The Gas Bag Bus: Weird Invention #1 of Many Strange Technologies
On occasion, new resources and ideas yield exciting possibilities for future technology, but their initial development can appear strange, haphazard, and even humorous. This is often because new ideas can require more than one technology for efficient implementation. Development improves the efficiency and aesthetic appeal of new technologies, but some industries require that the technological envelope be pushed to the limit. One such industry is transportation, which seeks to move goods and customers to their desired locations as cheaply, quickly, and comfortably as possible. On a passenger vehicle scale, solar-powered cars of the 1980's and 1990's provide evidence of the attempted implementation of cutting-edge technology. These types of advances are even more critical to mass transportation, because transportation services are typically government-operated and place low-cost technologies as a high priority. When budgeting a system of mass transportation, planners pensent maximum capacity, route usage, and fuel types as major factors.
Cost-Effective Indigenous Resources
In the Sichuan province of China (just south of China's geographical center), natural gas is a relatively cheap substance. This is because there are numerous underground natural gas reserves indigenous to the region. Therefore, engineers contrived the unique natural gas bag bus as a method of utilizing these reserves. The bus was most notably used in the municipality of Chongqing (east Sichuan) in an attempt to provide cheap transportation to Chinese citizens. It was so successful that crowds often fought over bus seats! Paul and Bernice Noll, who spent 11 years in China, snapped a picture of the bizarre vehicle that is visible above.
The Rubber Bag Truth of Natural Gas
Natural gas has a few unique properties that have thwarted attempts by many to make the substance easy and inexpensive to utilize for transportation. It is present in the earth's crust in gaseous form, although it can be processed and condensed into liquid. This requires cryogenic storage, however, which is certainly not inexpensive. The gaseous form is an equally problematic fuel for transports; a storage tank must be present to contain the fuel, and metal tanks are notoriously expensive even for small sizes. As a viable solution, the makers of the Chinese vehicle put a gigantic bag on top of the bus, which is clearly visible in the picture. Just like a normal gas tank, natural gas is pumped into the bag and then into the engine by high-pressure air hoses during operation (note the hose proceeding down near the ground in front of the left-front tire of the bus from the driver's point of view). A simple visible inspection shows that the above bus recently filled its tank, because the bag droops and deflates when the vehicle is low on fuel! The rubber system provided a low-cost and reliable method of mass transportation, and some of the buses continue to operate to this day.
The Chinese design may have had its origin in similar designs present in Great Britain in World War I and II, which used "town gas" or "coal gas" (also natural gas) to power buses via cloth bags that were also placed on top of the vehicles. These vehicles were improvised solutions that eased the shortage of petrol (gasoline) that was being utilized for military vehicles at the time. Capabilities of gas compression were certainly limited and virtually nonexistent in the early 20th century, and they remain expensive today, but the gas bag buses endure as living museums of technological evolution.
http://www.paulnoll.com/China/Excursions-2/Zigong-gas-bus.html (Image used by permission, and is the copyrighted and exclusive property of Paul and Bernice Noll)