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199 comments on The Energy Return of (Industrial) Solar - Passive Solar, PV, Wind and Hydro (#5 of 6)
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199 comments on The Energy Return of (Industrial) Solar - Passive Solar, PV, Wind and Hydro (#5 of 6)
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Great where it works being obviously southward facing homes that require heating *but have good sun* a significant fraction of the year. So basically it's useless in for example upstate NY where I live due to poor sunlight in the winter. As for the evac tubes, panels, etcetera, (not addressed in the original post) I ran the math on it, and discovered that in order to provide heat for a modest sized house (looking for 30,000 btus/hr) would require (30,000 btu = 8.8 kw = 8.8m^2 * 2 (winter sun is weaker than full summer) * 2 (inefficiency)*4 (8 hour day)) 140M^2 of collection paneling. That's larger than the typical modest house. In addition to that, it says nothing at all about the storage of that heat for the overnight.
I never said that the inverters were "falling apart" I said that they were the most maintenance intensive portion of the system, which they are. As for how they kill the eroei, well, off the cuff, they lose 5% of the energy that hits them, after that, the energy involved in manufacturing them and delivering them MUST be taken into account when calculating the eroei of the system. To fail to do so and just account for the energy in the panels themselves is simply to lie.
Look, when I am looking at eroei, I find it simplest to simply look at the finances. Anything with a 25 year amortization does *not* have a 10:1 eroei, to claim that it does means that the accounting of the energy inputs has been done incorrectly. Taking the meter turnings at the factory that produces the panels will always produce high eroei numbers. Mining the copper to make the inverter takes energy, as does the labor of the chinese guy who winds the inverter. frankly, there is no sink of money that isn't energy based, so the simplest and most accurate way to calculate eroei for anything wil be to look at the economics.
(30,000 btu = 8.8 kw = 8.8m^2 * 2 (winter sun is weaker than full summer) * 2 (inefficiency)*4 (8 hour day)) 140M^2 of collection paneling.
These numbers appear to be pulled out of a hat. You need to provide engineering substance to your above claim. Bald assertion does not do so.
Note most passive solar homes are very energy efficient, so comparisons to ordinary non-efficient homes is a case of apples and oranges, unless you are limiting your discussion to passive solar retrofitting of an existing home, where increased energy efficiency (insulation, airtightness) is normally implemented anyway.
I said that they were the most maintenance intensive portion of the system, which they are.
How much maintenance are you claiming they need? Mine has needed zero in the last 8 years. Of course, since PV panels really require no maintenance (mine have needed none in the last 8 years), your statement doesn't amount to much anyway. Please supply current data to support whatever claim you make.
In contrast to the vast supporting documentation you have posted? Seriously, I just browsed your last 50 posts and failed to find anything of substance in any of them. Even your own experiences with your PV system are biased anecdotal unscientific worthless tripe.
As for the numbers I was using in the 30kbtu example, they were highly optimistic numbers from one end to the other. look it up yourself.
As for the solar design necessitating the more energy efficient home design, I call BS on that, you are comparing apples to grapes if you compare the heating requirements on a brand new high efficiency home to that of the average US or European home. Simply put, that's cheating.
Just as an example of exactly HOW generous I was being with my numbers in my 30kbtu example, in upstate NY, december insolation is only *2* kwh/m^2/day.
http://rredc.nrel.gov/solar/old_data/nsrdb/redbook/atlas/serve.cgi
In my example, I gave it 4. you will also find that no passive solar collection panels or evac tubes on the market can come even close to the 50% efficiency that I allowed. If you're going to demand specific math, it's going to get *very* bad for your case very fast.
This all pertains to existing houses, new houses can easily enough improve in many ways. However, that's what I meant by "not in your lifetime" the average age of a residence in the US is something in the neighborhood of 25 years so if we were to start now mandatig that *every* new home were to be high efficiency, it would take 25 years to replace half the homes currently in use with the newer designs. That is entirely too slow to constitute a noticeable impact.
I also looked up MTBF for grid tied inverters, and I found that most manufacturers have 10 year design life as a "goal". this means that you can expect to be replacing the single most expensive single component of your "low maintenance" system every 10 years on average (I am making the assumption here that the panels themselves are modular and can be swapped out individually.)
The importance of energy efficiency is reflected in the amounts of energy that are available. For example, in Germany, with even less solar energy than your upstate New York location, PassiveHaus designs are able to utilize solar energy for
Indeed, PassivHaus homes cannot use more than 4746 btu/ft² per year in non-renewable heating energy.
From http://www.cepheus.de/eng/index.html;
"Cost-optimized solar thermal systems can meet about 40–60% of the entire low-temperature heat demand of a Passive House. The low remaining energy demand moreover makes something possible which would otherwise be unaffordable, and for which available supply would not suffice:
Over the annual balance, the remaining energy consumption (for space heating, domestic hot water and household electricity) is offset completely by renewable sources, making the Passive House fully primary-energy and climate neutral. This is being achieved in the CEPHEUS housing development in Hannover-Kronsberg"
Homes meeting the PassiveHouse requirements have been built in the US, such as this one near Chicago;
http://www.e-colab.org/ecolab/SmithHouse.html
So solar energy can be used for home heating needs when attention is paid to energy efficiency.
