When we launched the Clean Power Index, one of the common feature requests we heard about was a way to filter matching scores to remove energy from biomass generators.
Ofgem classifies biomass as renewable but some consumers prefer their electricity from sources such as wind and solar, which have zero operational emissions.
Issues in Ofgem data
In principle, a biomass filter should be trivial: each generator is categorised by technology. But there's a catch - Ofgem's REGO database misclassifies a non-trivial number of generators.
Of the 361 generators categorised as 'biomass', more than 15% have names that clearly suggest anaerobic digestion or other forms of biogas. This matters because emissions from biomass may be as high as 1 tCO2/MWh while biogas – particularly from waste streams – is commonly treated as largely emissions-free.
Suppliers have confirmed this misclassification. In one case, public data implies that nearly a third of a supplier's power comes from biomass but internal data puts the figure at under 1%.
The Matched proposal
To give users the filter they want (without penalising suppliers for known data issues), we'll invite suppliers to correct the record.
Suppliers will be able to submit:
- Generators that are misclassified
- The correct technology classification
- Supporting evidence
Initially, we won't prescribe a fixed evidentiary standard, since what's available varies by generator. Instead, we'll publish each supplier's submissions and supporting evidence in full, ensuring transparency and allowing scrutiny.
In the final week of February, we'll update the Clean Power Index with a biomass filter based on these corrected classifications. As a backstop, we'll automatically reclassify any generator whose name explicitly includes terms such as anaerobic digestion or biogas.
Making clean power visible
We believe this approach meets consumer expectations while treating suppliers fairly. This change aligns well with Matched's goal to improve the accuracy and credibility of public claims about what "clean electricity" really means.