Comments for "Algae is the answer to our energy problems" Video at VideoSift.com

By RhesusMonk

RhesusMonk (http://www.videosift.com/member/RhesusMonk) — Sun, 11 May 2008 21:11:31 -0700

*algae

By Crosswords

Crosswords (http://www.videosift.com/member/Crosswords) — Mon, 12 May 2008 00:01:23 -0700

So what's the hold up?

By jwray

jwray (http://jwray.videosift.com) — Mon, 12 May 2008 03:01:17 -0700

http://en.wikipedia.org/wiki/World_energy_resources_and_consumption

One Tenth of New Mexico would only receive 4*10^20 J of sunlight in a year, and the US uses 1.2*10^20 J per year, so he's assuming an efficiency of 30% for the whole process, including photosynthesis, refining and transportation of the final product? I call bullshit. Photosynthesis is typically less than 1% efficient, and even the most efficient known species of algae convert light to biomass at 3-6% efficiency.

Humans use 5*10^20 J per year, and over 80% of that is fossil fuel.

Only 4*10^24 J per year of sunlight reaches the earth (do the math)

Assuming photosynthesis efficiency of 1% and fermentation+distillation+transportation efficiency of 25%, you would have to cover 1/25 of the earth's cross-section with biofuel-growing (that's at least 1/4 of the total arable land, depending on latitude) to cover the world's energy needs. Burning biofuels still produces atmospheric pollution like ozone and nitrogen oxides. Elecrtic cars will pollute the atmosphere less than any biofuel internal-combustion car.

Anything based on photosynthesis is going to be wildly inefficient compared to solar thermal generators.

By rottenseed

rottenseed (http://rottenseed.videosift.com) — Tue, 13 May 2008 10:31:14 -0700

^we're so used to being dependent on one source of fuel that we can't think outside the box. Why would we automatically jump to the conclusion that we're trying to run the world on energy obtained through photosynthesis. It does, however, appear to be a reasonable supplementary energy source for maybe desert cities or something of that sort.