The Interstate Power and Light (IPL) subsidiary of Alliant Energy (NYSE: LNT) filed Nov. 14 with the Iowa Utilities Board (IUB) two applications seeking approval for construction of the proposed Marshalltown Generating Station (MGS) in Marshalltown, Iowa.
“Regulatory approval is the next step in the process to construct MGS,” said Tom Aller, President–IPL, in a Nov. 14 statement. “The applications filed today demonstrate the need for MGS and how the proposed natural gas-fired generating station contributes to IPL’s long-term energy resource plan. The energy resources plan balances the company’s supply of energy resources, provides safe and reliable service and maintains competitive costs for the benefit of customers.”
IPL’s application for generation siting certification (siting certification) must demonstrate that construction and operation of the MGS reasonably utilizes the state’s land, air and water resources. Also, operation of the MGS must be consistent with reliable electric operations and the Iowa Legislature’s intent to spur Iowa’s economic development.
The IUB’s decision to grant a certificate for construction of the proposed MGS is contingent upon IPL receiving all necessary permits and regulatory approvals related to the proposed project. IPL is also required to seek IUB approval of proposed ratemaking principles prior to investing in the project. Ratemaking principles are fixed for the life of the facility. IPL said it expects to receive an IUB decision on its application for the siting certification and the ratemaking principles in the fourth quarter 2013.
IPL also expects to make related filings with the Minnesota Public Utilities Commission in the next 30 days.
In August, IPL announced its long-term energy resources plan, which further balances IPL’s supply of generating resources by:
- Making approximately $440m in investments to reduce emissions and increase efficiency of IPL’s existing coal-fired units;
- Execution of a new nuclear purchase power agreement to purchase 431 MW of capacity and energy from the Duane Arnold Energy Center nuclear plant;
- Making an approximate $650-$750 million investment, excluding AFUDC and transmission upgrades, for construction of the MGS; and
- A continued commitment to renewable resources and energy efficiency.
MGS to be located next to existing Sutherland plant
The MGS will be made up of a power block containing two combustion turbine generators (CTGs), two heat recovery steam generators and a single steam turbine generator (STG), said the siting application. Northern Border Pipeline Co. owns a natural gastransmission pipeline running from the northwest to southeast across Iowa, which is located approximately 10 miles northeast of the site. Northern Natural Gas Co. owns natural gas pipelines running east and west located about two miles north of the site. Also, IPL currently procures natural gas for the operation of existing, adjacent Sutherland Generating Station units through the Northern Natural Gas pipelines.
The MGS will be an intermediate load, baseload-capable, combined-cycle facility comprising of three units. The MGS design will be based on an average of 260 starts per year, allowing dispatchers to place the MGS units in and out of service as required by transmission grid load and system reliability requirements. IPL expects the annual dispatch of the MGS will vary between a 10% and 50% capacity factor, dependent upon system requirements, Midwest ISO market considerations, and economic dispatch criteria.
The three MGS generating units will also be capable of baseload operations and capacity factors in excess of 70% as market conditions and transmission grid load profiles change over the life of the MGS. The MGS’s three electric power generating units will be configured in a 2×1 (two-on-one) combined-cycle configuration. The final size and detailed configuration of the generating equipment will not be known until after the procurement process. As an integrated system, the MGS will be capable of generating 580 MW to 630 MW during summer peak conditions.
There is an ITC Midwest LLC substation located slightly northeast of the MGS site. It is anticipated that the electrical interconnection of the MGS will be at 345 kV to a new ITC-M 345-kV substation, and that an existing ITC-M 115-kV transmission line route will be used to construct a 345-kV transmission line from the new substation easterly to an interconnection with existing 345-kV facilities near Cedar Rapids. It is also anticipated that the MGS will interconnect to the existing ITC-M 161-kV Marshalltown substation, which is located slightly northeast of the MGS plant location, via new 345/161-kV transformers.
The existing ITC-M 161-kV Marshalltown substation currently has three 161-kV lines, which respectively exit east to Traer, west to Timber Creek, and south to Jasper. ITC-M is currently rebuilding and converting an existing 115-kV line to 161-kV operation that exits north to Wellsburg. ITC-M also plans to convert an existing 115-kV line that exits the substation west to 161-kV operation by the end of 2014. There is also a connection to the 115/34.5-kV substation via a 161/115-kV transformer.
IPL submitted a generator interconnect request to the Midwest ISO for the MGS in November 2011. MISO is performing an interconnection study under queue position J233, which will determine all electric interconnection and network upgrades that will be required. IPL said it anticipates this study will be completed in late 2012.
IPL plans to fire gas, but plans dual-fuel capability
“The MGS will be fired primarily on natural gas,” the siting application noted. “IPL is soliciting bids for the project with a dual-fuel option. However, at this time, IPL does not see the need for a backup fuel source. IPL is still soliciting bids for the project with the dual-fuel option because it can foresee two changes in circumstance that may require an alternative fuel source in the future. First, IPL may determine it needs to install ‘black-start’ capability, which would necessitate dual-fuel capability to meet North American Electric Reliability Corporation (NERC) requirements. ‘Black-start’ capabilities, if provided, would enable the plant to start-up without relying on power from the transmission grid. Second, MISO may determine, for resource adequacy reasons, that either firm natural gas capacity or an alternate fuel source is required to ensure resource adequacy. IPL will continue to monitor the circumstances to determine if further action is warranted.”
The primary fuel for the CTGs and the HRSG duct burners (if provided) will be pipeline-quality natural gas. The MGS will require about 3,860 to 4,260 MCF (one thousand cubic feet) per hour of natural gas when operating both CTGs at their maximum rating during summer design conditions, the application said.
The plant construction will be bid as an EPC project. This will obligate one contractor to be responsible for achieving plant schedule and construction milestones. The request for proposals is scheduled to be sent to prospective bidders in November. A prequalification application was sent to about 28 bidders on Sept. 17, and the bidders list was finalized in November. Proposals from respective EPC bidders are expected to be received in the first quarter of 2013. The final selection and negotiation of the EPC bidders is scheduled to begin in the second quarter of 2013. The final selection and negotiation of the EPC contract is to be completed in the third quarter of 2013.
The plant is expected to be on-line in April 2017.