Towards the end of oil

For decades, hydrocarbons have been a panacea in terms of energy, but today the oil monopoly is ecologically untenable. But will the end of this idyll be chosen by human beings or imposed by the depletion of black gold resources? Chronicle of an announced end with specialist Michel Séranne, from the Geosciences Montpellier laboratory*.

Take a few living marine micro-organisms - animals, plants, bacteria, plankton. When they die, let them sink to the bottom of lakes or oceans where they will mix with sand, forming different layers of sediment. Deprive them of oxygen and adjust the temperature and pressure. Wait several tens of millions of years. You've got oil. An archaic, unchanging recipe for a timeless product.

• Watch the "C'est pas sorcier" video explaining the formation of oil

"Oil began to be used as an energy source as early as the 19th century, but its consumption exploded at the beginning of the 20th century with the invention of the automobile," recalls Michel Séranne. It has to be said that, as an energy source, petroleum had everything going for it. " It's a fluid, so you 'just' need a pipe to extract it from the subsoil, which makes it very easy to exploit compared with coal, for example", explains the geologist.

Oil addict

Easy to exploit, transport, store and use, oil represents a very cheap energy with all the advantages. "So easy that it was used recklessly, creating a veritable addiction to fossil fuels." In 2018, we passed the threshold of 100 million barrels of oil consumed per day worldwide. That's nearly 16 billion liters of black gold every day.

"Oil is consumed much faster than it is created: it takes tens of millions of years to form, and only a few seconds to burn up," says Michel Séranne. On our timescale, this makes it a non-renewable energy, and therefore a finite resource. This observation raises a recurring question: are we going to run out of available oil?

While the end of oil has been regularly announced since the 1980s, this deadline keeps getting pushed back as we get closer and closer to it. Because oil is still around. "Not only do we know more and more about natural reserves, and are therefore discovering new reservoirs, but there have also been major technological advances that have made it possible to exploit previously inaccessible resources. Today, we barely exploit 1/4 to 1/3 of the oil contained in deposits."

Untapped resources

Having first drained the most accessible reserves, we could now exploit more remote or difficult-to-access deposits. Not to mention all the known black gold resources that have not been exploited for geopolitical reasons, "such as in Venezuela, the Arctic or Alaska. The resources are likely to exist for more than another century," adds the geologist.

"In reality, the question is not whether there will still be oil, but rather how much we are prepared to pay for it. After all, less accessible deposits mean higher operating costs. Not to mention, of course, the ecological price, which "will be totally exorbitant, an unacceptable cost", reminds Michel Séranne. A real paradigm shift around the end of oil, which will not be suffered, but must be chosen.

And while the need for this energy transition is now accepted, for Michel Séranne it does not mean the end of oil: " For the time being, renewable energies represent less than 20% of the energy produced, and if we want to increase this proportion we need oil and gas, if only as a source of energy during this period. What we need to do is reduce the proportion of hydrocarbons as quickly as possible."

Indispensable geosciences

An energy transition that won't happen without oil, or without geologists. Not least because the materials needed to produce renewable energies are also hidden beneath our feet, and their exploitation requires an acute knowledge of geological formations. "Strategic metals such as cobalt, nickel and rare earths, of course, but also base metals such as steel, aluminum and copper, which are essential for the construction of wind turbines and solar panels.

But also because the subsoil represents a highly strategic point for energy storage. " The majority of renewable energies are said to be intermittent, so we need to be able to store them when they are produced so that we can use them when we need them, and natural reservoirs can meet these challenges," explains Michel Séranne. Knowledge and use of the local subsoil are thus a major challenge for the energy transition, which cannot be achieved without geosciences. " Developing research and teaching in order to make the most of it is becoming increasingly necessary to accompany the announced end of fossil fuels", points out Michel Séranne.

*GM (UM, CNRS, U Antilles)