[sci.electronics] Fuel efficiency

jeremy@perf2.asd.sgi.com (Jeremy Higdon) (09/24/90)

In article <38776@ucbvax.BERKELEY.EDU>, cameron@janus.Berkeley.EDU (Mike Williamson) writes:
>
> What we've seen in the last 10 years is that, as a result of lower
> fuel prices, fuel efficiency has been neglected so that cars sold today
> have an average efficiency lower than they did earlier in the 80's.
> Greater fuel consumption and higher pollution levels may have resulted
> from this lowering of the average standard.
> 

This is not true.  The CAFE for the last three years has hovered around
27, the highest since such records have been kept.  Also, pollution
standards are in grams per mile, not parts per million, so that the
average Lincoln Town Car puts out no more of the nasty pollutants
than a Honda Civic.

jym@remarque.berkeley.edu (Jym Dyer) (09/25/90)

> Also, pollution standards are in grams per mile, not parts per
> million, so that the average Lincoln Town Car puts out no more
> of the nasty pollutants than a Honda Civic.
.-.
|T|his sounds wrong to me.  If a Lincoln sucks up (e.g.) 3 times
`-' as much gas as a Honda, it's got to deal with (e.g.) 3 times
    as much output.
.-.
|A|lso, is carbon dioxide considered a pollutant in this scheme?
`-' <_Jym_>

P.S.:  Then again, Lincolns have gotten smaller and Hondas have
    gotten bigger . . . :-)

cramer@optilink.UUCP (Clayton Cramer) (09/26/90)

In article <JYM.90Sep24150347@remarque.berkeley.edu>, jym@remarque.berkeley.edu (Jym Dyer) writes:
> > Also, pollution standards are in grams per mile, not parts per
> > million, so that the average Lincoln Town Car puts out no more
> > of the nasty pollutants than a Honda Civic.
> .-.
> |T|his sounds wrong to me.  If a Lincoln sucks up (e.g.) 3 times
> `-' as much gas as a Honda, it's got to deal with (e.g.) 3 times
>     as much output.

Because emission standards are in grams per mile, It means that the 
Lincoln has to produce LESS pollutants from a gallon of gas than
the Honda.

> |A|lso, is carbon dioxide considered a pollutant in this scheme?

No.  But then again, if it were, humans would need air pollution
control devices.
-- 
Clayton E. Cramer {pyramid,pixar,tekbspa}!optilink!cramer
If "right of the people" in the Second Amendment doesn't refer to an
individual right, what does it refer to in the First & Fourth Amendments?
You must be kidding!  No company would hold opinions like mine!

chucko@ptolemy.arc.nasa.gov (Chuck Fry) (09/26/90)

In article <JYM.90Sep24150347@remarque.berkeley.edu>
jym@remarque.berkeley.edu (Jym Dyer) writes: 
>> Also, pollution standards are in grams per mile, not parts per
>> million, so that the average Lincoln Town Car puts out no more
>> of the nasty pollutants than a Honda Civic.
>.-.
>|T|his sounds wrong to me.  If a Lincoln sucks up (e.g.) 3 times
>`-' as much gas as a Honda, it's got to deal with (e.g.) 3 times
>    as much output.
>.-.
>|A|lso, is carbon dioxide considered a pollutant in this scheme?
>`-' <_Jym_>

You found the hidden "gotcha" in the law.  Yes, Lincolns burning 3
times as much gas as a Honda put out 3 times as much carbon dioxide.

By most emissions laws, oxides of nitrogen and unburned hydrocarbons
(the nasty precursors of LA-type smog) are limited in terms of grams
per mile.  Carbon monoxide is limited to a percentage of total exhaust
gas.  Other exhaust gases are not limited at all, except by the
Corporate Average Fuel Economy (CAFE) Federal standards, which permit
gas-guzzling cars to be sold by those companies willing to pay the
surcharge.

In some sense, the normal end products of carbon dioxide and water are
not really pollutants, since Mother Nature generates and uses them.
It's true that excesses of carbon dioxide from combustion can upset
the natural balance of the biosphere, but so can waste heat from
nuclear processes.  Hydroelectric, geothermal, and solar sources are
not sufficient to fill our current power needs.  This is the price of
a technological civilization.

BTW, the electric cars so beloved by some merely relocate the
pollution problems to the electric power utility.  I feel it's better
to make the problems apparent to those who cause them.  If you REALLY
want to do something about smog, find a more efficient way to travel.
Or move closer to work.  Don't smog up the Grand Canyon to clean up
LA.

