SageBrush
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Re: ABG: U.S. carbon emissions spike in 2018 after years of falling

Thu Jan 10, 2019 8:18 pm

Oilpan4 wrote:According to the IEA the US generated 1.2 Terra watt hours in 2017 with coal.
That would require about 240 Terra watts of installed PV capacity and a battery to store some of it.

Your numbers and PV replacement calc are way off.

https://www.eia.gov/tools/faqs/faq.php?id=427&t=3
What is U.S. electricity generation by energy source? In 2017, about 4,034 billion kilowatthours (kWh) (or 4.03 trillion kWh) of electricity were generated at utility-scale facilities in the United States. About 63% of this electricity generation was from fossil fuels (coal, natural gas, petroleum, and other gases).


Second, a well sited, single axis tracked utility PV array is good for about 2.5 kWh annual generation per STC watt.
Well sited on-shore wind produces about 3- 3.5 kWh annually per rated watt
Off-shore wind, about 4 - 5 kWh annually per rated watt

Units:
10^6 Mega = million
10^9 Giga = billion
10^12 Tera = trillion
10^15 Peta = quadrillion

Starting from 4.03 * 10^12 kWh annual US electricity generation,
63% is from fossils, = 2.54 * 10^12 kWh annually
Which rather conveniently then requires 10^12 watts = 1 TW of PV

If we predict equal shares of PV, on-shore and off-shore wind the average yield will be 3.4 kwh annually per watt installed,
And thus 2.54/3.4 TW = 0.75 TW = 750 GW required to replace the fossils currently used in electricity production.
In 2018 the US installed ~ 18 GW of PV/wind
In 2018 China installed 50 - 60 GW of PV/wind

Only politics stands in the way of increasing production way above 2018. I'm sure your teachers would agree.
Last edited by SageBrush on Wed Jan 16, 2019 12:13 pm, edited 1 time in total.
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Oilpan4
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Re: ABG: U.S. carbon emissions spike in 2018 after years of falling

Thu Jan 10, 2019 9:41 pm

Nope. Theres that blind optimism I was talking about.
Try and replace most fossil fuels with 1Tw worth of solar power and people people will be living in the dark.
Putting panels on Single axis tracking array with a single axis tracker will at least double the price of the install. You are better off just buying more panels.
I have looked around at pre-made single and multi axis modular tracking systems and was able to quickly rule them out as being economical here in newmexico.
If money is no object and the only thing that matters is getting the most watt hours out of the least panels because say your land area is limited, then sure it might be worth it.
All of the utility level installs here in new Mexico and texas i have seen in person and seen pictures of are fixed.
The worst thing about the trackers is they are the most unreliable part of the system, the tracking drive system will need to be replaced 2 or 3 times over the life of the panels. In additiom to the trackers I'm not convinced most of the tracking racks I have seen will last as long as the panels due to corrosion.

If you don't believe me then Google search how much installed capacity the US has right now. The installed capacity is 60 gigawatts as of the 3rd quarter of 2018.
So install about 17 times what we have now and we are at 1Tw of generating capacity. 1Tw of solar generating capacity is no where near enough to replace coal or natural gas when in 2017 we had 57ish gigawatts of solar capacity that only generated about 1.2% of all US watt hours needed.
1Tw of solar generating capacity would replace closer to 2/3 of coal power made in 2017.
If I were going to do it I would probably want to replace 1 watt of reliable coal or gas capacity with 7 or 8 watts of solar, for obvious reasons like the sun going down, but also reliability, disasters and to over come battery losses.

Normally I put up some crazy numbers to see who I'm dealing with.
Congratulations you are the first person to ever call me out, but you were still way off.
I like you.
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SageBrush
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Re: ABG: U.S. carbon emissions spike in 2018 after years of falling

Fri Jan 11, 2019 3:33 am

Oilpan4 wrote:[1]Nope.

[2]Putting panels on Single axis tracking array with a single axis tracker will at least double the price of the install.

[3]So install about 17 times what we have now and we are at 1Tw of generating capacity. 1Tw of solar generating capacity is no where near enough to replace coal or natural gas when in 2017 we had 57ish gigawatts of solar capacity that only generated about 1.2% of all US watt hours needed.

