Going to be underground…. (and why!)
If we are really going to ever convert massive amounts of carbon dioxide to value added products (apart from our trees and existing biomass already growing) Team Cleancarbon Energy bets it’s going to have to be underground due to the reactor volumes required as explained in this blog post.
..going to be underground…
In Star Trek II William Shatner playing up Captain Kirk while searching for researchers on the Genesis Device (who are also dramatically missing ex lover and son) comes to the realization in a scene where he thinks aloud:
KIRK: If Stage Two was completed, it was going to be underground. …It was going to be underground, she said.
SAAVIK: Stage Two of what?”
The CleanCarbon Energy strategy has its roots in a similar moment in, of all places, Grand Forks North Dakota. There team member Craig Pichach, already with his Mechanical Engineering degree from the University of Calgary, was working on his Chemical Engineering degree and researching microchannel reactors to lower the capital intensities of gas-to-liquids facilities. While Dr. Wayne Seames was drilling in how even these microchannel reactors at surface had capital costs making most GTL projects uneconomic, Pichach took a moment to discuss an idea on CO2 conversion with Dr. Brian Tande.
At the time Craig Pichach was big on microalgae to convert CO2 to biomass. He already knew that if one was using microalgae it was going to be a mixotroph – that is an organization that is both autotrophic (can convert CO2 to biomass) and heterotrophic (cannot fix carbon and has to essentially feed on a more complicated biomass). But talking to Tande he realized that practically if mass carbon fixation is possible it’s going to have to be underground and it will not be microalgae.
Because you use light the surface area requirements become excessive with your microalgae cell density limited to basically 1kg/m3 of water. The faster you grow your microalgae the higher the density gets… blocking the light penetration! For a 1000MW coal plant putting out ~15,000tpd+ of carbon dioxide (15,000,000kg/day) even if your microalgae doubles every hour you are going to need a reactor size greater than ~625,000m3. This actually isn’t so bad for such a massive amount of CO2. The problem though is that if you grow to these high densities the light will only penetrate 2m deep into the water. You can’t just have 625,000m3 of tankage, you need a pond with a surface area of 312,500m2 or 600m x 600m. Double that to account for inefficiencies and lighting and you need a pond over a kilometer by a kilometer long. Once your pond is that big, how are you going to keep it at 30 Centigrade? How do you prevent freezing in the winter? How are you going to get all the microalgae out – with Reverse Osmosis this would be quite expensive! How are you even going to make such a perfectly level pond? And what would the CAPEX be?
First thought that may come into mind is why not use artificial light to grow vertically to reduce your pond size? Unfortunately you now need to put in power to create those photons and due to inefficiencies you pretty much will end up putting more power into your lights than the products out.
How about fiberoptics? Some firms attempted just that to use fiberoptics to get increased microalgae densities. This showed some promise.
The other potential improvement and to reduce the water treatment is use a mixotroph microalgae like the fast growing Chlorella Sorokiniana. You first grow the microalgae to 1kg/m3 using artifical power but then grow it using anaerobic digester waste. When starved of CO2 Chlorella Sorokiniana will stop reproducing and grow in size while consuming waste acetic acid giving you higher biomass densities.
At the end of the day however when you look at the overall balance you real carbon sequestration then is being done by the acetic acid which already pretty much was being converted to syngas.
Dr. Brian Tande shook his head – you need something like those tube worms under the ocean that you can do this underground.
Why underground you could have a massive reactor. A massive geo-bioreactor.
And what of tube worms under the ocean? We will come back full circle later with the tube worms under the ocean but there is real power in considering that this has to occur underground.
Photosynthetic organisms are already converting carbon dioxide to biomass. If we try to boost this we are going to need huge volumes.
Option 1 is the ocean – grow lots of Ulva seaweed in the ocean. Many researchers have proposed dumping iron into the ocean to make this happen. This is a potential solution but not exactly an optimal one since we would be dumping lots of iron into the ocean. That being said we could then harvest all the ulva and gasify it to make value added products. Something potentially economic and doable. Our downhole flexfuel gasifiers would make excellent gasifiers for ulva. But does anyone want to dump iron into the ocean? What kind of damage will we do to the ecosystems?
Option 2 is something else underground.
We need an ecosystem already full of bacteria with waste water that preferably does not compete with photosynthetic organisms already consuming CO2 and probably providing us value added food. For that you have to go underground to brackish (salt) water formations and depleted oil and gas formations of which North America has a lot of with huge volumes. The volumes are there… but it’s going to have be to underground.
But now you need a lifeform which can fix carbon (an autotroph) that does not need sunlight. Does that exist?
Find out next blog post!
Quote of the Day:
“Every moment in business happens only once. The next Bill Gates will not build an operating system. The next Larry Page or Sergey Brin won’t make a search engine. And the next Mark Zuckerberg won’t create a social network. If you are copying these guys, you aren’t learning from them.
Of course, it’s easier to copy a model than to make something new. Doing what we already know how to do takes the world from 0 to n, adding more of something familiar. But every time we create something new, we go from 0 to 1. The act of creation is singular, as is the moment of creation, and the result is something fresh and strange.”
- Peter Thiel with Blake Masters, “Zero to One – Notes on Startups, or how to build the future”