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