Clean Energy Explained

According to the U.S. Energy Information Administration, about 60% of electricity generated in 2020 was from fossil fuels such as coal (19.3%) and natural gas (40.5%). While fossil fuels provide the majority of energy to U.S. homes, a variety of clean energy sources are growing contributors to the power grid. Around 20% (19.7%) was generated by emission-free nuclear energy, while another 20% (19.8%) was generated by renewable resources, including wind (8.4%), solar (2.3%), and hydropower (7.3%).

A 2020 Pew Research Center report on what Americans think the government should do about climate change found that there is bipartisan backing for the federal action on climate change. Around 79% of Americans agreed that developing alternative energy sources is an important priority. Still, understanding your options can be complex, and the terms we use to talk about environmentally friendly energy can be confusing. Is green energy clean energy? What’s the difference? Are carbon-free resources all sustainable? These are natural questions for anyone looking to reduce their carbon footprint.

How energy sources compare

Helpful guide to common terms

Clean Energy

Clean energy refers to energy produced with little to no greenhouse gas emissions. This includes low-carbon and carbon-free energy sources such as nuclear.


Reliability refers to the ability to offer a steady supply of power, like fossil fuels, nuclear and hydroelectric. Sources like solar and wind offer an intermittent supply that can fluctuate by time of day or changes in weather.

Renewable Energy

Renewable energy, also called "green" energy, refers to energy that comes from natural resources, such as wind, solar, and water. All renewable resources are considered "clean," though there is some debate over the impact of large-scale hydroelectric dams and wind farms on local wildlife.


Capacity is the ability to generate a significant share of the energy supply and meet additional demand as demand fluctuates. Fossil fuels and nuclear supply 86.6% of the U.S. energy needs. Significant investment in infrastructure and storage technology is needed before renewables are able to replace the supply provided by fossil fuels.

Sustainable Energy

Sustainable energy refers to energy sources that will not be depleted for the foreseeable future. All sources of renewable energy are considered sustainable. While nuclear energy is not always considered renewable, it is widely considered sustainable due to its lack of pollution and abundant supply.

How to take advantage of clean energy as a consumer

Clean energy is growing in popularity as an option for consumers. In fact, the amount of renewable energy used in the U.S. matched the share of energy produced from coal at 11.3% each the total of energy consumed in 2019, and actually exceeded the share of energy generated from coal in 2020 with 12.6% of the energy consumed produced from renewable sources vs only 9.9% from coal. There are many ways to purchase clean energy. Below are a few of the most popular and available clean energy options and their comparative strengths:

Nuclear energy is the largest non-fossil fuel electricity generation source in the United States. Nuclear power plants produced 790 Billion kilowatt hours of electricity in 2020. Commercial nuclear power plants have supplied around 20 percent of the nation’s electricity each year since 1990. In 2020, nuclear generation supplied nearly 52% of all clean energy in the US – more than all other sources of clean energy combined.


Nuclear plants use nuclear fission to generate electricity. Nuclear power plants are virtually always producing, providing valuable base-load electricity to communities. More than 471 million metric tons of carbon dioxide emissions were avoided in 2020 due to the electricity generated by nuclear power.


Choosing an energy supplier that also generates safe, reliable, carbon-free nuclear energy is an easy way to help ensure a low-carbon future.

Solar energy is a popular and fast growing renewable option for powering homes and businesses. In 2022 almost half the planned capacity additions will be solar.


In a conventional solar energy installation, solar panels are used to capture and convert sunlight into electricity. A wide range of consumers can adopt solar energy, from small-scale residential to large universities. Solar installations can be simple, such as rooftop panels to help power homes. Commercial use of solar often incorporates additional elements, such as battery storage.


Those who adopt solar energy systems for their homes benefit from increased home value and potentially lower energy costs, but high installation costs reduce overall savings. Solar reliability also can be challenging, since solar panels cannot charge at night and may be affected by inclement weather.

Wind energy represents around 8.4 percent of utility-scale electricity generation in the United States. Wind power is produced by a turbine system. Wind blows and turns blades connected to an electric generator to produce electricity. Land based and offshore wind farms operate across the country and continue to grow. Community and residential wind projects can be viable renewable energy options for customers with an appropriate amount of land.


While wind energy is clean and renewable, it's not without its limitations. Wind energy requires a lot of space, isn't equally available across geographies, and has similar reliability challenges to solar when the wind isn't blowing.

Clean electricity options from energy suppliers

Emission Free Energy Certificates

Some energy suppliers, including Energy Harbor, provide customers with simple and affordable access to clean energy by offering Emission Free Energy Certificates (EFECs). EFECs help consumers make more sustainable choices without significant expense and effort. Energy Harbor offers EFECs from four carbon-free nuclear generation units. These units are capable of generating more than thirty million EFEC’s annually, making Energy Harbor one of the few retailers able to offer EFECs to customers. Nuclear energy provides more than 52% of the carbon-free electricity in the United States.


Energy Harbor offers customers a wide selection of affordable green and carbon-free electricity plans that allow you to do your part to protect the environment. Compare plans in your area today.