I was hoping someone would catch that 
. You are right about the reactive losses, which engineer_comp_geek mentions above. I think the resistive losses are generally greater, except for underwater links, but that’s starting to get beyond my level of knowledge.
Regardless, HVDC really is the right choice once you get to the ~1000 km range. And it’s a proven concept, in use for decades. But the US has neglected its grid.
Thanks, Elf.
Thanks.
Edison vs. Westinghouse.
We cannot allow a pylon gap!
IANA EE, much less a high voltage power specialist, but IIRC …
At serious AC voltages “skin effect” gets significant even at power transmission’s comparatively low frequencies. Which multiplies the burden of AC sizing for peak voltage / amperage but only delivering the RMS value. Now they’re dealing with much of the bulk of the conductor carrying a small slice of the load while all the charge “crowds” into the relatively thin perimeter.
When high-temperature super-conductors first became science news, I recall a discussion about creating a storage battery which was essentially a giant semiconductor donut - electricity would be induced into and out of the device as required. someone suggested a coil about a quarter-mile diamter could store enough power for a small city, but would have to be built into bedrock so it didn’t blow itself apart when fully charged. Another possibility would be a small device in each household, but woe unto you if your liquid nitrogen refrigerant evaporated and a couple of megawatts suddenly turned to heat in your basement.
Apparently, one cubic meter of water can store 90kWh of thermal energy (more than most EV batteries). I wonder why there are no solutions like this for residential use.
Also, what are the challenges of bringing to market a high-temp thermal mass, such as the one discussed at this university site: Energy3?
The one shown there can also (allegedly) output electricity via a turbine. Seems nifty.
That’s about right. 1 m^3 of water is 1000 kg, and 1 kg water takes 4184 J to heat 1 C. For the full 0-100 C range, that comes to 418.4 MJ, or 116 kWh. You’d want a little margin on the endpoints, so 90 kWh is pretty reasonable.
Depending on how you used the thermal mass, you might get a lot less. If you’re just using it to chill water used for air conditioning, then the effective range might be more like 3-20 C, which brings it down to 20 kWh. Still, water is cheap, so you can use a lot more. And maybe you could add something to the water to bring down the freezing point a bit. Things are better on the hot side due to the difference between comfortable human levels and 100 C.
The Energy3 device looks interesting but I don’t think I would design it that way. Ideally, you want Carnot to work in your favor: that is, you can achieve greater than 100% heat pumping efficiency when the temperature difference is low. Their unit runs at 900 C so I’m certain it just uses resistive heating. But at the same time, 900 C isn’t very hot as far as turbines go, and so their efficiency there is only 22%. And if you use it for hot water, you also don’t get an efficiency multiplier.
Consider instead a system with two large water tanks. A heat pump goes between them, heating one to 97 C and the other to 3 C. It has an external ground loop in case one of the reservoirs hits its limit. The heat pump is efficient because its working range is going to stay in the ~40-94 C range. From there you can both cool your house and make hot water, so Carnot is doing double duty.
You do need larger reservoirs this way, since the temperature range is smaller, but it feels like this will be more efficient than the Energy3 system. For straight electrical needs, stick with a battery–that’s by far the most efficient system there (of course, you should time your heavy electrical loads, like the dryer and dishwasher, with the low rates).
Well, that’s just my intuition. The Energy3 people I’m sure have modeled their concept. It’s good to see that at least some version of the concept is out there.
Agreed that looking at the full picture is the correct approach, but assuming use of batteries with current technologies you also have to add in the cost of manufacture (energy) in producing those batteries. Lithium mining is expensive as well, and recycling also uses a lot of energy.
The current level of Li production is way short of that needed to replace ICE powered transport, and only 5% of batteries are recycled.
How does that compare to the manufacturing cost of an ICE engine, transmission and so forth?
EVs still have motors and a lot (most?) have a mechanical transmission. Fuel tanks are not complex!
ICE engines etc. have very long lives, recycling is low-tech and most of the materials are very common.
I can’t discuss your state, but here in Louisiana my annual average electricity consumption is 2000 kWhr. My multi year average in August is 2800 kWhr. My second highest months are July and January at 2500 kWhr. My cost per kilowatt is $0.085/kWhr. 3000 sq ft house. We keep our windows closed and the thermostat set at 78F.
I certainly can see how Dr. Strangelove got his numbers, but I just don’t understand how the referenced site got theirs. Those average consumption numbers look very low for all the states I am familiar with. Unless those numbers refer only to consumption for heating/cooling (which the site does not indicate), they are quite low in my experience. It just doesn’t match my experience either now or twenty-five years ago when I was living in a 1700 sq ft home.
Do you mean your monthly average electricity consumption is 2000 kWhr?
Yes it is. Median in Aug is 2900 kWhr. Median in April is 1600 kWhr.
is there any reason you need to keep the water liquid? Even just barely freezing it gives you the latent heat of fusion, which is considerable (on the other hand, the latent heat of vaporization is even more so, but pressurized steam can be inconvenient).
3000 ft^2 is a pretty big house. This site says the average home size in Louisiana is 1786 ft^2. So you’re using about 50% more energy than the average while your house is 70% bigger. That seems pretty reasonable.
It would definitely be nice to use the latent heat of fusion, but I think that’d present some engineering challenges. Ice doesn’t conduct heat very well, so as soon as it builds up on the cooling pipes, it’s going to reduce your ability to chill the reservoir further. And it would prevent the water from being pumped around, say through a heat exchanger.
Maybe you could mechanically remove the ice, so it floats to the top of the tank in chunks, while the bottom stays liquid. And you could use a secondary fluid to move the heat around to chill the air. So there are solutions, they just start to get more complicated.
Your ideas are intriguing to me and I wish to subscribe to your newsletter.
It’s easy for me to come up with ideas that I don’t have to implement 
. Really, most of what I come up with is based on a handful of principles. Unit analysis, Newton’s laws, Carnot, etc.
Thinking on it a bit more, what I described above though is not inherently more efficient than independent hot/cold systems. To pump a certain amount of heat, it takes energy proportional to the temperature difference. So two loops of, say 5-25 C and 25-95 C are the same as a single 5-95 C loop. Where you gain though is that you need only a single system, so all the various inefficiencies (pumping losses, etc.) would be roughly halved. And roughly half the cost, too, since there’s half the amount of equipment.
Looking around a bit, it does appear that systems along these lines aren’t totally unheard of for residences. Water chillers are available at least, and I see some talk about hot water systems as well. They just don’t seem to be that popular. I’m guessing it’s the same deal as solar and so many other things: people don’t like upfront costs, even if it easily pays for itself over a few years. And people don’t know how to judge the value of efficiency improvements when buying a new house, so existing homeowners are less inclined to install them.
Indeed. The simple truth is that all electric power that is generated is fed into the grid, and all electric power that is used is taken out from the grid. At all times, the sum of power generated must equal the sum of power consumed. If you pay your electricity supplier for green power, then this does not mean that “your” power actually comes from green sources; it’s not possible to assign power used to specific power sources. Instead, it simply means that the supplier who sold the green power is feeding green power into the grid - not necessarily at the same time, though, but averaged over longer time periods.