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Comment Re:Shouldn't have to run oil by rail (Score 1) 199

> as evidenced by the enourmous growth in PV generation as well.

No, that is evidence of government subsidies, and laws requiring them to charge a extra fee to customers directed to provide more clean energy.

The rate of growth has been enhanced by subsidies, but even without them, the industry would still be undergoing very rapid growth as costs have come down an order of magnitude.

Comment Re:Shouldn't have to run oil by rail (Score 1) 199

I love it how the goal-posts keep on moving - and how a solution has to solve 100% of the problems or it is a complete fail. Why can't a solution simply be a step in the right direction? Or a solution that works for a very large portion of the population?

On to your arguments:

Tesla will be able to get you from Virginia to Tuscon and Colorado via their Supercharger network in the next month or two. St Louis will be accessible by the end of the year.

Will it be as fast as a gas/diesel vehicle? No, but for cross-country road trips just rent a Prius if you're aiming for maximum speed and efficiency. And as many people will attest, actually slowing down an enjoying the scenery can enhance the road-trip experience. Or simply use a plug-in hybrid - all your local miles will be electric - and you can still have your road trips. The vast majority of your annual miles are within 40 miles of home - low hanging fruit.

As far as 18-wheelers: Most of that cargo should be moved to rail leaving short/medium haul trucking. Short-haul trucks can be electrified, medium-long haul can use natural gas and/or fuel cells. Railways can also be electrified (most trains are simply diesel generators that run electric motors, anyway). Aircraft are a tough nut to crack - bio-fuels are probably our best bet there in the near term.

And as far as power plants go - we need more low-carbon power plants regardless of whether or not we electrify the fleet. But a huge portion of the fleet can easily be powered without substantial changes to the electrical grid.

Comment Re:Shouldn't have to run oil by rail (Score 1) 199

PV can't become the dominant source without some fundamental change.

I would never claim otherwise. My math is for small residential installs. For larger installs the cost is already half - they are getting installed for $2/watt.

As far as "flex", sure they can flex, but of course the cost to run those plants goes up the more you flex them. There's a reason why all plants aim for 100% run-time. Similarly you can "flex" PV by simply reducing power output. Or by adding storage. Both of these will increase costs, but as we can see, costs are already reaching parity with conventional generation sources - as evidenced by the enourmous growth in PV generation as well.

Comment Re:Shouldn't have to run oil by rail (Score 1) 199

If/when solar becomes big enough so that it overwhelms the grid during the day, like I said earlier, we can easily shift charging to daytime from night. There are a lot of industrial loads that run at night to take advantage of low off-peak rates that I'm sure would prefer to run during the day as well.

Low interest loans are available that let you take advantage of solar with low money up front - you can easily roll the cost into your home loan.

At some point we will have enough solar so that storage is required, but by then costs are projected to be low enough to make it worth while regardless.

Solar will likely be a dominant energy source in the future as costs fall unless something better comes along. But still, it will be far from the only source of energy. My primary point is that solar today can provide energy for less than the cost of gas for the most efficient car on the market - and it takes a lot less solar PV than one might expect.

Comment Re:Shouldn't have to run oil by rail (Score 1) 199

Getting enough solar PV so that grid storage is required to make use of it is not going to happen overnight.

By the time you get to that point you'll have enough used EV batteries from old EVs to use for static grid storage for load shifting and the cost of solar PV will decline even further. The rest of the time, you'll plug in at work to charge instead of plugging in at home.

Solar PV will never be the sole energy source except in localized areas. It will always be more cost effective to use some other source of energy to get the rest of the way without a ton of storage, but instead of fossil fuels and all the drawbacks that come with burning those, perhaps it will be methane captured from landfill, sewage treatment plants, etc (not to mention whatever other renewables make sense in the area such as wind, geothermal, etc).

Comment Re:Shouldn't have to run oil by rail (Score 1) 199

Problem with solar is that its hard to run cars on it. Fix that, and we're walking in tall cotton.


Assuming 3 kWh / mi (less efficiency than your number) and driving 12,000 mi year for a consumption of 4,000 kWh / year.

In Phoenix, Arizona (one of the sunniest areas of the USA, 1 kW of solar PV will generate about 1600 kWh / year (data from PVWatts)
In Seattle, Washington (one of the least sunny areas of the USA, 1 kW of solar PV will generate about 1000 kWh / year.

