Electricity generated in Romania · 2016–2026

The cleanest hour of electricity generated in Romania

For the electricity Romania generates, the cleanest hour falls around midday in every month of the year. In July 2024–2026 midday averaged about 253 grams of CO₂-equivalent per kWh and the small hours about 326 grams. In January the day barely moves: 279 to 302 grams from midnight to midnight.

A drawn day over Romania at 12:00 in July: a dam in the Carpathians, a lignite power station, a gas plant, Cernavodă on the Danube, wind turbines in Dobrogea, a solar field and a village. — An ordinary day in 2024–2026, Romanian time. Each turning wind turbine stands for 100 MW of wind; the river below the dam widens with the megawatts from hydro, the steam and smoke grow with those from coal and gas, and the panels glint with those from the sun. The brown haze above the horizon thickens with that hour's grams of CO₂ per kWh. The dam, the lignite station and the gas plant stand for every plant of their kind; Cernavodă is Romania's only nuclear power station, on the Danube; the sun's height and its rising and setting times are those of Bucharest. At midday in July the panels give about 1,500 MW and gas falls back; at night nuclear, hydro, gas and coal remain.

The old advice to run the washing machine at night was about price, and price has its own page, linked below. For carbon, night was not the clean time even before the wave of solar panels: in July 2016–2019 midday was already cleaner than night, about 389 grams against 428, with the cleanest hour at 15:00. Since then, with 2.4 times as much solar on the grid at midday, the gap between night and midday has almost doubled, from 39 to 73 grams, and the cleanest hour has moved to 12:00. Year by year the hour wobbles: 2021 already had it at 12:00, 2023 had it at 15:00.

How much carbon is in a wash, by the hour it starts?

Pick the appliance and the month. The bars show grams of CO₂ for each start hour at the month's average intensity in 2024–2026 (2024–2025 for November and December). A washing machine takes 0.6 kWh on an eco cycle, a dishwasher 0.9 kWh, and the car charge is counted at 10 kWh, roughly 55 km of driving.

Month

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Cleanest hour: 12:00 — about 150 g for one wash.

The bars start at zero. A cycle longer than an hour also uses the hours after it; the bars count the whole cycle at its start hour, a small simplification beside the gaps between hours.

Since 2016 the day has deepened at midday

The year mean fell from about 400 grams per kWh in 2016 to about 282 grams in 2024–2025. In July, midday fell faster than night. With both periods moved by a year (2017–2020 against 2023–2026), the July gap between night and midday grows from 43 to 63 grams and the cleanest hour still moves from 15:00 to 12:00. The year 2026 runs to October; over the same months, January to October, 2024, 2025 and 2026 all sit at about 278–280 grams, so the yearly level has barely moved since 2023.

Year	Year mean	Cleanest July hour	July midday	July night
2016	399	16:00	387	416
2017	421	15:00	430	480
2018	404	15:00	354	388
2019	380	15:00	384	427
2020	316	16:00	349	391
2021	336	12:00	351	387
2022	350	13:00	357	418
2023	286	15:00	259	293
2024	283	12:00	286	347
2025	282	12:00	272	330
2026	278	12:00	201	301

Grams of CO₂-equivalent per kWh. Midday means the average of 11:00–15:00 and night of 01:00–04:00, Romanian time.

In Romania the hour matters less than in Germany or Poland

The gap between the cleanest and dirtiest hour, July 2024–2026. Cernavodă's nuclear output and hydro power hold the Romanian night close to the day. In Germany a July night is about 2.5 times as dirty as midday (497 against 197 grams); in Poland coal keeps both night and day high (759 and 437 grams).

Romania78 g/kWh

Germany325 g/kWh

Poland360 g/kWh

Against the daily mean, the gap is 26% in Romania, 87% in Germany and 57% in Poland. In January the gaps are 23 grams in Romania, 68 in Germany and 76 in Poland. Even with imports counted, as below, Romania's gap in July 2025 would be about 91 grams, against 71 in the published series for the same year.

Method and limits

The figures come from the hourly series published by Energy-Charts (Fraunhofer ISE): CO₂-equivalent intensity in g/kWh and generation by type for Romania, Germany and Poland, 2016–2026, converted from UTC to local time with daylight saving. From 2022 the series runs at quarter-hourly resolution; the page uses hourly averages. Each source's share comes only from generation; the intensity only from the published series.

Energy-Charts does not publish the method behind its intensity series. The series follows domestic generation closely: set beside the output of each source in the same hour, it fits about 1,300 grams per kWh for coal, 470 for gas and under 20 for nuclear, hydro, wind and solar (hour-by-hour correlation 0.97, 2024–2026), better than a version that adds imports at the neighbours' intensity. That is why this page speaks of electricity generated in Romania. Electricity used is a different sum: on July evenings, from 19:00 to 23:00, Romania's net imports are about 20% of the power it uses. With imports counted, evenings would come out dirtier than the small hours in 10 of the 12 months of 2025, most clearly from May to July, and the clean hour would spread into the afternoon; midday would still beat night in summer, and January would stay nearly flat, its cleanest hour perhaps moving to midnight. A separate recompute with the IPCC's 2014 life-cycle factors gives a lower level (about 231 grams per kWh in July 2024–2026, against 295) but its cleanest hour still falls between 11:00 and 13:00 in January and July.

Reported solar may include estimates for small installations. The cleanest hour is a monthly average: on a given day, wind and cloud can move it.