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Blog - Can algae be used to combat global warming? (changes)

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This page is a blog article in progress, written by David Tanzer. To discuss this article while it’s being written, visit the Azimuth Forum.

guest post by David Tanzer

Imagine if people really thought out loud, and brainstormed in a public forum. I may filter out 100 bad ideas, before I get to one that is even worth further consideration. Suppose that people were somehow not embarrassed to put their bad ideas, and the half-baked ones, along with the good ones, in a public discussion forum. (To combat the embarrassment factor, there could be mechanisms that allow contributors to say, I know this this is a half-baked idea, or even a bad idea, but I’m putting it out here into the flow nevertheless.) Imagine how the possibilities could exponentially increase, for people to have associations with other people’s partial ideas, that might eventually lead to something useful and important.

This suggests that an alternative mode of invention, which is now made possible by modern information technology, could be a fruitful way of addressing some of the complex, large-scale unsolved problems that threaten our life on Earth. The ones that I have in mind are safe energy, renewable energy, reduction of carbon emissions, and removal of carbon dioxide from the atmosphere. These problems exist on a social scale, and that suggests the use of a social forum for solving them.


Idea: using algae blooms to sequester carbon dioxide

What about adding a section to this page with ideas for carbon sequestration that are incomplete but which could plausibly be developed into effective technologies if inventive people work on them. Things that merit funding and further investigation.

The one I’m thinking of is the idea of using algae blooms to extract CO2 from the atmosphere. Here is a recent posting about it in the New York Times green blog. That approach seems to be to let the Algae fall to the bottom of the ocean and settle as sediment for a “long” time.

Here is a report on a discussion with Dr. James Lovelock, where the key idea is the pyrolysis of ocean algae. He is quoted there as saying that ocean algae represents over 70% of the Earth’s biomass. He is a consultant to the company that puts out the blog, which is developing some proprietary “pyrolyzer” technology.

Here is a picture of the cleanup effort for a large algae bloom that occurred off the coast of Quindao, China, in 2010. At that time it had grown to 150 square miles. The author states:

Another option that I haven’t seen presented yet, is to dry the algae to use as feedstock in making biochar. If the 2010 bloom ends up being anywhere close to the 2008 one, that is potentially a lot of biochar.

This incident also highlights the fact that the seeding of Algae blooms should not be taken lightly, as it is a significant form of geo-engineering.


I suggest that we organize a public forum for posing, brainstorming and solving such “grand technological challenges.” And find some appropriate terms of service, that would guarantee that all ideas contributed there posted will belong to the public domain.

Here is how I would phrase the public challenge regarding algae-based carbon sequestration:

Can we Effectively (and Safely) Harnesss Algae Blooms in the Ocean to Reduce Greenhouse Carbon Dioxide?

Technology now exists for seeding the growth of large Algae blooms in the ocean. When Algae are constructed in the process of photosynthesis, carbon dioxide is removed from the atmosphere, and converted into the organic molecules of the Algae cells. The larger the bloom, the more carbon is remove from the air. But in itself this does not remove carbon from the “carbon cycle,” because when the algae decompose, or when the fish eat the algae and they decompose, the carbon is returned to the air. Some approaches are based upon trapping the sediment from the algae at the bottom of the ocean. But a really durable, stable solution needs to somehow convert that algae into a permanent form that will not spontaneously return into the carbon cycle. Nature itself did this when it fossilized algae sediment into petroleum. So how can we build technology to “fossilize” and store algae that are created by artificially grown algae blooms?

Imagine a floating algae farm on the ocean, managed by robots run by solar power. Once the algae grows, what can the robots to fixate it? Now we’ll enter the realm of speculative ideas. They could compress it into bricks. Perhaps they could put the bricks into sealed capsules and let them drop to the bottom of the ocean? But how long could a sealed capsule really last for? If they only last 50 years, we’re just passing the buck a couple of generations. On the other hand, we are in desperate need of solutions now that would even get us to the next 50 years. Still let’s try to do better. Maybe it would be better to bury the bricks underground in dry mines. But how would we get the bricks there? How much energy would that require, and how much carbon dioxide would be released in the process of getting them there. Maybe the robots could some fine

<it>chemical</it>

work, to bind the dead algae into some kind of durable molecules that could drop to the bottom of the sea, and would not be usable as food by existing organisms. But what if a new organism evolved that could eat them?

Also note that we need to carefully consider the repercussions of large ocean algae farms on the environment of the ocean. Ideally we’d like a high efficiency machine on the ocean, which is using the full energy of the sun to bind CO2 into a permanent form. The smaller the factory can be, and the less stuff that it drops into the water, the better.


How large would the Algae farm need to be in order to make a significant difference? Clearly it depends on how fast they grow. How much Algae would have to grow to remove the amount of carbon in a gallon of gasoline? To get a rough handle on it, can anyone estimate a conversion factor between acres of continually growing ocean Algae and gallons burned per day of gasoline?


John Baez wrote:

Do some calculations and estimate how much algae it would take remove 10 gigatonnes of carbon from the air each year. Or… write a little blog article asking other people to do these calculations, and let me post it on the blog! I like the idea of technological challenges. If they get serious enough, we’d have to think about to make the ideas public-domain. Does anyone know an easy way? Just a copyright form on the blog?

As a very crude guide: all the land plants on Earth absorb about 120 gigatonnes of carbon from the air, while the oceans absorb a total of 90 gigatonnes. But most of this is re-emitted. So for a ‘complete solution to the carbon problem’, you’d algal blooms that are equal in effect to about 10% of either one of these natural processes.

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