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Eric the Red at 02:31 AM on 13 July 2011What we know and what we don't know
Yes Dikran, An exponential with a zero exponent is linear, so there is essential no different between the two. Using a continuation of past data works for the short term. At some point, the trend will change. We just do not know in which direction, how fast, or for how long. An example uses the 1970s prediction of mass starvation based on the exponential population increase and linearly rising food production. Nice quote. I need to remember that. -
CBDunkerson at 02:30 AM on 13 July 2011A Detailed Look at Renewable Baseload Energy
BBD wrote: "Please clarify for me why LAGI's use of peak 1000W/m2 x 20% for every single sunlight hour in its calculation is not incorrect? LAGI assumes 8 hours per day and 250 sunshine days a year" The Sun only shines 8 hours a day and 250 days a year on your planet? You should move. It is much sunnier here on planet Earth. -
Tom Curtis at 02:28 AM on 13 July 2011A Detailed Look at Renewable Baseload Energy
KR @294, your points are correct except for one. It is perfectly possible to design collectors with 2 axis tracking and zero waste space. There will be a loss of efficiency, but that will be inversely proportional to the size of the field and can be reduced to less than 5%. It is not economically worthwhile doing this because in most areas the land is so cheap relative to the cost of the collectors. Actually, LAGI's calculation of the minimum area needed is quite correct. ON the other hand, an estimate of three times LAGI's figures as the practical requirement is also valid, but only because economically, the land area is inconsequential as a cost (except in Singapore and other similarly crowded states). -
BBD at 02:20 AM on 13 July 2011A Detailed Look at Renewable Baseload Energy
KREither ~225 W/m^2 daily hour average * 24 * 365, or 1000 W/m^2 peak * 2000 hours effective time at that peak = ~2000 kWh/year/m^2. Please clarify for me why LAGI's use of peak 1000W/m2 x 20% for every single sunlight hour in its calculation is not incorrect? LAGI assumes 8 hours per day and 250 sunshine days a year and cacluates: 8 x 250 = 2000 hours BUT it uses 2000 hours of 200W/m2 (eg peak mid-day) output: 2000 x 200 = 400,000 or 400kWh Which is wrong. I do not understand you point about mixing equations in #288. I used the standard method instead of LAGI's because the annual average energy density is a much better indicator of annual average plant performance (assuming a conversion efficiency is included). The average raw energy density x plant conversion efficiency will give the most accurate estimate of average plant output. That's why it's the standard method (eg MacKay) for obtaining them.
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Tom Curtis at 02:19 AM on 13 July 2011A Detailed Look at Renewable Baseload Energy
BBD @292:"What I am doing avoids the trickery by LAGI, which uses peak for every single sunlight hour in its calculation."
Is that that same "trickery" that assumes there are only eight hours of daylight in any day? Or the same "trickery" that assumes that only 250 days of a year have clear skies in the Sahara? I don't see any complaints from you about LAGI's trickery that reduces the expected power generated. Regardless, as I have shown with the Albaquerque data, with 2-axis tracking, close to the equator you gain approximately the same energy for four hours on either side of noon. Hence there was no trickery from LAGI at all. -
KR at 02:10 AM on 13 July 2011A Detailed Look at Renewable Baseload Energy
Various readers - Given that solar power levels are presented in various formats, it's easy to miscalculate available energy due to a mis-conversion (as seen in this thread). The Wiki Insolation page, in the "Applications" section, has a conversion table that might be helpful in this regard. Given tropical insolation, and solar collection efficiencies of ~20%, roughly 500,000 km^2 of solar panels or CSP collection mirrors would supply an average of 23 TW to the world - sufficient for mid-century power supply including transportation. Note that there will be infrastructure (towers, supports, panel spacings, energy storage facilities, etc.) that enlarge this by some factor, but it's a reasonable estimate of what would be needed as collection area. Wind power follows similar calculations for area, and the Surface Area Required to Power the Whole World With Solar and Wind Power shows those at scale. Note that just solar or just wind isn't on anyone's horizon - nuclear, wave, geothermal, and biomass cann all make contributions as replacements for fossil fuels. But it at least gives some perspective. -
Tom Curtis at 02:07 AM on 13 July 2011A Detailed Look at Renewable Baseload Energy
BBD @288, there is not a "correct method". There are just different methods. In what you call the correct method, an implicit assumption is that all solar collectors are laid horizontal to the ground, and are never tilted to track the sun. That is, of course, a false assumption. In contrast, the LAGI method assumes that the projected power plants will use collectors which track the sun both for season and for time of day (ie, on two axis). That is also a false assumption, but closer to the truth. Further, as the are calculating the minimum area required to provide the worlds power, it is the correct approach. In calculating the minimum, they do not assume that if all the worlds power was generated by solar (which they recommend against), that the minimum area will be in fact achieved. If we look again at the summer solstice clear sky data for Albaguerque, New Mexico (below), you will see that both two axis tracking collectors, and single axis tracking collectors orientated on the North-South axis both collect nearly the same energy throughout day light hours. Significantly, they collect nearly the same value as at noon for the four hours on either side of noon, ie, for eight hours a day. That fact justifies LAGI's method.
