The 5 main alternatives to fossil fuels

There are five main technologies that are considered “renewable energy sources”. We’ve put together an info graphic below to compare the main five renewable energy options side by side”:

Read on for even more detail on these renewable sources:

Solar energy

One of the most popular types of renewable energy is solar power. Solar energy comes from the sun, which supplies our entire planet with the energy we need to survive. Using solar panels, we can harvest energy directly from sunlight and convert it to electricity that powers our homes and businesses. Solar energy can also be used to produce hot water or charge battery systems.

Solar energy has benefits both for your bank account and for the environment. The cost of solar is constantly dropping, and installing solar on your home will almost always save you money over the lifetime of your installation. On top of that, producing solar energy doesn’t pollute or release fossil fuels, which means you can dramatically reduce your environmental impact by installing solar.

Wind power

Another type of renewable energy that we interact with every day is the wind. When you feel the wind, you’re simply feeling air moving from place to place due to the uneven heating of Earth’s surface. We can capture the power of wind using massive turbines, which generate electricity when they spin.

While not always a practical option for an individual homeowner, wind power is becoming increasingly popular for utility-scale applications. Massive wind farms spanning many square miles can be seen around the world. Like solar energy, wind power is essentially pollution-free and is a growing and important renewable energy source supplying electricity to grids around the world. In 2017, wind farms produced more than six percent of the electricity used in the U.S.

Hydro-power

We can produce renewable energy from moving water just like we can from moving air. Energy is generated when moving water runs through a turbine, spinning it to produce electricity. This often happens at large dams or waterfalls, where water drops significantly in elevation. Two important places where hydro power  (also known as hydroelectricity) is produced are the Hoover Dam on the Colorado River and at Niagara Falls on the border between New York and Canada.

Many renewable energy sources have yet to make a significant impact on the overall U.S. electricity mix, but hydro power is already a major player. Large hydroelectric facilities around the country contributed 7.5% of the electricity used in the U.S. in 2017, and that number is growing. In addition to massive projects like the Hoover Dam, hydroelectricity can be produced through smaller projects, like underwater turbines and lower dams on small rivers and streams.

Hydro power is also a non-polluting energy source, as there are no emissions generated from hydroelectric facilities. However, hydro power does have a greater environmental impact than some other renewable sources of energy, because they can change water levels, currents, and migration paths for fish and other freshwater life.

Geothermal energy

Earth has a massive energy source contained within it. Heat trapped when our planet formed, combined with heat generated from radioactive decay in rocks deep beneath the crust, results in a massive amount of geothermal heat energy. Sometimes that heat escapes in large amounts all at once, which we see as volcanic eruptions on the surface.

We can capture and use geothermal energy by using steam from heated water to spin a turbine. In a geothermal spring system, water is pumped below ground. Once it is heated, it rises back to the surface in the form of steam and spins a turbine to generate electricity.

Additionally, geothermal heat can be used directly to provide heating or cooling to buildings. With this technology, known as a ground-source heat pump, a fluid is pumped below the ground surface to be heated or cooled, where the temperature is constant year-round at about 50 degrees.

While still a small part of our energy mix, geothermal energy is a promising renewable energy source, with massive potential for energy supply. In Iceland, for example, geothermal energy already accounts for 90 percent of home heating needs and 25 percent of electricity needs. However, there are some concerns with geothermal energy, including the cost of constructing a power plant and its relation to surface instability and earthquakes.

Biomass

One last example of renewable energy is biomass. Biomass energy refers to any energy produced from recently living organic matter like plants or animals. Biomass is a renewable resource because plants can be regrown relatively quickly, and they grow using renewable energy from the sun. Fuels like ethanol and bio diesel (both used for cars and trucks) also come from biomass.

Biomass fuels are also considered to be “carbon-neutral,” meaning they don’t put any extra carbon dioxide into the atmosphere. This is assumed to be true because, in principle, as long as new plants are planted and grown whenever plants are harvested and burned for energy, those new plants will take up the carbon produced by combustion, leading to no extra carbon added to the atmosphere. However, regrowing plant life takes time, and the degree to which biomass fuel is truly carbon-neutral is up for debate.

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