Killing two birds with one stone: Turning CO2 into biodiesel

[bascule]

This guy lives in Boulder and worked for Colorado State University, where I used to work:

 

http://www.dailycamera.com/news/2006/dec/08/inventor-turns-algae-into-fuel/

 

His idea is to trap the CO₂ output from coal-fired power plants and funnel it into enormous fields of enclosed algae pools. Coal-fired power plants produce 40% of America's carbon dioxide emissions, at least according to the article. The basic premise is to collect CO₂ from power plants and use it to feed pools of algae with carbon dioxide-enriched water:

 

The carbon-dioxide-rich water would flow to a farm — ideally spanning several square miles — consisting of hundreds or thousands of "photo bioreactors," which Sears characterized as "300-foot-long waterbeds." They are 20 feet wide and a foot deep.

 

The result? Biodiesel:

 

Harvested occasionally, the algae would produce between a gallon and two gallons of fuel per square meter per year in addition to carbohydrates and proteins that could be converted to fuel or feed, Sears said. He says his algae-based biodiesel production is 100 times more efficient than traditional biodiesel, which is primarily soy-based in the United States.

[bascule]

That's 170-340 barrels of oil per square mile per day (or 65-130 barrels of oil per square kilometer per day for the rest of the world)

[bascule]

This fuel, in a modern turbodiesel engine, will get you 40-60 mpg (17-26 km/L)

[Martin]

to give some benchmarks for comparison

 

Wikipedia on poplar SRC (short rotation coppice)

"After four years the plantation will be ready for harvest. Harvests take place on a two to five year cycle, shorter for Willow and longer for Poplar, and are carried out in winter after leaf fall when the soil is frozen. The established root system and the nutrients stored in the roots and stumps guarantee vigorous growth for the shoots. A plantation will yield from 8 to 18 tonnes of dry woodchip per hectare per year. A plantation can be harvested for up to thirty years before needing to be replanted."

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

 

about coppice plantation

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

 

a hectare is ten thousand sq. meter

so annual 10 tonnes per hectare equals one kilogram per sq. meter per year

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I don't know much about this. Maybe someone else would like to provide a benchmark. I think that one kilo of dry wood-chip per sq. meter per year is a rough benchmark for coppice wood production.

 

he is claiming one or two GALLONS OF FUEL OIL per sq meter year

 

that is at least an order of magnitude higher energy productivity per unit area, so I am skeptical but interested.

================

 

there should be some technical journal articles about pilot studies with this kind of oil-containing algae, that one could use to back up claims of very high energy production per unit area

[bascule]

that is at least an order of magnitude higher energy productivity per unit area, so I am skeptical but interested.

 

The article also claims two orders of magnitude higher energy productivity over soybeans.

[Martin]

The article also claims two orders of magnitude higher energy productivity over soybeans.

I realize, but that is a comparison I can't deal with. Ethanol from corn is wasteful and just a cynical way to subsidize corn agribusiness. I would put fuel oil from soy in the same basket. IIRC there are better oil crops in terms of energy captured in oil per acre per year. corn and soy growers are both politically powerful.

 

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my guess about how biofuel will turn out is that sure, there will be a spectrum of minor-league approaches that each meet some small fraction of energy demand but that one or two major approaches will dominate:

 

one could be algae (maybe even using CO2 enriched water to grow in) if some surprisingly high yield can be achieved.

 

could also be genetically modified poplar----breaking the cellulose to sugar and fermenting to ethanol is one use----straight burning is another.

 

Certain fast growing trees have the feature of a high tonnage yield without intensive cultivation---the capital cost and the annual inputs are comparatively low. Your Colorado guy's algae-oil approach sounds comparatively high tech and capital intensive. He seems to be counting on some kind of subsidy to make it work. But if the yield is as high as he says, per square meter year, then it might be able to run without crutches. I'll be interested to see.

[abskebabs]

Thinking about this, I'm not sure it's necessarily a good idea. Forgive me if I'm being hasty Bascule, but; you're taking CO2 produced from coal and using algae to rpoduce biofuel. What you gonna do with that: burn it. Now there's no problem with biofuel in general, as long as you're not increasing the maount of carbon in the atmmosphere(aka the cause of anthropogenic global warming), but aren't you in fact doing just that by carrying out this process. In effect isn't there no difference between this and the increase of CO2 in the atmorsphere besides the involvement of algae? I understand that it could be recycled by the very algae you're growing, but the bottom line is carbon that was locked away is getting into the atmosphere.