It is only if you assume the collectors will not track the sun during the day that LAGI's assumption is false. Indeed, during the winter solstice, a one axis tracking, N_S axis collector actually performs better during mid morning and mid afternoon than it does at noon (see chart @269 above). It should also be noted that the 2 axis tracking collectors do not perform as well in mid morning and afternoon as at noon (though much better than the N-S single axis tracking). That is because of the very low angle of the sun. Therefore LAGI's assumption only holds when the angle of the sun is not very low, ie, for sites in the tropics.
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BBD at 02:06 AM on 13 July 2011A Detailed Look at Renewable Baseload Energy
CBDunkerspnHowever, what you are doing is applying AVERAGE insolation for only the time per day and days per year when PEAK insolation is available. That is obviously incorrect.
The average includes the peak. What I am doing avoids the trickery by LAGI, which uses peak for every single sunlight hour in its calculation. That is obviously incorrect.Response:[DB] If you persist in casting aspersions of "trickery" to methodologies which give answers different to those methodologies which you employ, you will find it even more difficult to participate in this discussion...
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KR at 01:43 AM on 13 July 2011A Detailed Look at Renewable Baseload Energy
BBD - OK, I'll try this one last time. Yearly power incident on a tropical site: Either ~225 W/m^2 daily hour average * 24 * 365, or 1000 W/m^2 peak * 2000 hours effective time at that peak = ~2000 kWh/year/m^2. Don't mix the equations, BBD, don't cross the streams. The same amount of energy can be computed either way. 2000 kWh/year/m^2, collected with 20% efficiency, is 400 kWh/year/m^2 power output. --- Now, using your method correctly, given 228 W/m^2 as a 24 hours a day average, 365 days a year (MacKay figures), * 20% efficiency = 45.6 W/m^2 average power year round. 45.6 * 1,000,000 m^2/k^2 * 500,000 km^2 = 2.28*10^13 = 22.8 TW. --- Please, BBD, correct your math - use one equation or the other, but stop mixing the two. Your math is wrong, your conclusions are therefore wrong; you're scaling 24 hour daily averages with the time that peak power is available. -
CBDunkerson at 01:37 AM on 13 July 2011A Detailed Look at Renewable Baseload Energy
BBD: This is really quite simple. Either of the approaches below would be reasonable; 1000 W/m^2 peak insolation * 20% efficient panels * 8 peak hours per day * 250 peak days per year = 400 kWh OR 250 W/m^2 average insolation * 20% efficient panels * 24 hours per day * 365 days per year = 438 kWh However, what you are doing is applying AVERAGE insolation for only the time per day and days per year when PEAK insolation is available. That is obviously incorrect. -
Alec Cowan at 01:24 AM on 13 July 2011A Detailed Look at Renewable Baseload Energy
#276 Tom, I understand that when someone is saying "I'm gonna kill you", he or she probably doesn't mean it the literal way. But I wasn't going to read LAGI or whatever. BBD simply quoted them and nobody has said that BBD misquoted them. "...1000 watts that strikes the surface in each SM of land" is factually and utterly false; I'm tempted to add shamefully. That doesn't make the conclusions in LAGI wrong -in fact what everybody have quoted here looks 'rightish' at a conclussion level-. Also, that doesn't make BBD arithmetic a sound one either. The fact here is we are not talking of Aristotle. LAGI is not a dead scholar from times gone and the text is not written in a parchment so it's easy to use a text editor and change the content of the site. There's no excuse. In fact those verbal blunders allow the BBDs in the world to continue their harangues. That should concern you, not showing instead how deeply wrong is BBD's, or making of me a substitute target. Making infantile math like 20% of 1000 during 2000 only attracts the infants and allows the mathematically infantile to flit about. -
BBD at 01:16 AM on 13 July 2011A Detailed Look at Renewable Baseload Energy
KR Okay. LAGI has tied us all in knots. Let's try again. Here's my take for dissection: LAGI is based on an unrealistic estimate of output from solar plant. It generates an exaggerated value for this as follows: It takes the peaking mid-day figure of 1000W/m2 and applies a 20% efficiency: 1000 x 20% = 200W/m2 This figure will be correct for the middle of the day. It is the highest possible output the plant can achieve. Peak. LAGI then uses this peak value for every sunshine hour in its caclulation. It assumes 8 hours per day and 250 sunshine days a year. Perfectly reasonable. 8 x 250 = 2000 hours BUT - 2000 hours of 200W/m2 output: 2000 x 200 = 400,000 or 400kWh Which is a substantial exaggeration based on: - the incorrect assumption of constant 200W/m2 plant output - non-standard method This then forms the basis of its estimate of 500,000 km2 = 23W. The correct method is:average raw energy density x plant conversion efficiency = average output
200W/m2 x 20% = 40W/m2 It looks like I am applying a 20% conversion efficiency on top of LAGI's 20% conversion efficiency. But I am not. I'm using the standard method. This is why we are all confused. I am more convinced than ever that LAGI is a deliberate attempt to mislead. -
