On Sep 29, 2009, at 12:00 AM, Michel Jullian wrote:
2009/9/28 Horace Heffner <hheff...@mtaonline.net>:
On Sep 27, 2009, at 5:49 PM, mix...@bigpond.com wrote:
One thing that could be done now, and probably wouldn't be a
waste would
be
algoil. This could make a significant dent in fossil fuel
consumption, and
because it targets cars and trucks, isn't likely to be quickly
replaced by
CF,
even if that does pan out.
Yes, it is another viable form of solar energy that is plodding
along in
development.
Not nearly as viable as PV though, at least not on land, if you
consider land productivity. According to the attached "How far a car
can drive" graph, PV is 50 times more productive than the most
productive biofuel: one hectare (= 100m x 100m = 2.5 acres) of land
allows a car to drive 20-70 thousand km on biofuel, versus 3 million
km with PV. Source:
http://www.nanosolar.com/company/blog/going-all-electric.
Michel<FuelEfficiency.jpg>
I think algae will have its day. It will be an important energy
source for quite a while. The numbers given in the above table
distort the potential algae has. See:
http://www.oilgae.com/ref/report/digest/digest.html
"The yields of oil and fuels from algae are much higher (10-100
times) than competing energy crops"
Algae oil yields are already incredible compared to other bio-oil. See:
http://en.wikipedia.org/wiki/Table_of_biofuel_crop_yields
This oil can be blended with other oils to power truck and aircraft,
which is a niche photoelectric will be hard pressed to fill for a
long while.
Presently it is all a matter of economics:
http://en.wikipedia.org/wiki/Biodiesel
"Algae fuel yields have not yet been accurately determined, but DOE
is reported as saying that algae yield 30 times more energy per acre
than land crops such as soybeans.[52] Yields of 36 tonnes/hectare are
considered practical by Ami Ben-Amotz of the Institute of
Oceanography in Haifa, who has been farming Algae commercially for
over 20 years.[53]"
"Photosynthesis is known to have an efficiency rate of about 3-6% of
total solar radiation[57] and if the entire mass of a crop is
utilized for energy production, the overall efficiency of this chain
is currently about 1%[58] While this may compare unfavorably to solar
cells combined with an electric drive train, biodiesel is less costly
to deploy..."
So, I agree that ultimately it is true that other more efficient
solar energy collection systems, including photovoltaics, will
eventually take over the majority of energy production (given no new
energy breakthrough such as CF), a considerable infrastructure needs
to be produced to handle all aspects of energy needs, including
aircraft and trucking fuels.) For some time to come it appears algae
will have an economic energy niche, as well as other applications,
such as sewage processing, and food production. Eventually, algae,
which can grow in salt water, may eventually prove to be too valuable
as a food or fertilizer source to waste on energy production.
Best regards,
Horace Heffner
http://www.mtaonline.net/~hheffner/