 -- Chuck Fry  Chucko@Charon.ARC.NASA.GOV  ...!ames!ptolemy!chucko

jeremy@perf2.asd.sgi.com (Jeremy Higdon) (09/26/90)

In article <JYM.90Sep24150347@remarque.berkeley.edu>, jym@remarque.berkeley.edu (Jym Dyer) writes:
> > Also, pollution standards are in grams per mile, not parts per
> > million, so that the average Lincoln Town Car puts out no more
> > of the nasty pollutants than a Honda Civic.
> .-.
> |T|his sounds wrong to me.  If a Lincoln sucks up (e.g.) 3 times
> `-' as much gas as a Honda, it's got to deal with (e.g.) 3 times
>     as much output.
> .-.
> |A|lso, is carbon dioxide considered a pollutant in this scheme?
> `-' <_Jym_>
> 
> P.S.:  Then again, Lincolns have gotten smaller and Hondas have
>     gotten bigger . . . :-)


It may sound wrong, but it's true.  Ever since 1972, measurement of
emissions by the EPA have been in grams per mile, not parts per million.

I do not consider carbon dioxide a nasty pollutant.  Carbon monoxide,
oxides of nitrogen, and hydrocarbons are nasty pollutants.

Ordania-DM@cup.portal.com (Charles K Hughes) (09/27/90)

Chuck Fry writes:
>BTW, the electric cars so beloved by some merely relocate the
>pollution problems to the electric power utility.  I feel it's better
>to make the problems apparent to those who cause them.  If you REALLY
>want to do something about smog, find a more efficient way to travel.
>Or move closer to work.  Don't smog up the Grand Canyon to clean up
>LA.

  It is my opinion that 1 100kwatt generator produces less pollution than
100 1kwatt generators.  Why?  Because that 100kwatt generator is on a 
stable platform getting regular maintenance.  Tell the truth, how many 
of you out there have your car checked 3 times per day for problems?
Once per day?  Once per week?  Once per month?
  No, electric cars do not simply transfer the pollution problems to the
power utility.  They reduce pollution (both in terms of untuned engines,
and self-serve gas spills) and reduce the use of limited resources.
The power from the sun, even at the god awful conversion rate of 10% (or 
whatever solar cells happen to have currently) is much better than
burning fossil fuels.

>
> -- Chuck Fry  Chucko@Charon.ARC.NASA.GOV  ...!ames!ptolemy!chucko

Charles_K_Hughes@cup.portal.com

cameron@janus.Berkeley.EDU (Mike Williamson) (09/27/90)

>The power from the sun, even at the god awful conversion rate of 10% (or 
>whatever solar cells happen to have currently) is much better than
>burning fossil fuels.

Just so's people get an idea of how much power we're talking about currently,
there's about (extremely roughly) 1 kilowatt per square meter during the sunny
hours in the middle of the day (provided there's no clouds - but even with
some clouds a decent amount of power gets through).  At the nominal efficiency
of 10% this is about 100 watts/sqare meter.  Three people live at my house,
and our average daily useage is about 10 kilowatt-hours.  (PG&E rates are
about 10 cents a kWh so this is about a dollar a day).

So, to generate that power, given 5 hours of solar collection, takes about
2 kW, which at 10% efficiencies is 20 square meters - less than the surface
area of our roof.

The spatial dimensions are right, but panel efficiencies and panel and system
costs are still prohibitive, unless you build a house away from PG&E lines
(which a lot of people do in remote areas of the state).  So let's work on
cost and efficiency!  Rah!  Go bears!  Anyway, just some rough figures to
stimulate some thought about the rough state of the technology.  No criticisms
should be directed at this because I am disclaiming all this as super-approx-
imate and I am not trying to push anything down anyone's throat, I'm simply
posting this for those who have no idea how much (to lowest order) power and
cost is involved.

					Respectfully yours,

						Mike

ghhart@eos.ncsu.edu (GREGORY HUGHES HART) (09/28/90)