Alec Cowan at 00:49 AM on 13 July 2011The Medieval Warm(ish) Period In Pictures
#35 Rob, I've got the gridded data from climate normals 1961-1990 as an anomaly on a 1941-1970 base. This is the graphic -using a 250km radius-:
Now I have the problems of having two different grids and that those gridded data in Figure 1 are supposed to be plotted using a Matlab file. But I think that I'll finally manage to get a 5° grid for the image and to write a script to take gridded info from Figure 1 in order to develop a graphic that will approximately show what I am speaking form the very beginning. By eyeballing both images I could notice what I expected -what is dangerous itself: to expect- in comparison with Figure 1: even a bit warmer Iceland and Greenland, not so turbulent Mongols and Tartars, and about the "Figure 1" for LIA -Figure 2 in Mann et al- a confirmation of the reason for my city of birth to be established twice.
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Dikran Marsupial at 00:45 AM on 13 July 2011What we know and what we don't know
Eric the Red an exponential with a low rate constant can look "fairly linear", but it is still exponential. If you can show me an anlysis that robustly demonstrates that it is linear (rather than there just isn;'t enough data over shuch a short time span to distinguish between linear and exponential with statistical significance) then I am happy to stand corrected. The rise in CO2 is unaffected by our expectations, it is affected by our actions. As Niels Bhor said "Prediction is very difficult, especially about the future" - in the 70s they though we would all be flying around in our hovercars and would have a domestic robot doing our chores by now, but it hasnt happened. IMHO it is extremely rash to decide the action we should take now on the basis of what technological solutions the future may offer. There is an appreciable probability that such solutions will not be made available, or if they are they will be available too late. The advantage of predictions based on a continuation of what has gone before is that we know it is plausible a-priori. -
Eric the Red at 00:43 AM on 13 July 2011Trenberth on Tracking Earth’s energy: A key to climate variability and change
Ken, Nice post between the two theories. There may be other explanations for where the heat went, or why the heat has not reached the surface, which may be revealed when the data materializes. However, it does come down to two basic interpretations: either the heat is there, and we are just not measuing it (Trenberth), or the heat is not (Hansen). -
KR at 00:36 AM on 13 July 2011A Detailed Look at Renewable Baseload Energy
In my previous comment I am referring to pre-conversion energy available at tropical sites. Equations 1 and 2 yield the same numbers (with LAGI's figures being rather conservative), and hence LAGI is properly doing their math. -
Eric the Red at 00:35 AM on 13 July 2011What we know and what we don't know
Dikran, The CO2 rise was only exponential when you start from preindustrial levels. The rise has been fairly linear since 1975. Change is the only constant in our civilization, and no one could foresee the changes today 90 years ago, and we cannot foresee the changes 90 years from now. I do not think many people expect a contiued rise to 550 ppm by 2100. I do not think the point of this article to claim that we do not know anything at all, but rather what is certain, and what is uncertain. Nor do I think this article advocated not taking any action. -
KR at 00:34 AM on 13 July 2011A Detailed Look at Renewable Baseload Energy
BBD - To be as clear as possible: Power over the course of the year can be calculated in two different ways. (1) Daily average power/m^2 * number of hours per year, or 200 * 24 * 365. (2) Peak power/m^2 * effective number of hours peak power is available, or 1000 * 2000. You keep calculating it as: Daily average power/m^2 * effective number of hours peak power is available This is a fundamental math flaw, mixing the two equations. -
KR at 00:26 AM on 13 July 2011A Detailed Look at Renewable Baseload Energy
BBD - And... you repeat the error, by stating "200W/m2 x 2000 = 400kWh per m2" It's not 200W * 2000 hours, but 200W * 24 hours * 365 days. Or, 1000W * 2000 hours/year of available time for collection. 200W is daily per/hour average, while 1000W on the other hand is peak power that is then scaled by the hours that power is available (2000/year, or 5.5 hours a day, more, actually, tapered for morning/evening). Apples and oranges, BBD - you are taking a 24 hour daily average and then scaling again by a fraction of a day. This is an error. I simply don't know how to put that any more clearly, BBD. 200W daily average is already scaled by hourly availability - yet you scale it again! LAGI then (properly) applies a 20% conversion efficiency. 30% is possible for CSP, minus additional plant footprint - not unreasonable. -
BBD at 00:06 AM on 13 July 2011A Detailed Look at Renewable Baseload Energy
KR Yes! You've got it:LAGI figures of 1 KW/m^2 * 2000 hours = 2000 kWh/m^2/year before conversion efficiency applied. MacKay figures of Honolulu, HI, 248 W/h/m^2 daily average * 24 hours * 365 = 2172 kWh/m^2/year before conversion efficiency applied. No disagreement once scaling factors are accounted for.
