Sequestering CO2

by Win Wenger, Ph.D.
Winsights No. 108 (July/August 2009)

This one didn’t come by any specific technique, but probably came because I’ve been practicing use of some of our creativity techniques. The idea arrived in the evening of July 21, 2009, unbidden but welcome.

As you know, there has been a bit of discussion in recent years about the human-caused spike in CO2, a greenhouse gas trapping heat, in our atmosphere, accompanied by a rise in global temperatures apparently caused by that spike. As the global climate warms, glacial and polar ice is melting away; and all that melt water is raising oceanic sea levels at an accelerating rate, threatening to do a permanent New Orleans to all our coastal cities.

Various researchers—and various enterprises—are seeking to reduce atmospheric carbon dioxide levels by sequestering CO2 and/or carbon back underground. Most of their methods for trapping and sequestering carbon from the atmosphere involve industrial processes whose cost in energy-use itself produces a “carbon footprint,” and whose material costs raise doubts as to whether they could ever be applied on a scale large enough to significantly affect the global climate.

But here is a consideration:  What if we let nature, our abuse of which is what has gotten us in trouble, do most of the work for us of correcting the problem? Here is a way to significantly improve, perhaps even cure, the problem of excess CO2 in our atmosphere:

  1. At the lowest point of Death Valley, excavate even some feet deeper with dozers and explosives over a few square miles. (This is already well below sea level, even before such an excavation.
  2. Let in, or pump in, a little water, either fresh or brackish depending upon the type of algae to be used. Seed the resulting shallow lake with algae.
  3. The algae quickly overgrow and choke the lake.
  4. Let the mess dry out, cover it over with a few inches of sand or dirt.
  5. Let in, or pump in, a little more water atop all this and seed the resulting shallow lake with more algae, then repeat steps 3, 4, 5 until the millions of tons of carbon from all that algae are accumulated into a cubic mile or so of the lowest-lying reaches of Death Valley. That would then be one of the most fertile stretches of land on Earth, and with irrigation from the equipment mustered in steps 2 and 5, could be used either for agricultural purposes or to plant a forest.

Why Death Valley? Most of that blighted desert is already well below sea level. The carbon sequestered there would be unlikely to leak out to become a problem again somewhere else. There are several such places around the planet that could be so used, with favorable ecological effect upon their surroundings.

I don’t yet have a dollar cost guesstimate for this procedure, but with nature doing nearly all the work for us—growing that algae as she tends to do so very prolifically, from green-scummed ponds to oceanic algae “blooms”—I’m certain that the dollar costs are way less than with any of the other carbon-sequestration proposals offered thus far; and the scale of the project could well be sufficient to significantly help solve the global climate crisis.

Further, should conditions change, all that carbon would be lying there to be easily retrieved, to use either as fertilizer or as a fuel (I still think that fast-growing algae is the most economical path to alternative biofuel). For agricultural use, if an adequate large-scale system for charring that mass of algae can be found, that then provides a superfertilizer, most of the carbon of which stays in the ground after application.

Looks like a nice enterprise for someone to pick up on… Know anyone to whom it might be a good idea to pass this idea on?