“If it’s mineralized within a human lifetime, then we know we are on a successful pathway.”
Climatewire reports:
In a new experiment, Iceland is looking to replace its smokestacks with well injectors to permanently sequester its carbon dioxide emissions.
Researchers are now pumping CO2 underground in a process that will convert the greenhouse gas into rock. This technique may be a model for other power plants and factories to control their emissions, creating a climate change solution literally set in stone.
“Carbon dioxide capture and storage is important because we depend on fossil fuels, and we will depend on fossil fuels for the next 50 to 100 years,” said Juerg Matter, a professor of geochemistry at Columbia University.
“This is bad news for global climate change, especially greenhouse gases in the atmosphere. In terms of climate change, we have to decarbonize our energy infrastructure,” he added.
The CarbFix pilot program aims to resolve this problem by capturing carbon dioxide from the Hellisheiði Power Station, Iceland’s largest geothermal heat and energy facility and the second-largest in the world.
The 300-megawatt plant taps heat and gas pockets up to 1.2 miles below the surface to drive seven turbines. In the process, Hellisheiði releases steam, which makes up roughly 99.5 percent of its emissions. The rest is mostly carbon dioxide, along with small amounts of hydrogen sulfide, argon and methane.
Matter, who works with the program, said CarbFix is the first system that injects carbon dioxide into basalt, a form of volcanic rock. “The capacity of these rocks, the storage capacity, could be very large,” he said.
Going from acid to rock
Waste carbon dioxide is first separated from steam and then dissolved in water, forming carbonic acid. The solution is then pumped 550 yards underground into a basalt formation, where the acidity leaches elements like calcium and magnesium from the surrounding rocks. Over time, the solution flows through the basalt formation and these elements recombine to form minerals like limestone.
Iceland makes an ideal test site because the ground beneath the island nation is 90 percent basalt, which is formed by volcanic activity. The country also generates most of its electricity from geothermal sources.
However, CarbFix is not without its challenges. The project’s current phase injects carbon dioxide from a nearby geothermal well instead of the generation plant. Though the project started in 2007, the team only started injecting the well in January and will begin to inject from the geothermal plant itself in April.
“We assumed that the main difficult part of the experiment would be injecting the gas. Instead, we are delayed by the gas separation stage,” explained Edda Aradóttir, the project manager for CarbFix. “It has turned out to be a much more complex task than we thought”…
Separating gas from liquid is never as easy as it looks to be on paper. I worked for a number of years at a plant that scrubbed CO2 and H2S from a gas stream.
Since water was always present, corrosion is a perennial problem. Acid (like CO2 or H2S) + water + metal = corrosion.
As any competent handyman can tell you, if you don’t wipe your tools dry every time you use them, they will rust.
Only porous basalts can support induced carbonation. These are almost inevitably flood basalts such as those found in the Deccan and Siberian Traps, southern Brazil, and South Africa.
See “CO2 Flood tests on Basalt: An Examination of the Basalt and Basalt-Cement Interface.” (W.K. O’Connor and G.E. Rush, 2007). Most in situ basalts have never been naturally outgassed like these, and so are already saturated, and not porous.
Additionally, there is no guarantee that carbonated basalts will hold their fizz, especially when minor fluctuations in temperature or pressure occur.
Great idea, start a reasearch project to reduce the CO2 emmisions from a geothermal plant. Clearly a large potential for reducing CO2 emmisions when the flue gas is 99.5% steam and 0.5% CO2. And they thought the gas separation would be easy. Perhaps they should condense all the steam and CO2 and then add a Mentos? That drives CO2 out of water rapidly. I have an idea, start with a flue gas that has a much higher CO2 concentration. They are wasting time separating the gas and not learning how the rock formation helps to capture the CO2.
Feed a rock, starve an ocean. I’d rather see the carbon dioxide go
to feeding plankton, renewing the oceans.