Many stories around the world have been published in magazines and newspapers about solar vehicles, solar cars and the unlimited applications of solar energy. A lot of research is being performed to promote the use solar cars and to make their wide-spread use practical in the future. In some sense, however, all automobiles are solar-powered.

Almost all vehicles currently on the world's roads are powered by a petroleum derivative. Petroleum is pumped from deep in the earth. It was formed a long time ago from dead plants that used solar energy directly. Hence, petroleum energy is a type of solar energy captured in the petroleum products. When a petroleum product, such as gasoline is mixed with air and ignited in a conventional internal combustion engine, that ancient solar energy is released in a sudden explosion of gas that drives the piston and moves the vehicle.

Although we have never driven a vehicle that was not powered by a fossil fuel, the ancestors of the modern vehicle were powered by a variety of energy forms.
The steam power was the first used to mechanically drive road vehicles. In 1769, the French engineer Nicolas Cugnot modified a horse-drawn tractor, originally designed to pull a cannon by adding a drive mechanism and a steam engine. It seems that Cugnot's steam-driven tractor was not designed for long trips. Its top cruising speed was two miles per hour, and it had to stop every ten to fifteen minutes to build up steam.

Steam engines work by external combustion. The fuel used for external combustion engines is coal, wood or oil. The fuel is burned outside the engine to change water into steam, which dries the engine. Many steam-powered engines were developed in the eighteenth and nineteenth centuries, however, they have many serious problems among which is their tendency to explode. It is amusing to note that in Great Britain, in the 1830s, a law required steam-driven vehicles be preceded by a person on a horse, carrying a red flag.

Although considered since the seventeenth century, no break-through in the internal combustion engines was made until 1860 when the French inventor Etienne Lenoir built a small single-cylinder engine. The German engineer N. A. Otto adapted this design for a four-stroke engine that burned coal gas fuel in 1876. Eleven years later, Karl Benz put the internal combustion engine on the road in a three-wheeled vehicle, driven by chains like those on a bicycle. This was the first Mercedes, with a top speed of 13 km per hour.
There were more than seventy experimental internal combustion automobile manufacturers in the United States of America by 1895. Mostly, those were designed to use some form of petroleum products.

Some automobile manufacturers concentrated on electric cars, as they are very quiet compared to the very noisy internal combustion cars and they do not emit any fumes. Electric cars were the most popular cars in America in the 1890s. Their main problem was that they needed recharging after about fifty minutes of driving.
The cars with internal combustion engines became the most popular cars after they achieved higher speeds and assembly line mass production was introduced. The electric cars are being reconsidered after the dark face of fossil fuel is unveiled. The serious concern over the fossil fuel supplies, their pollution, high prices and dwindling supplies, caused the engineers to look once again at electric cars. This time new technologies are explored using the same old fuel: the solar energy.

For Yemen, solar energy is the energy of the future.