By Paula C. Squires
A report done for Dominion Virginia Power to evaluate offshore transmission options for future wind energy projects recommends building offshore substations. But it would cost a pretty penny: $652 million per platform, according to a study by ABB Power Systems Consulting.
A platform with two, 230,000-volt power lines could transmit to shore every 500 to 700 megawatts of wind-generated electricity constructed off the coast of Virginia, ABB says in its report. It builds on recommendations from an earlier Dominion study in 2010 that looked at potential on-shore interconnection options needed to support offshore wind generation. The Dominion study found that the existing transmission system in the Virginia Beach area could accommodate wind power generated from an area in the Atlantic ocean about 26 miles off the resort city’s coast. Transmission lines from four recommended offshore service platforms could be routed to two separate onshore interconnection points.
The $652 million estimate per platform includes equipment and submarine transmission cables. Asked who would pay for the platforms, Dominion Virginia Power spokesman Jim Norvelle said: “We don’t know the answer to that yet. That’s the challenge. We know it’s a good resource, but how can we get it to our customers at a reasonable cost?”
The report notes potential cost savings could be achieved through multiphase construction of platforms that would be added as wind power is generated. An estimate of up to 3,000 megawatts of power has been proposed for the offshore area identified for potential wind development.
“As public policy is developed to support wind farms off Virginia’s coast and leases are issued, Dominion will continue evaluating transmission options to ensure the identification of the lowest cost alternative for bringing offshore wind electricity to customers,” Scot Hathaway, vice president-electric transmission, said in a statement.
Dominion says it plans to respond to the federal Bureau of Ocean Energy Management’s call for information for wind generation in an 113,000–acre leasing wind energy area off Virginia Beach. The company has said that it wants to invest in offshore wind by installing as many as 100 to 400 turbines in the area.
The U.S. Department of Energy estimates that offshore wind generation would cost about 24 cents per kilowatt-hour; Dominion’s residential rates today for generation, transmission and distribution services are about 11 cents per kilowatt-hour. DOE recently awarded Dominion a $500,000 grant to work with partners to find ways to reduce the costs of offshore wind generation.