re: wind and sun resources
31 dec 1997
todd flach wrote:
>it will never be a good idea to design a system for a single building
>which can provide all its energy needs if the building lies "within" an
>existing infrastructure for distributing electricity.
that depends on the rate structure, no? my last monthly peco bill was $47
for electrical service, a $10 "customer charge" just for the grid connection,
independent of energy usage ("based on the cost of maintaining the service
lines and meter at your house, the cost of reading the meter, and the
printing and mailing of your bill"), and another $37 for 350 kwh of
electrical energy, 114 of which heated water, at an average price of
13.4 cents/kwh. if peco raised their prices a bit, especially the customer
charge, or if i used less electricity, i might set up some kind of little
independent system. with a $15 customer charge and 200 kwh/month, and no
change in the rate/kwh, i'd be paying about 21 cents/kwh for the energy.
at $20 and 100 kwh/month, it would cost 33 cents/kwh...
(peco wants its customers to reimburse its shareholders for all of its
"stranded costs" over the next few years, eg the limerick nuclear plant,
which peco calls "a good-faith investment." administrative law judge
louis g. cocheres recommended that peco's request be rejected, in an
80-page opinion including these words: "this case is one $3.773 billion
dollar, intentional train wreck. it occurred because management of the
peco energy company insisted on trying to ram its $3.773 billion dollar
train down a brand new, untried set of legislative tracks through a
firestorm of opposition in a four-month time period.")
>if we did design pv systems for new building as you propose,
whoa. i never proposed that...
>it would be tantamount to junking the existing infrastructe. bad idea.
it's unlikely everyone will do this, but if some do, the customer charge
for everyone else goes up, which encourages more frugalistas to do it...
a vicious circle, like mass transportation. poor peco.
>ergo, a local pv setup for such a building will always need a supplement
>from the grid,
ergo? :-) a grid connection would still be useful for large loads or
greater reliability, although 2 or 3 inverters sharing the load can
help a lot with that.
>forget all the mess required for meeting grid power specifications when
>sending surplus power back to the utility.
the circuitry is simple. the mess is mostly just transient:
greed, bureaucracy, politics, and paperwork.
>...snippage re: a spurious claim regarding backwards-installed lamp dimmers
it warn't spurious, and the dimmers need to be _designed_ backwards...
i know about this stuff. i've been designing electronics for 30 years.
>>passive solar house heating can work wonderfully down south, with lots
>>of sun and mild outdoor temperatures.
>problem is, it only needs to work for 2-3 weeks.
that depends on the place. abilene, tx, has heating degree days in every
month except june, july and august. san antonio adds may and september,
and a sunspace may be a fine place for a year-round passive solar water
heater (eg some bare big fin collectors with a thermosyphon warm-water
loop to an insulated tank on the floor above) or a simple regenerator
for an licl absorption dehumidification and cooling system.
>you would design a large part of your house to optimize 2-3 weeks of
>heating in cold weather (20 - 35 degrees f, brrr :)).
i would, eg d) below (now a large inexpensive part of my house, without
the hot tub, yet), but someone in abilene might heat their house with an
8'x12'x8' tall sunspace.
>that same room you then have to vent, cover up and draw the blinds
>for 4-7 months of the year.
venting and overhangs aren't a big deal. neither are grapes, trumpet vines,
clematis, runner beans and so on. drawing blinds is not as helpful as
having some movable exterior shading. my sunspace has a $100 16'x32' piece
of 80% black greenhouse shadecloth on a 36' pvc drainpipe roller with
some rope loops to lower it over the outside.
>i lived in south texas for 20+ years, and in norway 10+ years, and
>i can assure you, the optimal home designs for these two extremes
>are not the same.
duh. so what? oops, i mean "how interesting."
>>a sunspace shaded and vented in summertime can keep sun out of house
>>windows and keep the house cooler in summertime...
maybe not needed in norway.
