Pros and Cons of Alternative Energy Sources

^{As the number of people on Earth}

^{grows, so does the need for energy}

^{to make things work. So scientists are}

^{searching for alternative sources of energy.}

^{One alternative is nuclear power.}

^{Nuclear power does not cause air pollution.}

^{However, nuclear power must be handled}

^{carefully to prevent accidents that could}

^{have long-lasting negative effects on living}

^{things. That is why strict safety regulations}

^{at nuclear power stations are in place.}

^{In addition, much of the unwanted}

^{leftover material from nuclear plants is}

^{radioactive. It can be dangerous for a}

^{very long time if disposed of improperly}

^{Another alternative energy source is solar}

^{power. Some solar power stations have}

^{hundreds of large mirrors. These mirrors}

^{collect and focus sunlight on a large}

^{container of water to make the water boil.}

^{The boiling water produces steam, which}

^{powers machines to produce electricity.}

^{Wind is also an alternative source of}

^{power. People once used windmills to}

^{grind grains and pump water. Now wind}

^{farms use wind to generateelectricity. A wind farm is a large area of land, usually a treeless hill or other windy spot, on which groups of modern windmills operate}

_{Both solar and wind power are clean}

_{sources of energy. They depend on natural}

_{forces—sunlight and wind—to work}

_{effectively. However, sunlight varies with}

_{the weather and the time of day, and wind}

_{also comes and goes. Therefore, solar and}

_{wind power are not always available to}

_{generate electricity.}

_{Many buildings waste energy. They}

_{use oil, gas, or electricity for heat in the}

_{winter and for air-conditioning in the}

_{summer. To save energy, many architects}

_{and engineers are changing the way}

_{they design buildings.}

_{The model office}

_{building shown here is environmentally friendly. It uses sunlight and ventilation to heat and cool the building}

_{efficiently. In winter, warm air at the top}

_{heats cold air coming in at the bottom}