Development of ‘Green’ LNG through a CO₂ allocation procedure within a CO2 utilisation network in Qatar

Natural gas has a crucial role in minimising carbon emissions and is considered a transition fuel. Liquified natural gas (LNG), which is derived from natural gas is one of the most promising alternative fuels, and LNG producers are actively developing their methods to reduce or offset their carbon footprints. The allocation of carbon dioxide (CO₂) emissions is crucial in identifying who is responsible for reducing emissions at the economy or enterprise level. Different strategies for allocating CO₂ emissions have been developed and used during the last few decades. As such, this study introduces options for low carbon LNG within a CO₂ utilisation network in the state Qatar; where a linear programming (LP) model is developed to address the optimal CO_2, allocation based on environmental and economic objectives. The model considers a single CO₂ source (Qatar Gas), where a post combustion carbon capture technology (PCC) is utilised to capture the CO₂ emissions, and then allocated to 7 sinks that use CO₂ as input to their production (including Enhanced Oil Recovery (EOR)). Three scenarios are considered to allocate CO₂ to different sinks to obtain the optimal solution for each scenario. Scenario 1 had the highest total profit of 55 billion USD. The lowest CO₂ emissions were produced by scenario 2, which had zero emissions. Scenario 3 had a total profit of 20 billion USD and a total of 2 million CO₂ emissions. For all scenarios, EOR sinks had the highest CO₂ allocation. The total global warming potential through the lifecycle of LNG is reduced from 0.46 to 0.14 tonne CO₂e/tonne of LNG produced.