LAGI has used a reasonable estimate for average raw energy density of 200W/m2. It's properly conservative compared to those we have for SA (220W/m2) and Honolulu (248W/m2). It then takes this estimate, and treats it as 'capacity' - without a plant conversion efficiency factor - and uses it to get its footprint estimate. In LAGI:average raw energy density = plant output
LAGI does this:average raw energy density = average output
200W/m2 x 2000 = 400kWh per m2 Instead of this:average raw energy density x plant conversion efficiency = average output
200 x 15%* = 30W/m2 30W/m2 x 2000 = 60kWh per m2 That's why it is wrong. *This is an example only. Put in your preferred CEF, but remember, anything above 20% is getting fanciful. -
Dikran Marsupial at 00:05 AM on 13 July 2011What we know and what we don't know
Eric the Red We do know something very important about what lies in the future for CO2 emissions, which is that it is almost entirely in or own hands; if we want atmospheric CO2 to fall, we can make it happen; if we want it to stabilise we can make that happen too; if we are stupid enough to continue the exponential rise all we have to do is carry on with "business as usual". As regards climate sensitivity etc., the fact that we don't know anything for certain doesn't mean we don't know anything; not all theories that have yet to be refuted have equal support from the observations. Some theories are more plausible than others, and there is a well understood mechanism for determining the best course of action under uncertainty - namely statistical decision theory. So lack of certainty is not a good reason for not taking any action and waiting to see what will happen. -
Rob Honeycutt at 00:03 AM on 13 July 2011Trenberth on Tracking Earth’s energy: A key to climate variability and change
Ken... "we could not expect Asian aerosols to disappear anytime soon." You might be surprised on that one. The rate of change on almost every level in society in China is very rapid. The clean air act in the US had a pretty rapid affect on air pollution here. There is no reason to believe that China's responses to air pollution will be any slower. -
Eric the Red at 23:49 PM on 12 July 2011What we know and what we don't know
Very good analysis of what we do know, and the contentions that a majority of scientists believe that humans have contributed. The unknowns need to be assessed for what they are. We do not know what lies in the future for CO2 emission, nor do we know how much warming will be caused. Other contributors and feedbakcs are still being assessed. Lastly, we can only speculate on future effects based on observed effects. -
KR at 23:45 PM on 12 July 2011A Detailed Look at Renewable Baseload Energy
BBD - Comparisons, converting both 'apples' and 'oranges' into juice: LAGI figures of 1 KW/m^2 * 2000 hours = 2000 kWh/m^2/year before conversion efficiency applied. MacKay figures of Honolulu, HI, 248 W/h/m^2 daily average * 24 hours * 365 = 2172 kWh/m^2/year before conversion efficiency applied. No disagreement once scaling factors are accounted for. -
KR at 23:36 PM on 12 July 2011A Detailed Look at Renewable Baseload Energy
BBD - Reposting sometimes occurs when a page is refreshed; that's happened to me a number of times. -
BBD at 23:35 PM on 12 July 2011A Detailed Look at Renewable Baseload Energy
Moderator Dikram Marsupial I do not understand why the deleted comment has re-appeared. If I have somehow re-sent it I did so in errorModerator Response: [Dikran Marsupial] No problem, I have deleted it. I suspect KR is right, I've done the same thing myself more than once! -
KR at 23:35 PM on 12 July 2011A Detailed Look at Renewable Baseload Energy
BBD - MacKay does not indicate in that chart whether that is raw power or power over the course of the day. Looking at raw insolation for Africa, for example, extracting 400 kWh/m^2 over the course of the year represents about 20% of available power.
MacKay's chart looks like daily average insolation (including night), whereas the LAGI figures are raw insolation times hours that is available - Apples and oranges, BBD.
You state:
"LAGI says:
We can figure a capacity of .2KW per SM of land (an efficiency of 20% of the 1000 watts that strikes the surface in each SM of land). What it means is that average raw energy density at the surface is 200W/m2.
