Economic efficiency of alternative border carbon adjustment schemes: A case study of California Carbon Pricing and the Western North American power market

To be effective, policies addressing power sector carbon emissions in jurisdictions that are embedded in larger carbon markets must account for carbon embodied in imports and the potential for leakage. Yet analyses of alternative border carbon adjustment (BCA) policies that carefully model the impact of generation mix, net load distributions, and transmission limits are rare in the literature. With a generation-transmission expansion planning model of Western North America, we compare the impacts of alternative BCA schemes that California's carbon pricing system could implement. These include no BCA, facility (import source)-based deemed emission rate, a facility-neutral and constant (over-time) rate, and a facility-neutral and dynamic rate. Our results suggest that, when compared to no BCA or BCA using facility-based deemed rates, a facility-neutral BCA can improve efficiency by simultaneously lowering market-wide emissions and costs without raising California consumer expenditures. Emissions leakage also declines significantly. The precise value of the deemed rate affects these gains; setting it equal to marginal emission rates external to California is most efficient. We also show that California's carbon pricing encourages more interstate transmission expansion because power imports become more profitable. However, BCAs that cost-effectively lower total regional emissions will dampen those incentives.