 |
| Titel |
Stratospheric cooling and polar ozone loss due to H2 emissions of a global hydrogen economy |
| VerfasserIn |
T. Feck, J.-U. Grooß, M. Riese, B. Vogel |
| Konferenz |
EGU General Assembly 2009
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250026904
|
|
|
|
|
|
| Zusammenfassung |
| "Green" hydrogen is seen as a major element of the future energy supply to reduce
greenhouse gas emissions substantially. However, due to the possible interactions of
hydrogen (H2) with other atmospheric constituents there is a need to analyse the implications
of additional atmospheric H2 that could result from hydrogen leakage of a global hydrogen
infrastructure.
Emissions of molecular H2 can occur along the whole hydrogen process chain which
increase the tropospheric H2 burden. Across the tropical tropopause H2 reaches the
stratosphere where it is oxidised and forms water vapour (H2O). This causes increased
IR-emissions into space and hence a cooling of the stratosphere. Both effects, the increase of
stratospheric H2O and the cooling, enhances the potential of chlorine activation on liquid
sulfate aerosol and polar stratospheric clouds (PSCs), which increase polar ozone destruction.
Hence a global hydrogen economy could provoke polar ozone loss and could lead to
a substantial delay of the current projected recovery of the stratospheric ozone
layer.
Our investigations show that even if 90% of the current global fossil primary energy input
could be replaced by hydrogen and approximately 9.5% of the product gas would leak to the
atmosphere, the ozone loss would be increased between 15 to 26 Dobson Units (DU)
if the stratospheric CFC loading would retain unchanged. A consistency check
of the used approximation methods with the Chemical Lagrangian Model of the
Stratosphere (CLaMS) shows that this additional ozone loss can probably be treated as an
upper limit. Towards more realistic future H2 leakage rate assumptions (< 3%) the
additional ozone loss would be rather small (-¤ 10 DU). However, in all cases the full
damage would only occur if stratospheric CFC-levels would retain unchanged. Due to
the CFC-prohibition as a result of the Montreal Protocol the forecasts suggest a
decline of the stratospheric CFC loading about 50% until 2050. In this case our
calculations show that the addition effect would account for only less than 4 DU which is
equivalent to 1% of the current unperturbed ozone layer over the polar regions (- 400
DU). Hence the risk of a substantial damage to the stratospheric ozone layer due
to H2-emissions of a hydrogen economy is low compared to the positive climate
implications that would evolve from the avoidance of greenhouse gas emissions. |
|
|
|
|
|
|