The choice of words is fabulously confusing. One might even suspect deliberately so."
What LAGI actually states in that figure is: "Areas are calculated based on an assumption of 20% operating efficiency of collection devices and a 2000 hour per year natural solar input of 1000 watts per square meter striking the surface."
I found that quite clear - you have (mis)stated the figure, which shows your confusion on the LAGI statement. Raw insolation is on the order of 1000 W/m^2, not 200 W/m^2, and taking (as you have repeatedly) an output value of 200 W/m^2 and then applying conversion efficiency again is an error.
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And now for some math from your South Africa example:
5.25 kWh/m^2 per day * 365 days is 1916 kWh/year available; extracting 20% of that would be 383 kWh/m^2 - both numbers right about what LAGI estimates. An average of 220 W/m^2 over the course of the day looks about right for an insolation peak of 1000 W/m^2.
You keep confusing averages over the course of the day with peak insolation * hours available, BBD, and then claiming calculations based on the latter are incorrect. I don't believe it's worth discussing this matter further with you until we can agree on a common vocabulary.
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Ken Lambert at 23:34 PM on 12 July 2011Trenberth on Tracking Earth’s energy: A key to climate variability and change
Michael Sweet #11 This is remarkable statement: "Here we see real skepticism at work in science. Hansen has proposed that aerosols reflect more heat into space. Trenberth proposes that the missing heat has been absorbed into the deep ocean. Hansen is skeptical of Trenberth's results and Trenberth is skeptical of Hansen. Both of them will marshall their data to determine which is more correct (it may be a combination of both effects). In the end the data will determine who is correct. This is an example of real climate scientists debating the data." Probably the two most prominent climate scientists on the planet disagree about whether or not the warming imbalance is 0.9W/sq.m or 0.59W/sq.m over the last 5-6 years when the imbalance must in theory be increasing due to increased CO2GHG in the atmosphere. Dr Trenberth says the missing heat 'is there but we just can't yet measure it in the oceans' and Dr Hansen says the heat 'is not there because extra aerosols have reflected it out to space'. This seems to be a fundamental difference in how the trajectory of warming might evolve - as we could not expect Asian aerosols to disappear anytime soon. Dr Trenberth wrote: "While the planetary imbalance at TOA is too small to measure directly from satellite, instruments are far more stable than they are absolutely accurate. Tracking relative changes in Earth’s energy by measuring solar radiation in and infrared radiation out to space, and thus changes in the net radiation, seems to be at hand." The CERES satellite data quoted in the Aug09 paper for 2000-05 were adjusted to an estimated imbalance of 0.9W/sq.m from an absolute value of about +6.4W/sq.m. The latest data shown in Fig 3 above shows an Rt value varying around the 1.0W/sq.m. How is this data 'adjusted' from the absolute value? I would also like to ask Dr Trenberth whether the ENSO-La Nina cycles are 'internal' redistributions of global heat already within the system or are external global forcings which should be added to the RF and climate response terms to determine an imbalance. The final issue I query is how Dr Trenberth's 'missing heat' gets into the deep oceans in a relatively short few years. viz. "The overturning may involve the ocean down to several kilometers and can take many centuries to complete a cycle". -
Humanracesurvival at 23:28 PM on 12 July 2011Trenberth on Tracking Earth’s energy: A key to climate variability and change
Re #28, part of the top soils are "rocks" which too react with thermal energy. Thermal stress weathering (sometimes called insolation weathering)results from expansion or contraction of rock, caused by temperature changes. Thermal stress weathering comprises two main types, thermal shock and thermal fatigue. Thermal stress weathering is an important mechanism in deserts, where there is a large diurnal temperature range, hot in the day and cold at night. The repeated heating and cooling exerts stress on the outer layers of rocks, which can cause their outer layers to peel off in thin sheets. Forest fires and range fires are also known to cause significant weathering of rocks and boulders exposed along the ground surface. Intense, localized heat can rapidly expand a boulder. Although temperature changes are the principal driver, moisture can enhance thermal expansion in rock too. Pedology -
BBD at 23:19 PM on 12 July 2011A Detailed Look at Renewable Baseload Energy
Tom [posturing deleted]Moderator Response: [Dikran Marsupial] Skeptical science is for calm rational discussion of scientific issues relating to climate change. Rhetoric is not appropriate; please everybody let's get back to a more moderate, impersonal tone. -
BBD at 23:17 PM on 12 July 2011A Detailed Look at Renewable Baseload Energy
Oh, don't mind me. Here's what the Energy Department of the Republic of South Africa says about average raw energy density at the surface:Most areas in South Africa average more than 2 500 hours of sunshine per year, and average solar-radiation levels range between 4.5 and 6.5kWh/m2 in one day. The southern African region, and in fact the whole of Africa, has sunshine all year round. The annual 24-hour global solar radiation average is about 220 W/m2 for South Africa, compared with about 150 W/m2 for parts of the USA, and about 100 W/m2 for Europe and the United Kingdom. This makes South Africa's local resource one of the highest in the world.
