Fossil Fuels


While the next few sections of ‘Laying the Foundation’ are focused on energy, it’s important to understand that polluting energy sources are just one part of the problem. We’ll go over numerous examples in the main sections – but for now, just remember that it’s not only about how we produce energy – it’s also about what we use it for.


Everything needs energy. We need energy to get up on a Monday morning. Plants need energy to grow. Even our tectonic plates need energy to move. These are all intangibles, we will always need food, plants will always need sunlight, and the plates will keep moving as long as the Earth’s core remains a radioactive heat ball.

If we look around, we’ll notice other things like our electronics, ovens, light bulbs, beds, or walls. These are all things that needed energy to be manufactured, and some still require a continuous flow of energy during use, like TVs. Since we produce and use so many material objects every day, it shouldn’t come as a surprise that energy production is a major issue worldwide.

Fossil Fuels

Fossil fuels are non-renewable natural resources such as oil, coal, and natural gas that are burned daily to produce energy. We burn these specific fuels because they have high energy densities, meaning that we can extract a large amount of energy in a small amount of fuel. Combusting them releases that energy as heat, which we harness in different ways depending on the application.

When fossil fuels are burned, CO2 is produced in large amounts. As we’ve seen, continuously producing loads of CO2 leads to global warming and climate change. Unfortunately, it doesn’t stop there. Fossil fuel combustion also emits other polluting gases, like NOx and SOx gases, fine particulate matter, volatile organic compounds, or even mercury. These pollutants can then contaminate the surrounding environment if pollution control processes are absent. And while some fossil fuels emit less than others once burned, the bottom line remains that they all pollute too much.

There is clear consensus that the fossil fuel industry is the highest emitter of GHGs in the world, by far.

Largest Fossil Fuel Burners

There are a few energy-intensive sectors that consume incredible amounts of fossil fuels. The transportation sector is one of them, which isn’t very surprising considering that there are over 1 billion fossil-fuel-burning vehicles on the road every day. Another is the electricity production sector, where the energy released by fossil fuels during combustion is converted into electricity at power plants. The industrial sector is also a top consumer, since industries are free to choose the types of fuels they want to be powered with. With fossil fuels often being the cheapest option, they’re usually on the menu.

While pollution control regulations are in place in developed countries, other regions of the world aren’t so lucky. And although developed countries have gotten quite good at controlling toxic emissions, we don’t have many pollution control solutions in place for CO2. In fact, it’s sometimes the product of a control process [e.g. methane flaring].

Biodiversity is being significantly damaged because of fossil fuel combustion as well. Even though we can’t notice most of them, toxic pollutants released during combustion are present in nearby air, water, and soil – and threaten everyone who depends on breathing, drinking, or eating to survive. The release of these pollutants can also increase the likelihood of acid rain, ocean acidification, and eutrophication.

Since we care almost exclusively about what affects us, we’ll say it again: if our biodiversity falls, so do we.

Energy and Electricity Mixes

An ‘energy mix’ describes the mix of different energy sources used by a given organization/region. All energy sources hold a specific percentage of the total mix, which represents the share of energy produced by each fuel. All sources should add up to 100%. These days, there’s lots of talk about the newest renewable energy projects and how they’re pushing fossil fuels out of our energy mix. Unfortunately, that’s not even close to being true at a global scale.

In 2018, the ‘Big 3’ fossil fuels accounted for 81.3% of global energy production. Note that natural gas is far from being eco-friendly, as the name could suggest. It’s mostly methane [CH4], and burning it releases loads of CO2 and other pollutants – although it’s still less polluting than coal.

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It’s important to understand the difference between energy and electricity as we go along. Electricity is a form of energy, but energy doesn’t have to be electricity. For instance, energy can include the natural gas burned to heat homes, a car’s combusted gasoline, and electricity.

Electricity isn’t something we extract from nature, which is why it’s considered a secondary source of energy. Worldwide, around 18% of energy is in the form of electricity. Note that ‘power’ is often used interchangeably with ‘energy’, although power actually denotes the rate at which energy is generated or consumed.

To produce electricity, we can use fossil fuels, hydroelectric dams, nuclear power plants, or many types of renewables. Since electricity is produced by a blend of sources, we can evaluate an electricity mix – which describes the share of primary sources of energy used to produce electricity. Unfortunately, the global electricity mix is also dominated by fossil fuels, although some very rare regions of the world rely almost entirely on renewables like hydropower or geothermal for electricity production [both depend on local conditions, they’re not an example that the rest of the world can easily follow].

In 2019, the world’s electricity mix was dominated by the Big 3, accounting for roughly 63% of the mix.

To generate electricity in large quantities, fossil fuels are burned to heat a fluid, which then turns to steam. The steam rotates a turbine, and this motion is then converted to electricity to power homes, buildings, and factories if they’re connected to the grid. Some fossil-fueled power plants find slightly different methods to rotate the turbines [e.g. using different fluids or ‘big car engines’], but that’s doesn’t really matter since they all have roughly the same effects.

The energy source used varies greatly depending on the sector. For example, it makes sense that the transport sector is dominated by oil. It makes sense that the residential sector is dominated by electricity and natural gas. The graph below gives us a general idea of which energy sources are used in each sector, in developed countries. However, it doesn’t show which sectors are most energy intensive. We’ll find that out in later sections.