This is not to be confused with the winter solstice (21Dec12), which has the shortest total daylight of the year, and just happens to coincide with The End Of The World! a.k.a. the new year of the Mayan calendar. Coincidence? Not really, as the Mayan calendar is astronomically based, and the winter solstice marks the beginning of their calendar year, and this year the date rolls from 12.19.19.17.19 to 13.0.0.0.0 Despite using a base 20 number system, at least the new year's day on the Mayan calendar makes more sense than the cobbled together European based calendars (Julian & Gregorian).
Oh, and for our latitude, we have to wait until our new year's day to get past the latest sunrise.
Alright, it has been snowing here. Apparently only once about every decade is there a white Christmas in this part of Germany. If the current trend holds, this will be that year. And to tie this back to astronomical events: The sun is at such a low angle (currently <18.5 degrees above horizon at solar noon) and above the horizon for such a short time (currently 8hrs:22min), it doesn't seem like it will melt too soon. ...and since I spend a few days this past summer making the calculations, I can tell you that the current daily clear sky solar energy delivered to a 1sq.meter horizontal surface is 1.4kWh (...or about the same heat energy released as one hour of the big burner on the stove top set to medium-high, ...but distributed over 10sq.ft), and this energy is only 1/6 of the summer solstice amount. However it is cloudy every day, and the snow reflects most of that energy, we aren't even getting much solar heating to melt our snow.
OK. In a practical terms this means, the snow and ice are piling up but not melting, and this makes for a difficult commute by bike. Consequently I am using the train much more frequently than normally. And so is Betsy; she bought a month pass. Thank goodness for the trains when the weather is not fit for biking --and that is saying something, when it comes from me.
Joe,
ReplyDeleteStill like your blog and your Christmas posting!
Help me out here, I thought 1.4 kW/m^2 was the solar constant for energy striking the earth. (1.4 KWH for a sq meter for an hour when the sun is overhead.)
But taking your general point, how can anyone justify PV solar collectors in Germany?
Merry Christmas
Bob Heithoff
Yes, the "solar 'constant'" is 1.37 W/m^2. This is the POWER delivered to the top of earth's atmosphere. This number is not constant due to Earth's orbital eccentricity, but the difference between January (highest) and July (lowest) is very minor. However due to atmospheric and absorption and scattering, about 1.0 kW/m^2 is delivered to a perpendicular surface at ground level. (just some variables: precipitable water, local air pressure, ozone thickness, atmospheric turbidity, aerosols content).
ReplyDelete...but to your main point: "Germany has a solar resource like Alaska, right? --so why bother with solar energy?"
Well, I think the answer is culture, politics, economics, and history.
Sustainability is an ideal that can be achieved in northern Europe, and to that end, renewable energy is a primary component. For a point of comparison: surveys show that well over 90% of Germans recycle (which means separating waste into 5+ waste-streams for curbside pickup), while <30% of Americans do (even when it is a single bin for anything people think are "recyclables").
Limits on conventional (i.e. fossil) energy sources have also meant a sustained effort to find alternatives in Germany --clearly seen in wind industry development.
In the early 2000s, Germany was also a leader in PV technology, due to government incentives, such as "renewable energy (RE) tariffs" (renewable energy bought by the government through the local utility at a premium price). This was economically viable, because German companies built the PV panels and other German companies installed the PV panels, so the non-economic viability of PV panels under German skies was offset by the GDP producing manufactures and installers (which paid more taxes to pay for the RE tariffs).
Until the Chinese undercut the world market, by incentivizing manufacturing PV panals and not kWh delivered to the grid, Germany was making positive economic and RE gains.
There are still PV manufactures and installer in Germany, but the boom times seem to be over. The PV panels installed will continue to produce RE electricity for the next half century or more, and the government is obligate to by it at a premium for some time to come too.