Choosing between a Bilateral Embedded Generator Agreement (BEGA) and a Bilateral Embedded Licence Exemptible Large Generator Agreement (BELLA) can significantly affect the viability, cost, and timing of a connection, thereby impacting your project. It is crucial to understand the implications and the key decisions involved.
Who has the option of a BEGA or BELLA?
In Scotland, a large power station is typically defined as one with a capacity greater or equal to 10MW or 30MW for connections in the northern or southern Transmission Owner regions, respectively. Generators who wish to make a connection to the Distribution Network in Scotland and who are classed as a large power station, see Figure 1, may choose between obtaining a Bilateral Embedded Generation Agreement (BEGA) or a Bilateral Embedded Licence Exemptible Large Power Station Agreement (BELLA) with the National Energy System Operator (NESO).
It should be noted that, any large, embedded power station with a capacity >100MW will be licensed and are only offered a BEGA.
What is a BEGA?
A Bilateral Embedded Generator Agreement (BEGA) is designed for embedded generators whose exports are substantial enough to impact the flow of electricity at the local Grid Supply Point.
A BEGA sets out the provisions for generators to comply with the Connection & Use of System Code (CUSC), Grid Code and Balancing & Settlement Code (BSC). This agreement binds the generator and NESO to the applicable charges, requirements, and obligations for participating in the energy balancing market or Balancing Mechanism (BM).
A generator with a BEGA does not have a connection to the transmission system and therefore does not pay transmission connection charges, however, as the generator “uses” the transmission system, it pays the appropriate Transmission Network Use of System (TNUoS) charges, based on its Transmission Entry Capacity (TEC) value.
What is a BELLA?
A Bilateral Embedded Licence Exemptible Large Power Station Agreement (BELLA) was introduced in April 2005 when the National Grid Electricity System Operator (NGESO) became the System Operator for Great Britain, now NESO. BELLA addresses the need for the System Operator to have contractual agreements with large power stations, while also respecting the generators’ rights to choose not to participate in the Balancing Mechanism (BM) and avoid the associated infrastructure costs.
BELLA outlines the provisions for generators to comply with the Connection and Use of System Code (CUSC) and Grid Code. However, it does not require compliance with the Balancing and Settlement Code (BSC) because BELLA does not grant the generator rights to operate in the BM or export power onto the transmission system.
Power stations under a BELLA agreement are classified as Embedded Exemptible Large Power Stations (EELPS), meaning they are exempt from requiring a generation licence[1] . The owner or operator of an EELPS with a BELLA has a choice to appoint a Supplier or BSC Trading Party to be responsible for the output of the EELPS. Choosing a Supplier as lead registrant, they are registered in the Supplier Volume Allocation (SVA) Systems. If a BSC Trading Party is chosen, it must be registered in the Central Volume Allocation (CVA) system.
A power station with a BELLA does not ‘directly’ use the NETS since this is via the lead registrant referred to above. Accordingly, the generator of a BELLA does not pay BSUoS or TNUoS associated with the BM Unit directly. However, payments may flow between the power station and the lead registrant in accordance with a direct agreement.
Power stations under a BELLA do not have Transmission Entry Capacity (TEC), but their capacity is specified in Appendix A of the BELLA, under ‘Size of Power Station’.
[1] A generator with a BEGA may also be categorized as an EELPS. Both BELLAs and BEGAs may be registered under an Exempt Export BMU as part of an EELPS.
Figure 1 Size of power stations as defined in the GB Grid Code
Summary of BELLA and BEGA
| SUBJECT | BELLA USER | BEGA USER |
| Connection and Use of System Code (CUSC) | A BELLA User is signatory to the CUSC and must comply as applicable. | A BEGA User is signatory to the CUSC and must comply as applicable. |
| Grid Code | A BELLA User is signatory to the Grid Code and must comply as applicable. | A BEGA User is signatory to the Grid Code and must comply as applicable. |
| Balancing Settlement Code (BSC) | Not a party to the BSC – they must appoint a lead registrant (Supplier or BSC Trading Party) | Default position is that a BEGA User is a party to and complies with the BSC, however, they may appoint a BSC Trading Party as lead registrant. |
| Balancing Mechanism Unit (BMU) | No BMU for the BELLA User.