Any pennies dropped yet? -
Tom Curtis at 23:13 PM on 12 July 2011A Detailed Look at Renewable Baseload Energy
BBD @276, do you think it just might be possible that it sounds like they are trying to say something different from how you interpret it because they are trying to say something different from how you interpret it? Or do you hold it as a axiom that you cannot misinterpret what somebody else says? -
Tom Curtis at 23:05 PM on 12 July 2011A Detailed Look at Renewable Baseload Energy
Alec Cowan @274, LAGI do not assert that 1000 Watts strikes every square meter of land. You put that claim into their mouths. In other words, you verbaled them. Until you go to their site, and follow up the link in which they justify their claim, and show that they are claiming something ridiculous, you are accusing them of asserting falsehoods solely on the basis of your lazy interpretation. And I don't give a hoot what your views are on global warming or solar power, or anything, that is a nasty habit. My criticism of you has nothing to do with any disagreement I have with BBD. As is quite evident from his posts, he has not yet even caught on that LAGI make the claim that you are mistakenly rejecting. It does have everything to do with rejecting a style of criticism that insists on interpreting the views being discussed, not as they are understood by the author of that view, but by dressing that view up in a straight jacket of the critiques own devising, thus interpreting sensible claims as ridiculous. It is an argument style I strenuously dislike, because it is lazy, because it is dishonest, and because it makes actual debate impossible. -
Eric the Red at 23:03 PM on 12 July 2011The Medieval Warm(ish) Period In Pictures
Using the proxy data referenced by Albatross, Mann (2008) showed temperatures between 1000 and 1100 to be similar to 2000. The Moberg (2005) proxies (NH only) were highest in the 1000 - 1100 years. Loehle (2008) shows the highest global temperatures occurred ~900. Ljungqvist proxies show the highest NH temperatures centered around 1000. All these proxies show a distinct MWP, although the timing varies due to the proxies used. -
Jumper at 22:54 PM on 12 July 2011Trenberth on Tracking Earth’s energy: A key to climate variability and change
I was reading a thing by a denier and he seemed confused about energy in / out. I immediately thought of the quartz or glass tubes around kerosene heaters. The energy outflow is retarded and the catalytic metal sleeve becomes red hot; hotter than it would without the glass tube. Yet energy output is the same. (except for the catalysis itself!) The point is, even with much more retained heat, the net outflow will quickly reach equilibrium. I suppose I should have pointed that out to the denier. -
Jumper at 22:49 PM on 12 July 2011Trenberth on Tracking Earth’s energy: A key to climate variability and change
Interesting, Human. As a soil science person, I wondered about the energy difference between the top 10 meters of soil with, and without, groundwater. By my hypothesis, drought can mask the energy calculations. Unsure. Connolly says this dwarfed by oceans, if I read him correctly. -
BBD at 22:31 PM on 12 July 2011A Detailed Look at Renewable Baseload Energy
KRNo. LAGI, Tom, and myself have assumed 1 KW/m^2 raw energy intensity for a near equatorial site, which is then scaled by conversion efficiency and (quite importantly, and not done by LAGI) plant fill factor.
If you look at this set of values for average raw energy density at the surface range from 87W/m2 to 273W/m2. This is where I get my 200W/m2 raw energy average. I've been saying this over and over here. Perhaps now the penny will drop. Once more, for the record: 200W/m2 is a good estimate for average raw energy density at the surface for low latitude desert. So far, so good. But then LAGI causes much confusion by its use of the term 'capacity' (emphasis added):We can figure a capacity of .2KW per SM of land (an efficiency of 20% of the 1000 watts that strikes the surface in each SM of land). So now we know the capacity of each square meter and what our goal is. We have our capacity in KW so in order to figure out how much area we’ll need, we have to multiply it by the number of hours that we can expect each of those square meters of photovoltaic panel to be outputting the .2KW capacity (kilowatts x hours = kW•h).
LAGI does this:average raw energy density = average output
200W/m2 x 2000 = 400kWh per m2 Instead of this:average raw energy density x plant conversion efficiency = average output
200 x 15% = 30W/m2 30W/m2 x 2000 = 60kWh per m2 What I suggested at 271 is that you can see that LAGI is nonsense because it's entire calculation is based on solar plant with an average output of 200W/m2. It doesn't exist. Can you please, finally, just take a few minutes to think about this (eg #270 and #271). It beggars belief that something so obvious can be misunderstood for so long. -
Eric the Red at 22:28 PM on 12 July 20112010 - 2011: Earth's most extreme weather since 1816?
