You may have heard of the terms renewable and non-renewable energy before, but what do they actually mean?

Simply put, renewable energy is energy produced from sources that do not deplete or can be replenished within a human’s lifetime.(1)

Non-renewable energy is the opposite. Sources that will at some point run out.

To find out more, we explore each type of resource, how it’s harvested and turned into electricity and what part it plays on impacting our environment.

Renewable and non-renewable energy sources info-graphic Source:

Let’s dive in. Here’s what we’re going to cover:

Non-renewable Resources

Natural Gas

Renewable Resources



Non-renewable Sources

To better understand renewable energy, let’s start with the finite resources and why they are ‘finite’.

Finite energy resources include coal, oil, natural gas and uranium. Finite energy resources are found within the earth and have to be harvested and refined for use.


nonrenewable energy source - picture of coal

Photo by Juan Encalada on Unsplash

What is it?

Coal is a non-renewable resource that takes millions of years to produce. Coal is formed when dead plant matter decays into peat and is converted into coal by the heat and pressure of deep burial over millions of years.(2)

Key Stats

As a fossil fuel burned for heat, coal supplies about a quarter of the world’s primary energy and two-fifths of its electricity in 2019. (3) Coal is the most abundant non-renewable energy source we have.

How Coal Is Turned Into Electricity

Coal is mined and then processed into refined coal which can then be burned in power stations to produce electricity. How coal is mined and processed is explained in detail here.

coal fired plant diagram

Coal-fired plants produce electricity by burning coal in a boiler to produce steam. The steam produced, under tremendous pressure, flows into a turbine, which spins a generator to create electricity. The steam is then cooled, condensed back into water and returned to the boiler to start the process over.(4)

Impact on the environment 

According to the EIA, the following emissions are released in the process of coal combustion.

  • Sulfur dioxide (SO2), which contributes to acid rain and respiratory illnesses
  • Nitrogen oxides (NOx), which contribute to smog and respiratory illnesses
  • Particulates, which contribute to smog, haze, and respiratory illnesses and lung disease
  • Carbon dioxide (CO2), which is the primary greenhouse gas produced from burning fossil fuels (coal, oil, and natural gas)
  • Mercury and other heavy metals, which have been linked to both neurological and developmental damage in humans and other animals
  • Fly ash and bottom ash, which are residues created when power plants burn coal

Oil and Petroleum

nonrenewable energy source petroleum

What is it?

Oil and petroleum products come from fossil fuels, that are formed from plants and animals that lived millions of years ago. Read more about it here.

Key Stats

Petroleum only provides about 0.5% of electricity for the US and about 4% for the world. (5)

How Oil Products are Turned Into Electricity

Oil products are converted into electricity using one of three methods: conventional steam, combustion turbine or combined-cycle technology.

natural gas converting to electricity diagram

The process of refining crude oil is explained here.

Impact on the environment

All of these methods burn oil products, which pollutes the air just like coal. Coal and oil products have an added impact on the environment from drilling, transporting and refining these sources before they can be utilized for energy.(6)

Natural Gas

natural gas burner Photo by Parvesh Kumar on Unsplash

What is it?

Natural gas is formed when layers of decomposing plant and animal matter are exposed to intense heat and pressure under the surface of the Earth over millions of years.(7)

Key Stats

Natural gas generates the largest portion of electricity used in the US at 38% and 22% worldwide.(8, 9)

How Gas is Turned Into Electricity

Electricity is made from natural gas power plants that burn natural gas as their fuel. More about natural processing can be found here.

Impact on the Environment

Burning natural gas produces less environmental pollutants than coal or oil, but still significantly contributes to climate change since they produce carbon dioxide.(10)


uranium ore Source: wikimages on Pixabay

What is it?

Uranium is a heavy metal that has been used as an abundant source of concentrated energy for over 60 years.

Key Stats

About 10% of the world’s electricity is generated from uranium in nuclear reactors and about 19% for the US.

How Uranium is Turned Into Electricity

In a nuclear power station the fissioning of uranium atoms replaces the burning of coal or gas. ‘Burning’ the uranium produces energy electricity just like coal or gas. Learn more about uranium and how it is used here.

