Currently, about 85% of the oil that comes out of the ground is used as an energy source, with the remaining 15% being used to make plastics (around 7%), asphalt (2 -3%) of miscellaneous products.
And it is true that we shoot a lot, a lot of very useful chemicals from petroleum. “In the 6% of other products [que les carburants, les plastiques et l’asphalte]there are around 1,600 different products that can be found almost everywhere,” says Denis Rodrigue, professor of chemical engineering at Laval University and specialist in plastics.
Medicine has a great need for it, because almost all pharmaceutical products come from petroleum and its derivatives, the American Institute of Geosciences recently indicated. Many detergents also come from it, as well as a long list of substances of daily use.
Note that the same thing prevails for natural gas, although to a lesser extent. It's not 15% of the gas that is used for something other than providing energy, but 8% – largely for the manufacture of fertilizers, because we use the hydrogen contained in the molecules. of methane (CH4) to react with nitrogen (N) and thus produce ammonia (NH3), which is then transformed into nitrogen fertilizer.
In short, “it would be very difficult to completely do without oil overnight,” says Mr. Rodrigue.
In fact, adds University of Montreal physicist Normand Mousseau, who has worked extensively on the energy transition, “I have a hard time seeing how we could completely avoid oil for the coming decades.”
(Matthew Brown)
Question of costs…
There are essentially two main difficulties to overcome here, note the two researchers. The first is a question of cost: in the petrochemical industry, alternatives to oil already exist, but they are significantly more expensive.
“Non-petroleum resins are often made from agri-food or forestry residues,” explains Mr. Rodrigue. These are resins that we make with corn starch or wood cellulose, and we can derive plastics and other petrochemical products from that. But the problem is that we have to extract it from the residue [les branches et les «déchets» de la coupe forestière, par exemple, contiennent bien d’autres substances que la cellulose] to be able to use it as a base for polymerization [les plastiques sont des «polymères», donc des molécules faites comme des chaînes]and it’s this step that is expensive.”
Currently, Mr. Rodrigue illustrates, “if we talk about commonly used plastics, it costs around twice as much to produce from biomass as from oil. (…) And we must understand that the rule of thumb, in manufacturing, is that around half of the production cost of plastic objects comes from the raw material, so that is really not negligible.”
…and volumes
But even more than the price of bioplastics, it is the volumes involved that pose a problem, adds Mr. Mousseau.
“When you look at it application by application, you can find organic alternatives for almost everything,” he says. But when you look at the big picture, it doesn't work. (…) Everyone wants to use biomass to replace their business, whether for energy or for other things, so at some point, there are just not enough resources to completely avoid oil.”
A few figures are enough to be convinced. Global plastic production amounts to around 450 million tonnes per year, says Mr. Mousseau, while wood production is 1.5 billion tonnes – except that this wood is not available to replace oil since we already use it for other things.
According to calculations by the Chief Forester of Quebec, forest residues (bark, branches and foliage) represent approximately a third of the mass of harvested wood. On a global scale, this would potentially result in around 500 million tonnes of residue. This is more than the production of plastic, but these residues cannot be transformed into plastic at a ratio of 1 to 1 — there would be losses.
And that's not to mention that we already have other uses for these branches and pieces of bark, notably as a source of energy, as bedding for livestock, etc. And the same principle applies to agri-food residues — the stalks and leaves of corn plants, for example, can be used as bedding and for cattle feed.
In short, everything indicates that we will not be able to do without oil completely for a long time. “But already, if we eliminate the 85% that we use as a source of energy, that will already be the case,” says Mr. Mousseau. And as a very large part of GHG emissions occur during final combustion, the balance of plastics will depend on what we do with them at the end of their useful life.
Same story from Mr. Rodrigue: in the foreseeable future, we will not have much other choice than to continue to exploit oil for its non-energy uses, “and then, it becomes a management problem plastics at the end of their life.
* * * * *
Do you have questions about the world around you? Whether they concern physics, biology or any other discipline, our journalist will be happy to answer them. In our eyes, there is no “stupid question”, no question “too small” to be interesting! So write to us at: [email protected].
Related News :