CRIOS Methodology v3.3

Earlier methodology versions remain in effect for operators where v3.2 schema extensions don't apply (e.g., v3.1 for MMGD operators without per-installation ownership data). Each operator surfaces its own active version.

Overview

Karbera computes avoided emissions at hourly resolution using verified ONS dispatch. Verification depth varies by asset class: utility-scale plants are individually grid-verified; MMGD operators are reconciled against EPE PDGD aggregates where possible, modeled where not. Every per-row figure carries its verification tier so reviewers can audit the mechanism, not just the number.

Emission factors

Hourly AEF — the evidence layer, not an alternative offset

Karbera also computes the hourly Average Emission Factor (AEF) of the grid mix — fossil emissions ÷ total dispatched generation each hour, from ONS metered dispatch. For a hydro-dominated grid the AEF (~0.03–0.04 tCO₂/MWh) is roughly an order of magnitude below the dispatch marginal CM, because they answer different questions: the AEF describes the average intensity of all generation, while the CM describes the marginal fossil plant a new MWh actually displaces. Karbera uses the AEF as the verification / evidence layer — independent, metered proof that the credited MWh were physically delivered to the grid — beneath the official CM offset. The AEF is not presented as an alternative, lower offset value; the two are not interchangeable and are never netted against each other.

Surplus-hour analysis (disclosed, not applied)

In some hours the marginal MWh displaces almost nothing — surplus conditions where price sits at the regulatory floor. Using 2025 CCEE hourly settlement price (PLD) by submarket, the share of hours at the floor (R$58.60/MWh) was: Nordeste 45.6%, Norte 43.4%, Sudeste 23.2%, Sul 22.3%. A physically strict marginal factor would haircut those surplus hours, lowering the credited displacement for renewables-heavy submarkets. Karbera discloses this but does not apply it: the official MCTI Combined Margin ships unmodified as the factor of record. A surplus-hour-adjusted marginal factor is future (MEF-product) work.

Distributed loss-avoidance gross-up (Tier 1)

A distributed MWh delivered at or near the point of use avoids the transmission-and-distribution technical losses a central plant incurs, so it displaces more than one central MWh. For distributed generation only, Karbera applies a per-installation gross-up 1 / (1 − L), where L is the technical loss to the installation's connection voltage — always ≥ 1, a clean positive uplift. L is keyed per installation from its distributor, voltage class, and self-consumed-vs-injected modality (register attributes). The distributor loss factors are Brazil's official ANEEL SAMP declared/measured technical losses (SAMP - Balanço, PRORET Submódulo 2.6; medido variant, latest 12 published months per distributor), cited per figure. On the current distributed portfolio this adds ~10% to credited tonnes.

Real vs regulatory disclosure: SAMP publishes the real declared/measured losses used here. A distinct regulatory tariff-recognized loss % (PRORET-set) is used in tariff reviews and lives only in ANEEL's Perdas report base; the two can differ. Karbera credits at the real (SAMP) figure and discloses this choice. Grid-scale, transmission-connected plants receive no gross-up — they inject at the Rede Básica and avoid none of these losses.

Worked example for one hour of one plant.

• Offset = MCTI Combined Margin; AEF = evidence. The credited offset uses Brazil's official dispatch-analysis Combined Margin (a marginal factor). Karbera's hourly Average Emission Factor is retained as the independent metered evidence layer, not a second offset. A bespoke plant-specific Marginal Emission Factor (surplus-hour-adjusted, per the analysis above) is on the roadmap — scoped, not yet in development.
• Biomass treatment. Biomass is treated as zero-emission per IPCC convention. This assumes biomass is part of the short-term carbon cycle, which is debated in academic literature. Future versions may apply biomass-specific factors.
• Coverage. Currently restricted to plants individually tracked in ONS dispatch data. Plants in MMGD (Micro/Minigeração Distribuída) classifications are aggregated and not individually verifiable from public data alone. Operators may provide additional data to extend coverage.
• Losses. The grid emission factor itself is a busbar figure: it does not yet embed transmission-and-distribution losses or auxiliary consumption at thermal plants. This is a property of the factor, not of the whole method — distributed generation is already credited for the losses it avoids under the Tier-1 loss-avoidance treatment. Embedding loss and auxiliary adjustments into the factor for transmission-connected plants remains on the roadmap.

Karbera methodology is calibrated to first-principles scientific authorities and Brazilian regulatory data — not to commercial registry standards.

• UNFCCC CDM Tool 07
  Methodological tool for the calculation of the emission factor for an electricity system.
• IPCC AR6 Working Group III
  Mitigation of Climate Change — GWP values and lifecycle emission factors for fossil generation.
• World Bank Carbon Pricing Dashboard
  Reference benchmark for global carbon price ranges across compliance and voluntary markets.
• ONS Brazil — Geração por Usina em Base Horária
  Hourly dispatch data for every grid-connected plant in the SIN.
• EPE Brazil
  Empresa de Pesquisa Energética — thermal fuel emission factors and PDGD distributed-generation aggregates.
• MCTI Brazil
  Ministério da Ciência, Tecnologia e Inovações — Operating Margin factors used as comparative reference, not as Karbera's primary calculation.