Albatross, Trapp has concluded that CAPE is the dominant factor in determing supercell formation. That theory is not shared by all. Others maintain that vertical shear is most important. What is agreed upon is that when both are high, severe thunderstorm formation, and possible tornadic activity are most likely. We disagree on the same point. Currently, I am leaning towards wind shear being most important, but have not ruled out CAPE being most important. I am basing this on current studies which show available moisture increasing throughout the summer months, but wind shear decreasing, and consequently, severe storms decreasing as the summer progresses. -
Alec Cowan at 22:25 PM on 12 July 2011A Detailed Look at Renewable Baseload Energy
It looks for me now that all three of you are here because you enjoy the swamp. Tom, you chose to voluntarily ignore BBD in a recently deleted comment. Don't use me to continue your feud with that person. I told you that I don't need to be sold "solar". I'm telling you I don't need to be lectured about solar either. The notion of 1000 Watts striking every square meter of land on a regular basis is dead wrong. Don't build up a list of "buts" to excuse the author. That he or she may have been carried away by legitimate enthusiasm and a sales pitch mood, I agree, but that doesn't change how the world works. BBD, now part of your mind has realized your gruesome arithmetical mistakes after a spree of sterile debate caused by that mistake. The chosen strategy is asking others a written admission of the straw in their eyes. You are moving now to efficiency in a effort to keep your preformatted conclusions and simultaneously avoid the apologies about the rafter that any level-headed grown-up would give. I'm telling you: Tell yourself whatever you want, but it shows! It shows, and it's written! -
KR at 22:09 PM on 12 July 2011A Detailed Look at Renewable Baseload Energy
In my previous comment I may have underestimated the fill factor at Waldpolenz Solar Park and the CSP plants; to the extent that I have done so more energy per land area is available. I've found it rather difficult to get the numbers for these. Conversion efficiency of 15 to perhaps 20% of collected raw energy is possible with current technology photovoltaics, while CSP is rated at 30%+ for high temperature arrangements. But it's easier to densely fill the land with collectors for PV, so this CSP advantage may cancel out. -
Humanracesurvival at 21:56 PM on 12 July 2011Irregular Climate Episode 21
Video: More than 8 billion cubic metres of natural gas are lost in the US each year -
Alec Cowan at 21:46 PM on 12 July 2011The Medieval Warm(ish) Period In Pictures
@35 Wow, wow! It looked a bad copy of [- snip unnecessary disease references; some people around here actually have those problems -] Do I need to recite a creed to get clearance? It's difficult to me; I'm Postheist. But called to do it, and as my only objection is using the verb "believe", I say: I believe in an ongoing AGW that is endangering the biosphere in such a degree that an obstinate keeping of those trends in the eighties during a couple of centuries will provoke events of dire consequences in a global scale. That said, if you can avoid spotting a denier in disguise in every criticism you'll hear from me, you may explain for me what is the "it" in your "I think if you're wanting someone to rail against it should be Hubert Lamb?". I found that in English people tend to get cocky before talking clear. Additionally, as you should have realised from the start, I'm not saying that the so-called MWP wasn't just a regional development. I'm saying that Figure 1 can be misinterpreted as showing a cooling average because it's contrasted against a warm period. That is not bona fide, the same way that is not bonafide your innuendos of me being a climatard just because I don't agree automatically with what is shown here. Your belligerent summoning for me to have all the backing information of Mann, Zhang, Rutherford et al read and analyzed together with a search for alternative renders for that period, in less of 24 hours, in a working day, is not bonafide too.Moderator Response: [muoncounter] The only thing you need do to get 'clearance' (whatever that means), is keep your comments rational, on topic and supported by evidence. No one really cares about your 'creed' or your interpretation of English speech patterns. -
Humanracesurvival at 21:29 PM on 12 July 2011Trenberth on Tracking Earth’s energy: A key to climate variability and change
I meant to write Pedosphere -
Humanracesurvival at 21:15 PM on 12 July 2011Trenberth on Tracking Earth’s energy: A key to climate variability and change
