Monthly Archives: September 2010

White House solar panels: some historical behind-the-scenes info…

Interesting behind-the-scenes article from Tom Gocze, the person who installed the White House solar panels for Carter admin. He writes weekly for a Bangor Maine newspaper and has a business building huge tanks which can be used for hot water storage from solar or wood burning heating systems.


Huge Solar Hot Water Tanks

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Sudbury Valley School: Let it rain!

Today I was doing carpool pickup for the Stow “Sudbury Valley School Express” as I like to call it. Three kids under 8 to find. Good luck to me! 🙂 Older kids at SVS (and I’ve seen some 5 years olds!) can be trained pretty well to be ready at a certain time and wait at/near the parking lot or barn for their parent pickup, but for many parents of younger kids… we gotta go find ’em (and help them sign-out, if they need/want help).

And sometimes it goes pretty smoothly. Yeah right! If I’m lucky, 2 of them are in the same room and I quickly bump into someone else who has recently seen kid #3. But today I only found #1 quickly, #2 was not in any of the “usual” places, and #3 was last seen in the barn. And darn, it was raining! And once I found #3, now where did #1 go off to! Hilarious! 🙂

Actually, the raining part was pretty fun to be honest. I was in the right mood I guess. And I was wearing appropriate clothing and got to enjoy any number of kids playing joyfully in various degrees of soakingness out in the downpour. Some seemed mostly dry to start, so they had probably made the calculation that it was now OK (at ~3:45pm) to brave the rain since they’d be getting picked up soon and wouldn’t have to spend several hours shivering in wet clothes. But really, if someone gets cold, I can guarantee that warm/dry borrowed clothes would surely be offered up from any number of sources… other kids and staff.

And plenty of kids keeping inside too, of course. Or hanging out on one of the many covered porches — a nice combo of inside and outside for a warm rainy day. And I was lovin’ the piano music pouring out of the open second floor window. Love this place! Who wouldn’t!

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Filed under alternative education, Sudbury Schools and Sudbury Valley School

The miracle of garbage collection

I’m talking about for computer languages. And I guess I could include any number of miracles, that really makes using many programming languages like PHP as easy as speaking english (at least within the realm of the sorts of web application tasks I often encounter…)

– garbage collection / automatic memory allocation
– flexible typing / conversion / etc
– interpreted languages
– debuggers with stacks, stepping, breakpoints, etc.

Not having to worry about low-level hassles that these things take care of automatically makes things more fun for me. I know that there are others who love doing the above, and actually create those tools and make them better. Thank goodness for people like that. A lot smarter than I!

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contrarian and conflicting green priorities? not really.

1. People sometimes think it’s best to use spray foam and exterior foam to insulate really well. I think there are some cases where that is true, but not necessarily. It’s not only that it is more expensive, but also in many cases I don’t think it is good building science/physics/durability. Hence, not green. (link to old post) Generally I think cellulose is the way to go.

2. Sometimes it seems like using particleboard vs plywood is better or TJIs (wood i-joists) vs dimensional lumber (2x8s, 2x10s) are better. Smaller trees but more glue. But here’s a great article about that too. Again, local economy, susceptibility to mold, plus building practices don’t make it a no-brainer.

The basic advice I have is… when in doubt, go for local and the more labor intensive option. Better to put people to work than spend $$ on more expensive products. And when still in doubt, ask your Q at the Q&A section at Great info and great out-of-the-box green thinking happening over there!

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Put solar back on the white house? No brainer!

“It’s been almost a generation since solar panels President Carter installed on the White House roof were removed during renovations. Now, a group of climate activists armed with one of the original panels are on a road trip to the White House to get President Obama to put them back up.”

article here…

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“Want to end dependence on gasoline, forever? We’ll need to replace most cars and light trucks with electric vehicles (EVs). It’s doable, but not with today’s electric power grid.

Here’s the math: The United States burns 138 billion gallons of gasoline annually. The existing fleet of cars and light trucks averages about 25 miles per U.S. gallon, which translates to 3.5 trillion miles of driving.

With today’s technology, small electric cars and delivery vans get about 3.5 miles per kilowatt-hour. To do 3.5 trillion miles, we’d need to use about 1,000 terawatt-hours of electric energy (a terawatt is a trillion watts). Today’s U.S. power grid sells about 4,200 terawatt-hours annually, so to meet the need we’d have to boost electricity production by about 25 percent.

However, driving an electric car 50 miles costs less than 15 kilowatt-hours, and that can be generated daily with a 2.6-kilowatt (kW) photovoltaic array costing, at today’s prices and incentives, about $9,000. (That’s 2.6 kW times $5 per watt, less the 30 percent federal tax credit. It costs less in competitive markets and states with good local incentives.) Think of getting a lifetime supply of gasoline for $9,000. With 15 kilowatt-hours a day, you could drive a car 19,000 miles a year. The system will pay for itself in three or four years in saved gasoline. After that, you drive the car, and every subsequent EV you may own, for the cost of insurance, tires and wiper fluid.

Americans own more than 250 million passenger vehicles, an appalling number for a population of 300 million. We have about 100 million households. Assuming two cars per household, a gasoline-free future is possible, providing each household has access to the equivalent of 5 kW of solar or wind power, either on site or located remotely. Double that distributed power source, and most household electric needs are covered, too.

