In just a few decades, plastic has become an inseparable component of our planet. This material is found in the ocean depths as well as in geological strata in the form of “plastistone”, a new type of sedimentary rock formed by the fusion of plastic waste and natural rocks. Plastic pollution is such that the UN is currently working on an international treaty to limit its proliferation.
Faced with the scale of the problem, researchers, linked to the plastic and oil industries, are interested in a controversial solution: transforming plastic back into fuel. This process, detailed in an article on the Popular Mechanics site, aims to transform this waste into energy which could power boilers, turbines and diesel engines and several initiatives of this type are being studied around the world.
The main process to date – you have surely already heard of it – is that of pyrolysis which consists of heating plastic to nearly 900°C, in the absence of oxygen, to break the molecular chains and obtain hydrocarbons. Usually, this operation converts around 60% of the processed plastic into pyrolysis oil or “bio-oil”, usable as an energy source.
Yale researchers recently increased the yield of this process to 66% without using a catalyst, a potentially game-changing step that reduces the costs and maintenance burdens inherent to these substances. To consider the generalization of the process, the scientists tested their method with industrial carbon felt, a resistant and common commercial material. They managed to convert almost 56% of plastic into bio-oil, encouraging results showing that the solution is technically adaptable.
Real solution or insufficient bandage?
Despite this progress, the pyrolysis process remains energy-intensive. The energy required generates CO2 and other waste, prompting some experts to claim that it is an “industrial illusion” that does not fundamentally solve the problem of dependence on fossil fuels.
Scientists recognize that the ecological and industrial profitability of the process remains to be demonstrated. To do better, it will be necessary to reduce the energy consumption of treatment and better control secondary emissions. As long as global production of single-use plastics increases, these innovations will only provide partial and insufficient solutions. The performance and simplicity of the device are, however, encouraging signs for large-scale use.
This type of advanced recycling takes place in the context of a profound modification of the earth’s geology and biology linked to plastic pollution: the microplastics in our bodies or the “plastistones” found on all continents are the symbol of a lasting footprint, just like other markers of the Anthropocene.
At this stage, the best solution remains reducing the production of new plastics and limiting its invasion of the environment at the source.
