Energy is fundamental to human life.
Fossil fuels generate most of our energy. Burning these fossil fuels releases greenhouse gases. Greenhouse gas emissions contribute to climate change.
The Problem: Our survival depends on energy, yet generating that energy by burning fossil fuels threatens our survival.
The Solution: The solution is to adopt sources of energy that produce lower amounts of greenhouse gases.
Renewable energy resources offer two advantages. First, they are ‘clean’, which means that their greenhouse gases emissions are negligible compared to those of fossil fuels. Second, no matter how much of them we use, they will never run out.
Sources of renewable energy include the sun, the wind, water, bio-fuels, and geothermal energy. They can be used to replace the fossil fuels responsible for climate change.
Solar energy comes from the sun, our largest energy source. Sunlight can power home heating, cooling and lighting. Sunlight can be converted directly into electricity through photovoltaic cells or it can be used to boil water, which produces steam that powers an electric generator. Many rural households in the developing world rely on solar energy.
Abundant in the United States, hydropower lets gravity cause flowing water to turn generators that produce electricity. Hydropower stations must be built close to water, typically a river. Although proponents see water as an ideal fuel to generate electricity because it is free and doesn’t pollute, critics of hydropower argue that the dams it requires disrupt natural habitats. Water supplies for hydropower may also be reduced by climate change in some locations.
Biofuels grow originally from plants, which capture solar energy through photosynthesis. Currently they serve principally for automobile transportation. These fuels can be used separately or be combined with gasoline or diesel fuel. One type of biofuel is ethanol, which is made from sugars found in plants and trees. Biodiesel is a fuel made with vegetable oils, fats, or greases, such as might come from restaurant deep fryers. Although biofuels are generally more expensive than gasoline both in economic and energy terms at the present time, they can produce lower levels of greenhouse gas emissions in some cases.
Below the surface of the Earth, below the topsoil, are several layers of rock, which are very hot. Steam and hot water, produced by this intense heat, can heat buildings or generate electricity. Used directly, hot water from the Earth serves for bathing, heating, and agriculture. The steam from the Earth can also power turbines to generate electricity.