Energy stories in the news are amazingly predictable. They ballyhoo a scientific breakthrough so “new and exciting” it’s sure to affect everyone who uses electricity. Then the promises about efficiency, environmental sensitivity, cheap power, and so forth begin.
Three energy ideas that get just this kind of publicity are superconductivity, nuclear fusion, and coal gasification. But when will these promises become reality?
The idea behind superconductivity is easy to understand. In the electrical systems we have now, electricity travels through wires made of metals that are good conductors of the electrical current. But they’re not perfect. There is some resistance to the flow of electrons, creating heat that escapes as a byproduct. That wastes energy, and the constant heat causes other problems in the electric transmission system.
Scientists have discovered that certain metals and ceramic compounds conduct electricity much better when they are supercooled to temperatures many hundreds of degrees lower than the freezing point of water. Using liquid helium or liquid nitrogen as the coolant, coils of wire made of these metals or ceramics can carry large amounts of electricity for years without giving off any heat. The materials become “superconductors.” With no wasted energy in the form of heat, superconductivity promises to improve efficiency.
Transmission lines made of superconducting materials would dramatically improve the electric utility grid, offering high efficiency and reducing maintenance costs. But today’s power lines are exposed to extremes of weather in very un-laboratory-like environments. The challenge for scientists and engineers is to figure out a way to make superconductivity practical—this technology will likely take decades to become reality, and probably only in very limited applications. Instead of in transmission lines, superconductivity may prove more practical for storing electric energy.
Nuclear fusion is already an extremely common form of energy—it’s what makes our sun shine every day and billions of stars glimmer every night. Nuclear fusion differs in several important ways from nuclear fission, a technology already in use here on earth. In fact, nuclear fission reactors currently supply 20 percent of the nation’s electricity. In present-day nuclear reactors, fission splits a larger atom (such as uranium) into fragments, releasing energy. That energy can be used to heat water, creating steam to turn turbines that produce electricity.
Fusion, by contrast, joins two light elements (such as hydrogen or helium) to form a more massive element, releasing energy as the elements fuse together. This goes on continually in stars, but there are at least three major problems to solve before the energy released by fusion can be used on Earth.
First, nuclear fusion doesn’t occur at typical earthly temperatures; it requires temperatures many millions of times hotter than boiling water. In laboratory experiments, scientists have achieved temperatures even hotter than the center of the sun. But that was only for a brief time.
The second obstacle to making nuclear fusion practical is figuring out a way to sustain those ultra-high temperatures for a long enough period of time to produce substantial amounts of usable energy.
Once that’s accomplished, the third step will be designing, building, and operating a demonstration fusion power plant—and that’s likely to take several decades.
Coal is a gas
The innovations required to make superconductivity or nuclear fusion practical are vastly different from anything in use today. But another kind of experimental power plant builds on familiar technology and is well on the way to becoming part of the world’s energy systems.
Coal gasification works very much like a typical coal-fired generating plant. But instead of simply burning the coal to produce steam for turbines, the gasification process uses steam first to break down the coal (or any other carbon-based fuel) into its basic chemical parts. Using high temperatures and pressures, the coal turns into a gaseous compound; the carbon monoxide, hydrogen, and other parts can be extracted and used for a variety of purposes.
During President Bush’s first term, he announced that the United States would begin a $1 billion, 10-year demonstration project to use coal gasification as the main component of the world’s first coal-based, zero-emissions electricity and hydrogen generating plant. The U.S. Department of Energy’s “FutureGen” project’s goals are to develop an advanced coal-based power system capable of achieving up to 50 percent thermal efficiency, at a capital cost of $1,000 per kilowatt or less, in five years. The year 2010 may see this energy promise become a reality.
TO FIND OUT MORE
To find out more about each of these energy innovations, visit these Web sites:
Nuclear fusion/the Princeton Plasma Physics Laboratory
Coal gasification/U.S. Dept. of Energy