If you've lived through a few complete economic cycles, then you know that tough times tend to breed innovation. It's during difficult times when conventional thinking gets challenged.
Such was the case back in the late 1970s when the second Arab Oil Embargo rocked the country and caused gas long lines at gas stations and spot fuel shortages. At that time, unknown to many, General Motors had a huge staff of engineers working on turbine engines capable of powering passenger cars and trucks.
Somebody at GM saw the potential of marrying their turbine technology with America's enormous coal reserves (the 250 billion tons of recoverable coal according to the Energy Department). The offspring of this idea broke cover in 1982.
The car was a behemoth; a 1978 Cadillac Eldorado fitted with a turbine engine that ran on coal dust. The ahead of the main turbine inlet, a Rube Goldberg assembly shuttled and literally blew the finely powered coal into the turbine where it was ignited, lazily accelerating the huge Eldorado around GM's Warren, Michigan Technical Center.
Of course, when the oil spigot turned back on and gasoline prices dropped, development of the coal-burning turbine stopped. By the mid-1990s, GM stopped all automotive turbine development, concluding that hybrids and eventually hydrogen would be the path toward transportation's future.
Times are tough again. And the innovations are surfacing. Along with the Scuderi twin-piston system there's the High Efficiency Hybrid Cycle (HEHC) engine from LiquidPiston. Like Scuderi, the HEHC engine is based on thermodynamic studies that point toward an internal combustion engine that is significantly more efficient than current designs.
The HEHC's design is a sort of rotary engine. The compression, combustion and expansion (power) cycles occur in different chambers, allowing for independent optimization of each occurrence. The engine borrows ideas from the Otto, Diesel, Atkinson, and Rankine cycles. According to the designers, Dr. Shkolnik and Alexander Shkolnik, several critical design features make the LiquidPiston engine architecture both versatile and capable of outperforming conventional engines on all parameters.
The result is an engine with the following characteristics compared to similarly sized diesel and gasoline-powered piston engines:
- Significantly improved engine efficiency, reaching 50%
- Reduced size and weight by 50%
- Reduced parts count by 85%, which leads to: lower cost of production and greater reliability
- Reduced NOx emissions by 70%
- Reduced CO2 emissions by 50%
The engine has received attention and development dollars from a U.S. Army grant, and is currently being studied by prospective partners for various applications, including stationary generators.
With such promising performance potential, the HEHC engine could be something you'll see under the hood of a lightweight vehicle a decade or more in the future. Much more development needs to happen between now and then, though.