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electric versus petrol mowers; electric versus petrol home heating
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a_plutonium@hotmail.com
science forum Guru


Joined: 11 Sep 2005
Posts: 1063

PostPosted: Sat May 06, 2006 6:02 am    Post subject: electric versus petrol mowers; electric versus petrol home heating Reply with quote

Interesting concept is nagging me lately. I wanted to know when did
electric lawnmowers become cheaper than gasoline powered lawnmowers in
history. Thinking that the recent spike in petrol makes electric
superior, and, not realizing that electric had been superior all along.
But that electric powered home heating was never superior to petrol
home heating, even though the recent spike in petrol fuel.

So I was playing around with numbers of 6 horsepower, 740 watts, 14
cents kw/hour.

Then I came to the realization that it is the size if the device or the
machinery involved as to whether electric is superior to that of
mechanical (petrol). That an electric lawnmower was always more
efficient and cost saving than a petrol lawnmower, but that electric
heating was never as efficient as petrol heating.

So the concept of size of the set-up is very much the determinant
between electric and a fossil fuel set up. Keeping in mind that the
electric power itself often comes from a fossil fuel power plant. But
what I am considering here is the machinery and apparatus size.

Electricity has been superior in devices of something going round and
round whereas petrol is superior in the production of heat.

Perhaps theoretical physics has already covered these ideas, perhaps
not.

Anyway, there seems to be a concept that involves the size of a set-up
and where a round and round motion are involved is superior to
electricity and not gasoline driven devices.

And the reason petrol lawnmowers are used more often is the freedom of
not having to drag a line and getting the line snagged, and not the
higher cost of petrol mowers.

Archimedes Plutonium
www.iw.net/~a_plutonium
whole entire Universe is just one big atom
where dots of the electron-dot-cloud are galaxies
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Surfer
science forum beginner


Joined: 10 Apr 2006
Posts: 8

PostPosted: Sat May 06, 2006 7:45 am    Post subject: Re: electric versus petrol mowers; electric versus petrol home heating Reply with quote

On 5 May 2006 23:02:40 -0700, a_plutonium@hotmail.com wrote:

Quote:

That an electric lawnmower was always more
efficient and cost saving than a petrol lawnmower, but that electric
heating was never as efficient as petrol heating.

An electric motor is more efficient because it converts a greater

proportion of input energy into mechanical energy than a petrol motor.

In contrast a petrol motor converts a large proportion of input energy
into waste heat.

Quote:

Electricity has been superior in devices of something going round and
round whereas petrol is superior in the production of heat.

Electrical heaters are pretty well 100% efficient at converting

electrical energy to heat.

So if electric heating costs more, its because electricity is more
expensive.

That could depend on geography. In a country which had cheap
hydro-power, but no petroleum, it might be cheaper to use electric
heating than oil heating.
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CWatters
science forum Guru Wannabe


Joined: 01 May 2005
Posts: 120

PostPosted: Sat May 06, 2006 12:02 pm    Post subject: Re: electric versus petrol mowers; electric versus petrol home heating Reply with quote

<a_plutonium@hotmail.com> wrote in message
news:1146895360.789761.159460@j73g2000cwa.googlegroups.com...
Quote:

And the reason petrol lawnmowers are used more often is the freedom of
not having to drag a line and getting the line snagged, and not the
higher cost of petrol mowers.

You could argue that the weight of the mower is also an important factor.
The heavier the better if you want a nice flat lawn with classic stripes.
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Herman Family
science forum Guru Wannabe


Joined: 14 Jun 2005
Posts: 173

PostPosted: Sat May 06, 2006 2:22 pm    Post subject: Re: electric versus petrol mowers; electric versus petrol home heating Reply with quote

"Surfer" <surfer@no.spam.net> wrote in message
news:l6jo52lspp43l6kk0857opg08p9euputnr@4ax.com...
Quote:
On 5 May 2006 23:02:40 -0700, a_plutonium@hotmail.com wrote:


That an electric lawnmower was always more
efficient and cost saving than a petrol lawnmower, but that electric
heating was never as efficient as petrol heating.

