Life-cycle assessment of the Norwegian waste-to-energy sector: Current situation, implications of carbon capture and storage and circular economy

The European Union's approach to waste management is based on the waste hierarchy, which sets the following priority: prevention, reuse, recycling, energy recovery and disposal. Recently, the European Commission has revised... [ view full abstract ]

The European Union's approach to waste management is based on the waste hierarchy, which sets the following priority: prevention, reuse, recycling, energy recovery and disposal. Recently, the European Commission has revised legislative proposals on waste and adopted an ambitious Circular Economy Package. As a result, Europe and most OECD countries are moving towards a recycling society, one where waste is not only avoided but also used as a resource

In addition, climate change is regarded as a major global challenge, and energy industries have contributed to approximately 32% of global CO₂ emissions over the last 20 years. The de-carbonization of the energy sector requires a massive transformation; involving an increase of renewable shares in the energy mix, improvements in power plant efficiency and the incorporation of carbon capture and storage (CCS) processes.

The specific aims of this study is to environmentally assess: (1) the current situation of the Norwegian WtE sector, (2) the influence of the implementation of the circular economy package, (3) the addition of CCS on the current WtE system, (4) to benchmark (1), (2) and (3) with a landfill scenario in order to check the waste hierarchy concept.

Process based life-cycle assessment (LCA) with system expansion is combined with process modelling and mathematical optimization in this study. The environmental impacts are assessed with: Climate change impact potential (CCIP) with global warming with time horizon of 100 years (GWP100) as indicator, freshwater eutrophication potential (FEP), human toxicity potential (HTP) and ozone depletion potential (ODP) as mid-point impact categories and nitrogen oxides, sulfur dioxide, carbon monoxide and particulate matters as single stressors. A sensitivity analysis is conducted on the climate metrics by using GWP100, global temperature with time horizon of 100 years (GTP100) and the potential effects of the near time climate forcers.

The CCS scenario is favored for CCIP. For all the other impact categories and stressors, the environmental burdens are increased for CCS compared to the WtE scenario due to the additional fuel consumed by the CO₂ captures process and the use of solvent. For the Circular Economy scenario, the fossil fuel consumed in the recycling processes  and the new waste streams generated makes it rank worst than the WtE and CCS for FEP, ODP and HTP. For all the single stressors assessed, the waste hierarchy is hold: Circular Economy ranking best, then energy recovery scenarios (WtE and CCS) and Landfill.

Not all the materials can be recycled; and resources consumption, emissions, losses, contaminations as well as additional new waste stream occur while material recycling. Circular economy may actually give WtE system the opportunity to strengthen and expand its role towards new or little developed value chains such as secondary raw materials production (metals and minerals from ash, building materials from ash). This expansion might also give a push towards new, advanced concepts, such as Carbon Capture Utilization and Storage (CCUS), energy storage and flexibility and new- or multi-products systems (e.g. waste refineries, biofuel production, biogas + WtE).