 

On the other hand, I am very much for Coal if we can find an enviromentally viable way of "locking it up", and with regard to this perhaps you have a point with producing biodiesel, as this could be stowed away, and carbon prevented from reaching the atmosphere. O the other hand biodiesel canbe harnessed as biological life and its products are all around us. One avenue which I am surpriesed is not harnessed more or attempted to be is the use of organic waste(human, animal, medical the list goes on...) biological products that could be used to produce a kind of biofuel. This is already done in a crude way in many countries by the way of biogas reacters using excrement, but I'm sure much more sophisticated methods are available. It would definitely be better than increasing the price of foood to produce biofuel, who knows maybe in a few years we will have a cut throat competitive poo market:eyebrow: ?

 

Also have you heard of thermal depolymerization? It's a speculative tachnology that made me get excited about this whole biofuel business. I'd appreciate it if you checked it out and told me what you think of it.

[Glider]

Thinking about this, I'm not sure it's necessarily a good idea. Forgive me if I'm being hasty Bascule, but; you're taking CO2 produced from coal and using algae to rpoduce biofuel. What you gonna do with that: burn it. Now there's no problem with biofuel in general, as long as you're not increasing the maount of carbon in the atmmosphere(aka the cause of anthropogenic global warming), but aren't you in fact doing just that by carrying out this process. In effect isn't there no difference between this and the increase of CO2 in the atmorsphere besides the involvement of algae? I understand that it could be recycled by the very algae you're growing, but the bottom line is carbon that was locked away is getting into the atmosphere.

Not really, because, in effect, you'd be buring the same coal twice (i.e. once to produce the initial CO2 and then again from the biodeisel produced by the algae from the same initial CO2). So yes, you'd still be producing CO2, but not from burning both coal and deisel, it would be from the deisel only. Plus, the algae would release a lot of oxygen during photosynthesis.

[abskebabs]

Not really, because, in effect, you'd be buring the same coal twice (i.e. once to produce the initial CO2 and then again from the biodeisel produced by the algae from the same initial CO2). So yes, you'd still be producing CO2, but not from burning both coal and deisel, it would be from the deisel only. Plus, the algae would release a lot of oxygen during photosynthesis.

Yes but regardless of whether you burn or don't burn the coal, basically the carbon has been transeferred into a different form, i.e. diesel by the algae. You burn the diesel and still release CO2 into the atmosphere. The main thing is this was carbon that was locked away that gets released into the atmosphere, and this is what is causing global warming as far as I can see. There is no problem with most biofuels, as essentially the carbon dioxide is being recycled by the same crops and plants from which the carbon based fuel originates.

 

I understand algae will release oxygen into the atmosphere, I just don't see this solving any problems because the net amount of CO2 would still increase by this process, if applied in such a way. Also growing algae on a massive scale to counter the co2 increase, but really I don't see this being much different from planting lots of trees. You may as well just have your coal plant and surround it with a forest, instead of having the trouble of converting it to diesel:eyebrow:

[ecoli]

Yes but regardless of whether you burn or don't burn the coal, basically the carbon has been transeferred into a different form, i.e. diesel by the algae. You burn the diesel and still release CO2 into the atmosphere. The main thing is this was carbon that was locked away that gets released into the atmosphere, and this is what is causing global warming as far as I can see. There is no problem with most biofuels, as essentially the carbon dioxide is being recycled by the same crops and plants from which the carbon based fuel originates.

 

I understand algae will release oxygen into the atmosphere, I just don't see this solving any problems because the net amount of CO2 would still increase by this process, if applied in such a way. Also growing algae on a massive scale to counter the co2 increase, but really I don't see this being much different from planting lots of trees. You may as well just have your coal plant and surround it with a forest, instead of having the trouble of converting it to diesel:eyebrow:

 

However, the forest is not as productive in terms of usable energy.

 

The idea is that, if we going to be burning coal anyway, why not get a second energy source out of it?