An electric motor is more efficient because it converts a greater
proportion of input energy into mechanical energy than a petrol motor.

In contrast a petrol motor converts a large proportion of input energy
into waste heat.


Electricity has been superior in devices of something going round and
round whereas petrol is superior in the production of heat.

Electrical heaters are pretty well 100% efficient at converting
electrical energy to heat.

So if electric heating costs more, its because electricity is more
expensive.

That could depend on geography. In a country which had cheap
hydro-power, but no petroleum, it might be cheaper to use electric
heating than oil heating.



You really have to do a total analysis on this to get the right picture.
The electric motor required that electricity be produced. That took a
certain amount of fuel to do it, with concommitant emissions. The
electrical production wasn't perfectly efficient, probably 39 percent or so.
There were losses in the lines, about 3 percent. I'm probably off a bit on
the numbers, and they vary a bit from location to location. The electric
motor itself is only so efficient (quite efficient, but not perfectly
efficient). Now you look at your gasoline engine. It has a certain
efficiency.

If you really want to go further, you could look at the quantity of gras cut
per unit of enenrgy. You'll find that the good old fashioned push reel
mower probably beats them all. It also actually cuts the grass instead of
erroding it into submission.

Michael
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Jan Panteltje
science forum Guru Wannabe


Joined: 06 May 2005
Posts: 295

PostPosted: Sat May 06, 2006 2:52 pm    Post subject: Re: electric versus petrol mowers; electric versus petrol home heating Reply with quote

On a sunny day (Sat, 06 May 2006 14:22:10 GMT) it happened "Herman Family"
<ecalptsudwaseht.in.reverse@frontiernet.net> wrote in
<mi27g.203$Oh1.134@news01.roc.ny>:

Quote:
If you really want to go further, you could look at the quantity of gras cut
per unit of enenrgy. You'll find that the good old fashioned push reel
mower probably beats them all. It also actually cuts the grass instead of
erroding it into submission.

Michael

I have seen goats and sheep here.
Provide fertilizer, milk, wool, play for the kids.
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Herman Family
science forum Guru Wannabe


Joined: 14 Jun 2005
Posts: 173

PostPosted: Sun May 07, 2006 3:35 am    Post subject: Re: electric versus petrol mowers; electric versus petrol home heating Reply with quote

"Jan Panteltje" <pNaonStpealmtje@yahoo.com> wrote in message
news:e3id6m$q3b$1@news.datemas.de...
Quote:
On a sunny day (Sat, 06 May 2006 14:22:10 GMT) it happened "Herman Family"
ecalptsudwaseht.in.reverse@frontiernet.net> wrote in
mi27g.203$Oh1.134@news01.roc.ny>:

If you really want to go further, you could look at the quantity of gras
cut
per unit of enenrgy. You'll find that the good old fashioned push reel
mower probably beats them all. It also actually cuts the grass instead of
erroding it into submission.

Michael

I have seen goats and sheep here.
Provide fertilizer, milk, wool, play for the kids.

I haven't seen sheep handle good lawns. They tend to eat just the weeds.

In particular, they eat one kind of weed for a while, then another kind, and
so on, rather than just randomly munch. It's fun to watch them. They don't
like being left alone.

They are indeed fun to play with and make good pets, though when they are
chasing folks around the house their hooves don't grip hardwood floors too
well so they sort of slide on the turns. You have to keep their wool fairly
clean or else they stink a bit. They don't mind being washed, but they do
not like the spin cycle.

