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steve
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 Posted: Thu Jul 03, 2008 4:26 pm Post subject: Ethanol vs Photovoltaic |
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As I understand it photosynthesis is ~6% efficient and then conversion
to ethanol is ~65%. Thus ignoring all the costs of growing,
fertilizing, transporting… less than 4% of the energy from the sun is
captured in ethanol. Some analysis I’ve seen say that a total energy
accounting results in a efficiency of <0.
OTOH photovoltaic cells are 10 to 20% efficient. My son, the
electrical engineer, tells me that some approach 50%. But that they
are expensive.
Am I missing something here?
Steve |
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Bill Penrose
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| Posted: Thu Jul 03, 2008 5:42 pm Post subject: Re: Ethanol vs Photovoltaic |
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On Jul 3, 9:26 am, steve <SJgerdem...@yahoo.com> wrote:
| Quote: |
Am I missing something here?
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The farm lobby and Govt subsidies.
DB |
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Yevgen Barsukov
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| Posted: Thu Jul 03, 2008 7:32 pm Post subject: Re: Ethanol vs Photovoltaic |
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On Jul 3, 11:26 am, steve <SJgerdem...@yahoo.com> wrote:
| Quote: |
As I understand it photosynthesis is ~6% efficient and then conversion
to ethanol is ~65%. Thus ignoring all the costs of growing,
fertilizing, transporting… less than 4% of the energy from the sun is
captured in ethanol. Some analysis I’ve seen say that a total energy
accounting results in a efficiency of <0.
OTOH photovoltaic cells are 10 to 20% efficient. My son, the
electrical engineer, tells me that some approach 50%. But that they
are expensive.
Am I missing something here?
Steve
|
You are missing how VERY expensive solar cells are. Think about
covering you roof with Pentium processors. Main cost component
in processor IC is silicon, and so it is in solar cells - because
they are made of solid ultra-pure silicon mono-crystal slices!.
To get the cost of present 20% efficient solar cells back, you need
to power your house for 10-20 years (and at that time they will
degrade
and you have to trash them). Basically it is not economical at this
point,
except for the areas where there is no grid - for example on Mars or
on
remote outpost in Arizona desert.
To make it economical at present electricity prices, solar cells W/$
has
to improve 2-3 times (developments in this direction include
polysilicone
cells and thin film cells, that trade efficiency for price).
Increase of electricity prices 2-3 times will also
make them economical...
Regards,
Yevgen |
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dlzc
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| Posted: Thu Jul 03, 2008 8:14 pm Post subject: Re: Ethanol vs Photovoltaic |
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Dear Mark Thorson:
On Jul 3, 12:53 pm, Mark Thorson <nos...@sonic.net> wrote:
| Quote: |
Yevgen Barsukov wrote:
To make it economical at present electricity prices,
solar cells W/$ has to improve 2-3 times
(developments in this direction include polysilicone
cells and thin film cells, that trade efficiency for price).
Increase of electricity prices 2-3 times will also
make them economical...
That wouldn't overcome solar's unreliability.
|
... in most locales where people choose to live ...
| Quote: |
You can't have more than about 20% solar in the
energy mix powering the grid, because the
operating reserve needed to back up the solar
would be too expensive. This is because you
can't control the clouds, and you need to have
generators running in hot standby mode ready
to take over when clouds move over your solar
array.
|
A rare occurence here in the desert. However an increasing amount of
atmosphere and then the Earth itself gets in the way once a day... for
several hours. ;>)
| Quote: |
A similar problem exists for wind power.
|
I was servicing an ozone generator once when the clouds came over. A
significant amount of static charge followed them. 125 each 80pF
cells charged to more than 1000 volts... I wonder if that could not be
harvested too?
David A. Smith |
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Mark Thorson
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| Posted: Fri Jul 04, 2008 12:53 am Post subject: Re: Ethanol vs Photovoltaic |
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Yevgen Barsukov wrote:
| Quote: |
To make it economical at present electricity prices, solar cells W/$
has
to improve 2-3 times (developments in this direction include
polysilicone
cells and thin film cells, that trade efficiency for price).
