Burying the greenhouse gas

New tool could aid safe underground storage of CO2

Deborah Halber, News Office Correspondent
November 17, 2008

To prevent global warming, researchers and policymakers are exploring a variety of options to significantly cut the amount of carbon dioxide that reaches the atmosphere. One possible approach involves capturing greenhouse gases such as carbon dioxide at the source -- an electric power plant, for example -- and then injecting them underground.

While theoretically promising, the technique has never been tested in a full-scale industrial operation. But now MIT engineers have come up with a new software tool to determine how much CO2 can be sequestered safely in geological formations.

The work will be reported Nov. 18 at the 9th International Conference on Greenhouse Gas Control Technologies (GHGT-9), to be held Nov. 16-20 in Washington, D.C.

According to the 2007 MIT study, "The Future of Coal," and other sources, capturing CO2 at coal-burning power plants and storing it in deep geological basins will mitigate its negative effects on the atmosphere.

However, injecting too much CO2 could create or enlarge underground faults that may become conduits for CO2 to travel back up to the atmosphere, said Ruben Juanes, assistant professor of civil and environmental engineering (CEE) and one of the authors of the work. "Our model is a simple, effective way to calculate how much CO2 a basin can store safely. It is the first to look at large scales and take into account the effects of flow dynamics on the stored CO2," he said.

Already Juanes and co-author CEE graduate student Michael L. Szulczewski have applied their model to the Fox Hills Sandstone in the Powder River basin straddling Montana and Wyoming. They found that the formation would hold around 5 gigatons of CO2 -- more than half of all the CO2 emitted by the United States each year.

A geological basin is a large underground bowl between 100 and 1,000 kilometers wide and 5,000 kilometers deep that has filled over millennia with layers of sand, fine-grained clays, and other sediments that are eventually consolidated into porous rock. Some of the layers contain brine and are called deep saline aquifers. CO2 would be injected into the aquifers through wells.

The MIT model predicts how much a plume of CO2 will migrate from its injection well and the path it is likely to take due to underground slopes and groundwater flow.

"A lot of people have done studies at small scales," Szulczewski said. "If we're going to offset emissions, however, we're going to inject a lot of CO2 into the subsurface. This requires thinking at the basin scale."

"Despite the fact that our model applies at the basin scale, it is very simple. Using only pen and paper, you take geological parameters such as porosity, temperature and pressure to calculate storage capacity," Szulczewski said. "Other methods suffer from major shortcomings of accuracy, complexity or scale."

Juanes studies a phenomenon called capillary trapping, through which CO2, liquefied by the pressure of the Earth, is trapped as small blobs in the briny water (picture bubbles of oil in vinegar). The CO2 dispersed throughout the basin's structural pores eventually dissolves and reacts with reservoir rocks to precipitate out into harmless carbonate minerals.

CO2 has been sequestered in small pilot projects in Norway, Algeria and elsewhere. In 2004, 1,600 tons of CO2 were injected 1,500 meters into high-permeability brine-bearing sandstone of the Frio formation beneath the Gulf coast of Texas. Current proposals call for injecting billions of tons within the continental United States.

The GHGT-9 conference is organized by MIT in collaboration with the IEA Greenhouse Gas R&D Programme (IEA GHG), with sponsorship from the U.S. Department of Energy.

This research was supported by the McClelland Fund, administered by the MIT Energy Initiative, and by the Reed Research Fund.

This article was originally published by MIT and can be seen below:


Green Home Tips

Posted by Sasha Kirey On 3:43 PM
Do you consider yourself to be a green living friendly person?

Chances are that you would love to become greener, but you think that it is going to require too much time and extra effort. I know that it may seem overwhelming at first and you may feel like you do not know where to begin, but the reality is that it is actually quite easy to green up your life.

Let me suggest just a few simple steps that will help you become greener and more earth friendly:

Start Recycling

You know these blue plastic boxes the city is providing you for free? Why not start using it. It will only take a little bit of extra time to sort out all your plastic bottles and put them in that blue box. It is well worth the effort and it will make our environment greener.

Ride a bike when you can!

So, why not take that bike that has been seating in your garage for years and take it out for a little ride in the neighborhood next time you need to go somewhere close by. Biking is an excellent exercise that will not only help you build your legs, but it will also spare the unnecessary emission deposits into the environment. Simply put, Biking is healthy, fun and refreshing.

Get those energy efficient bulbs.

Next time you go shopping to Wall Mart or Home Improvement Store, why not get those energy efficient bulbs and replace all the regular bulbs in your home, or in the stair way if you live in a small apartment building.

Shovel Like there is no tomorrow.

I know winter is just around the corner. So next time it snows hold yourself from starting that crazy snow shoveling machine and grab a shovel instead! Shoveling can be a great exercise that builds muscles and burns the extra pounds!

Alright those were some simple tips that come to mind and can be a great way to get you started thinking about all the other ways you can green up your life. Now that we got our mind going, let's move to more advanced ways to green up your home.

Energy Efficient Home Improvements:

Here are some of the ways you can make your home greener next time you are doing renovations in your home.

Energy Efficient Windows

Are your old windows letting cold air in from the street and are difficult to open. Why not replace your old windows with energy efficient windows that will help keep your home warmer or cooler depending on the season and will save you tons of money on heating and cooling costs.

Green Roofing for slope roofs

Is your old roof curling and cracking? Perhaps it is time to upgrade to a newer energy efficient roof. There are many green roofing options available. Consider installing green roofing system made out of steel, aluminum or copper. Metal can provide excellent energy efficiency benefits and a new metal roof could last a lifetime of your home.

Energy Efficient roofing for flat roofs

If your house has a flat roof and metal roof is not an option, then you can still benefit from an energy efficient IB cool flat roof system that reflects solar radiation and can outlast most conventional roofs by a factor of 3! You could also get your roof set up with roof integrated solar panels that can provide some free electricity for your home. Talking about the ways to really go green!

You can find energy efficient roofing contractors listed in Specialty Roofing Directory.

Save money on heating

Turn down the heat in you appartment during the day and save some money!

As a tip of the day you can find more environmentally friendly blogs at Blog Directory by Blogzoop.

As always, I welcome your comments, let me know what you think!