Renewable energy is useful energy that regenerates naturally within a relative short span of time, such as a human lifetime. In contrast, nonrenewable energy either doesn’t regenerate at all or else renews over an extremely long time. Here are renewable energy examples, the pros and cons of each of the types of renewable energy, and a look at whether they are carbon neutral.
Renewable Energy Examples
Renewable energy harnesses energy from the Sun, wind, water, and living plants. While these energy sources are constantly replenished, there are limitations. For example, solar energy is available during the day. Wind power is available when a breeze is blowing. Renewable energy finds use in power generation, but they are also used directly for heating/cooling and transportation.
How many types of renewable energy there are depends on whether you classify wind power as a type of solar energy and whether you group tidal power in with hydropower:
- Wind power
- Solar power
- Hydro power
- Tidal power
- Biomass or Bioenergy
Nuclear energy typically is not considered a type of renewable energy. This is because although nuclear energy itself is renewable, the fuels we use (e.g., uranium) are limited resources. However, nuclear energy is a zero-carbon energy source, so it’s often discussed together with renewable energy sources as a form of clean and sustainable power.
Carbon Neutral and Zero-Carbon Energy
A carbon neutral energy source makes no net release of carbon dioxide (CO2) into the atmosphere. It still generates the greenhouse gas, but often offsets CO2 release by other means, such as planting trees or taking in more carbon than it releases. A zero-carbon energy source is a carbon-neutral energy source that releases no carbon dioxide.
Some types of renewable energy are carbon neutral or zero-carbon, but others produce as much (or more) carbon dioxide as nonrenewable energy. Biomass is not carbon neutral because burning the fuel isn’t much different from burning fossil fuels. The other types of renewable energy don’t release carbon dioxide directly, but manufacturing the materials and structures they use may or may not be carbon neutral processes. So, it’s important to look at the whole process of energy production to determine its effect on the environment and global warming.
Closer Look at the Types of Renewable Energy
Here are definitions of the types of renewable energy, examples of their use, and their pros and cons.
Wind power is a form of solar power because the temperature gradient caused by solar heating produces wind. Examples of wind power range from simple windmills to large wind farms. Wind turns the turbines, allowing mechanical energy to do work or be converted into electricity.
Pros: Wind power is clean power that doesn’t cause air pollution. It doesn’t release carbon dioxide. Wind farm maintenance creates jobs.
Cons: The turbines threaten birds and other wildlife. They can be noisy, are often located far from where the power is needed, and are considered eyesores. The degradation of the turbines can have an environmental impact. Wind power requires routine maintenance. Not all locations get enough wind to make this renewable energy source practical.
Solar power captures radiant energy from the Sun and uses it to heat water, store light, or generate electricity. Photovoltaic cells are a common example of solar power. But, simply heating a home or pool using sunlight are examples of solar power.
Pros: Solar power is clean energy. Some forms require little to no maintenance. For example, solar thermal heating simply absorbs energy to heat water or homes.
Cons: There is a high initial cost for solar cells. They aren’t very efficient and some locations don’t get enough sunlight to make them practical. While using solar power is clean, the cells use mined resources. Mining and fabrication might not be eco-friendly or energy efficient.
Geothermal power captures heat trapped below the Earth’s surface, usually near volcanoes or geysers. As an example, a geothermal power plant pumps water into a hot spot, producing steam which turns turbines and generates electricity. Technically, any temperature difference between the soil and another surface offers the option to heat/cool homes or generate power.
Pros: Geothermal power is clean energy that leaves very little visible footprint on land. Unlike solar or wind power, it’s constantly available.
Cons: The main “con” is that not all areas are geologically active. Geothermal power plants are more susceptible to earthquake damage due to where they are built.
Hydropower is power production using flowing water. Usually, this is electricity produced by rivers and streams. The water spins turbines and generates electricity. An example of hydropower is the Grand Coulee Dam, but some off-grid homes use streams to generate power on a smaller scale. Another form of hydropower moves water between two reservoirs of different elevations.
Pros: Most of the world’s population lives near water, so there isn’t a large distance between the site of power generation and its use. Hydroelectric power works on both large scales and small ones. It’s generally an environmentally friendly option, with some exceptions.
Cons: Dams and changing water levels affect fish and other organisms. Hydroelectric facilities that pump water use more energy than they produce.
Tidal power is a form of hydropower. Here, wave energy generates electricity. Another type relies on temperature gradients between water layers.
Pros: Tidal power is constantly available. It’s a clean type of renewable energy.
Cons: Tidal power isn’t available away from the ocean or large lakes. The mechanisms that capture energy disrupt tidal ecosystems. Tidal power is affected by weather.
Biomass or Biofuel
Biomass energy comes from plants and animals. Sources include wood, wood waste, grains, animal fats, food scraps, leaves, algae, and municipal solid waste. For example, ethanol and biodiesel come from biomass. Biomass supplies energy when it’s burned directly for heat and vehicles and indirectly when the heat generates steam to generate electricity.
Pros: There are many biomass sources. This form of energy often recycles waste materials.
Cons: Burning biomass is comparable, in terms of pollution, to burning fossil fuels.
- Harvey, Chelsea; Heikkinen, Nina (March 23, 2018). “Congress Says Biomass Is Carbon Neutral, but Scientists Disagree“. Scientific American.
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