Discovery Science: Technology – Alternative Propulsion Systems

Technology – Alternative Propulsion Systems

Gasoline and other combustible chemical fuels contain huge amounts of energy per pint or pound. However, the burning gases released into the air contribute to global warming, while dwindling oil reserves drive gasoline prices ever higher. The need for alternative fuels is urgent.

One alternative to combustion engines is the electric motor. Contrary to popular belief, this is not a new idea; in fact, electric cars already existed in the 1830s, decades before the inventions of Gottlieb Daimler and Karl Benz. The first automobile to exceed 60 miles per hour (100 km/h) was propelled by electricity. However, because of its constant breakdowns, it was nicknamed “la jamais contente” (French for “she who is never satisfied”).

Unfortunately due to technical limitations and high costs, electric vehicle technology was neglected in favor of the combustion engine. Electric motors, nevertheless, have considerable advantages in principle: they are highly efficient (wasting very little energy), lightweight, and they produce no exhaust during their operation.

Furthermore, they can transfer power effectively to the drive-train at almost any speed, and they can use the kinetic energy of braking to generate additional electricity. On the other hand, electric cars also have significant drawbacks to consider. In terms of energy supply, batteries can only store relatively little energy per unit of weight, which explains why ordinary car batteries are so heavy.

Even today a limited range of operation is the main argument against the purchase of a fully electric car.


It is not quite true that an electric car produces no emissions; the electricity used to power it must be produced somehow. If it comes from a coal-fired or natural-gas power plant, the pollution is merely shifted from the car’s exhaust pipe to the plant’s smokestacks.

The situation is different for solar cars (or electric cars charged using solar power): these so-called solarmobiles are truly emission-free. In principle they can also get by without storing electricity in batteries. Unfortunately, however, today’s solar cells are still unable to provide a sufficient flow of power to transport several people at a reasonable speed.


There is a type of vehicle that avoids many difficulties facing its counterparts, since it uses at least two energy sources, with two energy storage systems built into the car Hybrid vehicles use one-third less fuel than comparable models with traditional gas or diesel engines.

They achieve this by using both a combustion engine and an electric motor. The two systems complement each other, allowing each to be used optimally. Moreover, like trains and streetcars, these vehicles generate additional electricity during the process of braking.