Alternatives to an Energy Steam Turbine
- Photovoltaic cells, also called solar cells, produce electricity directly from light. The energy in light moves electric charges in specially treated silicon, producing an electric current. Communications satellites use photovoltaic cells exclusively, as the sun's energy is particularly strong in space. Some earthbound electric utilities have also begun to use large banks of photovoltaic panels for electric power. Though solar cells enjoy a number of technical advantages, the cost of a kilowatt-hour of photovoltaic electricity remains higher than that from steam turbines.
- When sheets of two different metals are pressed together and heated, they produce a voltage between them. Physicists call this the thermoelectric effect. The amount of electricity it produces is relatively small; however, deep-space probes, heart pacemakers and underground electronic devices use this technology to produce power from the heat of radioactive plutonium. The plutonium produces its own heat energy for thousands of years. Thermoelectric power is most practical for extremely remote and hard-to-reach places in permanent darkness.
- A betavoltaic battery uses a radioactive source, such as tritium (a hydrogen isotope), that emits charged subatomic particles. A silicon semiconductor device turns the charged particles into electricity. As with the thermoelectric effect, this technology is a way to provide power in remote, dark places. As betavoltaic devices use relatively benign radioactive materials instead of plutonium, a hazardous element, they pose fewer safety challenges.
- A fuel cell is a battery that produces electricity while consuming a fuel such as hydrogen or natural gas. Rather than use combustion to produce heat, fuel cells generate electricity directly through a noncombustion chemical reaction. Fuel cells produce energy silently without any moving parts. The best have efficiencies approaching 70 percent, comparing favorably with a steam turbine's 40 percent efficiency.