A Franco-British publication contradicts American work published in 2003, according to which such a transition would present a danger for the stratospheric ozone layer.
In the space of a few decades, the scarcity of fossil fuels, as well as their impact on the climate, should compel industrialists to find energy alternatives to oil, coal and natural gas.
Hydrogen, through the fuel cell - which produces electricity and water from hydrogen and oxygen - is the alternative around which the largest consensus has been formed.
However, the climate impact of an economy based on this energy alternative remains the subject of debate.
According to a Franco-British study recently published by Geophysical Research Letters, such a “hydrogen economy” would have little impact on the chemical balances of the Earth's atmosphere. While they do not clash with the consensus that has developed around hydrogen as an energy alternative to oil, these results contradict work previously carried out by American researchers (Le Monde, June 16, 2003).
In June 2003, the journal Science released the findings of a simulation conducted by researchers at the Jet Propulsion Laboratory and the California Institute of Technology, according to which the replacement of fossil fuels by hydrogen would significantly degrade the layer of stratospheric ozone.
The principle of the fuel cell was not called into question. But given the imperfections of light gas production and delivery technologies, the authors of the study assumed a loss of 10% to 20% of the hydrogen used to replace fossil fuels. The quantities of hydrogen thus released into the atmosphere would then represent between 60 and 120 million tonnes.
According to the authors of the study published by Science, such inputs would upset the chemical equilibria of the upper layers of the atmosphere, contributing to an increase in the concentration of stratospheric water vapor and to the cooling of the highest regions of the Earth's sky. . From where reactions of transformation of inactive brominated and chlorinated compounds, in molecules harmful for ozone.
The publication of this work has caused controversy. The journal Science published, in October 2003, several letters from scientists calling for the results of this simulation to be considered with caution and criticizing the hypothesis of a leak rate of between 10% and 20%.
Source: LeMonde, May 2004
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