In order to fight climate change, we need to curb our consumption of fossil resources. This has been shown in many studies and several of them even quantify how much of the remaining fossil resources need to be left in the ground. In the energy sector this is possible through “decarbonisation”. However, this strategy is not feasible for organic chemistry, which is defined by the use of carbon. So, for the important chemical and plastic industries, we need to find alternative carbon sources in order to shift towards a more sustainable and climate-friendly production and consumption. We call these alternative carbon sources “renewable carbon”.
Staying with the widely-accepted concept of “decarbonisation” is not only inaccurate for the chemical and plastics industry, it is also potentially harmful, since it shifts attention away from the necessity of carbon use and therefore from the question of the “right” carbon sources. Furthermore, in light of growing scarcity of other finite resources – metals, minerals, rare earths – carbon will be an important backbone of humankind’s product needs, since it is available in almost unlimited quantities in the atmosphere.
The equivalent to decarbonisation in the energy sector is a transition to renewable carbon in the chemical and plastics industries.
There are only three sources of renewable carbon. Renewable carbon comes from sources which can be (re)grown (biosphere), (re)captured (technosphere & atmosphere) or (re)cycled (technosphere):
Biosphere: Renewable carbon gained from all types of biomass
- Food crops
- Non-food crops
- Side streams, by-products and biogenic waste
- Includes measurable bio-based carbon content as well as “biomass balance and free allocation” approach
Technosphere and atmosphere: Renewable carbon from direct CO2 utilisation
- Fossil point sources (while they still exist)
- Biogenic point sources (permanently available)
- Direct air capture
Technosphere: Renewable carbon from recycling of already existing plastics and other organic materials
- Mechanical: limited quantities and qualities, limited in handling of mixed fractions
- Chemical: gasification, pyrolysis, solvolysis and more, early technology stage, first commercial plants in five years expected
- Enzymatical: early stage technology
- Incineration, but only with CO2 capture and utilisation (CCU)
In order to provide the full benefits of these technologies, all of them should run on renewable energies in order to avoid additional fossil fuels consumption for the supply of carbon as a material. However, this is a long-term vision and the first steps should be taken as soon as possible to account for the urgency of the climate crisis. For CCU processes that require energy, the use of renewable energy is indispensable.