“If it’s mineralized within a human lifetime, then we know we are on a successful pathway.”
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”…