EU and US regulations have recently introduced requirements for calling e-fuels ‘green’ or ‘renewable’, focusing on deliverability and additionality around renewable energy certificates (RECs) in emission inventories. At the same time, advocates of impact-based accounting argue for global REC markets, purposefully abandoning deliverability in favor of enabling cost-effective displacement of fossil power generation. At this point, the extent to which claims by individual e-fuel producers diverge from actual emissions under different potential regulations remains unclear. This study uses a hypothetical e-methanol case to investigate (1) how accounting requirements of different policy regimes affect the accuracy of inventory emissions, and (2) how these reported values compare with emissions estimated under an impact-based accounting perspective. Our results show that hourly energy matching is needed for accurate inventory accounting. When production is not aligned in time and place with renewable generation, reported emissions increase substantially. If RECs are non-additional, emissions can be 14–28 times higher than stated for hourly energy matching under inventory accounting, with carbon intensities exceeding those of the fossil reference fuel, stressing the critical role of additionality. Out of six scenarios, only hourly energy matching results in methanol that can be considered renewable according to EU regulation (i.e. below 28.2 gCO2e/MJ). Impact-based accounting shows potential for larger reductions, up to almost three times the inventory emissions when based on RECs from regions with high marginal emission factors. However, these reductions do not influence the company’s inventory and should be treated as complementary to it. Thus, to ensure accurate inventory claims, deliverability and additionality are crucial. Although based on a single e-fuel producer, the findings can apply broadly to other electricity consumers.

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