So in Seattle you need about 4 kW of solar PV and in Phoenix you need about 2.5 kW of solar PV. Solar PV is only around $4 / W or less for a residential install (without tax credits rebates or other subsidies) and will last at least 20 years. So for 20 years of driving or 240,000 miles, your energy will cost between $10,000-$16,000, or about $0.04-$0.07 / mile which is cheaper or equal to the cost of fueling a 50 mpg Prius!

Conclusion: Driving on solar power is possible today and cheaper than gasoline!

Comment Re:solar pannels are low voltage (Score 1) 579

I can imagine that there are way to keep it safe until it reaches the convertor (which converts it to AC and ramps up voltage to 110 or 220 depending on your region).

Yeah, they are called micro-inverters. They convert the 25-40V DC from each panel into 240V AC (or 208V if on 3-phase) in a small box at the panel. Then you run 240VAC down from the roof into your utility panel.

When grid goes away (like when a firefighter flips the main circuit breaker or pulls the meter), the only electricity you have left is 25-50VDC at each solar panel which isn't going to hurt anyone.

Comment Re:Peak demand time (Score 1) 579

FWIW, the peak demand in California typically occurs about 6PM, well after most PV installations fall off the grid (peak production from solar occurs at 12noon and solar output is largely gone after 3PM).

Peak demand varies depending on the time of year.

In the winter, peak is around 7-8pm.

In the summer, peak is around 3-4pm. Note that "solar noon" in the summer is actually around 1pm thanks to daylight savings, not 12pm.

Solar doesn't help at all with peak shaving in the winter, but it does help a lot in the summer. Peak grid demand is always in the summer due to air conditioning load.

This implies that grid tied PV solar without some sort of power storage is NOT an effective source of peak shaving.

Again, depends highly on the time of year and weather conditions. But yes, some grid storage would be very effective at eliminating more of the peak, but it wouldn't take much, just enough to shift a small portion of the generation a couple hours later.

Comment Re:How's that supposed to help? (Score 1) 148

See? By varying load and the magic of Ohm's law I can now tell voltage changes from resistance changes.

Very cool way of detecting circuit impedance. I guess the trick will be figuring out at what point do you say "hey, the resistance is changing too much, let's just slow down some amount" or "hey, the resistance is changing too much, I better shut down immediately".

This also depends on Tesla being able to accurately control exactly how much current is being pulled as well.

Comment Re:How's that supposed to help? (Score 1) 148

They already do that, by monitoring the voltage drop when the load is applied. That doesn't cover all cases though, because fires are more often caused by high resistance or intermittent junctions. If you get say a 5% voltage drop because of wire resistance it's probably no big deal because the heat dissipation is spread out over the length of the wiring. A similar drop caused by a poor junction might glow because it's concentrated in one spot. I believe that poor junctions often exhibit short term fluctuations because they're loose and intermittent, and that's the additional thing that this software mod looks for.

The real trick is distinguishing short term fluctuations that are caused by a flaky connection from some short term fluctuations caused by other big applicance turning on and off (you know, like an electric range/oven/water-heater/air-conditioner/pool-pump/etc)...

Arc-Fault-Detection may pick up some of the failure modes that lead to these issues, but when you are pulling 240V/40A to charge the car (9600W) It wouldn't take much of an issue to melt down a receptacle. And it won't pick up a high resistance connection in an outlet. A 3V drop in a small area (120W) probably more than enough to burn up a receptacle in the time it takes to charge the car but would otherwise be completely normal in most charging situations.

The proper fix here is to install a thermoswitch in the plug that triggers either a significant reduction in charge current, or shuts down charging completely.

Comment Re:Tesla can't fix the basic problem (Score 3, Informative) 148

You never see 208V measured from hot-hot in homes unless you have severe voltage sag - only 240V single phase with 120V measured from each hot to ground.

208V is commonly seen in commercial 3-phase situations, though, where you tap 2 out of 3 hots and each hot is 120V measured to ground.

Comment Re:Tesla can't fix the basic problem (Score 2) 148

Your typical house runs on 240V single phase power fed by two hots and a neutral.

Each hot is 120V, but shifted 180* out of phase, so you get 240V measured across both hots. The neutral handles any imbalance in power draw across the two hots.

Your typical household appliance runs on a single hot split phase at 120V and current is returned on the neutral line.

There's really no reason why we couldn't start using 240V directly these days and eliminate the neutral as long as all your appliances are able to run on 240V instead of 120V. Most modern electronics will run on both without issue.

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