Increase of electricity prices 2-3 times will also
make them economical...
|
That wouldn't overcome solar's unreliability.
You can't have more than about 20% solar in the
energy mix powering the grid, because the
operating reserve needed to back up the solar
would be too expensive. This is because you
can't control the clouds, and you need to have
generators running in hot standby mode ready
to take over when clouds move over your solar
array. A similar problem exists for wind power. |
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Mark Thorson
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| Posted: Fri Jul 04, 2008 1:38 am Post subject: Re: Ethanol vs Photovoltaic |
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dlzc wrote:
| Quote: |
I was servicing an ozone generator once when the clouds came over. A
significant amount of static charge followed them. 125 each 80pF
cells charged to more than 1000 volts... I wonder if that could not be
harvested too?
|
Solar needs a large operating reserve because it is unreliable,
as compared to hydro, nuclear, or any kind of fossil fuel.
Electrostatic would be unreliable squared. |
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trigonometry1972@gmail.co
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| Posted: Sat Jul 05, 2008 7:21 am Post subject: Re: Ethanol vs Photovoltaic |
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On Jul 3, 1:38 pm, Mark Thorson <nos...@sonic.net> wrote:
| Quote: |
dlzc wrote:
I was servicing an ozone generator once when the clouds came over. A
significant amount of static charge followed them. 125 each 80pF
cells charged to more than 1000 volts... I wonder if that could not be
harvested too?
Solar needs a large operating reserve because it is unreliable,
as compared to hydro, nuclear, or any kind of fossil fuel.
Electrostatic would be unreliable squared.
|
I will say solar and wind works better with grids containing
a large hydro component as the water saved serves a battery
in a manner of speaking. |
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Yevgen Barsukov
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| Posted: Sat Jul 05, 2008 2:47 pm Post subject: Re: Ethanol vs Photovoltaic |
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On Jul 3, 12:53 pm, Mark Thorson <nos...@sonic.net> wrote:
| Quote: |
Yevgen Barsukov wrote:
To make it economical at present electricity prices, solar cells W/$
has
to improve 2-3 times (developments in this direction include
polysilicone
cells and thin film cells, that trade efficiency for price).
Increase of electricity prices 2-3 times will also
make them economical...
That wouldn't overcome solar's unreliability.
You can't have more than about 20% solar in the
energy mix powering the grid, because the
operating reserve needed to back up the solar
would be too expensive. This is because you
can't control the clouds, and you need to have
generators running in hot standby mode ready
to take over when clouds move over your solar
array. A similar problem exists for wind power.
|
That is correct, but there are some favorable
correlations between peak demand on solar
peak - during the day. Also air-conditioning
usage increase at the same time where
solar is most effective.
Grid is already has massive generator overcapacity to
deal with just a few hours of high demand.
Solar might actually reduce the needed overcapacity
because it is active during this times.
Regards,
Yevgen |
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N:dlzc D:aol T:com (dlzc)
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| Posted: Sat Jul 05, 2008 9:08 pm Post subject: Re: Ethanol vs Photovoltaic |
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Dear trigonometry1972:
<trigonometry1972@gmail.com> wrote in message
news:f877999b-0019-40aa-82bb-adbed719dd1f@c65g2000hsa.googlegroups.com...
On Jul 3, 1:38 pm, Mark Thorson <nos...@sonic.net> wrote:
| Quote: |
dlzc wrote:
I was servicing an ozone generator once when
the clouds came over. A significant amount of
static charge followed them. 125 each 80pF
cells charged to more than 1000 volts... I
wonder if that could not be harvested too?
Solar needs a large operating reserve because
it is unreliable, as compared to hydro, nuclear,
or any kind of fossil fuel.
Electrostatic would be unreliable squared.
I will say solar and wind works better with grids
containing a large hydro component as the
water saved serves a battery in a manner of
speaking.
|
Hydro should not be part of a permanent plan, IMHO. Rivers (and
hence dams and their resulting reservoirs) end up on fault lines,
and the last thing I want to press down on on an egg, are fault
lines.
Each such installation has been observed to decrease the
surrounding elevation.
.... as much as I like boating.
