Automobile. For 30 years, General Motors believed in the turbine engine, why did it fail?

For more than three decades, General Motors and some of its competitors have been trying to design turbines for automobiles. The goal wasn't to break new speed records, but rather to offer a viable alternative to internal combustion engines, capable of using a range of alternative fuels at a time when the world feared a crude oil shortage.

On paper, the turbine engine has many advantages. Turbine engines draw in air. This air is compressed by a series of rotating blades, then mixed with fuel and ignited. The energy thus produced is used to turn the turbine, which turns the drive shaft, and therefore the wheels.

Turbines also have some advantages. They have far fewer moving parts than conventional engines, which makes them, at least in theory, more reliable. In addition, they are compact, smooth, and stable, with minimal vibration.

Finally, turbine engines can be powered by propane, kerosene, aviation fuel, landfill gas, ammonia—in short, any fuel. Chrysler once demonstrated this with a car running on tequila!

General Motors began researching turbine engines as early as the 1940s, as documents at the GM Heritage Center show. But problems quickly arose: turbine engines run extremely hot, with exhaust temperatures that can exceed 400°C.

They are also inefficient at low speeds, expensive to produce, and highly polluting. After several years of study, GM launched a series of turbine-powered concept cars, starting with the 1954 XP-21 Firebird 1, the first gas turbine-powered automobile ever built and tested in the United States.

Two years later, the Firebird 1 was naturally followed by the Firebird II. A concept car with a titanium body but closer to the appearance of a real car. A Firebird III, all angles and fins, with two curved cockpits for the driver and passenger, was also presented. But why stop at cars?

At the same time, GM extended the experiment to buses under the name Turbocruisers. The original Turbocruiser, unveiled in 1953, was the world's first turbine-powered bus. Following the same principle as for turbine-powered cars, GM would develop Turbocruisers II, III, IV, and V over the next two decades.

For the 1964 New York World's Fair, the Bison concept made a splash with a cab lower than a conventional truck and a fully glazed cockpit. The cab had no doors; the hood opened forward like a clamshell.

The Bison was then equipped with a twin-turbine engine, designed to produce 1,000 horsepower, housed in a nacelle behind the cab but in front of the trailer. Inside, the steering wheel was replaced by an aircraft-style two-handle stick, and the center console was equipped with a telephone.

In June 1981, at an event marking the 25th anniversary of the GM Technical Center in Warren, Michigan, GM unveiled a new approach to turbine engines: coal. That day, GM showcased a Cadillac Eldorado and an Oldsmobile Delta 88 equipped with engines powered by ultrafine coal dust, whose particles, three microns in diameter, are finer than powdered sugar.

“Because coal is a particularly attractive fuel due to its abundance in the United States, it could significantly reduce our dependence on imported oil if it could be developed for automotive use,” a GM statement said.

The idea isn't exactly new. Rudolf Diesel, the inventor of the diesel engine, had experimented with coal dust as a fuel decades earlier. In GM's experiments, the powdered coal was stored in a tank under the hood, connected to an air compressor that blew the fuel into the turbine engine.

GM had previously tested engines powered by coal-derived methanol, but using coal dust directly was considered far more efficient and potentially much cheaper than gasoline. Coal is a much cheaper fuel source than oil.

What seems obvious today wasn't so obvious at the time, but unsolvable problems quickly arose. Burning coal produces ash, smoke, high levels of sulfur, and various other pollutants. But GM's main idea at the time was to think about alternative solutions in the event of the end of oil.

“We’re just trying to show that we’re not going to run out of energy anytime soon,” said GM vice president Howard Kehrl. “We’ll be able to keep using cars as we know them today for centuries.”

Jeffrey Luke, a GM veteran now serving as GM's executive chief engineer for worldwide engines, reflected on GM's turbine venture. The primary reason for the turbine engine's failure was that it performed poorly at low speeds, significantly impacting its efficiency and driving its fuel consumption to unacceptable levels, along with very high nitrogen oxide emissions.

Add to that the use of expensive materials and you can understand this failure. One thing is certain: with current standards, there is no chance of seeing such an engine on our roads.