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[DSLF] Digest Number 887
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There are 3 messages in this issue.
Topics in this digest:
1. Re: energy savings...
From: Steve Davis <w2sgd@juno...>
2. Re: Night quotes
From: Brad_Bergstrom <bergstrm@valdosta...>
3. Re: energy savings...
From: "John L. Liebenthal" <jll@srv...>
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Message: 1
Date: Mon, 30 Dec 2002 09:48:46 -0500
From: Steve Davis <w2sgd@juno...>
Subject: Re: energy savings...
James Benya wrote:
> BTW, dark sky fans, the difference between an average
> auto and SUV would power about 50 average street lights.
Taking a few cars off the road is a good idea -- retiring a whole bunch
of streetlights.
Hit it, Cliff! The Haas theme song: "Cars come with self-illuminating
devices."
See "LP Basics" > "Light Efficiency" on my web site.
Steve, w2sgd@juno...
Dark Skies for the Adirondacks
http://www.timesunion.com/communities/darksky
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Message: 2
Date: Mon, 30 Dec 2002 15:20:52 -0500 (EST)
From: Brad_Bergstrom <bergstrm@valdosta...>
Subject: Re: Night quotes
One of my favorites (and so succinct):
"Technology hath vanquished the night!" Edward Abbey
----------------------------------------------------------------------------
Brad Bergstrom, Ph.D., Professor TEL 229-333-5770 /-5759
Department of Biology FAX 229-245-6585
Valdosta State University e-mail: bergstrm@valdosta...
Valdosta, GA 31698-0015 Home: 229-333-0743
Home Page-- http://www.valdosta.edu/~bergstrm/
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Message: 3
Date: Mon, 30 Dec 2002 15:12:37 -0700
From: "John L. Liebenthal" <jll@srv...>
Subject: Re: energy savings...
At 03:27 PM 12/29/02 , you wrote:
>My math works out this way:
>
Right. And we can try it this way.
34*mph/mpg=kw fuel energy consumption rate because gasoline has about 34
kw-hr
of energy per gallon
46*mph/mpg=hp fuel energy consumption rate
So a Chevy Tahoe 4wd at 60mph getting 17mpg [the EPA highway rating] burns
120kw of fuel [kwh/hour]
A Honda Civic hybrid at 60mph getting 51mpg [the EPA highway rating] burns
40kw of fuel
The difference is 80kw fuel energy rate.
James Benya's typical building uses 1.5w/square foot. Based on the US average
electrical power plant efficiency of 1/3, it is burning 4.5w [0.0045kw] of
fuel
per square foot. On this more system-oriented basis, driving a Civic hybrid
rather than a Chevy Tahoe 4wd would light about 18000 square feet of
building.
If one set up the engine to drive a generator, one could get lots of power,
because only about 7% of the power goes to move the vehicle on average.
If the electric power source were a current gas turbine plant at 50%
efficiency, that would make the building square footage about 27000.
As to global warming [CO2], <http://www.fueleconomy.gov/>http://www.fuel
economy.gov/ from which my numbers come lists the emissions for 15000 miles of
driving as 4.1 tons for the Civic Hybrid and 12.9 tons for the Tahoe [based on
combined mpg]. The difference, 8.8 tons per 15000 miles comes to about 1.2
pounds of CO2 per mile or 70 pounds per hour at 60 mph.
Power from coal or gasoline puts out about the same pounds of CO2 per fuel kwh
[lb/hr of CO2 per fuel kw] and natural gas is about 2/3 to 3/4 as much.
The other pollutants are not so easy to figure: too many variables. Sorry.
Maybe the bottom line here is that big vehicles are expensive, dirty, and they
kill lots of people. Outside of that, people think, they're fine.
Time to get back on topic?
Jack Liebenthal
Victor ID
208/354-8001
more at
<http://www.srv.net/~jll/jackjean.html>http://www.onewest.net/~jll/jackjean.
html
[Non-text portions of this message have been removed]
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