David A. Smith |
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Mark Thorson
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| Posted: Sat Jul 05, 2008 9:49 pm Post subject: Re: Ethanol vs Photovoltaic |
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"trigonometry1972@gmail.com |" wrote:
| Quote: |
I will say solar and wind works better with grids containing
a large hydro component as the water saved serves a battery
in a manner of speaking.
|
You need natural gas peaker plants that are
spinning and synchronized to the grid to handle
sudden drops in solar array output. Those
generators can be throttled up faster than
any other source of power. Hydro takes several
minutes to throttle up, during which time the
cloud over your solar array may have moved on. |
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trigonometry1972@gmail.co
Guest
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| Posted: Sun Jul 06, 2008 10:46 am Post subject: Re: Ethanol vs Photovoltaic |
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On Jul 5, 9:08 am, "N:dlzc D:aol T:com \(dlzc\)" <dl...@cox.net>
wrote:
| Quote: |
Dear trigonometry1972:
trigonometry1...@gmail.com> wrote in message
news:f877999b-0019-40aa-82bb-adbed719dd1f@c65g2000hsa.googlegroups.com...
On Jul 3, 1:38 pm, Mark Thorson <nos...@sonic.net> wrote:
dlzc wrote:
I was servicing an ozone generator once when
the clouds came over. A significant amount of
static charge followed them. 125 each 80pF
cells charged to more than 1000 volts... I
wonder if that could not be harvested too?
Solar needs a large operating reserve because
it is unreliable, as compared to hydro, nuclear,
or any kind of fossil fuel.
Electrostatic would be unreliable squared.
I will say solar and wind works better with grids
containing a large hydro component as the
water saved serves a battery in a manner of
speaking.
Hydro should not be part of a permanent plan, IMHO. Rivers (and
hence dams and their resulting reservoirs) end up on fault lines,
and the last thing I want to press down on on an egg, are fault
lines.
Each such installation has been observed to decrease the
surrounding elevation.
... as much as I like boating.
David A. Smith
|
Nothing is permanent. If nothing else the reservoirs fill
with sediment. Nor is this to mention the problems
the dams cause for the various fish runs and the related
issue of tribal rights.
That bring to mind a nightmare scenario in which an earthquake
ruptures the Grand Coolee Dam which in turn takes out
every dam on the Columbia below it and WPPSS number 2 nuclear
power plant, its spent rods, and perhaps some of buried nuclear waste
out
in the Hanford nuclear reservation.
I shudder to utter this scenario.......Trig |
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dlzc
Guest
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| Posted: Mon Jul 07, 2008 2:47 pm Post subject: Re: Ethanol vs Photovoltaic |
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Dear trigonometry1972:
On Jul 6, 3:46 am, "trigonometry1...@gmail.com |"
<trigonometry1...@gmail.com> wrote:
| Quote: |
On Jul 5, 9:08 am, "N:dlzcD:aol T:com \(dlzc\)" <dl...@cox.net
wrote:
...
Hydro should not be part of a permanent plan,
IMHO. Rivers (and hence dams and their
resulting reservoirs) end up on fault lines, and
the last thing I want to press down on on an
egg, are fault lines.
Each such installation has been observed to
decrease the surrounding elevation.
... as much as I like boating.
Nothing is permanent. If nothing else the
reservoirs fill with sediment.
|
Sediment weighs more than water.
| Quote: |
Nor is this to mention the problems the dams
cause for the various fish runs and the related
issue of tribal rights.
That bring to mind a nightmare scenario in
which an earthquake ruptures the Grand
Coolee Dam which in turn takes out every
dam on the Columbia below it and WPPSS
number 2 nuclear power plant, its spent
rods, and perhaps some of buried nuclear
waste out in the Hanford nuclear reservation.
I shudder to utter this scenario.......
|
That is how Nature does it. River deltas are unusally high in
background radiation. The heavy metals that get picked up by the
river, gets settled out as soon as the stream velocity drops.
Of course, it is not spent fuel rods... insurance will fix it all
though, right? ;>(
I sure wish such were considered a harvestable resource. Seems like
it is such a hazard being "ignored", when it could yield a good deal
of salable material... material we also spent good deal of political
capital in obtaining intially.
David A. Smith |
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