Please note that the study takes the energy that the wind turbine produce and calculate how much green house gases a natural gas-fired power plant would create producing the same amount of energy.
The fundamental question that the study ask is if the wind turbine would replace an existing natural gas-fired power plant, how much less green house gases would it produce compared to keeping the natural gas-fired power plant, and how does that compared to the production emissions of the wind turbine.
Battery backup isn't a needed as much as many thing in the real world. Those gas power plants we already have are not going anywhere, so we still use them when there isn't much wind. Though battery is something we should be building instead (and are).
Instead, civilian energy demands and energy independence are the motivating factors. Look at how Ontario leveraged its electricity supply in the early days of the trade war.
https://world-nuclear.org/information-library/country-profil...
When you also add the cost of battery backup.
Spain and Portugal have just experienced the first taste of that fact.
Batteries/storage do not produce energy so they don't displace any energy in this kind of calculations. They can be viewed as a small efficiency increase of existing wind turbines, in which case they do have a form of greenhouse gas payback time, although the energy must not be counted twice for both the turbine and battery, and the increased wear and tear on the wind turbine may impact the result.
Wind generally has an production rate of around 50%, which mean that countries like Denmark that has already reached over 100% wind production still only have energy for half of their consumption. This mean the storage need is fairly massive, which they currently solve by importing energy from fossil fueled thermal power stations, nuclear and hydropower from nearby countries. Constructing more wind power at this point does not seem economical for power companies, and any storage solution like lithium, reverse hydro, and so on are also not economical (as in, there is basically zero investment into it outside of government subsidized initiatives). As such, wind has in that location seem to have reached its ability to displace any more fossil fuel.
- methane has a higher absorption than CO2
incorrect. CO2 has a dipole moment amd c-infinity-v symmetry so it absorbs way more
- methane has higher absorption in open windows of IR frequencies
also incorrect. the water band don't overlap with CO2
- methane has a longer atmospheric half-life
incorrect. you can look up the numbers on this. i believe it was believed to have a longer half life a few decades ago but detailed isotopic studies have disproved it?
you have to dig really deep to figure out that there is I think? an estimated self-shading effect of CO2 that changes the marginal absorbance of a single molecule. but this assumes a uniform distribution of CO2 in the atmosphere and no scattering. anyways i think this is not spoken of because it also reminds that the effect of Co2 is logarthmic (A = log(T))
I'm not aware of anyone asserting that methane has a longer half life than CO2, just the opposite. It has a shorter half life, is more powerful a GHG, and then decomposes into CO2 and H2O to add insult to injury.
https://climate.mit.edu/ask-mit/what-makes-methane-more-pote...