18-2 Diesel Fuel
18-2 The Invenergy October 2015 Application states:
During the infrequent periods when the Facility is requested to fire one of the gas turbines on oil, the daily water demand for the Facility will increase to approximately 925,000 gpd, or 0.925 MGD for each day of oil firing. Although the total water ruse of the Facility increases when firing ultra low sulfur diesel (ULSD) oil, the total number of days that the Facility will be required to fire oil will typically be determined by the grid operator (ISO-NE) based on the severity of winter conditions when there is a need to conserve natural gas for heating needs of the region. Generally, based on history, the number of days per year the Facility will be requested to use ULSD will be approximately five days. (October 2015 EFSB Application, Page 18).
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To put the above in perspective, over the last five years with the current limited pipeline capacity into the region, there has been an average of only five days per year when gas fired electric generation was asked to switch to distillate oil. Five days per year means, if the Project had existed for the last five years, that the Project would have fired natural gas 98.6% of the time, and as a result, the Project’s daily water use and wastewater discharge would have been in the range of 102,240 gpd and 69,000 gpd respectively 98.6% of the year. Projecting forward with the natural gas pipeline expansions underway, the total annual days of Project oil firing should lessen with the increasing supplies of natural gas helping to reduce winter shortage of this critical fuel to the region.
Provide a confirmation from ISO-NE that this information is accurate. We understand that the plant can operate in this condition for as long as 3.6 days based on information provided by John Niland of Invenergy. Would the expected days be consecutive or not? Please provide information for operating in this condition for the last five years.
RESPONSE:
Please see Invenergy’s Responses to the Town’s 16th data requests, particularly 16-2 and 16-4. Invenergy checked with multiple ISO-NE staff members in Operations and System Planning and was informed that ISO-NE does not provide confirmation as to when generators should be expected to switch to ULSD. What the ISO-NE could provide was data on when a Reserve Constraint Penalty Factor (“RCPF”) Activation event had occurred over the past five years (and back to 2006). Please see the publically available spreadsheet which can be found at:
https://www.iso-ne.com/static-assets/documents/2015/12/rcpf_event_data_from_may_2015.xlsx
The RCPF indicates when reserves (peakers) were called upon, which can be a good indicator of when dual fuel units may have had to switch to oil.
The availability of natural gas is monitored by ISO-NE, who may declare a “Cold Weather Event,” a “Cold Weather Watch” or a “Cold Weather Warning” according to its market rules. Natural gas will be deemed to be unavailable when the natural gas supplier informs the Clear River Energy Center (“CREC”) that the natural gas supply is being curtailed or if there is a Force Majeure event.
Invenergy examined the publically available data over the past five years from data of duel fuel units running on oil were built using the Velocity Suite Online application, created by ABB Group, Inc. (“ABB”). The ABB Database of Unit Generation & Emissions - Hourly (Standard) provides unit-level hourly generation and emissions data for fossil-fuel generating units. This data comes from the United States Environmental Protection Agency (CEMS reporting), ISO-NE and the Nuclear Regulatory Commission.
The CEMS database can be accessed directly from this public website:
Invenergy has included this data in th#e attached spreadsheet which includes the raw data and its source reference. Invenergy summarized the data to show the oil fired and dual fuel units run times (in hours) both annually and monthly for all units. This is the data used to create the maps that were included in Invenergy’s Response to the Town’s 16th Set of Data Requests. The summary data tab provides the number of hours each unit ran on oil by year and the maximum consecutive run time on oil.
The reason that Invenergy provided the map for these units in Invenergy’s Response to the Town’s 16th Set of Data Requests is that most of these units are not on the main pipeline (with the exception of Ocean State Power), and as can be seen from the maps that further away from the main pipeline a unit is located or if it is a highly constrained area like downtown Boston or Providence, the consecutive run times for these units increases as compared to other units that are closer to the main pipeline. Based on this data, Invenergy expects that the times when the unit would need to switch to oil would be short lived, i.e. less than a day, however the facility has been configured to allow for longer duration runs on oil should it be necessary.