Transmission expansion map
There are a number of reasons why America needs to invest in its power grid. A congested and obsolete power grid limits consumers’ access to lower cost power. A congested grid is also inefficient and prone to blackouts. These factors alone cost American consumers tens of billions of dollars per year in elevated electric rates and lost productivity.
In their 20% Wind Energy by 2020 Report, the U.S. Department of Energy identified transmission limitation as the largest obstacle to realizing the economic, environmental, and energy security benefits of obtaining 20% of our electricity from wind power. Currently, around 135,000 megawatts of proposed wind projects, more than enough to meet 20% of our electricity needs, are waiting in line to connect to the grid because there is not enough transmission capacity to carry the electricity they would produce.
Some of the best wind resources in the country are located in areas where the existing grid is either weak and congested or non-existent. By expanding and upgrading transmission systems, the nation can put these world-class wind resources to use. Moreover, by facilitating the expansion and geographical dispersion of wind power across a wide area, an upgraded transmission grid makes it even easier to reliably integrate wind energy. When wind output is slowing at one location, it is often increasing somewhere else, canceling out both changes.
The 20% Wind Energy Report suggests that the most effective transmission upgrade to improve grid reliability and connect wind-rich areas of the country to major load centers would be to build a nation-wide “backbone high-voltage transmission” system to provide “trunk-line transmission” capacity to transport wind power. One concept of a high voltage 765 kV AC transmission overlay to access 400 GW of wind power is represented in the map below from the 20% report.
Conceptual map of what an expanded transmission grid might look like – courtesy of AEP from the U.S. DOE “20% Wind Energy by 2030” report.
Other studies have suggested that extra high voltage (perhaps 800 kV) DC lines could also be cost effective for transporting large quantities of wind power long distances. One study, the Eastern Wind Integration and Transmission Study, examined four separate scenarios using up to ten 800 kV HVDC lines. Other studies addressing HVDC lines include the Eastern Interconnection Planning Collaborative and the Joint Coordinated System Plan.