(If Supplier is appointed lead registrant, then EELPS included in Supplier Base BM Unit (SVA), or if BSC Trading Party is appointed as lead registrant then EELPS included in a stand-alone BM Unit (CVA), which may be an Exempt Export BMU on application). |
Default is for the BEGA User to be lead registrant and to carry out their own trading, otherwise they appoint a BSC Trading Party.
In both cases they must register a stand-alone BM Unit (CVA), which may be an Exempt Export BMU on application. |
| Balancing Services Use of System (BSUoS) charges | A BELLA User has no BMU therefore BSUoS is not directly applicable. (Lead registrant of BMU will be liable).
Note: BSUoS is only charged on Demand, Exempt Export BMUs are not charged when exporting but are charged when importing. |
The BEGA User (or registered BSC Trading Party) is liable for BSUoS.
Note: BSUoS is only charged on Demand, Exempt Export BMUs are not charged when exporting but are charged when importing. |
| Transmission Network Use of System (TNUoS) charges | A BELLA User has no BMU therefore TNUoS is not directly applicable.
The Lead registrant of a power station under 100MW and SVA registered will have its output included in the Supplier Base BMU as negative demand thus reducing the amount of demand TNUoS charged. If CVA registered it will be paid negative demand TNUoS based on an average of the metered output in the TRIAD (the 3 highest settlement periods in the previous 1 November to 28 February window). If the average metered volume over the TRIAD results in an import, then demand TNUoS charges are charged. |
A BEGA User (or registered BSC Trading Party) is liable for TNUoS.
A power station under 100MW and CVA registered will be paid negative demand TNUoS based on an average of the metered export output in the TRIAD (the 3 highest settlement periods in the previous 1 November to 28 February window). If the average metered volume over the TRIAD results in an import, then demand TNUoS charges are charged. |
| TEC Rights / Capacity | A BELLA User has embedded MW capacity, and does not hold TEC. | A BEGA User has TEC rights.
(Generation TNUoS is not liable if TEC < 100MW) |
| Physical Notifications (PNs)
A PN for a BMU is the expected level of export or import for that BMU in the absence of the BM Bid-Offer Acceptances from NGESO |
A BELLA User must submit PNs and Maximum Export Limit (MEL) data in accordance with the Grid Code. This may be made via a web-based submission interface (MPSI) or alternatively via EDT, see below. | A BEGA User is required to submit PNs as part of their dynamic data via EDT, see below. |
| Electronic Data Transfer (EDT)
EDT is used by Trading Agents to inform National Grid of changes to data, e.g. PN’s, price data and dynamic data |
This is not mandatory for a BELLA User but is optional for providing PNs, see above. | A BEGA User must participate in the Balancing Mechanism, so EDT must be installed at their nominated Trading Point. |
| Electronic Dispatch Logging (EDL)
All generators that wish to participate in the BM are required to install EDL – electronic messaging and acceptance service |
As a BELLA User does not participate in the BM therefore EDL is not applicable.
EXCEPT For those power stations (generally over 50MW) which have Mandatory Services/ Ancillary Services Agreements and are required to provide reactive power and frequency response, which are instructed via EDL. |
A BEGA User must participate in the Balancing Mechanism, so EDL is required at their nominated Control Point. |
How PSC can help
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PSC’s global energy experts will help your organization deliver innovative solutions. Please find out more about our capabilities in this area and contact us to talk about the first steps.
References
[1] A generator with a BEGA may also be categorized as an EELPS. Both BELLAs and BEGAs may be registered under an Exempt Export BMU as part of an EELPS.
[2] Transmission Owner (TO)