Impact on the Environment

Most of the impact of uranium on the environment comes from mining and milling after it is extracted from the earth. Regardless of how uranium is extracted from rock, the processes leave behind radioactive waste.(11)


Now that you understand more about each non-renewable resource, you might understand the importance of discussing what renewable resource options we have. Renewables are becoming increasingly important and help to conserve the nation’s natural resources and reduce the impact of non-renewables on the environment.

Renewable Energy Stats

Renewable energy made 26% up of global electricity generation in 2018, and it is projected to grow every year.(12)

renewable energy growth bar graph

According to a market analysis by the IEA, renewable power capacity is set to expand by 50% between 2019 and 2024, led by solar PV. (13)


What Renewable Energy Sources Are There?

Renewable energy sources include sun, wind, rain, tides, waves, geothermal heat and biomass. Renewables are defined as resources that are naturally replenished on a human timescale. (14)


biomass example wooden logs Photo by Dima Kolesnyk on Unsplash

What is it?

Biomass is a renewable energy source that comes from harvesting plant or animal material. Even though these sources are used up during processing, they are classified as renewable because photosynthesis cycles the CO2 back into new crops.

Examples of biomass are wood, crops, alcohol fuels and garbage.

biomass examples diagram

Key Stats

Currently biomass covers approximately 10 percent of the global energy supply, of which two-thirds is used in developing countries for cooking and heating. In 2009, about 13 percent of biomass use was consumed for heat and power generation, while the industrial sector consumed 15 percent and transportation 4 percent.(15, 16)

How Biomass is Turned into Electricity

Solid biomass can be converted to energy by burning it. Biomass actually contains the stored energy of the sun and this energy is released when it is burned.

Impact on the Environment

According to the EIA, Burning either fossil fuels or biomass releases carbon dioxide (CO2), a greenhouse gas. However, the plants that are the source of biomass for energy capture almost the same amount of CO2 through photosynthesis while growing as is released when biomass is burned, which can make biomass a carbon-neutral energy source.

Geothermal Energy

geothermal steam escaping cracks in the earth's surface Photo by Dan Meyers on Unsplash

What is it?

Geothermal energy is heat that comes from deep within the earth’s surface. It is carried to the surface of the earth by water or steam and can be used as clean energy if located close to regions that are strongly affected by movement of Earth’s tectonic plates.

Key Stats

This key renewable source covers a significant share of electricity demand in countries like Iceland, El Salvador, New Zealand, Kenya, and Philippines and more than 90% of heating demand in Iceland. However, since this type of energy source is dependent on location it provides just 0.4% of electricity generation for the US.

How Geothermal is Turned into Electricity

how geothermal works source:

Once this type of energy is harnessed, it goes through a geothermal power plant and is converted into electricity. Read more about geothermal energy here and here.

Impact on the Environment

Although geothermal produces less negative impact on the environment versus non-renewable sources, The environmental effects of geothermal development and power generation include the changes in land use associated with exploration and plant construction, noise and sight pollution, the discharge of water and gases, the production of foul odours, and soil subsidence.(17)

Wind Energy

windmills in a field Photo by on Unsplash

What is it?

Wind energy is, you guessed it! Powered by the wind. Also called wind power, it refers to the process of creating electricity using the wind, or air flows that occur naturally in the earth’s atmosphere. Modern wind turbines are used to capture kinetic energy from the wind and generate electricity. (18)

Key Stats

Wind power provides 1.9 percent of all the energy consumed in the United States. (19) Wind power production throughout the world varies widely depending on the country.

The worldwide total cumulative installed electricity generation capacity from wind power has increased rapidly since the start of the third millennium, and as of the end of 2019, it amounts to 651 GW. (20)

wind power stats

How Wind is Turned into Electricity

Wind becomes electricity from kinetic energy caused by the spinning of the blades on the turbine. The kinetic energy is transferred into a generator which turns it into electricity to be distributed. (21)

wind power conversion diagram source:

Impact on the Environment

Wind power is significantly less harmful to the environment than non-renewables but poses some adverse effects like the potential to reduce, fragment, or degrade habitat for wildlife, fish, and plants. Furthermore, spinning turbine blades can pose a threat to flying wildlife like birds and bats. These effects can be limited by investing in research that enables the innovation and development of cost-effective technologies that can minimize wildlife impacts at land-based and offshore wind farms. (22)

Hydropower Energy

hydropower plant Photo by American Public Power Association on Unsplash

What is it?

