Use of commingling to avoid propane addition at biomethane injection points

1. Use of commingling to avoid propane addition at biomethane injection points • Objective of the measurement regime for CV • Protect downstream customers • Comply with Gas (Calculation of Thermal Energy) Regulations • At suitable locations where sufficient gas grid flow exists, commingling may be sufficient to produce a blended CV that does not trigger CV “cap” • CV of “pure” biomethane flow measured and used to establish energy content of gas input (and for RHI purposes) but not for testing against the local network CV re triggering CV cap • CV of commingled flow measured downstream of blending point and tested against network CV for purposes of CV cap

2. Remote CV monitoring at Adnams

3. Example of how this works in practice – based on Adnams • Biomethane flow CV = 36.6 MJ/m3 (120 m3/h max) • Network FWACV = 39.6 MJ/m3 • Minimum flow to blending point = 5 * BM flow • Worst case blended CV = 39.1 MJ/m3 • This is 0.5 MJ/m3 less than Network FWACV; does not trigger cap • If biomethane flow were included in area FWACV calculation, it would have negligible effect on FWACV • No consumers supplied with gas prior to blending

4. Conclusions • Blending and remote CV monitoring can in some cases avoid the need for propane addition • In other cases blending can limit the period for which propane addition is required (and/or the volume of propane to be input) to periods of low network flow • Financial benefit to biomethane producer • Environmental benefit from mitigating fossil fuel addition • GDNs should be incentivised to identify and implement commingling opportunities