Two major high-voltage direct current (HVDC) underground electric transmission projects are moving forward in New York City and Iowa. Is this the future of long-distance transmission?
New York City last week (Sept.2) saw the beginning of a key element in an innovative power transmission line connecting clean Canadian hydro to the city’s distribution system. Workers began transforming a former fuel oil storage site at the Astoria power station in the city into an alternating current conversion station for Hydro-Quebec power moving to New York via an underground and underwater 400-kV HVDC line running 339 miles from the Canadian border to the site in Queens, where it will be converted from DC to AC, then into the distribution grid.
The converter station is the end point in the $6 billion Champlain Hudson Power Express (CHPE, colloquially known as “Chippy”) project, which is fully permitted. Construction began in Nov. 2022. According to CHPE, “Over 100 reels of high-voltage direct current (HVDC) cable have now arrived at Port of Albany and been transported throughout the state where they will be prepared for installation.” The project is expected to be in service in 2026, delivering 1,250 MW of low-cost Canadian hydro to high-cost New York City.
According to the company, two five-inch-diameter cables will run from the Hertel substation in La Prairie, Canada, partly underground and under Lake Champlain and the Hudson River, eventually terminating in Queens. CHPE said in August that Caldwell Marine International has begun laying articulated concrete mattresses in Lake Champlain, using divers, to “protect existing lakebed assets.” The project developer is Transmission Developers Inc., a Blackstone-owned company.
In preparing for the actual construction of the converter station, according to Reuters, workers “have already removed six tanks that previously stored 12 million gallons (45.4 million liters) of heavy oil for burning in power plants and nearly four miles (6.44 km) of piping from the site.”
The CHPE project falls under the New York State Energy Research and Development Authority’s “Tier 4” program, aimed at boosting renewable energy in the city, which has long relied on oil and, more recently, natural gas for its electric generation, and improve grid reliability. In 2021, the city saw the closure of the 2,000-MW, two-unit Indian Point nuclear power plant, which supplied about 25% of the city’s power.
At the ceremony celebrating construction of the converter station, New York Democratic Gov. Kathy Hochul said, “Renewable energy plays a critical role in the transformation of our power grid while creating a cleaner environment for our future generations.”
In Iowa, on Sept. 13, the Iowa Utilities Board approved plans for that state’s portion of the $3.5 billion, 525-kV, 350-mile SOO Green HVDC Link Project underground HVDC line between Iowa and Illinois, connecting the Midcontinent Independent System Operator and the PJM Interconnection with some 2,100-MW of wind power. The route is along railroad rights-of-way (the approach Sprint pioneered in building its fiber optic landline network in the days of the restructuring of the telephone industry). Most of the route is along Canadian Pacific Kansas City rail system. The Iowa board approved use of eminent domain for the project. The Iowa portion amounts to 173 miles.
In its decision, the IUB commented, “The proposed route is less intrusive than a standard above-ground transmission line and follows statutorily-encouraged transmission routes along railroads and existing public road rights-of-way.” The project will operate as a merchant power line, so retail electric customers will not be on the hook for the costs.
The board concluded, “The electric transmission line is necessary to provide adequate electric utility service and is assistive to Iowa electric customers by supporting reliability and regional transmission organization cross-seam transmission. As participants in regional transmission organizations, reliability is increased by improved ability to both send and, more importantly, receive power if MISO is experiencing generation shortfalls. The transmission line will also provide improved market access for existing Iowa generation, for which members of the public may be responsible for as part of a utility’s rate base and may provide economic benefit on that basis.”
According to Utility Dive, MISO and PJM are currently considering the proposed power line in the two regional transmission operator’s interconnect review process. The developers are looking for approval from the two ISOs in 2025 with operation in 2009.
Underground HVDC technology has some attractive characteristics compared to conventional AC overhead electric transmission, the spidery lines hanging from steel towers or, in the case of some of the oldest lines, wooden poles.
An online comparison looks at the strengths and weaknesses of AC versus DC transmission. Among the strengths of DC power lines:
- “Inductance is not present in the DC transmission lines, hence the voltage drop is less. Therefore, it has good voltage regulation….
- “In DC transmission lines, no capacitance is present, thus no power loss….
- “The DC transmission is free from the effects of stability and surges….
- “The construction of DC transmission lines is less complicated….
- “The DC transmission lines do not interfere the communication lines….”
The author of the comparison, Manish Kumar Saini of DCR University of Science and Technology in Murthal, India, concludes that “it is clear that the high-voltage DC transmission is superior to the high-voltage AC transmission.”
As underground HVDC projects are gathering steam, Congress is beginning to look at enhancing overall electric transmission in the U.S. On Sept. 15, Sen. John Hickenlooper (D-Colo.) and Rep. Scott Peters (D-Calif.) introduced the “BIG WIRES act,” short for the “Building Integrated Grids With Inter-Regional Energy Supply Act.
According to a Hickenlooper press release, “the bill would require each of the FERC transmission planning regions to be able to transfer 30% of their peak electrical loads to neighboring regions, working to close current gaps in the nation’s transmission network: instead of building new highways, building new exit ramps off the existing interstate.” Hickenlooper is a junior member of the Senate Energy and Natural Resources Committee and its public lands, forests, and mining subcommittee. Peters is a mid-ranked minority member of the House Energy and Commerce Committee and its energy, climate, and grid security subcommittee, which has FERC jurisdiction.
–Kennedy Maize
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