[1]Let's keep opinion out of this, and I would appreciate it if you would refrain from "crazy numbers." You wrote that we should believe that you know what you are talking about, and that
To replace natural gas and coal you are looking at more like 500 Terra watts.
I wrote above that ONE TW is required, which means your self proclaimed educated statement is off 500 fold. We will continue this discussion a little more until you are convinced of the one TW additional PV to replace current fossil use for utility scale electricity generation.

[2] https://pv-magazine-usa.com/2018/10/04/ ... love-them/
https://emp.lbl.gov/utility-scale-solar
Summary: Over 80% of utility PV is now built with single axis tracking. That is expected to increase.

[3] There are multiple errors here. A couple of the most important:
1. You are not accounting for the change in yield per watt over time. Read https://emp.lbl.gov/utility-scale-solar
2. In 2017 the Utility PV capacity was ~ 25 GW at end of the year, so ~ 20 GW average through 2017. You are conflating utility PV with total installed. https://www.eia.gov/electricity/annual/ ... 04_03.html
https://www.eia.gov/tools/faqs/faq.php?id=427&t=3

That 20 GW average in 2017 supplied 1.3% of the US total utility electricity generation so
20 * (100/1.3) = 1.54 TW is needed for complete replacement.
But fossils are 63% of the total so actual replacement required is
1.54 TW * 0.63 = .98 TW. The actual number is less since the capacity factor of new PV has improved to 27.2% as noted in the lbl.gov link above. *


* In order for you to x-check the two approaches I showed you with each other, you have to convert capacity factor (CF) to yield:
A CF of 27.2% is equal to 365 days a year * 24 hours a day * 27.2% of rated STC watts = 2.38 kWh per watt* year
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Oilpan4
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Re: ABG: U.S. carbon emissions spike in 2018 after years of falling

Fri Jan 11, 2019 7:56 am

That's why I used yearly average for 2017. So what's added would have to be built in the same regions as the existing 60 Gw.
Depending on how much of the panels are up north has a lot to do with it. For example where my parents live in maine, I would probably expect to replace 1 coal fired watt with up to 20 solar watts during the winter.
I would expect to see as little as 3 to 5% utilization with no snow on the panels, being optimistic and there is someone or something that clears the snow off the panels.
Because snow covered panels on a cloudy day, are pretty much useless.
Hopefully large amounts of solar don't get put in there.

Me personally I'm putting my panels on manual tilt. In the summer around 80 degrees up from the horizon is what I want for summer solstice.
For winter solstice closer to 55 degrees, I would have to look up the exact degrees.
But I figure I can add manual tilt to ground mount if I build it my self for a 5% increase in cost and that will yield 10 to 20% more power.

I notice the article neglected to mention cost versus production numbers.
Putting utility installs on trackers must be something they do up north because I don't see it at all around here.

All I can think of is they are spending other peoples money to build these things.
I think the only time I have seen a large install on trackers was the university of new Mexico, but that probably wasn't utility owned.
On home installs I hear about a lot of buyers remorse when it comes to trackers.
They're awesome until they break almost as soon as the warranty is up.
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SageBrush
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Re: ABG: U.S. carbon emissions spike in 2018 after years of falling

Fri Jan 11, 2019 12:27 pm

Oilpan4 wrote:That's why I used yearly average for 2017. So what's added would have to be built in the same regions as the existing 60 Gw.
Your calculation mixes up apples and oranges.
By the end of 2017, 1.3% of US utility power was from PV. Of the 50 or so GW of PV installed in the US at that time, about 25 GW of that total was routed through the utilities. The 1.3% number does not include the other ~ 35 GW. Once you correct that error you should also come up with ~ 1 TW of PV to replace current fossil fuel use for electricity generation in the utility power sector.

Regarding PV tracking, I am sure that circumstances dictate its use. But it is undeniable that utility scale PV has adopted it wholesale in the past year or two. Residential PV ? Not at all. Commercial PV ? Not to any degree I am aware of.