>>it's interesting to calculate the cost of saving vs generating a watt,
>>for small and large systems. someone here posted a part of a report that
>>estimated how much electrical energy could be saved by conservation, vs
>>new generation, for the same capital cost in millions. conservation won.
by a very large margin, at least 20:1, as i recall.
>i expect this comparison is qualified mainly by the assumed costs of fossil
>fuel and the pollution.
interest rates and the whole schmear, except maybe gulf wars.
>>in the small, would you
>>a) unplug 5x60 watt 1000 hour 55 cent 865 lumen incandescents
>>(300 watts, 4,325 lumens) and replace them with a sears hardware
>>fixture costing $9.99, including 2 40 watt 20,000 hour 2250 lumen
>>4' fluorescents (80 watts, 4,500 lumens), or
>>b) buy enough pvs to make
>>220wx8h per day, including installation, batteries and inverters, or
(to make up for using the 5 incandescents.)
>>c) put 1 or 2 $929 honda generators in your basement to supply 1,500 or
>>3,000 watts of electrical power in the winter, along with 25k or 50k btu/h
>>of house heat, while burning 0.23 or 0.46 gallons of gasoline per hour or
>more people will choose c) for mountain cabins in the future since
>they want 28" tv's, surround-sound stereos, microwave ovens and hot water
>to add to the rustic ambience of these places.
and space heat. one of these guys might be enough to power a neighborhood.
>>d) add a 32' wide x 12' deep x 16' tall plastic film lean-to sunspace
>>with 384 ft^2 of two-story floorspace (including a hot tub? :-) made from
>>$500 worth of standard commercial greenhouse components to the south side
>>of your house to collect 31 kw (106k btu/h) of peak solar house heat?
>...here in norway, there's too much snow for d) to work as prescribed,
maybe, although when plastic film greenhouses collapse under snow, it's
the curved galvanized pipes on 4' centers that give way, not the 0.006"
polyethylene film, and heating the greenhouse prevents that, if snow falls
at less than 3" per hour. my greenhouse sunspace pipes have the straight
sections in the ground, and the curved sections that are normally in the
ground are bolted to the eave of the house 16' up, which means it's very
unlikely to collapse under snow, or even a pickup truck parked on top.
>but with a sturdier design and materials, it works great. costs quite
>a bit more, but is probably still worth it.
you might want to use bayer's new urethane greenhouse plastic, which is
clearer and stronger than polyethylene film and has a 10 year guarantee.
it costs about 35 cents/ft^2, vs 5 cents. another option with a 10 year
guarantee is clear polycarbonate plastic made by replex, which costs
about $1.25/ft^2, but that only comes in rolls 49" wide.
>...a) is losing popularity because people want "high-quality" light, which is
>"warm" and "natural" as opposed to flourescents, which despite big
>improvements, are still perceived as giving "artificial" light.
i guess some people feel that way, and i've heard that 100 or 120 hz
fluorescent flicker interferes with the eye's saggital motion while
reading, and fluorescents put out about 15% more light for the same power
at higher frequencies, so i like the idea of "electronic ballasts," eg
50 khz tesla coils :-)
>hence, the new, small 12-volt halogen lamps are taking completely over.
>i don't know what the overall lighting efficiency is for these,
i think it can be a bit higher (maybe 20%?) than higher voltage versions,
because the filament can be smaller and thicker and hotter, but i guess
there are also transformer and wiring losses, maybe 15%... from the 1997
ge frosted incandescent, 685 lumens, 60 watts, ie 11.4 lumens/watt.
12 v halogen flood, 400 lumens, 50 watt, ie 8 lumens per watt.
4' warm white fluorescent, 3200 lumens, 40 watts, ie 80 lumens/watt.
metal halide, 1900 lumens, 32 watts, ie 59 lumens/watt.
high pressure sodium, 3600 lumens, 50 watts, ie 72 lumens/watt.
>...it's a difficult comparison, because people want soft, warm lighting
>in only parts of their rooms instead of high-coverage, saturating ceiling
>lighting like in the food store.
that's good for energy conservation. smart lights that turn on or
brighten when you get near them...