RWTH: Net zero emissions are possible

Since the early 1950s, synthetic plastics have found their way into almost every area of ​​life, including packaging, transportation, buildings, and healthcare. As a result, plastic consumption increased twenty-fold between 1964 and 2014, from 15 to 311 million tons per year. Increasing pollution of the environment with plastic waste is a consequence, plus global oil consumption and the greenhouse gas emissions (GHG emissions) associated with production.

Raoul Meys, Chair for Technical Thermodynamics at RWTH Aachen University, and Professor André Bardow, Chair for Energy and Process System Technology at ETH Zurich and formerly RWTH, are now showing in a study that a combination of recycling, biomass use and carbon capture and use (CCU ), so-called net zero GHG emissions from plastics can be achieved. The study is based on a new holistic model of global plastic production and disposal and has now been presented in the journal Science.

Net zero means that all human-made GHG emissions are removed from the atmosphere and the carbon footprint is zero. In order to achieve net zero emissions, all three circular technologies recycling, biomass use and carbon capture and use must be used. Strategies for reducing GHG emissions include decarbonising the energy supply in the plastics supply chain from oil exploration to plastics production and replacing fossil carbon inputs with closed loop technologies such as chemical and mechanical recycling, biomass utilization, and carbon capture and use.

With an optimal combination, the energy requirement of the circular industry can be reduced to such an extent that it is up to 53 percent lower than in a fossil industry with extensive carbon capture and storage (CCS). In addition, the operating costs for net zero-emission plastics are in the same order of magnitude as for linear fossil fuel production with CCS and can even be significantly reduced under favorable conditions. Even if the lower energy requirement may seem unusual at first, it can be explained by energy savings over the entire life cycle and recycling: The fossil, bio- and CO2-based paths can only recover the energy contained in the plastics by incinerating waste, which inevitably leads to inefficiencies and thus energy is lost. In contrast, recycling preserves the energy content of plastics by reusing them and thus lowers the net energy requirement. However, in order to achieve the maximum cost-saving potential, biomass and CO2 must be available at low cost, the production and supply of oil must be made more expensive, and investment incentives for recycling must be set.

The authors show that the use of political instruments to increase the availability of plastic waste as a resource and to create economic incentives for increased investment in biomass and CO2 use can promote the path to plastics with net zero emissions. In this way, the circular economy could redesign production systems in such a way that, by decoupling fossil carbon resources, plastics can be achieved with net zero emissions with lower energy requirements and lower operating costs. Economic and ecological well-being would be linked in this way.