Hydropower is energy harvested from flowing water. It is one of the first sources used for electricity generation. Until 2019 hydropower was the largest source of total annual U.S. renewable electricity generation.

Key Stats

In 2019, hydroelectricity accounted for about 6.6% of total U.S. utility-scale electricity generation and 38% of total utility-scale renewable electricity generation. Hydroelectricity’s share of total U.S. electricity generation has decreased over time, mainly because of increases in electricity generation from other sources. (23)

How Hydropower is Turned into Electricity

Hydropower relies on the water cycle. In order to understand hydropower it’s important to understand this. The water cycle consists of three steps:

  1. Solar energy heats water on the surface of rivers, lakes, and oceans, which causes the water to evaporate.
  2. Water vapor condenses into clouds and falls as precipitation—rain and snow.
  3. Precipitation collects in streams and rivers, which empty into oceans and lakes, where it evaporates and begins the cycle again.

The amount of precipitation determines the amount of water that can be used for hydropower. Hydropower plants are located near points of moving water. At hydropower plants water flows through a pipe, or penstock, then pushes against and turns blades in a turbine to spin a generator to produce electricity. (24)

Impact on the Environment

There are some impacts of hydropower on the environment including the use of dams which can interfere with fish migration. Hydropower turbines may also kill some of the fish that pass through it.  The dams may also change the ecology of the river and which can have lasting effects on not just the river but surrounding areas. (25)

Solar Energy

solar panels Photo by Mariana Proença on Unsplash

What is Solar Energy?

The sun is the ultimate source for for all energy sources and has been producing energy for billions of years.

How Does Solar Energy Work?

The sun produces energy in the form of heat. The heat is then collected and can be used or transformed into electricity. Solar photovoltaic (PV) devices are used to convert light (photons) to electricity (voltage). This is called the photovoltaic effect. (26)

Key Stats

In 2020, solar installations were up by 42% over last year and had the largest Q1 ever.(27)

Worldwide, solar PV keeps growing each year throughout the world, and has seen the largest growth in countries like China, US and Europe.

However, the share of solar energy used is still small in comparison to non-renewables.

Impact on the Environment

Solar energy does not produce pollution or greenhouse gases. Solar energy can significantly impact the environment when using solar PV panels to replace other sources of energy that have a large impact on the environment.

A few minor impacts on the environment is the use of materials used to manufacture PV panels can be toxic if leaked into the environment. In addition, land that is cleared out to be used for large solar installations could negatively affect the environment. However in the case of installing solar on existing rooftops and farmland can help to eliminate this impact. (28)

Breakdown: Renewables vs. Non-renewables

The use of non-renewables still dominates energy production worldwide. In 2019, renewable energy accounted for merely 11% of energy consumption in the US.

U.S. energy consumption graph

Worldwide, although renewable sources are starting to climb in the last 20 years, traditional biofuels (non-renewables) continue to dominate global energy consumption.

In 2014, the share of world energy consumption for electricity generation by source was coal at 41%, natural gas at 22%, nuclear at 11%, hydro at 16%, other sources (solar, wind, geothermal, biomass, etc.) at 6% and oil at 4%. Coal and natural gas were the most used energy fuels for generating electricity. (30)

global renewable energy consumption

How long will non-renewable energy sources last?

It is impossible to tell exactly how long our reserves of non-renewable sources will last since our methods of extracting continue to evolve. However, according to predictions, at the rate we are consuming currently, we have around 100 years for even coal, our most abundant source, to be consumed.

solarEnergyCapacity oil production estimation graph

Are you considering making the switch to solar? 

At ADT Solar we’re happy to answer any and all questions you may have about switching to renewable solar energy. If you’d like to learn more, or are interested in scheduling a free consultation, simply reach out to us today!