Many of the greatest innovations – if carefully investigated – can be seen to be the result of of an inventor recognizing other inventions had made it possible to achieve a long awaited dream.
For example, the story of the Wright Brothers’ first flight is incomplete without the story of the internal combustion engine. The idea that powered flight was impossible came from an understanding on the part of well informed technologists that steam engines were too heavy to be supported by aerodynamic forces. The Wright Brothers, unencumbered by the weight of conventional scientific wisdom, recognized that the development of lightweight, high powered gasoline engines had altered the equation.
The Adams Engine is based on the realization that two technologies – the gas turbine and the high temperature reactor – can be combined to realize a long standing human dream of a clean, low cost source of power.
With the exception of machines that are moved by water or wind, essentially all power producers are machines that convert heat energy into work. Almost any source of heat can be used, but the characteristics of the available heat source play a large role in the capability of the heat engine.
In fact, the lightweight internal combustion engine that enabled the Wright Brothers’ flight was itself enabled by the discovery and refinement of petroleum, a fuel source that was clean enough to be burned inside rapidly moving pistons. Coal, which was still the king of fossil fuels at the time, produced too much ash. The IC engine, first invented in the 1820s, was not commercially interesting for more than 30 years after its invention because whale oil, the dominant form of clean burning fuel, cost as much as $2.50 per gallon (1850s dollars).
In a similar way, the gas turbine, a heat engine that is simpler and less costly than a piston engine, showed little commercial potential until the natural gas industry demonstrated that it could reliably deliver low cost, clean burning fuel.
The availability of cheap gas in developed countries has led to gas turbine sales, while the intense competition in the industry has encouraged technology improvements that make gas turbines even more cost effective compared to traditional steam power plants. Based on current projections, it appears that the gas turbine is destined to fulfill the majority of the new power plant market in the United States and much of western Europe.
According to “Gas-turbine industry prepares to become a base-load supplier” (April 1996 issue of Electric Light and Power), new steam plant projects dropped from nearly 70,000 MW in 1970 to less than 30,000 MW in 1994 while gas turbine installations increased from than 5,000 MW in 1970 to more than 33,000 MW in 1994. The trend seems obvious.
While the gas turbine industry is rightfully proud of its competitive stance, there are storm clouds on the horizon that threaten its continued march to dominance.
Some industry observers wonder how long natural gas will remain inexpensive enough to allow it to favorably compete in the electric power market. Some analysts are already claiming that the time has come when natural gas prices will slow future developments. Since July of 1995, the weighted average price of natural gas traded on the NYMEX exchange has increased from $1.47 per million BTU to $2.40 per million BTU. At the higher price, the fuel cost for electricity, even with a highly efficient combined cycle machine is about 1.4 cents per kilowatt hour.
For comparison, the total production cost of electricity (fuel plus operations and maintenance) from the top twenty five electrical plants in the United States over the period from 1990 to 1993 was less than 1.4 cents per kilowatt hour.
The gas turbine industry recognizes that its future depends on developing turbines that use lower cost fuels. Several industry and government sponsored research projects are aimed at developing externally heated gas turbines and coal gasification to allow the machines to use coal heat. There is a better fuel available.
Atomic Gas Turbines
Almost as soon as it was recognized that uranium could provide a steady source of heat in almost unlimited quantities, scientists recognized that a nuclear reactor would be an ideal heat source for gas turbine engines, which work with a continuous heat input. The fact that fission produces no ash or corrosive combustion products made it seem even more appropriate to marry reactors directly to turbines.
Two big hurdles needed to be overcome before the marriage could be consummated. First of all, the gas turbine itself needed further development. Early models were only good for a few hundred hours because of the close tolerances and high temperature stresses inherent in the technology.
The other requirement was a reactor that could produce sufficiently high gas temperatures without releasing fission products. Though fission is potentially a clean source of heat, a means must exist to ensure that the small volume of potentially dangerous waste products are retained in a controlled location.
Several early attempts at atomic gas turbines were less than a complete success because of the limitations on both reactors and turbines. The Army ML-1 of the early 1960s (see “ML-1 Mobile Power System: Reactor in a Box” November 1995 AEI), for example, achieved a thermal efficiency of less than 10 percent, largely because the reactor could only produce gas temperatures of approximately 750 C, far below the 1100 C available for combustion turbines of the same vintage.
Advanced ceramic coatings now available have been used in reactors with the demonstrated ability to produce continuous gas temperatures of 1000 C or more. There are huge existing inventories of nuclear fuel materials that can be purchased for the equivalent of less than 50 cents per million BTU, or less than 1/5th of the cost of natural gas.
Fortunately for the competitive prospects of a tiny company like Adams Atomic Engines, established companies in the power equipment industry seem unaware of the opportunity provided by matching gas turbine engines with nuclear reactors.