number of engine stages operating could be manually selected to override the automatic transitions and provide smooth operation.

[The engine suggested in item 11 above would have many of the advantages of an internal-combustion/electric hybrid with no batteries, no requirement for new types of special fueling or recharging stations, no lack of sustained power availability when required, no extra weight, and only modestly increased complexity and cost. It would be expected to provide substantially inproved fuel efficiency over conventional internal-combustion power trains with no lack of performance when needed.]
Advances in bearing design and lubricants could reduce frictional forces, and further advances in tire design might be able to reduce rolling resistance.

The challenge to automotive marketers and engineers is to solve the problems of providing vehicles with significantly improved fuel efficiency and the possibility of carbon-neutral operation without sacrificing size, safety, comfort, or performance. It is not sufficient simply to rely on designs of the past — large V8 SUVs and pickups, small cramped underpowered economy cars — to provide vehicles for the future. What we learned from emissions requirements imposed in the 1970s is that what at first may appear difficult or impossible often becomes reality with time and ingenuity. It doesn't happen without effort, and effort is often not applied without mandate.