 

If you don't use the algae pools, the CO2 is just going to get into the atmosphere anyway. Yes, the fossil fuel consumption is not the ideal long term solution, but there's nothing wrong with improving the effiecency if coal burning is going to continue in the near future (and it look like it will, by all accounts).

 

Basically, you're saying, that we shouldn't improve one technology because it's overall harmfull. However, not investing in the algae pools doesn't mean we'll stop using coal.

[John Cuthber]

It looks like a neat idea. A couple of thoughts struck me. We are going to burn the coal anyway because, at least in the short term, we need the energy. We might as well recyle the CO2.

In the slightly longer term we can reuse the "diesel" to run the power station rather than engines. That way you get, effectively, a solar power station.

With combined heat and power technology we can squeeze even better efficiency out of this idea.

[abskebabs]

Basically, you're saying, that we shouldn't improve one technology because it's overall harmfull. However, not investing in the algae pools doesn't mean we'll stop using coal.

I'm not necessarily blanket against the technology, I have a bit more of an open mind about that, I just think it would be more productive in the long term to store much of this carbon back under the Earth. Regarding that, perhaps a halfway solution could be reached. We could burn half of the biodiesel that was going to be released into the atmosphere, and restore half of it underground. These could be used as emergency reserves once we have a global cooling crisis;) . Now that's killing 2 birds with one stone!

 

I can see this also not being a bad idea if we use the algae to constantly recycle the carbon from the burned biodiesel that they produce. It then again depends on how efficiently they do this on how viable and realistic such a process is.

 

Also, as a side note, as this is not my area of expertise, what organisms are generally considered the more efficient bulk photosynthesizers? Or am I already betraying the fact that this depends entirely on the conditions and required scale?

[Glider]

Yes but regardless of whether you burn or don't burn the coal, basically the carbon has been transeferred into a different form, i.e. diesel by the algae. You burn the diesel and still release CO2 into the atmosphere. The main thing is this was carbon that was locked away that gets released into the atmosphere, and this is what is causing global warming as far as I can see. There is no problem with most biofuels, as essentially the carbon dioxide is being recycled by the same crops and plants from which the carbon based fuel originates.

I agree and I do take your point, there will still be a net release of CO2 from burning fossil fuel. I was just noting that the advantage in this case is that the same fossil fuel would, in effect, be getting burned twice (first as coal, then as biodeisel), which has to be an improvement on the current system of buring the coal once, and normal deisel once. In those terms, yes, you would still be releasing CO2 from fossil fuels, but there would be a net reduction compared to the current system, and any reduction, given the state of the current system, would be a good thing.

 

I understand algae will release oxygen into the atmosphere, I just don't see this solving any problems because the net amount of CO2 would still increase by this process, if applied in such a way.

Again, I agree with you. My referring to the oxygen released was really just noting the nature of the waste product from converting CO2 from burning coal into biodeisel.

Also growing algae on a massive scale to counter the co2 increase, but really I don't see this being much different from planting lots of trees. You may as well just have your coal plant and surround it with a forest, instead of having the trouble of converting it to diesel:eyebrow:

But that way, the coal would only be burnt once and people would still use deisel.

 

However, I agree strongly with your tree idea. Given the proportion of any given tree that is carbon, I can't think of a more efficent way of locking up carbon in a useful form. Fast growing broadleafed softwood forests would lock up millions of tons of carbon per year (not only in the wood, think of the millions of tons of leaves that are grown and shed each year). Not only would burning the that timber be carbon neutral, but building things with it would make it carbon negative.

[dttom]

while, the factories seem not to be releasing carbon dioxide and also other gases like sulfur dioxide, hence it is a mixture of gases just containing carbon dioxide as a member released but not pure carbon dioxide. Then there would be a need to separate carbon dioxide from the remaining before supplying it to the algae, wouldn't this process be expansive and not economic?

another problem is about the transportation which also need capital to support. if it is a matter not economic I don't think there would be anyone to support, though doing good to the environment.

[ironizer]

Dude, to build an enclosed pool that covers several square miles is about as impractical as hauling hydrogen from jupiter. Not only it will cost billions of dollars, it will also require vast amounts of fossil fuels to build. No free lunch, sorry.