Most of us assume and accept it as a fact that fossil fuels are nonrenewable. Have you ever really understood why?
After all, fossil fuels are natural resources and they occur naturally and directly in nature. Coal, oil, and natural gas are formed on their own on earth and extracted as it is.
As these facts are indisputable, the question remains unanswered as to why fossil fuels are not renewable resources. If they can form once, why can’t they form again?
As we use up the fossil fuels, won’t more of them form deep inside the earth?
If they can, why are fossil fuels treated as nonrenewable resources? If they can’t, why not?
This article explores this often ignored and forgotten question about the renewability of fossil fuels. Here you will also find answers to questions like “Is fossil fuel formation happening today?” and “How much is left?”.
What is a renewable resource?
To understand the meaning of a nonrenewable resource, let’s begin with resources that are renewable.
Natural resources that get renewed or replenished as we use them up are called renewable resources. The rule of thumb to identify a renewable energy resource is to check whether it ever gets depleted. Even if you are unable to understand how it is replenished or from where it is coming from, as long as the quantity available to you remains the same, it is a renewable energy resource.
The perfect example is sunlight. Every single day from dawn to dusk, we, on earth, receive sunlight. On cloudy days, the sunlight may not reach the surface of the earth but we know that the sun is shining above the cloud and some of it is filtering through.
Sunlight is a renewable energy resource. As long as the sun is shining, we receive solar radiation or sunlight.
The same can be said about wind and water. As the sun heats up the earth and the atmosphere unevenly, the wind blows. Water is a natural resource that is constantly recycled through a natural process known as the water cycle. All the water we use up will some way or the other end up as water vapor. When it rains, it comes back to earth as water.
Sunlight, wind, and water are available to us in the same quantity, irrespective of how much we use them. This makes all of them renewable resources.
What is a nonrenewable resource?
The simple answer is that it is something that is not renewable. When a natural resource doesn’t get replenished as we use it up, it is a nonrenewable resource.
A good example is iron. Or any other metal or mineral. All of them are available on earth in limited quantities – some more abundant than others. Iron and other minerals are made in stars, red supergiant ones, during the nuclear fusion process. All minerals came to earth millions of years ago when a supernova explosion occurred and fragments of minerals were blasted into space.
There is no way the earth can replenish the supply of these minerals. Once these are extracted from the earth and used to manufacture goods to make our lives better and easier, they are lost forever.
This is similar to water in a bottle. As we drink the water, the water level comes down and eventually, the bottle will be empty.
How are fossil fuels formed?
Fossil fuels are formed from dead plants and animals that get buried in the rock formations, i.e., fossilized. Hence the name fossil fuels.
The commonly used fossil fuels are coal, crude oil or petroleum, and natural gas. The origins are different for each one of them. While coal is formed from the fossilized remains of dead plants, crude oil and natural gas come from dead marine organisms, mostly zooplankton and algae.
Tens of millions of years ago these plants and marine organisms died and got buried under sand, silt, and rock. As more and more rock formations built up on the top, the heat and pressure exerted by these top layers on the fossilized remains turned them into fossil fuels.
Coal and oil, once formed, remains in reservoirs, beds, or seams until it is excavated. However, natural gas will rise up through rock cracks and porous rocks until it comes up against an obstruction on its path. Due to this, natural gas is usually found in the pores of sedimentary rocks.
The fossil fuels we are using up now were formed from the dead organisms and plants that existed several million years ago, even before the age of dinosaurs.
Why are fossil fuels classified as nonrenewables?
The answer to this lies in how fossil fuels are formed. As described above, fossil fuels take millions of years to form under specific geological conditions.
Until the advent of the Industrial Revolution, our use of coal was minimal. It was used mostly for domestic needs and metallurgical work. However, things changed overnight with the Industrial Revolution. More and more machines running on coal were invented, leading to skyrocketing in coal use. By the end of the 19th century, coal-fired power plants also came up. Coal was getting mined at faster rates than at any time in the history of mankind.
The coal that we are using now has taken hundreds of millions of years to form. We are now mining coal and burning it to generate electricity, heat buildings, and for other needs.
