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Comment by andreasley | Hacker News Reader

I've noticed that Switzerland, using a lot of hydropower, has a worse intensity than I expected.

The CO2 numbers for the different types of power generation seem to come from Wikipedia [1], where Hydropower has a median gCO2eq/kWh of 24 and a maximum of 2200 – much worse than coal. This seems to be based on the fact that large areas may be flooded when filling the dam initially, and CO2 from rotting plants is released [2]. The numbers vary depending on the amount of vegetation.

According to a study [3] from 2012, "electricity generated in storage hydropower stations in Switzerland causes emissions of 10.8 g CO2-eq/kWh", so it's less than shown in the emissions chart and comparable to nuclear.

[1] https://en.wikipedia.org/wiki/Life-cycle_greenhouse-gas_emis...

[2] https://www.newscientist.com/article/dn7046-hydroelectric-po...

[3] http://esu-services.ch/fileadmin/download/publicLCI/flury-20... [PDF]

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> I've noticed that Switzerland, using a lot of hydropower, has a worse intensity than I expected.

The carbon intensity on the map seems to be for consumed kWh, not produced kWh. The map indicates Switzerland imports a lot of electricity from Austria and Germany which have a much higher carbon intensity.

And this is a good representation, because this way it doesn't allow you to outsource your carbon emissions to countries that no one looks at (not on map, or not considered responsible for anything by activists).

Also, if it is really live data, all the high alpine hydro is just pumped storage now. In winter, the high reservoirs don't get much natural feed when no ice is thawing and any new precipitation will decoratively stick to the slopes until spring.

Also CERN is currently offline for the winter which gets most of its power from France imports.

I was talking to a CERN physicist once who joked that the reason for the LHC winter shutdown was because France needed heating. It's probably more to do with economics but it's almost true. France has a lot of cheap nuclear power in the summer, and only limited pumped storage capacity to cache it with.

Then this map is irrelevant. Winds blowing out of a country with high CO2 emission actually don't mean anything, since there is not actually high CO2 emission there, they import it from elesewhere.

Wind is there to show potential for wind energy collection from wind farms.

CO2 from rotting plants is not a problem, as that is basically "current" not "fossilized" carbon that is being released.

That is true, but if the reservoir causes said "current" carbon to be emitted as CH4 not CO2 it will have a much higher greenhouse effect than it would under ordinary circumstances.

Ch4 is fairly temperary with limited long term effects after 20 years.*

Yes, you see numbers over 0-20 vs 0-100 but things look different at 0-20 vs 20-100.

I guess the low end of the spectrum is for non-dam based hydro. Northern Ireland has tidal power from the tide coming into and going out of a natural lough

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