Are we close to fossil fuel depletion?

As we keep on using oil, gas and coal for our energy needs, we’re bound to run out of fuel sooner or later. With global population growth and the development of formerly undeveloped countries, energy demand is growing fast: a nearly 50 percent jump in global energy demand by 2035 is expected.
Renewable energies will be able to supply some of that energy, but we’re still counting on fossil fuels to provide the largest part. Is that realistic? How much longer can we continue to guzzle up fossil fuels?
The question has been asked and answered many times, but the answer seems to be different each time. This is because the answer depends on “proven” reserves.



What are ‘proven reserves’?

Proven reserves are not simply the amount of fuel that we know of, which is still in the ground.
If you can’t get it out of the ground, or can’t make money doing it, it doesn’t matter how much is down there, it simply won’t go on the proven reserves list.
In order to be a proven reserve it must be possible to extract the fuel using current technologies and in such a way that companies are sure they can make a profit.Since new technologies are developed continuously, new reserves are regularly added.
Until a few years ago for example, giant oil rigs like the Deepwater Horizon didn’t exist, and so all oil fields lying at the bottom of deep seas were effectively off limits. Therefore they simply didn’t go on the ledger as “proved” reserves.

Plenty of deposits around the world are not part of proven reserves, even though their location is perfectly known. This is because they aren’t accessible, or simply wouldn’t be profitable to drill or mine with current technology and at current fuel prices. But with improved technology or when the price for fuel increases those deposits may then become part of proven reserves.
This future technology is usually considered in Probable and Discovered reserve numbers.

What are Probable Reserves?

All fossil fuels with a 50% probability of being produced in the future are considered Probable Reserves. This will depend on the development of new technologies and fossil fuel prices.

What are Discovered Reserves?

Discovered reserves are fossil fuel deposits which have a 5-10% possibility of being produced in the future.

Unconventional sources of oil are not counted as part of oil reserves!

To pump oil, it first needs to be discovered. The peak of world oilfield discoveries occurred in 1965. According to the Association for the Study of Peak Oil and Gas (ASPO), the rate of discovery has been falling steadily since. This leads to a general fear that oil will be depleted soon.
However, unconventional sources, such as heavy crude oil, oil sands, and oil shale are not yet counted as part of oil reserves.
Oil companies can now book them as proven reserves after opening a strip mine or thermal facility for extraction. These unconventional sources are more labor and resource intensive to produce. They also require extra energy to refine. This results not only in higher production costs, but also in up to three times more greenhouse gas emissions per barrel.

Authorities familiar with these resources believe that the world’s ultimate reserves of unconventional oil are several times as large as those of conventional oil and will be highly profitable for companies as a result of higher prices in the 21st century.

Despite the large quantities of oil available in non-conventional sources, it can be argued that limitations on production prevent them from becoming an effective substitute for conventional crude oil.
Extracting oil from these sources requires a lot of energy. In the end the energy needed to extract the oil will be less than the energetic value of the oil extracted. Studies show that it will not be possible to reach high enough volumes to prevent peak oil.

Currently, between one and five barrels of oil are recovered for each barrel-equivalent of energy used in the recovery process. Once it costs the equivalent energy of 1 barrel of oil to recover 1 barrel of oil, the oil production is no longer a net energy source. This happens long before the resource is physically exhausted.

How do we estimate how much longer fuel sources will last?

Besides the amount of available fuel, there’s another thing we have to keep in mind when estimating how much longer fuel sources around the world will last: How much fuel do we use per year?
If we calculate how much proven reserves there are and how much fuel we use per year we can estimate how many years we can continue to use fossil fuels.


In 2009 proved reserves were estimated as follows with that year’s fuel consumption in mind:

• Oil: 46 years (depleted in 2055)

• Natural gas: 63 years (depleted in 2072)

• Coal: 119 years (depleted in 2128)

Fortunately, besides proven reserves there are still ‘probable’ and ‘discovered’ reserves. These may become a part of future ‘proven reserves’ as new technology becomes available. Therefore it’s possible that oil will last for another 100 years or maybe even more. The same can be said about gas and coal.


It all depends on technology, economy and energy consumption. Nothing is certain, except the fact that one day we will run out of fossil fuels.
Even though technology is developing fast and new reserves are added regularly, we are using up fossil fuels at ever increasing speed.

We may run out even faster than the numbers above if we use up more fuel than expected and if new technologies develop slower than expected. Or inversely, fossil fuels may last a while longer when new technologies are developed faster than expected or when fuel prices increase. But eventually they will be finished.

It’s possible to make oil or gas out of coal and there’s still a lot of coal left.
However, once oil and later on gas are finished, we’ll be using up coal much faster than anticipated because coal will then have to replace oil and gas as a fuel, unless we discover other means to replace fossil fuels, such as renewable energy.One thing is certain: We will run out of cheap oil before we run out of oil. In this sense, the depletion date is irrelevant. Once oil, and other fossil fuels, become more expensive than renewable energy it will no longer be economically feasible to extract fossil fuels and renewable energies will then develop very fast.

Those who already invest in the development of renewable energies now, so that they have them ready when fossil fuel prices start to rise, will make a fortune. It’s therefore wise for governments worldwide to start looking into the development of renewable energy technology right now and not wait until it’s too late.