A Comprehensive Guide to Energy Sources

Learn about the different types of energy sources, their characteristics, and their environmental footprint.

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What are Energy Sources?

Energy sources pertain to the various means by which power can be generated. The process starts by capturing energy from renewable and non-renewable sources and converting it into secondary forms like electricity and fuel. Then, they are transmitted through various channels (e.g., power lines) to fuel industrial and everyday activities.


Energy sources can be classified into two categories: renewable and non-renewable. This section will explore these energy source types in detail.

Non Renewable Energy

Non-renewable energy, also known as conventional energy, refers to finite sources of power, such as petroleum, natural gas, and coal. Because of its affordability and scalability in terms of production, it has held a major share of the global energy pool for hundreds of years. In 2019, it constituted over 85 percent of the world’s energy supply.

However, its supplies can be easily exhausted, given the limited resources that can be extracted from specific locations and the amount of time it takes to replenish them. Moreover, it poses significant environmental risks due to its greenhouse gas (GHG) emissions and the resulting pollution from its residual particulates and byproducts.

Renewable Energy

Renewable energy harnesses power from naturally occurring and constantly replenishing resources, such as sunlight, wind, and water. Since it runs abundantly and releases fewer harmful gasses into the atmosphere, this type of energy source offers a cleaner and more sustainable alternative to traditional energy sources.

Many businesses are now transitioning to clean energy sources as part of their efforts to reduce their carbon footprint and diversify their energy supply. However, the downsides of this type lie in the intermittent nature of its sources and the initial costs associated with it.

Energy Sources Examples

After discussing the types of energy sources, it’s time to delve deeper into the specific sources that fall under each category. Listed below are the most common examples of energy sources:

Fossil Fuels

Fossil fuels are non-renewable sources of energy that have been formed from the remains of prehistoric animals and plants. These carbon-rich buried reserves are extracted using various methods (e.g., drilling, fracking) to create energy for heating and other purposes.

Examples of fossil fuels include the following:

  • Coal – a black, rock-like substance used to produce heat, electricity, and steel
  • Natural gas – a colorless, odorless gas that is mostly made of methane
  • Petroleum – a hydrocarbon mixture that is refined into gasoline, diesel, and other fuels

Fossil fuels are the world’s primary energy source, supplying four-fifths of the global energy mix in 2021. And while they are readily available and cheaper to produce, they also run on limited amounts, take long periods to replenish, and significantly contribute to global carbon emissions.

Nuclear Energy

Nuclear energy is a zero-emission energy source produced from nuclear fission, the process of splitting uranium atoms to generate power. It releases massive amounts of energy with relatively small amounts of fuel and zero GHG emissions, making it a clean and highly efficient resource. However, this energy source requires strong safety precautions, such as proper handling and disposal of radioactive waste, to prevent contamination and accidents.

Solar Energy

Solar energy is a renewable energy resource that utilizes solar panels for power generation. These panels, typically installed on rooftops and large fields, absorb the energy from the sun’s rays and convert them into electricity. Solar power has been an increasingly popular option for clean energy as one of the more cost-effective and versatile sources, but its performance is subject to weather conditions.

Wind Energy

Wind energy is an alternative energy source that harnesses the power of the wind using wind turbines. Since wind power heavily relies on weather conditions, wind turbines are usually placed in areas with high wind speeds like open plains and coastal regions. However, they can negatively impact the surrounding wildlife and create too much noise when poorly maintained.

Geothermal Energy

Geothermal energy is another clean energy source that taps into the Earth’s natural heat to produce electricity. It utilizes geothermal power plants or heat pumps to access hot water and steam for power generation. While it doesn’t rely on intermittent weather conditions to work, its production is limited to areas with high levels of geothermal activity.

Hydroelectric Energy

Hydroelectric power utilizes moving water from reservoirs to generate electricity. In 2021, this renewable energy source has accounted for over 6 percent of the world’s energy supply.

Hydroelectric energy is one of the most reliable clean energy sources, given the longevity of hydroelectric power plants. But on the flip side, constructing these dams can have adverse environmental effects, such as habitat destruction and local water supply issues.

Biomass Energy

Biomass energy is a renewable resource derived from wood, crops, waste, and other organic materials. This can be converted to electricity for daily activities or biofuels for vehicles.

Since it utilizes currently existing organisms, biomass is a more viable alternative to fossil fuels. However, the materials for this source should be replenished sustainably to avoid harming the environment.

Environmental Impacts

Energy sources have varying levels of impact on the environment, including these 4 key areas:

  • Climate change – Energy production belongs to the main drivers of climate change, accounting for three-quarters of the world’s total carbon emissions. A substantial portion of this can be attributed to fossil fuel activities, which release heavy amounts of GHGs into the atmosphere.
  • Air pollution – Fossil fuels, biomass, and nuclear produce harmful particles that can contaminate the air and endanger human health. Exposure to these pollutants can put individuals at risk for respiratory issues, heart problems, and even cancer.
  • Water pollution – Improper extraction of fossil fuels and poor handling of nuclear can also pollute bodies of water. For instance, oil spills and uncontrolled nuclear reactions can contaminate water sources and, in turn, harm the marine ecosystem.
  • Ecological destruction – Certain energy sources require infrastructure that can alter the ecosystem of the place where it is built. Building reservoirs for hydroelectric energy, for example, can result in habitat loss for the local flora and fauna.

FAQs about Energy Sources

Fossil fuels are considered the most common sources of energy, as they comprise a substantial portion of the global energy supply. For centuries, they have been the dominant energy sources, but they come with several drawbacks, such as finite availability and environmental impacts.

The most sustainable sources of energy are renewable ones, such as solar and wind power. These are replenished naturally and emit zero GHGs or pollutants during operations, making them cleaner alternatives to fossil fuels. In recent years, they are steadily gaining traction in the energy market as the world shifts from traditional to greener power sources.

Transitioning to greener energy sources comes with its own challenges, such as the following:

  • Intermittency of energy sources (especially wind and solar)
  • Upfront costs associated with building and maintaining infrastructure
  • Need for energy storage solutions for a steady supply of electricity
  • Scalability of renewable energy systems to consistently meet energy demand
Leizel Estrellas
Article by

Leizel Estrellas

SafetyCulture Content Specialist
Leizel Estrellas is a content writer and researcher for SafetyCulture. Her academic and professional training as a researcher allows her to write meaningful articles that create a lasting impact. As a content specialist, she strives to promote a culture of safety in the workplace through accessible and reader-friendly content. With her high-quality work, she is keen on helping businesses across industries identify issues and opportunities to improve every day.