Nord Stream 1 and 2: methane leaks revised downwards
Leaks from the Nord Stream 1 and 2 gas pipelines released some 70,000 tonnes of methane, according to an estimate Wednesday by French researchers based on atmospheric observations. “These are significant figures, equivalent to 2% of French emissions or the emissions of a city like Paris over one year, this is not good news, but not a climate bomb”noted Philippe Ciais, researcher at the Commissariat for Atomic Energy and Alternative Energies (CEA), at the Laboratory of Climate and Environmental Sciences.
These estimates are much lower than the first produced by experts or NGOs in the days following the explosions on the gas pipelines, on September 26, which were based on estimates of the quantities of gas contained in the pipes. Many estimated them at around 300,000 tons. Natural gas is methane.
CEA researchers carried out simulations based on readings from stations of the European observation network Icos, which monitors the fluxes of atmospheric concentrations of greenhouse gases. The station readings that tracked the methane releases were modeled according to some 10,000 scenarios. With the winds, the fumes first rose towards southern Sweden, then turned west to pass over Norway and the United Kingdom, before being spotted, in much weaker quantities, to the tip of Brittany.
“We are a little surprised” by these results, recognized Philippe Ciais, during a videoconference. “Was there less gas in the pipes? Did some of the methane dissolve in the water, which doesn’t seem too possible? We don’t have an explanation.”he acknowledged, while emphasizing “that as the “pipe” empties the pressure decreases”which could have affected the quantities of gas expelled. “Perhaps after a very large release at the start, the flows decreased until they fell below the detectable level compared to the natural signal” in the atmosphere, says Antoine Berchet, who led the modeling.
The readings show a very strong peak in discharges on September 27, which fell from the 28th, before a new, lower peak on the 1st.er october. The researchers stressed that this first study should anyway “to be confirmed by other modellers”.