olelog

Emission to the atmosphere of greenhouse gases, mainly resulting from combustion of fossil fuels, is considered a major player in global warming. Carbon dioxide (CO₂) is the main greenhouse gas, accounting for around 65%. Carbon capture and storage (CCS) is an approach to mitigate global warming by capturing carbon dioxide (CO₂) from large point sources such as fossil fuel power plants and storing it instead of releasing it into the atmosphere.

Since 1996 the Norwegian oil and gas company Statoil has been injecting 1 million ton CO₂ per year into a salt water containing sand layer, called the Utsira formation, which lies 1 km below the bottom of the North sea. Other countries in Northern Europe have very advanced plans (some under construction) to store CO₂ in terrestrial reservoirs, typically consisting of sand or sandstone (aquifers) sealed by an overlying layer of clay or other impermeable rock.

There are, however, concerns about putting large amounts of CO₂ into the ground. You don’t want any leakage so that it seeps up to atmosphere, which is missing the point by the injection. In the case of deep ocean storage, there is a risk of greatly increasing the problem of ocean acidification, a problem that also stems from the excess of carbon dioxide already in the atmosphere and oceans. (So far there has been no leakage from the Norwegian Sleipner project).

It would be better if the CO₂ through chemical reactions were bound in minerals. E.g. a reaction between calcium (Ca) and CO₂ to form (stable) calcium carbonate (CaCO₃).

According to a paper published online (and with open access!) deep-sea basalt offers a unique environment for CO₂ storage (or CO₂ sequestration as it is often called). The paper by Goldberg et al. is titled Carbon dioxide sequestration in deep-sea basalt (PNAS of 22 July 2008, vol. 105. no. 29). Oceanic crust is mainly composed of basalt (welling up at mid-ocean ridges), which means that vast volumes of seawater-filled pore space are available. Within deep-sea basalt aquifers, the injected CO₂ mixes with seawater and reacts with basalt, both of which are rich in elements with which the carbon dioxide can react. The release of Ca² and Mg² ions from basalt will form stable carbonate minerals as reaction products.

Important mechanisms for trapping CO₂ injected within deep-sea basalt further include
i) blanketing deep-sea sediments, which form a low-permeability stratigraphic barrier impeding vertical fluid migration;
ii) the formation of CO₂ hydrate, which is denser and less soluble than liquid CO₂ in sea-water of 2°C;
iii) gravitational trapping at water depths of at least 2,700 m, where injected CO₂ is denser than typical seawater, causing it to sink.
All three of these mechanisms are simultaneously available within ocean crust, providing independent protective barriers that could safely isolate the oceans, oceanic ecosystems,
and the atmosphere from leakage of CO₂ escaping from deep-sea basalt aquifers.

The deep-sea basalt region of the Juan de Fuca Plate off the coast of Oregon and Washington is suggested as CO₂ storage region for US. Here an area of 68,000 km2 has water depths of at least 2,700 m and a covering sediment thickness of at least 200 m. The total storage capacity for injected CO2 in this area is 208 gigaton of carbon.

• http://www.pnas.org/content/105/29/9920.abstract
• http://environmentalresearchweb.org/cws/article/futures/35017

A small fact sheet in pdf format about the Norweian Sleipner project and the Utsira fomation can be downloaded from:
http://www.bellona.org/factsheets/1191928198.67

See also my post on Carbon Dioxide Storage

Arizona geology has a recent post on geologic sequestration of CO2 here.

This may be old news to you, but I first heard it on TV a couple of days ago.

Methane produced by farting and burping cows worldwide currently accounts for 4% of greenhouse gas emissions. That is reason enough to do something about it. In my post on Cow Anti-Methane Pill I wrote that scientists are working to develop a pill that, in combination with a special anti-flatulence diet, can reduce the amount of methane produced as part of the natural grass fermentation process in the cow's stomach. Maybe we can do better than that.

Kangaroo farts could ease global warming. Cows and kangaroos live on practical the same diet (plenty of grass, if you ask me), but thanks to special bacteria in their stomachs, kangaroo flatulence contains no methane. It would certainly be nice if you could transfer that bacteria to cattle and sheep who emit large quantities of the harmful gas. The bacteria also makes the digestive process much more efficient and could potentially save millions of dollars/euros in feed costs for farmers and graziers, as the animals would get something like 10 to 15 per cent more energy out of the feed they are eating.

It will probably take researchers at least three years to isolate the bacteria, before they can even start to develop a way of transferring it to animals such as cattle and sheep.

Another suggestion is of course to eat more kangaroos. It's low in fat, it's got high protein levels, it's very clean in the sense that basically it's the ultimate free range animal. It doesn't get drenched, it doesn't get vaccinated, it utilises food right across the landscape, it moves around to where the food is good, so all in all it's a good food. It might take a while for kangaroos to become popular barbecue fare, but with concern over global warming growing in the world's driest inhabited continent, Australians could soon be ready to try almost anything to cut emissions.

And, yes, I have tasted kangaroo, and like it, so I know what I am talking about. I am in fact on a low fat diet, but kangaroo is a bit difficult to get in my part of the world. So please, Australian farmers, produce more kangaroo meat, and export some of it to Europe.

• http://www.news.com.au/dailytelegraph/story/0,22049,22879806-5001028,00.html
• http://www.theage.com.au/news/climate-watch/quest-to-make-cattle-fart-like-marsupials/2007/12/06/1196812922326.html




PS: I have, fair enough, been reminded that transport of meat over long distances is an extreme waste of energy. Consumption of local goods is far more sustainable! I apologise