World agreements have stipulated that global temperature should be kept below 2 degrees Celsius above pre-industrial levels to reduce the risks of climate change. However, there is no one path, technology or solution to achieve this. One potential solution is a range of
processes known as carbon dioxide utilisation. With this process, CO2 from waste streams can be captured and used to produce other chemicals.
This research focuses on measuring the potential of these conversion processes to avoid environmental impacts and be part of the carbon mitigation agenda. Currently, there is no consensus on how to evaluate these impacts and interpret them in a way that allows for comparison. Therefore, a multi-disciplinary environmental impact assessment framework with specific guidelines for carbon dioxide utilisation processes was developed. To test this new framework, two case studies were chosen: methanol and urea synthesis.
Results for the methanol case study showed at best a carbon neutral scenario when methanol is produced through catalytic hydrogenation of CO2 with renewable H2 compared to methanol from natural gas (0.1 kg of CO2 avoided/kg methanol). For urea,the best scenario sees up to 1.3 kg of CO2 avoided/kg of urea produced in a scenario
where an electrolyser connected to wind power supplies H2 for ammonia synthesis is compared to ammonia produced from fossil fuels. System expansion was used to allocate
emissions in all case studies.
Twenty indicators were used for scenario analysis and ranking of each process. Six different rankings were used to analyse impacts. For both case studies, the highest
utilisation potential was calculated with a combination of CO2 capture and an utilisation process based on renewable energy. This framework is a decision making tool that can help guide CO2 chemical transformation processes towards reaching environmental targets and contribute to lessening the effects of climate change.
