Frequently Asked Questions: Local Curtailments
Local Curtailments are implemented to resolve capacity constraint issues in localized sections of PG&E's pipeline system; i.e., if demand is projected to exceed the capacity on a local gas transmission or distribution system. A Local Curtailment may be implemented when local system temperatures are expected to drop below Cold Winter Day (CWD) temperatures. Local noncore customers may be required to curtail gas usage to ensure local core customer demand is met.
Local Curtailments may also be implemented when a pipeline has been damaged and supply deliveries are threatened. Local Curtailments are intended to reduce physical demand on the affected pipeline system. Unless Involuntary Diversions are in effect at the same time as a curtailment, a customer's supply will not be diverted.
PG&E determines which noncore end-use customers are asked to curtail usage during Local Curtailments based on the following criteria:
- The local transmission or distribution systems affected. These systems are segmented into local gas curtailment zones.
- Volume of noncore gas usage allowed
- Severity of the conditions
- Need for additional load reduction or curtailment in additional zones
PG&E utilizes two winter design criteria for its local transmission systems, which is on file with the California Public Utilities Commission, to ensure reliable gas service.
- Abnormal Peak Day (APD) is the coldest temperature that is expected to be exceeded, on average, once within a 90-year period. For APD design, core customer loads are assumed to be operating at 100% of their projected APD load. All noncore end-use customers are assumed to be fully curtailed in this design scenario. For most systems, APD is the more stringent criteria used for design.
- Cold Winter Day (CWD) is used to ensure reliable gas service for systems that have significant commercial or industrial loads. CWD is a demand scenario defined by core customers using 75% of their projected APD daily loads and all noncore end-use customers using their maximum demand that is reasonable for the winter season. This design scenario is intended to ensure that under most cold weather events, all core and noncore end-use customers can continue to use gas.
Why doesn't PG&E have enough capacity in its local transmission systems to avoid curtailing noncore end-use customers?
PG&E designs its local transmission systems to meet two basic criteria in the winter: APD and CWD. The systems are planned to adequately supply service to customers under these design criteria. When local conditions exceed CWD design levels and approach APD levels, a Local Curtailment of some noncore end-use customers may be necessary.
Generally, Cold Weather Alerts will precede curtailment notification. The end-use customer PG&E Account Managers will advise all end-use customers of Cold Weather Alerts. To be prepared in advance for possible curtailments, noncore end-use customers should discuss their specific gas supply needs with their suppliers.
Noncore end-use customers who are to be curtailed will be notified by their PG&E Account Manager and provided with information about how much gas (Mcf per hour) they will be allowed to use for the designated curtailment period. Noncore end-use customers may be required to either decrease or fully curtail their gas usage.
Noncore end-use customers who are required to curtail usage during a Local Curtailment event should notify their suppliers immediately. While gas Schedule G-BAL monthly balancing provisions are in effect during a Local Curtailment, we encourage suppliers and affected end-use customers to be in communication with each other so that the volume of gas supply is sufficient for the allowed burn.
No. Only noncore end-use customers who are connected to, or downstream of, the constrained local transmission or distribution system will be subject to the Local Curtailment.
Yes. The Local Curtailment noncompliance charge for each Decatherm of usage in excess of the designated maximum allowed usage shall equal $50.00 plus the Daily Citygate Index (The Daily Citygate Index is the PG&E Daily Citygate Index Price as published in Gas Daily, rounded up to the next whole dollar. If the price is not published on a given day, the previous published price will apply).
In order to protect its system, PG&E may also temporarily shut off gas service to any customer that fails to comply with the Local Curtailment.
If a supplier is able to schedule gas into the PG&E system during a Local Curtailment day, can the end-use customer avoid being curtailed?
No. Local curtailments are called due to capacity constraints in a particular area. Although suppliers may be able to schedule deliveries into PG&E's intrastate pipeline system, the local transmission pipelines do not have enough capacity to then deliver the gas to the customer.
If an end-use customer has been curtailed in the past, will it always be curtailed in the event of a Local Curtailment?
Not necessarily. For each extreme winter event, PG&E creates specific local capacity curtailment lists which are designed to require the minimum amount of load relief needed to prevent customer demand on the local transmission system from exceeding design capacity. While a customer may have been curtailed in order to obtain the necessary relief during a past Local Curtailment, conditions may vary, and as such it may not be necessary to curtail that same customer in the future. The nature and severity of local conditions causing the constraint will dictate the action necessary to maintain the integrity of the local transmission system.
Local Curtailments are called to alleviate local capacity constraints on the local transmission pipeline system. This is most often due to high core and noncore loads in response to temperatures dropping below PG&E's CWD design criteria. Supply vs. demand does not drive the need for Local Curtailments; rather, capacity vs. demand drives the need for Local Curtailments. If total system supply is insufficient to meet demand and deliveries to core customers are threatened, an Involuntary Diversion may be called. In such a scenario, all available supplies will be used to serve core customers, including diverting some or all supplies intended for noncore customers.
PG&E will announce Local Curtailments to suppliers via the Pipe Ranger Web site. Suppliers will also be contacted by a CGT Account or Sales Representative and provided with (1) the names of their noncore end-use customers affected by Local Curtailments, and (2) the amount of gas these noncore customers are allowed to burn hourly (in Dth). PG&E encourages suppliers to communicate with their affected noncore end-use customers prior to, during, and after the curtailment in order to ensure that supply is sufficient for the allowed burn. G-BAL monthly balancing provisions are in effect during a Local Curtailment, which means that any monthly over or under supply to a noncore customer will need to be within a 5% tolerance band by the close of the imbalance trading period in order to avoid a cashout.