Michael
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The Ghost In The Machine1
science forum Guru


Joined: 25 Mar 2005
Posts: 1551

PostPosted: Sun May 07, 2006 4:00 am    Post subject: Re: electric versus petrol mowers; electric versus petrol home heating Reply with quote

On Sat, 06 May 2006 17:06:02 +0930, Surfer wrote:

Quote:
On 5 May 2006 23:02:40 -0700, a_plutonium@hotmail.com wrote:


That an electric lawnmower was always more efficient and cost saving than
a petrol lawnmower, but that electric heating was never as efficient as
petrol heating.

An electric motor is more efficient because it converts a greater
proportion of input energy into mechanical energy than a petrol motor.

In contrast a petrol motor converts a large proportion of input energy
into waste heat.

I have a problem with this -- not because you're actually wrong, but
because I am wondering precisely how much input energy is converted into
waste heat in the generators. :-)

In short, system A: a petrol motor on a small frame cuts grass.

System B: a large diesel generator sends electric energy over wires to a
homeowner's electric motor, sitting on a small frame and cutting grass.

I suspect B is still more efficient but do wonder. There are also other
sources of electric energy, of course, such as hydroelectric, solar,
tidal, nuclear, and geothermal.

Quote:


Electricity has been superior in devices of something going round and
round whereas petrol is superior in the production of heat.

Electrical heaters are pretty well 100% efficient at converting
electrical energy to heat.

So if electric heating costs more, its because electricity is more
expensive.

That could depend on geography. In a country which had cheap
hydro-power, but no petroleum, it might be cheaper to use electric
heating than oil heating.

Especially if one can use a heat pump.

--
#191, ewill3@earthlink.net
It's still legal to go .sigless.
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Herman Family
science forum Guru Wannabe


Joined: 14 Jun 2005
Posts: 173

PostPosted: Sun May 07, 2006 4:04 am    Post subject: Re: electric versus petrol mowers; electric versus petrol home heating Reply with quote

"The Ghost In The Machine" <ewill3@earthlink.net> wrote in message
news:pan.2006.05.07.03.17.41.888436@earthlink.net...
Quote:
On Sat, 06 May 2006 17:06:02 +0930, Surfer wrote:

On 5 May 2006 23:02:40 -0700, a_plutonium@hotmail.com wrote:


That an electric lawnmower was always more efficient and cost saving than
a petrol lawnmower, but that electric heating was never as efficient as
petrol heating.

An electric motor is more efficient because it converts a greater
proportion of input energy into mechanical energy than a petrol motor.

In contrast a petrol motor converts a large proportion of input energy
into waste heat.

I have a problem with this -- not because you're actually wrong, but
because I am wondering precisely how much input energy is converted into
waste heat in the generators. :-)

In short, system A: a petrol motor on a small frame cuts grass.

System B: a large diesel generator sends electric energy over wires to a
homeowner's electric motor, sitting on a small frame and cutting grass.

I suspect B is still more efficient but do wonder. There are also other
sources of electric energy, of course, such as hydroelectric, solar,
tidal, nuclear, and geothermal.



Electricity has been superior in devices of something going round and
round whereas petrol is superior in the production of heat.

Electrical heaters are pretty well 100% efficient at converting
electrical energy to heat.

So if electric heating costs more, its because electricity is more
expensive.

That could depend on geography. In a country which had cheap
hydro-power, but no petroleum, it might be cheaper to use electric
heating than oil heating.

Especially if one can use a heat pump.

--
#191, ewill3@earthlink.net
It's still legal to go .sigless.


I agree. Generators are in the order of 95+ percent efficient. Powering
the generator is the tough problem. A large turbine is pretty good. Diesel
reciprocating motors are pretty good too. The problem is that a lot of
folks do the analysis from the plug outward. I've dealt with a number of
green earth types who never realized that the electricity that they were
advocating actually was produced somewhere.

