Non-renewable energy: definition and types

Non-renewable energy: definition and types

The pitfalls of fossil fuels

Non-renewable energy is energy derived from finite resources that are not replaced quickly enough to keep up with the speed of consumption. For perspective, non-renewable energy sources will not be replenished in our lifetime, or, more accurately, many human lifetimes. Most non-renewable energy sources are fossil fuels such as petroleum and crude oil, coal, and natural gas¬, but nuclear fuel, mainly used to produce electricity, is also generally classified as nonrenewable.

Fossil fuels: definitions and disadvantages

Fossil fuels take their name from their origins, as they were formed out of the buried, carbon-rich remains of millennia-old plants and animals. Indeed, the vast majority of fossil fuel deposits were formed between 540 million and 65 million years ago. Over time, underground compression of these aforementioned organisms gradually gave rise to a mineral called kerogen, which geothermal heat then combined with to form fossil fuels.

Fossil fuels are harmful in part because when heated, they release carbon dioxide into the atmosphere, which ultimately disrupts the balance of carbon in the earth, ocean, and air. Given fossil fuels’ formation process, the carbon found in them has been sequestered underground for millions of years; when this carbon is released into the atmosphere, temperatures increase too quickly for organisms to keep pace and adapt. Hence, the term “global warming”, which first entered the public lexicon in a 1975 magazine article by researcher, scientist and climate change pioneer Wallace Smith Broecker.

For many decades prior to Broecker sounding that first global warming alarm, as well as many decades after, the unsustainable, carbon dioxide-releasing practice of burning fossil fuels generated most of the energy required to “fuel” modern society’s highly industrialized economies and lifestyles. Fossil fuels have been essential in areas spanning public and private transport to home electricity to plastics production. The planet has paid handsomely for our globalized economy and ever-increasing focus on efficiency and output, as evidenced in myriad areas: water and air pollution, climate change, and the health and environmental effects associated with practices like fracking, a controversial method of oil and natural gas extraction.

While the transition away from fossil fuels and other non-renewables toward clean energy is underway, the bulk of human society’s energy still comes from nonrenewable resources. Fossil fuels still dominate globally, providing for about 80 percent of the total energy used each year, according to National Geographic; some researchers estimate that it is closer to 85 percent. In the high-consuming United States, by way of illustration, primary energy sources are 89 percent nonrenewable (when nuclear power is factored into the total, along with fossil fuels).

Main types of fossil fuels

There are three main types of fossil fuels: coal, petroleum (oil), and natural gas.


Coal is combustible black or brown rock, used primarily used as a fuel; you may also see references to “peat” or “anthracite”, which are two sub-types. It was also the chief driver of the Industrial Revolution of the 18th and 19th centuries, when the foundation was laid for many modern manufacturing processes. While abundant, reliable, and inexpensive, coal is highly polluting when burned. Mining for coal is also a notoriously dangerous occupation, with miners facing constant exposure to toxic dust and the looming threat of on-site explosions.


Also referred to as oil or crude oil, petroleum keeps much of the world’s wheels spinning: about half of the world’s supply of this liquid fossil fuel is converted into gasoline. Petroleum is an easily portable source of (nonrenewable) energy that allows people to stay on the move. But the disadvantages of petroleum in this day and age cannot be ignored: burning gasoline releases toxins into the air that humans breathe. Oil is extracted via a range of drilling methods that carry with them many inherent risks, including possible oil spills, which can be devastating for the environment.


Natural gas, mostly composed of methane, is found underground in reservoirs. Primary uses of natural gas are in heating, cooking, and generating electricity. Compared to oil and coal, natural gas is a “cleaner” fossil fuel, since it releases fewer pollutants into the air when burned (carbon dioxide and water vapor exclusively). But the natural gas extraction processes can come with a host of environmental problems and disasters, such as increasing the possibility of small earthquakes and water contamination.


Nuclear power is sourced from radioactive elements. While not a fossil fuel, nuclear is usually classified as a nonrenewable form of energy, largely because most nuclear reactors rely on uranium as a source of fuel. (There is a finite supply of uranium in the world). Used to produce electricity, nuclear power does have some key advantages over fossil fuels—namely, it contributes significantly less to air pollution and carbon emissions. One study by the American Chemical Society even indicated that between 1971 and 2009, nuclear power helped prevent 1.84 million premature deaths related to air pollution and 64 billion tons of greenhouse gas emissions. However, nuclear energy remains hotly contested because of the radioactivity threats nuclear power plants pose to people and the environment, as seen in devastating nuclear accidents like the Chernobyl disaster of 1986, which took place outside the city of Pripyat in the Ukrainian SSR.

Why non-renewables still dominate

Despite their limited supply and the devastation they can inflict, our world remains dependent on non-renewables—fossil fuels in particular. For all of their defects and dangers, fossil fuels are dense in (instant) energy and are relatively inexpensive to process. Additionally, fossil fuel storage methods are uncomplicated and the fuels can be shipped anywhere in the world.

While many governments, some corporations, and other key actors now recognize the urgency of switching to alternative energy sources and reducing CO2 emissions, effectively achieving this will require a sustained, costly, long-term overhaul of existing systems and infrastructures. International solidarity and collaboration on this transition is crucial to combating climate change and ensuring a clean energy future.