In article <38826@ucbvax.BERKELEY.EDU>, cameron@janus.Berkeley.EDU (Mike
Williamson) writes:
> >The power from the sun, even at the god awful conversion rate of 10% (or 
> >whatever solar cells happen to have currently) is much better than
> >burning fossil fuels.
> 
> Just so's people get an idea of how much power we're talking about currently,
> there's about (extremely roughly) 1 kilowatt per square meter during
the sunny
> hours in the middle of the day (provided there's no clouds - but even with
> some clouds a decent amount of power gets through).  At the nominal
efficiency
> of 10% this is about 100 watts/sqare meter.  Three people live at my house,
> and our average daily useage is about 10 kilowatt-hours.  (PG&E rates are
> about 10 cents a kWh so this is about a dollar a day).
> 
> So, to generate that power, given 5 hours of solar collection, takes about
> 2 kW, which at 10% efficiencies is 20 square meters - less than the surface
> area of our roof.
> 
> The spatial dimensions are right, but panel efficiencies and panel and system
> costs are still prohibitive, unless you build a house away from PG&E lines
> (which a lot of people do in remote areas of the state).  So let's work on
> cost and efficiency!  Rah!  Go bears!  Anyway, just some rough figures to
> stimulate some thought about the rough state of the technology.  No
criticisms
> should be directed at this because I am disclaiming all this as super-approx-
> imate and I am not trying to push anything down anyone's throat, I'm simply
> posting this for those who have no idea how much (to lowest order) power and
> cost is involved.
> 
> 					Respectfully yours,
> 
> 						Mike

Hasn't there been some advancement in solar cells recently by using
something (germanium-something) instead of silicon, with an efficiency
of much more than 10% (25-30%?)

Anyone know the latest?

myers@hpfcdj.HP.COM (Bob Myers) (09/29/90)

>BTW, the electric cars so beloved by some merely relocate the
>pollution problems to the electric power utility.  I feel it's better

True, but let us also not forget that it's MUCH easier to clean up these
problems at a large centralized power producer than it is to clean up millions
of individual sources.  Overall, such a move would be a win for the
environment.  Especially if, along with the move to electric vehicles, there
is a move to cleaner sources of electricity, such as solar, hydrodynamic,
geothermal (and even, in some cases and with appropriate designs, nuclear).
Not to mention the more "exotic" but just as clean sources which are 
potentially "just around the corner," such as solar satellites or ocean 
thermal.


Bob Myers  KC0EW   HP Graphics Tech. Div.|  Opinions expressed here are not
                   Ft. Collins, Colorado |  those of my employer or any other
myers@fc.hp.com                          |  sentient life-form on this planet.

cameron@janus.Berkeley.EDU (Mike Williamson) (09/29/90)

>Hasn't there been some advancement in solar cells recently by using
>something (germanium-something) instead of silicon, with an efficiency
>of much more than 10% (25-30%?)
>
>Anyone know the latest?

As far as I know, there have been a number of different cells made with
materials other than silicon which have higher efficiencies, some as high
as 35%.  Unfortunately, these are much more expensive than the basic silicon
cells that are most widely available.  (how much more expensive I can't say)
In addition, those high efficiencies were measured under ideal lab conditions
(optimal light, temperature, etc.) and those cells would have a diminished
efficiency in actual practical use (but by how much I can't say - they still
would probably be more efficient than basic silicon).

Gallium-arsenide integrated circuits are faster than silicon circuits, but
are more expensive.  Similarly, gallium-arsenide cells are more efficient
than silicon cells, but are also more expensive.

					-Mike

phil@brahms.amd.com (Phil Ngai) (10/01/90)

In article <38826@ucbvax.BERKELEY.EDU> cameron@janus.Berkeley.EDU
|Three people live at my house,
|and our average daily useage is about 10 kilowatt-hours.

Hm. My car battery is about 600 WH and costs about $30. I think you'll
find the economies of scale that car battery manufacture has to be
very hard to beat. So you'd need to invest about $500 in the
battery array. Not too bad, but you also need the inverter
and power management electronics. I guess the cost of the solar
array will be the dominant factor.

|No criticisms
|should be directed at this because I am disclaiming all this as super-approx-
|imate and I am not trying to push anything down anyone's throat, I'm simply

I'm just trying to give you some more numbers to work with.

--
Phil Ngai, phil@amd.com		{uunet,decwrl,ucbvax}!amdcad!phil
The Sierra Club is trying to stop CA-237 from being made into a freeway.

henry@zoo.toronto.edu (Henry Spencer) (10/01/90)

In article <1990Oct1.055518.21205@amd.com> phil@brahms.amd.com (Phil Ngai) writes:
>Hm. My car battery is about 600 WH and costs about $30. I think you'll
>find the economies of scale that car battery manufacture has to be
>very hard to beat. So you'd need to invest about $500 in the
>battery array...

If you're into using batteries in bulk, truck batteries would be better.
It is indeed hard to beat them as a cost-effective storage system; one
of SDI's experimental railgun projects saved quite a bit of money by
powering the thing from a building full of Sears DieHards rather than
the high-tech homopolar generator originally proposed.
-- 
Imagine life with OS/360 the standard  | Henry Spencer at U of Toronto Zoology
operating system.  Now think about X.  |  henry@zoo.toronto.edu   utzoo!henry