renewable energy sources

Renewable energy examples: five alternatives to fossil fuels

Technologies like solar and wind power are becoming more common across the globe, and are both examples of renewable energy sources. There are several ways to generate power from renewable sources. These alternatives to fossil fuels will become an even more important part of our power generation mix in the years to come.

What are renewable energy sources?

Renewable energy sources are sources of energy that is constantly replenished through natural processes. These resources are often also referred to as alternative or renewable energy, mainly because they are a fuel option that can replace conventional non-renewable fossil fuels. Fossil fuels, like oil and coal, produce energy when they are burned, but their supply is limited because they don’t naturally replenish on a short enough timescale for humans to use.

Renewable energy sources are beneficial because they have a very limited negative environmental impact when compared to fossil fuels. In the past, they were too expensive to be used widely. However, that’s changing – many renewable energy sources are cost-effective, and some can even be a smart financial decision for homeowners, businesses, and governments. In particular, solar energy is a great option for property owners who want to reduce their environmental footprint while saving money. You can learn just how much solar will save you while helping the environment with EnergySage’s Solar Calculator.

The five main renewable energy examples

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

Five types of renewable energy resources

infographic comparing five types of renewable energy

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.


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 hydropower (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 hydropower 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.

Hydropower is also a non-polluting energy source, as there are no emissions generated from hydroelectric facilities. However, hydropower 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.


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 biodiesel (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.

Solar energy is the most practical renewable energy source for homeowners

If you are looking to reduce your environmental footprint and save money in the process, you might want to look in to going solar. With solar prices continuing to fall, the time to start generating power from the sun is now.

On the EnergySage Solar Marketplace, you can solicit quotes from high-quality, pre-vetted solar installers near you. By comparing solar quotes, you can be sure you are getting the best deal for solar. If you are in the early stages of shopping for solar and want a ballpark estimate for an installation, check out our Solar Calculator that can show you the up front costs and long-term savings you could see from a solar energy system.

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About Jacob Marsh

Jacob is a researcher and content writer at EnergySage, where he's an expert on current issues–and new technology!–in the solar industry. With a background in environmental and geological science, Jacob brings an analytical perspective and passion for conservation to help solar shoppers make the right energy choices for their wallet and the environment. Outside of EnergySage, you can find him playing Ultimate Frisbee or learning a new, obscure board game.

15 thoughts on “Renewable energy examples: five alternatives to fossil fuels

  1. Mazuba Mushota Mafwenko

    Thank you so much. A useful piece of writing to teach my children the different types of renewable sources of energy.

  2. Matthew Monley

    Let me start by stating that I believe the mysterious Greek Fire of ancient times was actually pure sodium. It is a metal, and the Greeks would have rendered it by using an archaic solar oven or parabolic reflector similar to Archimedes’ death ray to melt salt. When sodium is purified it combusts on contact with water and that is what the Greeks would have launched at enemy ships.

    Now, if you take a 1 meter magnifying lens and use it to focus sunlight, a heat sink could reach over 1000 degrees almost instantly. If an adjacent chamber is equipped with one-way valves to release the gases inside, it will become a hot vacuum when it cools slightly. Adding steam to that hot vacuum chamber will cause the water vapor to fracture into hydrogen and oxygen gas. If salt water were distilled from the chamber then it would result in a hot vacuum lined with molten sodium, which would ignite the hydrogen and oxygen from the steam when it was reintroduced. This process could fire a cannon, or if it were over-pressured could potentially become an atom bomb. It is possible to use solar energy to burn seawater as fuel!

    A nuclear reactor typically burns no hotter than 700°F and is used to generate steam to spin turbines. With a lens 1.5 meters in diameter, a temperature of 2000°F is easily achieved. An array of lenses and tubes as big as a football field utilizing concentrated solar energy and seawater would be fierce competition for any nuclear plant 6-12 hours a day, without the radioactive toxic waste. Given the vast potential present in a simple salt brine, burning our limitless seawater as fuel with a meter-sized magnifying lens seems like a viable alternative source of energy.

    We could convert the water to hydrogen and burn that, but an even simpler option would be to use a pool (or brick) of hot NaCl at around 1000°F as a heat sink for pressurized distillation of seawater. Simply drop some saltwater into the pool; the steam is distilled and the salt stays behind as part of the mechanism. Also, since salt can be used to store heat overnight the machine could remain operational 24/7 once established. A pipeline could be built with lenses to move seawater inland and generate electricity along the way.

    This would solve both the energy crisis and the water crisis at the same time. I should mention the dangers involved in working with this level of solar radiation. Protective equipment and ventilation of chlorine gas produced by melting salt is a must.

    Thanks for reading


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