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Sounds good, but how much CO2 production do those precursors imply? I've seen too many over-enthusiastic write-ups for bio-solar technologies that don't include

by PaulAJ 11y ago

Sounds good, but how much CO2 production do those precursors imply? I've seen too many over-enthusiastic write-ups for bio-solar technologies that don't include the carbon cost of the inputs. Of course if the answer is "not much" then this could be big.

trhway 11y ago
>Sounds good, but how much CO2 production do those precursors imply? I've seen too many over-enthusiastic write-ups for bio-solar technologies that don't include the carbon cost of the inputs. from the article: "Normally, algae convert carbon dioxide during photosynthesis into biomass or sugars." The issue with these technologies isn't CO2 balance (that balance is great - CO2 is input, hydrocarbons is output), the issue is productization, i.e. reaching the technological stage which would be able to attract massive investment. With cheap oil [i.e. with major costs of oil externalized in today's society and economy] these technologies face uphill battle. (compare - if Big Oil wants pipeline or drill somewhere, the government uses all its ultimate power, like eminent domain domestically or aircraft carriers internationally, to make it happen and push it through public interests here or there, if you want a pond for algae ...)
- regularfry 11y ago
  Productisation inherently has to overcome the fundamental energy density problem: with photosynthesis, you've got an upper limit of about 300W/m2 that you can ever capture. To get energetically useful amounts of fuel out, that means you need acres of the stuff. Not impossible, but a right pain to keep your chosen strain dominant in the sort of volumes that area implies.
  - trhway 11y ago
    >that means you need acres of the stuff. in a hot desert unused for anything else. From https://en.wikipedia.org/wiki/Algae_fuel https://en.wikipedia.org/wiki/Algae_fuel "The United States Department of Energy estimates that if algae fuel replaced all the petroleum fuel in the United States, it would require 15,000 square miles (39,000 km2), which is only 0.42% of the U.S. map,[10] or about half of the land area of Maine. This is less than 1/7 the area of corn harvested in the United States in 2000.[11]" A federal scale project with political, social and economical effects comparable with atomic bomb development. 15000 sq. miles sucking in CO2 and producing fuel. Saudi princes and Putin may go enjoy themselves. Well, with a lot of rich and politically connected Texas oilmen as well ... and this is the main issue, not the energy density :) And with another oily Texan about to be elected, we can forget about any serious advancements for the next 8 years (he'll get us into another war and thus will stay for the full show)
    - regularfry 11y ago
      > in a hot desert unused for anything else. Yeah, but you've still got to keep very tight biological control over that vast area. I can't think of any other type of project which is directly comparable. > 15000 sq. miles sucking in CO2 and producing fuel. Better off producing plastic feedstocks. I like this tech for sequestering CO2 much better than the usual "pump it into the ground and hope it doesn't leak" scheme.
    - ebiester 11y ago
      Where does the water come from?
    - entee 11y ago
      The hardest thing about algal fuels is keeping your bioreactor working at peak efficiency. This is quite difficult, consider the following: Problem: Outside organisms keep contaminating your pools of algae. Solution: cover them up. Problem: your reactor surface keeps fouling Solution: open it up and wash it Problem: Now you gotta clean the whole thing to make sure you don't have contamination Problem: some parts of the pool are far denser in algae than others leading to inefficiency Solution: pump/stir it! Problem: now you have to move huge volumes of water. Plus your equipment could foul/breakdown Partial solution: solar powered pumps. Fouling still an issue though Problem: Organisms raised in water take a lot of water with them for the ride even when you spin/filter them out for harvesting Partial solution: Dry it out with energy, maybe more sun? Now you need more space. After all this you have to wonder whether the cost and additional energy invested leaves you with enough left over to make sense. It's not impossible, and I believe it's the only real way to a sustainable future, but it's really, really, really hard to scale these things up.

by PaulAJ 11y ago

trhway 11y ago

>Sounds good, but how much CO2 production do those precursors imply? I've seen too many over-enthusiastic write-ups for bio-solar technologies that don't include the carbon cost of the inputs. from the article: "Normally, algae convert carbon dioxide during photosynthesis into biomass or sugars." The issue with these technologies isn't CO2 balance (that balance is great - CO2 is input, hydrocarbons is output), the issue is productization, i.e. reaching the technological stage which would be able to attract massive investment. With cheap oil [i.e. with major costs of oil externalized in today's society and economy] these technologies face uphill battle. (compare - if Big Oil wants pipeline or drill somewhere, the government uses all its ultimate power, like eminent domain domestically or aircraft carriers internationally, to make it happen and push it through public interests here or there, if you want a pond for algae ...)

regularfry 11y ago
Productisation inherently has to overcome the fundamental energy density problem: with photosynthesis, you've got an upper limit of about 300W/m2 that you can ever capture. To get energetically useful amounts of fuel out, that means you need acres of the stuff. Not impossible, but a right pain to keep your chosen strain dominant in the sort of volumes that area implies.
- trhway 11y ago
  >that means you need acres of the stuff. in a hot desert unused for anything else. From https://en.wikipedia.org/wiki/Algae_fuel https://en.wikipedia.org/wiki/Algae_fuel "The United States Department of Energy estimates that if algae fuel replaced all the petroleum fuel in the United States, it would require 15,000 square miles (39,000 km2), which is only 0.42% of the U.S. map,[10] or about half of the land area of Maine. This is less than 1/7 the area of corn harvested in the United States in 2000.[11]" A federal scale project with political, social and economical effects comparable with atomic bomb development. 15000 sq. miles sucking in CO2 and producing fuel. Saudi princes and Putin may go enjoy themselves. Well, with a lot of rich and politically connected Texas oilmen as well ... and this is the main issue, not the energy density :) And with another oily Texan about to be elected, we can forget about any serious advancements for the next 8 years (he'll get us into another war and thus will stay for the full show)
  - regularfry 11y ago
    > in a hot desert unused for anything else. Yeah, but you've still got to keep very tight biological control over that vast area. I can't think of any other type of project which is directly comparable. > 15000 sq. miles sucking in CO2 and producing fuel. Better off producing plastic feedstocks. I like this tech for sequestering CO2 much better than the usual "pump it into the ground and hope it doesn't leak" scheme.
  - ebiester 11y ago
    Where does the water come from?
  - entee 11y ago
    The hardest thing about algal fuels is keeping your bioreactor working at peak efficiency. This is quite difficult, consider the following: Problem: Outside organisms keep contaminating your pools of algae. Solution: cover them up. Problem: your reactor surface keeps fouling Solution: open it up and wash it Problem: Now you gotta clean the whole thing to make sure you don't have contamination Problem: some parts of the pool are far denser in algae than others leading to inefficiency Solution: pump/stir it! Problem: now you have to move huge volumes of water. Plus your equipment could foul/breakdown Partial solution: solar powered pumps. Fouling still an issue though Problem: Organisms raised in water take a lot of water with them for the ride even when you spin/filter them out for harvesting Partial solution: Dry it out with energy, maybe more sun? Now you need more space. After all this you have to wonder whether the cost and additional energy invested leaves you with enough left over to make sense. It's not impossible, and I believe it's the only real way to a sustainable future, but it's really, really, really hard to scale these things up.