Locking CO2 Away For Good

HobbySpacer writes: "The BBC reports that waste CO2 from methane extraction in the North Sea has been succesfully pumped back into the pourous sandstone beneath the ocean for the past 6 years without any signs of leaking. Carbon sequestration techniques like this are looking increasingly practical. CO2 is being pumped back into depleted oil fields, where it also helps extract remaining oil deposits, and into coalseams. The ocean is the biggest natural bank of CO2 but tests of ocean sequestration in Hawaii and Norway have been blocked by environmentalists who hate this kind of quick fix approach to the CO2 problem. But with developing countries like India and China certain to rely on their large coal reserves, sequestration may be the only realistic approach to reducing their CO2 output. An Economist article discusses currently available steam reformation technology that could allow a coal plant to output power and neatly separated CO2 and hydrogen. The non-polluting hydrogen is then available for cars with fuel cells while the CO2 is stuffed away."

Comments

This is really cool and all but...

[eggstasy]

What if something weird happens and the CO2 gets released in massive amounts? Like, a bomb, or a sinking ship, or an earthquake? Really though, the Earth's crust isn't a very stable place in its natural state and we don't have the resources and technology to put huge reinforced structures under the ocean to store the CO2 properly.
The ocean floor in particular is a very unstable place. If you look at the pacific, all those tiny little islands were made by volcanos that appeared there all of a sudden, out of the blue, with no early warning. Apparently there are some "hotspots" in the magma layers below our surface, which puncture the Earth's crust forming temporary volcanos, that go extinct as the crust moves tectonically away from the hotspot below it. You never know what might hit an undersea CO2 deposit even if it was a solid, well engineered structure. The crust is very thin there! Cave-ins, earthquakes, volcanic activity in general, you wouldnt want to live at the bottom of the sea.
It sounds like a quick hack that will solve the problem temporarily, but I can just see the CO2 getting released sooner or later.

Re:This is really cool and all but...

[0x69]

The CO2 would be in thousands or millions of old oil wells, coal seams, etc. and millions of square miles of deep ocean. Any one of those spots could have a problem & release some small fraction of 1% of the CO2.

If anything big enough to release a large fraction of the CO2 comes along (giant asteroid, Iraq's "Planet Buster" nuclear doomsday device, etc.), then we'll have *far* greater worries than the CO2 release.

Re:This is really cool and all but...

[sofar]

Near surface natural CO2 deposits (dry ice) have been discovered and found to be a huge danger to anything that comes around. These deposits generally lie very shallow under the seafloor and can be meters in thickness. The biggest danger is not their sudden release and toxic effects of that, but lies in a totally different factor.

In several ocean slopes (offshore norway, east coast US) these deposits suddenly gave way in history, allowing the cover of these deposits to start sliding down the oceanic ramps. The gasses maybe killed some fish, but the Norway slide triggerd a tidal wave that reached elevations of over 100m in height when it crashed into the north of Scotland (that's 500-1000km further), destructing everything in it's path.

Another danger is to ships and constructions. The massive amount of gasses makes the sea like a giant bubblebath. Anyone that every played with a rubber duck that barely floats in a bubblebath knows what happens when you turn on the bubbles hard enough: it sinks. A massive gas pipe blowout just below an oil righ in the North Sea caused a complete oil/gas rig to sink like a rock a few decades ago.

That said CO2 looks like a dangerous thing to toy with, but that's not the case in the oil fields we are talking about here.

Most of these fields are at enormous depths, the typical North sea fields (in which these experiments have been done for quite a while) are at depths of over 500m. The rocks at that location are much more stable, and at 800m we're talking about serious tough rocks.

Using CO2 to extract the oil better (by pressurizing depleted oil fields) and returning the CO2 they are hitting the jackpot twice: First they can revive old fields relatively cheap and extract more oil, and secondly they can do something back for the environment in a very safe way.

The argument of cave-ins, earthquakes are however very serious ones. The typical example of a colorado experiment where fluids were injected into deep crustal fissures resulting in earthquakes occuring daily instead of yearly warn us against toying with the earth's structure.

That said one must conclude that CO2 injection must be evaluated before it is even tried. As a geologist from the Netherlands I can honestly say this news is not new. CO2 injection has been discussed for over a decade now and thes tests were done in several other fields in small scale before this larger experiment by statoil.

When you say "in general, you wouldnt want to live at the bottom of the sea" I can vough for that too, if you think the bottom of the sea is a safe place then you are wrong! But pumping some CO2 to fill up a hole you created again might be better than leaving the hole there. At least we should put a cover on the hole after we finished using it.