Michael
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Paul E. Bennett
science forum beginner


Joined: 13 Jun 2005
Posts: 45

PostPosted: Sun May 07, 2006 6:16 am    Post subject: Re: electric versus petrol mowers; electric versus petrol home heating Reply with quote

The Ghost In The Machine wrote:

Quote:
I have a problem with this -- not because you're actually wrong, but
because I am wondering precisely how much input energy is converted into
waste heat in the generators. Smile

Depends where you draw the system boundary line. The OP had declared he was
only considering the end user's premises where the fuel input was
electricity from the socket or petrol from a can.

Quote:
In short, system A: a petrol motor on a small frame cuts grass.

System B: a large diesel generator sends electric energy over wires to a
homeowner's electric motor, sitting on a small frame and cutting grass.

I suspect B is still more efficient but do wonder. There are also other
sources of electric energy, of course, such as hydroelectric, solar,
tidal, nuclear, and geothermal.

Considering that there are now solar powered lawn-mowers that, entirely left
to themselves, will keep a lawn in good trim all year round. The only fuel
they get is sunlight but they convert this to electrical energy and will
just wander the lawn for as long as this energy input keeps it going. Could
you come up with a self fueling petrol version of this? How would it
compare efficiency wise?

--
********************************************************************
Paul E. Bennett ....................<email://peb@amleth.demon.co.uk>
Forth based HIDECS Consultancy .....<http://www.amleth.demon.co.uk/>
Mob: +44 (0)7811-639972
Tel: +44 (0)1235-811095
Going Forth Safely ..... EBA. www.electric-boat-association.org.uk..
********************************************************************
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Jan Panteltje
science forum Guru Wannabe


Joined: 06 May 2005
Posts: 295

PostPosted: Sun May 07, 2006 12:40 pm    Post subject: Re: electric versus petrol mowers; electric versus petrol home heating Reply with quote

On a sunny day (Sun, 07 May 2006 03:35:16 GMT) it happened "Herman Family"
<ecalptsudwaseht.in.reverse@frontiernet.net> wrote in
<UVd7g.262$Oh1.19@news01.roc.ny>:

Quote:

"Jan Panteltje" <pNaonStpealmtje@yahoo.com> wrote in message
news:e3id6m$q3b$1@news.datemas.de...
On a sunny day (Sat, 06 May 2006 14:22:10 GMT) it happened "Herman Family"
ecalptsudwaseht.in.reverse@frontiernet.net> wrote in
mi27g.203$Oh1.134@news01.roc.ny>:

If you really want to go further, you could look at the quantity of gras
cut
per unit of enenrgy. You'll find that the good old fashioned push reel
mower probably beats them all. It also actually cuts the grass instead of
erroding it into submission.

Michael

I have seen goats and sheep here.
Provide fertilizer, milk, wool, play for the kids.

I haven't seen sheep handle good lawns. They tend to eat just the weeds.
In particular, they eat one kind of weed for a while, then another kind, and
so on, rather than just randomly munch. It's fun to watch them. They don't
like being left alone.

They are indeed fun to play with and make good pets, though when they are
chasing folks around the house their hooves don't grip hardwood floors too
well so they sort of slide on the turns. You have to keep their wool fairly
clean or else they stink a bit. They don't mind being washed, but they do
not like the spin cycle.

Michael
Bisons?
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Everett M. Greene
science forum beginner


Joined: 09 Aug 2005
Posts: 32

PostPosted: Sat May 27, 2006 4:56 pm    Post subject: Re: electric versus petrol mowers; electric versus petrol home heating Reply with quote

"CWatters" <colin.watters@turnersNOSPAMoak.plus.net> writes:
Quote:
a_plutonium@hotmail.com> wrote

And the reason petrol lawnmowers are used more often is the freedom of
not having to drag a line and getting the line snagged, and not the
higher cost of petrol mowers.

You could argue that the weight of the mower is also an important factor.
The heavier the better if you want a nice flat lawn with classic stripes.

My landscape maintainer says she wants the lightest mower
possible. Electric mowers are fine for smaller lawns.

Now if I could just find a replacement motor for a very
light Black & Decker electric mower of 1970 vintage...
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