Under this scheme, does it make sense to package solar modules with new electric vehicle sales? You bet it does.

–Seth Masia, Solar Today, Sept/Oct 2010, page 18

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Massachusetts solar is hot!

You might think that solar energy is not for Massachusetts or New England. You’d be wrong! Even though the sun is not as strong here as in other parts of the country, the electricity (and other energy) prices here are quite high, so that makes solar quite a good deal. And this is even before considering tax credits and SRECs. Depending on how quickly you think energy will increase in price, the dollar payback can be quite quick on a PV system.

And if you are a DIYer, I suggest you check out and the SolarHeat discussion group. Lots of amazing info and people to ask questions of.

So… go solar! And for local inspiration in Massachusetts, go visit someone who already has solar electricity (photovoltaics), solar thermal heating, or solar hot water heating. A good way to find such people is the NESEA green buildings tour list. CLICK HERE

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Yes, our electricity bill was only 68 cents, but…

Yes, our electricity bill was only 68 cents thanks to our solar electric panels, but… what I am personally more interested in is the KWh. So here we go! (We have a grid-tied PV system. 30 panels. 6.9 KW total.)

It’s actually a little tricky to figure out how many KWh we actually used because the way our particular utility-meter works (maybe it’s different for some other people) is that it can’t show/know how much electricity we used straight off the PVs. It only knows what we took from the power plant, and what we sent out to the plant/grid.
(It shows 2 numbers rather than just 1 as a house without solar-electricity panels does.)

Anyway, here’s the math:

Available to use = Actually used

Available to use:
a) The 875 KWh we generated (from an avg of July and August from our monthly PV stats as reported by our Enphase microinverters — they DO know what they are doing, unlike the meter!)
b) The 231 KWh we used from the power plant (from our bill)
TOTAL: 1106 KWh

Actually used:
a) 714 (used by someone else out there on the grid… as reported by our bill)
b) X (or… “smiley face” in honor of Francis “Sandy” Hill who liked to use little drawings of clouds, squirrels, etc. instead of X, Y, Z, greek letters, etc when doing math in his lectures.)

Available to use = Actually used
1106 = 714 + (smiley face)
(smiley face) = 392 KWh

OK, so we used 392 Kwh. Not bad! Especially considering our silly heat pumps have (as far as I can tell) had on the coil “pre-heater” which pulls approximately 50W 24/7. So we can subtract roughly 36 KWh (50 * 24 * 30 / 1000) from this in future bills I hope. So that’s ~350 KWh per month. And that is not only electricity use for lights, computers, etc. But also:
2. cooking (our stove is electric)
3. AC
4. hot water for showers, etc (our hot water heater is electric… soon to also be a heat pump too)

Vs (to get a point of reference as to what is typical… again, not usually including cooking or hot water I imagine… since most people will use natural gas and such… which, unless you are using a heat pump with electricity is a good idea):
“The average residential electric bill in Wellesley is for approximately 950-kilowatt hours”

Anyway…. Go negawatts! That’s what is really cool. More so than our $0.68 electricity bill.

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On Heat Pumps. Geothermal and otherwise

Look people, heat pumps are not that great! Ok, they are kinda great, but here’s the thing… they still run on electricity, ya know? Here’s the math:

1. Making electricity at a power plant: Three units of fossil fuels in, one unit of electricity out.
2. Then it flows to your house. One unit of electricity in (to the heat pump), and THREE units of heat come out. (assuming a COP — coefficient of performance — of 3 … if you are lucky)

Notice something?


Yes, you could have just burned some natural gas or propane in a 96% efficient propane furnace right at your house and still been at ~3! And especially (in the case of geothermal) have saved yourself a whole boat load of money in up-front costs!

Now, it’s true… you do get AC “for free”.

And it’s also true… heat pumps now work perfectly fine, even in New England and Canada (Air source heat pumps even work fine down to -5F nowadays). But you’ve still got to remember that the problem that remains is the power-plant (in)efficiency of ~33%.

Now, sure, if you…
1. Live in a part of the country where there is lots of hydro-electricity (Montana?)
2. Pay a little extra on your electricity bill for renewable sources (in MA, anyone who gets their electricity from a non-municipal company can do this) (e.g. GREENUP)
3. Have solar-electricity (PV) panels on your roof
… then you can feel a little better about using electricity instead of propane or whatever.

1. I do think there is some merit to “site-generated” electricity (PVs)
2. And using electricity does in theory mean you have perhaps more stable prices
(than propane,etc).

So OK, get excited about heat pumps I guess. But stick with the air-source rather than the ground-source (geothermal). The added expense of the ground-loop installation is not worth it from what I have heard from those who have been involved in projects where they have been installed. Ask Marc Rosenbaum who in recent years seems to shy away from specifying the ground-source.

What would be better? Well… if you don’t live in a particularly urban area, then I think a efficient wood stove or pellet stove might be better. People will argue about that… “too much particulate pollution” and “if everyone used wood we’d have no more trees”, but I think both are probably not quite right. Especially if we got our act together in the US (like Europe) and had more options for gasifying wood stoves / pellet stoves / wood-chip stoves.

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