Process emissions from wastewater treatment at Águas e Energia do Porto rose from 4,310 tCO2e in 2023 to 5,911 tCO2e in 2025, an increase of 37.1%. Over the same two years the company cut its total energy consumption by 9.0%, from 21,638.2 MWh to 19,688.6 MWh.
Clean electricity is already counted
Porto's municipal company buys electricity backed by guarantees of origin, so its market-based scope 2 emissions were zero in 2023, 2024 and 2025. Self-generated renewable electricity rose from 351.1 MWh to 1,041.4 MWh between 2023 and 2025, and photovoltaic capacity across the municipal universe reached 2,489 kWp in 2025.
Where the footprint now sits
That leaves two sources. Treatment processes made up 94.5% of scope 1 emissions in 2025, and scope 3, mostly purchased goods and capital goods, was 11,578 tCO2e, or 64.9% of the market-based total of 17,836 tCO2e. The total rose 3.1% from 17,300 tCO2e in 2023. Biogas use in the company's operations fell 46.7% over the same period, to 1,399.4 MWh.
A 2030 objective
The Municipality of Porto, which owns the company outright, aims for carbon neutrality by 2030 through about an 85% cut in emissions and offsetting of the remaining 15%. Water reuse, another lever, stood at 0.0% of treated wastewater in ERSAR's assessments for 2022 to 2024, although a membrane pilot at the Freixo plant has produced class A water since November 2022.
How Porto's drainage, renewal and capital plans fit this agenda, what executing 67.4% of its 2025 investment budget means for the 2026–2030 plan, and which contract targets it missed in 2025 are examined in the full report. The full report, Water Utility of the Future: Águas do Porto, is available for USD 499. For a free overview, read the Águas do Porto Utility Snapshot.