Solar Southwest Initiative

Electricity transmission, often underappreciated and occasionally maligned, is an essential part of an economy with high energy demands and even more crucial in a carbon-constrained world.

Renewable energy resources vary in strength from place to place. The Western US and the Great Plains have some of the strongest on-land renewable energy sources (sun, wind, and geothermal); the Great Lakes and offshore locations in both Atlantic and Pacific Oceans have some very high quality wind resources.

Demand for energy is not concentrated where renewable energy is most economically harvested or available at appreciable strength, so using existing high voltage transmission and building new transmission will be part of a sustainable clean energy system. Even within regions with favorable renewable resources, people have tended to settle where the wind and sun are not quite as intense. The expense of putting transmission underground has historically been many times that of conventional high voltage lines so is only feasible in dense urban areas for short distances. On the other hand, transmission corridors are narrow and carry in them power for many millions of people: the high voltage line called the Pacific Intertie, for instance, can carry enough electricity for 5 million homes in a right of way approximately 50 feet wide.

Besides the compactness of a high-voltage line, one of the benefits of long-distance high voltage transmission is how little power is lost, even when sent several thousand miles. Transmission and distribution losses in the US grid are currently around 7% of total system power. If desert power plants were connected with load centers on the East Coast by high-voltage DC lines, just 15% of the power would be lost in transmission from end to end. Furthermore, high voltage DC lines or HVDC, have few of the electromagnetic fields that some people fear have negative health effects.

Both high-voltage AC (HVAC) and HVDC have their places in an efficient electrical distribution system. HVAC is less expensive to build for short distances and it is easier to tap into along the way allowing for more of a branch-like distribution structure. HVDC is better suited for long distance point-to-point transmission because of its lower losses and narrower footprint per unit power.

The building of new long distance transmission is key if we are to keep our twin commitments both to shielding the planet from the effects of fossil fuel combustion and to an urban, suburban and rural lifestyle that is heavily dependent upon powered devices. An effective transmission system that is connected to centers of demand and the strongest supply of renewable energy will have a lighter footprint, be less expensive, and be more quickly built than a more distributed energy system that may emerge a few decades hence. Figuring out the routes and exact technical specifications of such a system should be carried out with the utmost in transparency, spirit of compromise, and sense of urgency given the high cost of delay and lack of inclusiveness.

California through RETI and Texas through CREZ have started such a process to work out long-term state plans for siting and building transmission that will enable a clean energy future. A Southwest-wide extension of state-by-state initiatives will create a basis for a stable regional and eventually national low-carbon grid.