Visualizing The U.S. Electric Grid

This is awesome! You can see existing transmission line and power plant locations, “sources of power” for each state, proposed wind and solar transmission lines, etc. Wow! LINK

My only question is the accuracy, but I didn’t look closely to see what the source of all of this info is. For instance, the generation mix is quite a bit different than what I received in my National Grid bill each month. See that that here. For instance: 28% nuclear vs a supposed state average of 12% (from the NPR page)

Observations of a Sudbury school volunteer

This is a nice Sudbury Valley explanation that comes at it from a slightly different angle than I’ve heard before. The author volunteers at a Sudbury school one day a week, and is the parent of a student. But his main job is at a K-5 after-school program. LINK TO ARTICLE

A few quotes:

“Far from being little lord-of-the-flies centers where mere anarchy is loosed, Sudbury schools are communities that are run by the students, for the students. There are plenty of rules, but they are neither arbitrarily imposed from on high, nor artificially “decided on”…

“Not even when one kid stormed off in anger did anyone so much as look at me as anything but another player. ”

“I’m an empiricist too, and I speak from experience. The kids I work with at the after-school program aren’t miserable. They haven’t had their love of life stamped out of them, or their creativity. This isn’t because I’ve imported as many Sudbury-esque features into my class as I can adapt, but because the kids come from families who love them to go to a school run by teachers who care, and because, well, they’re kids. But …. ”

How many showers can we dish out until the sun shines again?

Until we get real and install some better solar hot-water heating — with a 1500 gallon unpressurized drainback tank (we’ll see!) — we will have a 105 gallon Rheem Marathon electric hot water heater being heated by a Geyser heat pump hot water heater.

My question is how many showers can be had when the sun isn’t shining (due to nighttime or clouds) without having to turn on the heat pump and use non PV electricity. Time for some algebra!

First the assumptions. And let’s make some guess at a usage pattern rather than really doing algebra and solving for n (when n=number of showers)
1. Hot water temp on the hot water heater set to 130F
2. Showers will have H20 Kinetic 1.5 gallon/minute shower heads
3. There will be some mixing with cold water since 130F is too hot for a shower. But let’s just be conservative and say we use a full 1.5 gallons per minute.
4. Pretend like we know the incoming well-water temp (let’s say it’s 50F)
5. Pretend there is no heat loss thru the tank walls and no significant temp stratification. (The Marathon is pretty well insulated…)
6. Timer that switches the HW heater off during night-time hours to prevent slipping into non-solar usage.

Ok so, let’s see what the tank temp (assuming no stratification) is after 2 10-minute long showers is (as a guess of what the tank might be able to handle)

So that’s… 1.5 gallon/minute * 2 * 10 = 30 gallons of outgoing 130F water getting replaced by 50F
So in the tank we will now have
30gallons * 50F
75gallons * 130F
which is an average of (30*50+75*130)/105 = 107.14F

And I think that’s still warm enough for a short shower, so given my conservative numbers, we could have several people taking showers before the sun comes up on our PV array without having to pay for a full-priced KWh from our currently non-net-metering electric company.

I think. And we will have to try to run things like dishwashers and washing machines during the day probably/ideally.