Connecting Eastern and Western Grids; Macrogrid Design – a Strategic US Infrastructure Investment

Recalling rationale motivating the US Interstate Highway System of the 1950’s, this presentation describes a recently completed multi-organization effort to quantify benefits of bridging the US Eastern and Western Interconnections with a macrogrid, under a high-renewables future. Given the existing “seam” between the two interconnections, a co-optimized infrastructure planning model was developed to assess tradeoffs between investments in cross-seam HVDC transmission, AC & DC transmission needs within each interconnection, generation investment costs, and operational costs, while satisfying different policy compliance constraints. This work was performed using industry-vetted expansion planning and production cost models of the North American power grid. Results from the analysis indicate that under high wind/solar growth scenarios, the cost of cross-seam transmission is outweighed by the generation-related savings it produces. The presence of other macrogrid benefits, including grid reliability, resilience, and adaptability, suggest that cross-seam transmission is a highly attractive infrastructure development strongly in the national interest. We conclude the talk identifying ways to move forward on developing high capacity cross-seam HVDC transmission.