Connecticut council issues draft findings on 785-MW CPV Towantic project

The Connecticut Siting Council is taking comment until May 7 on its draft findings of fact, dated April 30, related to an application by CPV Towantic LLC for a change in a prior approval for a gas-fired power project.

In June 1999, the council granted a Certificate of Environmental Compatibility and Public Need to Towantic Energy LLC for the construction, maintenance, and operation of a 512-MW facility located approximately 4,000 feet north of the Prokop Road and Towantic Hill Road intersection in the Town of Oxford, Conn.

In February 2012, CPV Towantic Holding Co. LLC and Towantic Energy Holdings LLC, the parent company of Towantic Energy LLC, entered into an agreement pursuant to which CPV Towantic Holding acquired a majority interest in Towantic Energy LLC. Thereafter, Towantic Energy LLC was renamed CPV Towantic LLC. In November 2014, CPV Towantic submitted to the council a petition to reopen and modify, turning this into a 785-MW, dual-fuel, combined cycle project, which has a total estimated cost of about $1 billion.

The draft findings of fact recounts a long history for this project of protests, some years old and others filed more recently related to the new changes.

On the side of benefits for this project, the council’s findings noted that since 1999, approximately 498 MW of existing generation has retired from Connecticut. More recently, 547 MW of existing generation in Connecticut has announced its retirement by 2017. Approximately 2,888 MW of existing generation within New England (but outside of Connecticut) is expected to retire by mid 2017. Of the 2,888 MW, the 604-MW Vermont Yankee Nuclear Power Plant retired in late 2014. According to ISO New England’s 2014 Regional System Plan, the New England region is expected to require 424 MW in 2019/2020 to meet the installed capacity requirement. This is expected to increase to a shortage of 1,155 MW by 2023/2024, taking into account load and energy efficiency forecasts and known retirements totaling approximately 3,200 MW.

The findings noted that CPV qualified for, bid into, and cleared ISO-NE’s ninth Forward Capacity Auction (FCA9) which began and ended on Feb. 2, 2015. This auction is for the June 2018-May 2019 commitment period. Approximately 1,427 MW of new resources cleared, with the proposed CPV facility counting for 725 MW, which is on the order of the summer rating of the plant of 740 MW at 90 degrees Fahrenheit (F) and burning natural gas. CPV’s dual-fuel (gas and oil) capability would be useful in the New England fuel mix to deal with the problem of winter peaks when gas becomes unavailable.

The rating of 785 MW is based on net power plant output at 59 degrees Fahrenheit (F), with natural gas as the fuel, and operation at 100% capacity. The project would use a combined-cycle configuration with two General Electric 7HA.01 combustion-gas turbines and one steam turbine. The previously-approved combined-cycle configuration utilized two GE 7FA.03 combustion-gas turbines in addition to the steam turbine. The GE 7FA.03 combustion turbines were claimed to be the most efficient at the time of the original approval. Currently, the proposed GE 7HA.01 turbines are claimed to be the most efficient and flexible available. The GE 7HA.01 has a 5.4% improvement in efficiency over the originally approved combustion turbine model because of its lower heat rate of 6,402 British Thermal Units (Btu) per kilowatt-hour (kWh) as compared to the approved GE 7FA.03 turbine, which has a heat rate of 6,770 Btu/kWh. A lower heat rate is more efficient because a smaller fuel consumption rate is needed to generate a given amount of electrical power.

The Spectra Energy Algonquin natural gas transmission line right of way is located immediately north of the subject property. Similar to the approved power plant’s design, the proposed CPV facility would have an overhead connection from its 115-kV switchyard to three existing overhead 115-kV transmission lines.

Unlike the approved plant, the revised project includes the capability of duct firing. Duct firing is the introduction of fuel into the heat recovery steam generator to augment or boost power output. Duct firing provides incremental capacity in the steam cycle at a very low cost per kW and at relatively good efficiency. Specifically, duct firing at 90 degrees F can add 53 MW in the summer with an incremental heat rate of 8,224 Btu/kWh, and in the winter, it can add 32 MW with an incremental heat rate of 8,234 Btu/kWh at 20 degrees F.

The plant is not proposed to have black start capability. However, CPV will consult with ISO-NE to investigate the possibility of an upgrade to black start capability. A final determination would depend on technical feasibility, ISO-NE and Federal Energy Regulatory Commission approval of a CPV-specific compensation mechanism, and successful incorporation into the state-issued air permit. However, CPV’s assessment is that there is not enough land on the site to accommodate black start capability unless other land is acquired.

About Barry Cassell 20414 Articles
Barry Cassell is Chief Analyst for GenerationHub covering coal and emission controls issues, projects and policy. He has covered the coal and power generation industry for more than 24 years, beginning in November 2011 at GenerationHub and prior to that as editor of SNL Energy’s Coal Report. He was formerly with Coal Outlook for 15 years as the publication’s editor and contributing writer, and prior to that he was editor of Coal & Synfuels Technology and associate editor of The Energy Report. He has a bachelor’s degree from Central Michigan University.