Once again, if it involves changing out the actual home, then you can look for no help here in your lifetime. I never said that you couldn't build a home capable of being heated by passive solar, I said that if you wait for passive solar to make significant inroads into the energy picture, you're going to be waiting a LONG time. It's great for individuals building single new homes on large lots, basically useless for anything else, and will have no impact on fossil fuel demand for decades at a minimum.
It's great for individuals building single new homes on large lots, basically useless for anything else
Wrong yet again;
and will have no impact on fossil fuel demand for decades at a minimum.
Unsupported assertion.
Nice developments. Makes no difference to the point though. I have explained time and again that the average age of a dwelling in the industrialized world is 25 years, and that therefore if ALL new homes were built to this standard, then half the homes would have been replaced in 25 years, Since residential heating represents 10% roughly of fossil fuel consumption that would give us an overall improvement of 0.2% per year IF we instituted a crash project to institute Passive solar construction. This is assuming that there is exactly zero growth in population AND that each home uses zero fossil fuels. neither of which is the case.
So like I said, totally useless. Being pigheaded about it serves you poorly.
There's no one following this but us now, so you can drop the posturing and derogatory language, which only weakens your argument anyway.
You made some overly narrow assumptions in your math.
First, don't assume that solar technology will be implemented in a vacuum; other aspects of home energy use is also dropping, like high efficiency refrigerators, CFL, lower energy computers, etc., etc, as shown in the PassivHaus examples above. So the 0.2% becomes at least 0.3%
Secondly, as building energy consumes 1/3 of US energy consumption, commercial and industrial building also can take advantage of passive and active solar. And they tend to renovate much more often than every 25 years. So instead of 10%, we are looking at 33% and the the 0.3% becomes 1%.
http://www.eere.energy.gov/buildings/database/mtxview.cfm?CFID=22259466&...
A yearly 1% reduction in energy use provides positive impacts right from the start. Add in energy efficiency improvements to the other domains, such as transportation and industrial processes, and quite a bit of progress can be made.
Well, you're still here, and the conversation has finally come around to a 2 sided discussion of math, so we're finally at the point when you deserve better treatment than insults (you have to admit that your "long on opinion and short on substance and accuracy" is a statement deserving of the contempt I gave it, particularly since I was right in every aspect of the post). So okay, lets go from there.
The other efficiency improvements you mentioned fall outside of this discussion really, CFLs are quite unrelated to passive solar construction. In fact, these things go to prove my point, CFLs and efficient windows are being installed as fast as sylvania anderson can make them, despite which, residential energy demand is still increasing.
As for passive solar and efficiency tweaks on commercial/industrial structures, I think you can look for very minimal improvements there, industry is usually pretty well on top of the efficiency curve, for example, it's a long time since I have seen an incandescent bulb in a commercial or industrial building, they've pretty much been fluorescent for the last 30 years. Also, industrial applications are far less able to be successfully met with passive solar. Sure, you may be able to heat the building with passive solar, but you won't be able to provide process steam or run machinery on it, so at best you're looking at maybe 1/4 of the energy that enters an industrial/commercial site being able to be met with passive solar (yes, I did just pull that 1/4 out of my butt, feel free to find a citation if you dislike that number).
Now, as regards the total fraction of energy that we're working with,
https://eed.llnl.gov/flow/pdf/USEnFlow02-quads.pdf
Shows that only very small amounts of oil go to either residential or commercial applications. In the residential applications we are therefore primarily looking at savings of natural gas and coal electric. That makes this really not about peak oil at all, but more about climate change and carbon reduction. Just wanted to have that said.
Now, is passive solar useful for cooling? No, not really, about the best it can do in most climates is a reduction in A/C energy. In most climates that require heating can it totally replace heating energy? Not really, they can significantly reduce it, yes, but never eliminate. Can you cook with passive solar? no, not really, you still need natural gas or grid electric for that. Can they eliminate the need for lighting? no, not really, at best they reduce the need to nights and cloudy days. so once again, I was being very generous in my 0.2% assessment. Really, if we were to figure that a good passive house uses half the outside energy compared to a traditional house, we'd be pretty close, hyperbole notwithstanding.
passive solar isn't junk, it's great where it works, and I see no reason not to encourage deployment of it to all degrees possible, but it isn't going to make a difference to peak oil or climate change on anything except the very long term, it's just another too little too late type measure.
As for "active solar" (PV) the emergy doesn't work, it's still a loser. This is reflected in the financial math. There's just no real point in installing them yet. An honest and full accounting of all the energy that is involved in gettin gthem in operation on your house will show that they are an energy sink, not a source.
TBH, it's fair to compare passive solar to hybrid cars, yes, they are a good technology, and there's no reason not to pursue them, but the problem is several orders of magnitude too large for them to have enough of an impact. You're trying to put out a housefire with an eyedropper.