Grid interconnections and decarbonization pathways for carbon neutrality of Northeast Asia

As the three major greenhouse gas emitters in Northeast Asia (NEA), China, South Korea, and Japan, have joined the global carbon neutrality movement, this study examines interstate power transmissions between the countries to be considered for optimal technology pathways towards the net zero emission target. Using a bottom-up least-cost energy system model, intertemporal investment decisions are made between 2015 and 2065 in 10-year time steps subject to short-term/long-term emission targets in a range of carbon prices (0,100,200,300 USD/tCO2). Results show that under the carbon neutrality target, interstate power trade enables earlier carbon phaseout at a lower cost by increasing renewables utilizations and reduces investment burdens for high-cost carbon-neutral technologies like hydrogen. We find grid interconnections increase renewable penetrations at all nodes, while carbon pricing above 200 USD/tCO2 is required to ensure all participating nodes benefit from earlier carbon reduction. Ambitious carbon pricing is also important for closing gaps in emission impacts of short-term and long-term emission targets, calling for urgent actions to remove market distortion in power sectors. Lastly, sensitivity analysis to trade limits and nuclear utilization shows trade makes a greater contribution to carbon phaseout with relaxed trade terms and nuclear deployment.