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> If we need 1TWh we need a few hundred thousand turbines. I think the problem is that once you start analyzing the issue at scale the only solution that could
by robomartin 5y ago
> If we need 1TWh we need a few hundred thousand turbines.
I think the problem is that once you start analyzing the issue at scale the only solution that could be real today would be a widely distributed nuclear power generation system across the entire country. If we use a 1 GW reactor as the baseline, that means over a thousand power plants need to be built. While the distribution would not be uniform, for sake of easy numbers we can make this assumption and divide by 50 states. That means we need 20 new 1 GW class nuclear power plants per state. California might need 50, while Montana might be able to do with 5. Don't know, I did not model it to that level of detail.
The point is the scale of the requirement is absolutely massive. Almost unimaginable. And so, we have people in politics talking about no more internal combustion engines in 25 years and everyone conveniently ignores the physics that makes this absolutely impossible unless we start doing serious work immediately.
Solar sounds interesting on paper until you live the reality of solar. My 13 kW array is grossly inadequate for charging electric vehicles because the energy capacity I need has to be in excess of what we are using to run the home. We do a shit job of building efficient homes, so things like cooling your home in the heat of Southern California can easily run 5 kW for much of the day. The fantasy of a 13 kW array is that it is a 13 kW array. Well, it isn't. My peaks are around 8 kW on average. I reach 10 kW during a very narrow window of time in the year, the rest of the time this is what it looks like (actual data):
https://i.imgur.com/LTMNDO1.png https://i.imgur.com/LTMNDO1.png
So, if you have two electric vehicles, an air conditioning system pulling 5 kW and other normal things in a normal home, well, this system is not adequate. I would have to probably install a 35 kW system to service all of it.
How many people are going go install 30+ kW systems on their homes to join the electric vehicle revolution? Even better: Most roofs simply don't have that much room. Add to this the fact that solar viability diminishes as you move north and you quickly realize solar isn't a magic-wand solution.
And, of course, now comes the problem of only having energy available while the sun is up. Which means you probably want a massive battery bank to store it and use it to charge your vehicles at night. AC to DC power conversion is in the order of 80% efficient. Charging, depending on technology, is about the same. So, you go from solar to charging and probably store about 65% of the energy you collect. Then you have to charge your vehicle at night. You have to convert it one more time. This means another 20% to 30% efficiency hit. In other words, the store-and-forward model is likely in the 50% range for energy (panel output to energy level in the car).
Physics is really heartless about this stuff. Most of the people (and politicians) pushing this stuff never bother to do any math, and, if they do, they conveniently ignore it.
To answer the obvious question: No, I am not going to upsize my system to 35 kW. That would be ridiculous and, in Los Angeles County, the building permit and regulatory issues you'd run into to put such a system on a home that more typically ends-up with a 7 kW system would be insane beyond description.
EDIT:
One of the reasons for which my array peaks out at 8 kW is that the Los Angeles County Building and Permit department would not allow me to tilt the array to the optimal angle (about 34 degrees if I remember correctly). The array was built with the approved tilt angle of ten degrees. This is due to what I am going to call arcane regional planning rules and other issues. They also made me install --no bullshit-- 64000 lbs of concrete footings and design the array and structure for 200 mile per hour winds. The entire experience was beyond surreal and ridiculous. Want to talk about "clean" energy? Care to guess the CO2 contribution of making 64,000 lbs of concrete, which should include all the processes required to procure the raw materials, transport to the plant, make the concrete, mix it, load it into massive trucks, deliver and install it? I haven't done the math, but I would not be surprised if it exceeds the environmental benefit of having "clean energy" at home. Live and learn.
- matthewdgreen 5y agoYou shouldn't be installing a 30KW system, but it's entirely reasonable for utilities to deploy 30KW of utility-scale solar on your behalf. According to 2021Q1 numbers that's $23-26K of capital investment. Plus I imagine with some logistical effort the utilities can deliver it to wherever your car is parked during the day, rather than bothering with a second set of batteries. Not sure why we're comparing utility-scale nuclear to artisanal home solar power.
- rsj_hn 5y ago> They also made me install --no bullshit-- 64000 lbs of concrete footings and design the array and structure for 200 mile per hour winds. Wait, what? Can you elaborate on why this was necessary? Thank you also for the useful data.
- robomartin 5y agoThe system is built on what they call a ground-mount structure. In other words, it isn't on our roof. The entire thing is supported by eight columns. The county decided we needed over a cubic yard of concrete under each column. By the time we did the math and the realities of digging holes (hint: contractors don't use Solidworks to dig holes), the average footing worked out to about 8000 lbs of concrete. Once the plan checker got his mind set to these dimensions it was over. There was no way to convince him to apply any kind of logic to it. He quoted stuff like the 200 mile per our wind rating (also ridiculous) we had to certify the structure for. I even hired a nationwide civil engineering firm to try to apply pressure for a change. No. he would not allow us to proceed unless we went with his requirements. It went beyond that, they issued insane fire rating requirements for the entire thing. My guess is that the project went $50K over budget because of these guys. Which means it will never pay for itself...ever. I would have done a million times better if I burned half the cash and put the rest on Bitcoin (which, at the time, would have felt like burning it). So, it is a beautiful system but it was a complete waste of time and money. It made me wonder about the overall realities of solar in practice. If I knew then what I know now I would have never moved one finger to install solar. BTW, I have neighbors with solar regrets for different reasons. One has to wonder.