Let me return this discussion to your original point I am refuting: that PV/wind have no practical path in our lifetimes to displace the lion's share of fossils used in electricity generation in the US power industry. Hopefully by now you agree that just the opposite is true.
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LTLFTcomposite
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Re: ABG: U.S. carbon emissions spike in 2018 after years of falling

Sat Jan 12, 2019 9:33 pm

The only reason any of this is a problem is because we got off on the wrong track building the wrong nuclear reactor designs nearly half a century ago. Just because it made sense for a nuclear submarine doesn't mean it was the way to go for power plants.
It's quite sad when you think of it.
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SageBrush
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Re: ABG: U.S. carbon emissions spike in 2018 after years of falling

Sat Jan 12, 2019 10:55 pm

Oilpan4 wrote:I have a hot water heat pump.
Using hot water to store solar sounds like a lot of hot water.

http://www.fsec.ucf.edu/en/publications ... 464-15.pdf
Summary:
18% of residential energy use
~ 20 gallons of heated water per capita per day for residential use*

Hot water is an obvious and simple way to time shift substantial PV even if we exclude non-residential and radiant applications.

*
20 gallons = ~ 76 liters = 76,000 ml
'Hot water' is heated ~ 40 C
4.2 joules to heat one cc one C
So per capita,
76000*40*4.2 joules = 3.5 kWh per capita per day of PV used as resistance heating or ~ 1 - 1.5 kWh per capita per day with a heat pump


---
And just to mention industrial process water heating:
https://www.epa.gov/rhc/renewable-indus ... ocess-heat


--
Note that I have not mentioned radiant water heating since I am skeptical of its use instead of A-S heat pumps but it is certainly another potential almost untapped sink for time shifted electricity
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Oilpan4
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Re: ABG: U.S. carbon emissions spike in 2018 after years of falling

Sun Jan 13, 2019 1:48 am

Rolling out wide scale wind and solar power will probably end up like Germany.
The price of electricity will roughly double in less than 2 decade and a good portion of the population will not be able to afford it.

So how that's a good idea?
Double the price of electricity, while trying to get people to adopt a single electric vehicle to a 2 car household which will increase home power use by 20% to 40%.
Anything can happen if money is no object, doesn't make it a good idea

Adding the leaf makes up about 1/5 to 1/3 of the power my home uses, add a plug in hybrid to the mix, power for vehicles will likely make up about half the power we use.

Making electricity more expensive isn't how you get more people to adopt electric vehicles.
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iPlug
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Re: ABG: U.S. carbon emissions spike in 2018 after years of falling

Sun Jan 13, 2019 4:02 pm

California is the appropriate comparison here. We have a large percentage of non-CO2 electrical energy generation. Unlike Germany we do not make up for it with the fossil fuels/coal. Our coal use is minimal and almost entirely imported. Natural gas usage is declining overall the last three years here.

CO2 free energy can get more expensive, particularly as it occupies a greater and greater share of electricity generation.

But it is not correct that it is more expensive than fossil fuels. Fossil fuel utilizers get a discount when buying that source of electricity, but the rest of society pays the balance with negative externalities. The total cost is not cheaper.
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GRA
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Re: ABG: U.S. carbon emissions spike in 2018 after years of falling

Sun Jan 13, 2019 4:03 pm

Since an awful lot of numbers are getting thrown around in the discussion, may I suggest (yet again) that Vaclav Smil's "Energy Transitions: Global and National Perspectives" would be a good source for getting everyone on the same page with regards to the numbers?

BTW, my thanks to Sagebrush for pointing out the shift to single-axis trackers for utility scale projects, as that's a very recent trend I wasn't aware of (being mainly involved/interested in off-grid and residential-scale AE, where tracking was abandoned except for the occasional PV-direct water pumping system once module prices dropped enough to make tracking relatively more expensive, for the reason Oilpan4 states). I see the utilities are still staying away from dual-axis trackers for PV, presumably for the same reasons (extra land is generally cheaper for utility projects). Only CSP with a power tower really needs dual-axis; it's almost never worth the extra cost/maintenance otherwise.
Last edited by GRA on Mon Jan 14, 2019 6:33 pm, edited 1 time in total.
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