"the exchange of energy between the atmosphere and ocean is ubiquitous, so that heat once sequestered can resurface at a later time to affect weather and climate on a global scale" I'm missing a more in depth part about the atmosphere/hydrosphere interconnection - how the changing weathering process affects land mass and flux of heat content therein. "although some heat has gone into the record breaking loss of Arctic sea ice, and some has undoubtedly contributed to unprecedented melting of Greenland and Antarctica, these anomalies are unable to account for much of the measured TOA energy (Fig. 4). This gives rise to the concept of “missing energy” " Could this indicate an uptake of permafrost melt and other such processes, increase of weathering-erosion of the pedoshere? In the sense that decomposition of organic materials, the soil permafrost environment transition into a more fluid "unstable" state, could account for the missing heat? -
KR at 21:09 PM on 12 July 2011A Detailed Look at Renewable Baseload Energy
BBD - Aha, a light dawns (so to speak). "Here's what LAGI does: - reasonably assumes 200W/m2 raw energy density - multiplies 200W/m2 by the estimate of 2000 hours p/a of direct sunlight: 200W/m2 x 2000 = 400kWh per m2 - and on this assumption estimates: - 500,000 km2 = 23TW Plant conversion efficiency is not calculated." (emphasis added) No. LAGI, Tom, and myself have assumed 1 KW/m^2 raw energy intensity for a near equatorial site, which is then scaled by conversion efficiency and (quite importantly, and not done by LAGI) plant fill factor. 1KW * 0.2 efficiency * 2000 p/a = 400kWh/m^2 including plant efficiency. You appear to have applied the LAGI 20% efficiency twice, BBD, and are starting from a raw power a factor of five too low. Did you read Tom's post here? Showing insolation for New Mexico, with irradiance of ~1 KW/m^2? Where are you getting 200 W/m^2 for tropic raw power? You are incorrect. [Waldpolenz Solar Park in Germany, incidentally, has a fill factor (collection to plant areas) of ~30%, a conversion efficiency of ~12%, so 30% is quite achievable with current tech for PV - scaling up LAGI's land estimates by 3.3 at most for PV. Most current CSP plants have lower fill factors, ~15%, although some have hit 30% (Solar Millennium, Ridgecrest CA, parabolic trough, appears to be at 30%). So scaling up LAGI's estimates by 3.3 is reasonable for a physically achievable power station. Downscaling raw power by 5, on the other hand, is not.] -
Eric (skeptic) at 21:07 PM on 12 July 2011Over the tipping point
#13, Artful Dodger, I answered that question in another thread /argument.php?p=2&t=113&&a=80#54888 and a link to a simple spreadsheet. There was general agreement that if we stopped now, the current level would fall half way back to preindustrial within 50 years.Moderator Response:(DB) Umm, no, there was not "general agreement"; please re-read the responses and look for mine and Sphaerica's comments (the guest post by Dr Franszen has discussion supporting Dodger's position on oceanic outgassing of CO2).
Edit:
[DB] The post I referenced is the Seawater Equilibria thread. The relevant discussion I alluded to starts at comment 30. Specific relevant comments are numbers 33, 41, 43, 45, 67, 78 and 81.
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Eric (skeptic) at 20:45 PM on 12 July 2011Trenberth on Tracking Earth’s energy: A key to climate variability and change
One thing I don't understand is short term variability in GAT, for example, in the first column here: http://vortex.nsstc.uah.edu/data/msu/t2lt/uahncdc.lt Looking at that first column, there is a clear AGW and clear ENSO response. But there is also a month-to-month variability that can be as much as 0.1 or 0.2 This variability even tracks down to the day timeframe although that is more unusual. My question is, is there an energy transfer with the ocean over such short time intervals, or is it just lost to space and regained later? -
BBD at 20:22 PM on 12 July 2011A Detailed Look at Renewable Baseload Energy
Since there seems to be something of a mental log-jam going on here, how about a different framing of the problem with LAGI: LAGI calculates: 200W/m2 x 2000 = 400kWh per m2 Average output capacity per square metre is given as: 200W/m2 What kind of solar plant delivers an average output capacity of 200W/m2? See it now? -
Rob Painting at 19:28 PM on 12 July 2011The Medieval Warm(ish) Period In Pictures
Camburn @ 32 - The Sargasso sea was warm in the MWP. See figure 2 above. Mike Mann is well aware I'm sure. -
BBD at 19:11 PM on 12 July 2011A Detailed Look at Renewable Baseload Energy
Tom You are not addressing #264. At #252, you said (and not for the first time - it is your entire argument):LAGI do not use a 200 Watt insolation value (which they give as 1000 W/m^2), and they do not omitting the panel conversion efficiency (which they give as 20%).
But that is exactly what LAGI does. It multiplies 200W/m2 by the estimate of 2000 hours p/a of direct sunlight: 200W/m2 x 2000 = 400kWh per m2 And on this assumption estimates: 500,000 km2 = 23TW Plant conversion efficiency is not calculated Instead of this:average raw energy density x plant conversion efficiency = average output
LAGI does this:average raw energy density = average output
200W/m2 x 2000 = 400kWh per m2 I show this, again, at #264. Please respond to this. Do not introduce any extraneous argument. Respond to this alone. Politely. You must: - show that it is incorrect or - admit that LAGI is in error # 264.
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