Federal agencies have published the Final Environmental Impact Statement for the TransWest Express Transmission Project, a regional electric transmission system proposed by TransWest Express LLC to add 3,000 MW of transmission capacity to the western U.S. electric grid, provide access to cost-effective wind energy supplies and reduce regional greenhouse-gas emissions.
A Notice of Availability of the Final EIS from the U.S. Department of the Interior and U.S. Department of Energy is anticipated to appear in the May 1 Federal Register, TransWest said in an April 30 announcement. The notice begins a 30-day availability period.
The Final EIS was prepared by the U.S. Bureau of Land Management and the Western Area Power Administration, which is part of the U.S. Department of Energy, as joint lead federal agencies. It results from more than six years of environmental analysis, public input and collaboration among 50 federal, state and local cooperating agencies.
After review of thousands of miles of potential routes, the Final EIS also identifies the agencies’ preferred alternative from south-central Wyoming, to the site of a potential interconnection to the existing grid near Delta, Utah, and then to the Marketplace Hub in southern Nevada, where this electricity hub wheels power from Hoover Dam and other sources and provides interconnections to the California, Nevada and Arizona grids. Two-thirds of the approximately 730-mile preferred alternative route lies on federal land principally managed by BLM. The TWE Project follows designated utility corridors and is co-located with existing transmission when possible to avoid and minimize impacts.
“Completing this major federal environmental analysis is an important milestone that advances the TWE Project closer to construction while furthering national goals to create access to high-capacity renewable energy resources. We look forward to BLM and Western issuing their records of decision in the months ahead,” said Bill Miller, president and CEO of TransWest, an independent transmission developer. “We appreciate the work of BLM and Western, and the local communities, to develop a route for the project that reflects environmental balance, economic viability and extensive public input.”
“We are here to help strengthen the energy highway by connecting communities with reliable power and clean generation,” said Western CEO and Administrator Mark Gabriel. “Our coordinated work with BLM on this comprehensive review of the environmental impacts and mitigation measures has been productive and will guide our future decision-making.”
Western is supporting the development of the TWE Project. Following the Final EIS availability period, BLM and Western each will issue a record of decision that documents the agency’s decision pursuant to its unique purpose and need, including any required conditions and stipulations.
The TWE Project is a 600-kV high-voltage direct current (HVDC) transmission line engineered with typical lower-visibility lattice structures to complement existing lines in the western landscape. It is designed to deliver about 20,000 gigawatt-hours per year of clean and sustainable energy to multiple utilities in California, Nevada and Arizona. South-central Wyoming is home to the nation’s highest-capacity onshore wind energy resources, with capacity factors in excess of 40%.
In addition, the TWE Project will create a critical link between the diverse renewable resources in the Rocky Mountain and Desert Southwest regions to efficiently transmit energy to utilities in both regions when the wind blows and the sun shines. This will foster a cleaner, more resilient western U.S. power grid while also helping address integration challenges.
Two design options have been included to maintain project flexibility, the Final EIS said.
- Under Design Option 2, the company would construct a 600-kV DC transmission line to deliver energy from the Northern Terminal near Sinclair, Wyoming, to a new alternating current (AC)/DC converter station near the existing IPP substation near Delta, Utah. From the new AC/DC converter station in Utah, a single circuit 1,500-MW, 500-kV AC transmission line would be constructed to one of the existing substations in the Eldorado Valley, in Boulder City, Nevada (Marketplace Hub).
- Under Design Option 3, the project would utilize a two-phase approach. During phase one, the portion of the transmission line from Sinclair, Wyoming, to the IPP substation near Delta, Utah, would be constructed (with 3,000-MW, 600-kV DC capability for phase two conversion) and operated as a 1,500-MW, 500-kV AC transmission system. Phase two would involve constructing the remaining portion of the 3,000-MW, 600-kV DC line from IPP to the Southern Terminal, south of Boulder City, Nevada, construction of the Northern and Southern terminals and ground electrode systems, and converting operations to a DC system. This approach would be required if the demand for Wyoming resources in the Desert Southwest proves to be slower in development than expected.