the Air Vent

Because the world needs another opinion

Posts Tagged ‘biofuels’

Super Algae Bio-Diesel Energy

Posted by Jeff Id on November 25, 2008

I received an interesting link from Richard M part of his comment is below the rest is HERE.

Richard M Says:
November 24, 2008 at 10:35 pm e

I believe there is some hope for one bio-feul … algae. It has significantly better output than does corn, soy, etc. There is a new tecnology currently being test marketed that uses a vertical arrangement to get more output. They claim 33,000 gals/acre/year.

The great thing about comments on a small blog like mine is that I read each and every one. Along with my natural lack of political correctness I also am unafraid of being wrong. I do it quite often as my wife will happily tell you. Check out the link above, it is pretty interesting.

They claim 33,000 gallons per acre of vegetable oil created using a cool structure which stacks the algae in tubes. This is a huge claim considering that corn produces like 50 gallons per acre or something. Pond algae was the previous best at an inflated 900 gallons of oil per acre. Pretty exciting stuff if it’s true really.

Well we know that bio is a form of solar. Typically there is a very low conversion rate for sunlight into the oil, a bunch of light energy is wasted and a bunch more is put into plant proteins and other things not related to the final product – oil. So the first thing I did was check on how much sunlight energy per acre we can count on. These are just estimates- back of the napkin calcs – but they will give us a smell test.

Direct high noon sunlight is about 1000 Watts/m^2 on a clear day.

If we have 12 hours of top quality sunlight

1000 Watts/m^2* 12 hr/day * 365days/yr* 3600 sec/hour = 15,768,000,000 Watt-s /m^2

Then we assume a cosine distribution for daylight intensity of 63% of peak energy (an optics thing, the approximate average of the cos function)

Assume again that most places will only receive 70% of this amount of light. (also high estimate)

15,768,000,000 Watt-s /m^2* .63 * .7 = 6,953,688,000 Watt-Sec/m^2

1 acre = 4047 sq meters

28,141,575,000,000 Watt-Sec/acre or — Joules per acre in proper units.

How many Joules per acre are there in 33,000 gallons of vegetable oil. Well my 5 minute search didn’t reveal any value for algae veggie oil but it did reveal that wikipedia was using my guesstimated value of 1 gal veggie oil to 1 gal gasoline. They are both hydrocarbons after all. Ripping hydrogen off a carbon chain (oils are to my knowledge all carbon chain based) and combining with oxygen produces the nearly the same energy from nearly every oil type fuel. In college grad school I taught a fuels and lubes lab to keep shoes on my feet.

Well gas is about 121,000,000 joules per gallon so we get 33,000*121,000,000 = 3,993,000,000,000 Joules per acre.

This means that 3,993,000,000,000/28,141,575,000,000 * 100 =14.1% of the total sunlight is converted into oil. This is a huge number.

Look at the system they used.


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Energy and politics

Posted by Jeff Id on August 10, 2008

Ok I just wrote an entire article about energy. I started small and before I knew it I had several pages. Unfortunately what I first posted contained some ugly errors and I had to repost. I screwed up and my first real post got deleted …..completely. I think I can recreate my 4 hours of work a bit faster this time but I am frustrated.

Right now there is a big discussion about drilling for oil vs alternative energy or both. Alternative “green” energy includes biofuel, solar, nuclear, wind, wave, geothermal, and others I’m sure. The now not green energy includes any form of wood, oil, natural gas, coal or anything with evil carbon in it. Why isn’t wood a good biofuel? I can’t figure that out.

As often is the case in what appears to be complicated, a small amount of math can give some interesting results.  Let’s do some energy calculations for fun.

To begin with we in the US used 28.352 trillion BTU’s of power for our cars in 2005. Our power plants produced 39.928 trillion BTU’s in 05 according to the department of energy here.

In watts hours (a different unit than btu which means the same thing like feet and meters) we produced 11.7 trillion watt hours electrically and our cars used 8.3 trillion watt hours. The net result in 2007 is about 390million gallons of gas burned with each gallon containing 121million Joules of energy. A Joule is an energy measure similar to BTU.  The vast majority of the gas is burned in cars.

If you use 1 joule per second you are using a power of 1 watt.

So our cars use 390 million gallons per day x 121 million joules or 4.71 x 10^16 joules/day or 546 billion joules per second which is 546 billion watts —– Wow!

For interest the total gallons per second is 390/3600sec/hr/24 or 4513 gallons/second.

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