Chapter 24. Chapter 24: Sun, Wind, and Water Energy
In what ways can we harness geothermal energy and the power of water...?
Guiding Question 24.3
In what ways can we harness geothermal energy and the power of water, and what are some of the trade-offs associated with each resource?
Why You Should Care
Geothermal energy can be used to describe two rather different things. Geothermal heat pumps, also called ground-source heat pumps, are devices that take advantage of the nearly constant temperature (~13°C or 55°F) below the soil's surface. Just like air-source heat pumps, geothermal systems "concentrate" and move heat from the outside in or vice versa. They are more efficient than air source heat pumps, however, because in the summer, they don’t have to pump heat from indoors into an already hot outside, and in the winter, they don’t have to pump heat out of an already cold outside indoors. These systems require drilling or digging to install the underground tubing and are costly but can pay for themselves within a few years. Some electric companies and local governments provide incentives to install ground source systems because households with efficient heating and cooling systems put less strain on the power grid. Geothermal energy also refers to harnessing the natural heat of the molten rock beneath Earth’s crust. Most often, this involves tapping into natural sources of heated groundwater (hot springs) or harnessing the heat of the rock to heat water. The resulting steam or hot water spins turbines to make electricity or is used directly to supply heat to homes with heating systems that have radiators or radiant floors. In some volcanically active regions, like Iceland, geothermal energy can provide fairly cheap, clean power, but those regions are relatively rare.
Water energy is currently the most important sustainable energy source in terms of usage, but its usefulness is limited. Hydroelectric power plants use the kinetic energy of dammed rivers to drive electric turbines. The power is usually cheaper to produce than in coal power plants, doesn’t pollute, and is constant, unlike wind or solar power, but there are drawbacks. Not every area has river valleys that are suitable for creating dams. Damming rivers also inundates formerly dry land, which can displace people, take away productive farmland, and destroy habitats for endemic species. Another way to harness the power of water is to use wave and tidal energy. These systems use underwater turbines in coastal areas to create electricity. The technology for these systems is relatively new, so it is costly, and the environmental impacts still remain to be seen.
So none of the sustainable energy sources are without drawbacks, but, unlike fossil fuels, they are renewable and cause less environmental damage.
Question Test Your Vocabulary
Choose the correct term for each of the following definitions:
| Term | Definition |
|---|---|
| hbXZlsAsQBHQJWT09MtZ/PhFXyJvCSnzNICJ7XDChviK6fp94kpt/TCpmjeFtafQ1Aggl+2cc4EXGiX8aVzS4u9ySSmb5HRqOERr31I3HPqF3Q2T | The heat stored underground, contained in either rocks or fluids. |
| f2xVUxpWhS+gdQS+BrE9iZoGde0jbEu3SQyh8Sa2iVWU7UEDqOprpWQYthlbdJKYLpbbJDHibW2kG/DqBn+2HQK0P7zeodu5Zyz61S8Mw302anmX | A system that actively moves heat from underground into a house to warm it or removes heat from a house to cool it. |
| 8VvNRyNqOowVCt+XVZRHjbMp8Bllhoqt4Qi45Xnre4PNBswOjDGcQGznaoNid1Dpe4wHj9kxYi26qDdPF14wiZQtNT9cAkiBBiXDsCILZz06wqeU | Power plants that use the heat of hydrothermal reservoirs to produce steam and turn turbines to generate electricity. |
| X5IQ/X7g89OfkP5IO19Dg8DMXGQ9Xv9d8YKB/VfgeIf51F1D8vIJNLnJWaslrW6wZBhnejQvotDLXm9fXjCBiCauZQMc0pMepgxsXxW8LyaAW5LR | The energy produced from moving water. |