The story is the same for petroleum and natural gas. The rate at which we are consuming them is nowhere near its replenishment rate. In the above analogy, consider a tap dripping water into the bottle at the rate of one drop in an hour or so. When we are draining the water in the bottle in a few seconds, what good are the few drops of water inflow?
When the extraction rate is so high that the meager replenishment rate becomes inconsequential, it is as good as there is no replenishment happening. This is exactly what is happening with fossil fuels. Though coal, crude oil, and natural gas are forming even today, they are nowhere close to replacing the quantity mined or extracted.
For this reason, fossil fuels are treated as nonrenewable sources in all respects.
Are fossil fuels still forming today?
The answer to this question would be yes. The formation process is ongoing and never stops.
Let’s consider the case of coal. The first stage of coal formation is the accumulation of peat, which is deposits of plant matter, in mires. Mires are large stretches of swampy or boggy land. Some parts of the world where this process is more noticeable are Altiplano in the Andes and Indonesia.
Mires are stagnant water bodies with the growth of reeds and trees. Plant matter continues to build up in these marshlands and lagoons. Peat buildup is also happening in higher altitude landscapes in lake beds fed by rain or glaciers.
The accumulation of peat is an infinitesimally slow process, often happening at the rate of 1 millimeter in an entire year. In places where there are more plants and trees like in the tropical regions, this rate would be higher. It can be as high as 2-3 millimeters annually.
At this rate of peat formation, it takes anywhere between 10-60 thousand years to gather enough peat for a 3-meter coal seam. Mind it, this is merely an accumulation of uncompressed peat.
In the next stage of coal formation, this accumulated peat gets buried in sand, silt, and other sedimentary rock formations. Often a river changing its course, an alteration in sea level, or a volcanic eruption is the trigger for this turn of events.
The sedimentary deposits on top of the peat buildup exert pressure on it, leading to the expulsion of water from it and compression. The thickness of the peat layer will come down by one-tenth at this stage. When the sediment layer above the peat will keep building, exerting more and more pressure.
The layer of sediments needs to be 3-4 kilometers in thickness for the transformation to begin in peat. For each kilometer of thickness, the temperature goes up by about 30°C (86°F). The peat will slowly turn into coal due to the chemical reactions triggered by high temperature and pressure exerted by the thick sediment layer above.
During this chemical transformation, volatile substances are released, leading to more compression of the peat layer. Ultimately, peat transforms from being plant matter like cellulose and lignin to a geopolymer containing pure concentrated carbon. The final product would be nothing like plant matter.
The amount of transformation in peat can be gauged by the type of coal formed. While lignite and brown coal occupies the lowest level in the transformation chart for coal, black or bituminous coal involves an additional and longer chemical process. The ultimate in coal is anthracite which is formed when high temperature and pressure are exerted by the sedimentary deposits for prolonged periods.
This entire process of accumulation of peat to the formation of coal takes millions of years. In different parts of the world, this process is happening continuously and at various stages.
So, how much fossil fuels are available now?
This is the all-important question troubling us today. How long do we have to find an equally versatile alternative to coal, oil, and natural gas?
Finding an accurate answer to this question is hard as we are still in the process of discovering new deposits and reservoirs of fossil fuels underground. We can only estimate future discoveries.
However, using various estimation methods, the scientific community has arrived at a figure. Crude oil and natural gas should last us for 60-70 years more at the present rate of consumption. Coal will last longer. Some estimates place it at 100-150 years, others disagree with this and estimate that we will run out of coal in 400-500 years.
Technically speaking, fossil fuels are renewable resources if we use them sparingly to align with their rate of formation. Their formation is so slow that unless we stop using fossil fuels altogether, we cannot achieve this balance. As this is not a realistic possibility, for all practical purposes, fossil fuels are considered nonrenewable resources.
We may run out of fossil fuels in our lifetime. This is not something that will happen in some distant future. It is high time we wake up to the dire situation and take action. We need to shake off our dependence on fossil fuels. And, the worst part is there is nothing we can do about this.
Fossil fuels may last for a century or more. But unless we stop burning fossil fuels, the real question is will we survive the devastating effects of global warming and climate change?