From Iceland to Wyoming and Switzerland to Texas, carbon capture plants are under construction or working away to suck CO2 out of the air and store it underground. A pilot project in Kenya will soon join their ranks, except it will be focused more on the storage part than the capture part.
Cella Mineral Storage is aiming to store CO2 by injecting it into water then pumping that water underground, where it will make contact with volcanic rock. A chemical reaction will occur between the minerals in the rock and the CO2, causing the CO2 to turn to stone in a process called mineralization.
Mineralization occurs naturally, but Cella wants to speed it up; it’s an attempt to start righting a balance that’s been thrown out of whack over the last 200 or so years.
Speeding Up the Carbon Cycle
We know there’s been more and more CO2 dumped into Earth’s atmosphere over the last few decades, and that these carbon emissions are contributing to climate change. But the part we may not remember is that the total amount of carbon in Earth’s ecosystem doesn’t change much. Carbon isn’t escaping to nor coming from outer space; Earth and its atmosphere are a closed environment. It’s where on Earth the carbon is located that’s constantly changing.
The process of carbon atoms moving from Earth into the atmosphere and eventually back to Earth, where they get stored in rocks, sediments, the ocean, and living things, is called the carbon cycle. Carbon gets released into the atmosphere when plants or animals die, volcanoes erupt, or most notably for our purposes, when humans burn fossil fuels for energy.
Burning coal, oil, and natural gas inserted a fire hose (or rather, many of them) into the carbon cycle that had been mostly humming along smoothly for millennia; we sped up one end of the cycle without any way of counterbalancing it on the other end. That’s the problem direct air capture plants aim to solve, and what Cella wants to do in Kenya.
Chemical Reactions
Most carbon capture projects inject CO2 into underground rock reservoirs, where it eventually dissolves into groundwater and solidifies through chemical reactions with certain minerals. Dissolving CO2 in water before injecting it underground accelerates the process and makes it harder for small amounts of the carbon to escape before it’s mineralized. Carbon storage experiments in Iceland found that 90 percent of the CO2 that was captured this way transformed into minerals in just two years.
Basalt rock, specifically, is rich in calcium and magnesium, which react with CO2 to make calcite, dolomite, and magnesite. Basalt is a volcanic rock formed from cooled lava. It can be found all over the Earth and continues to form today at active rift sites—one of which is in Iceland, and another the East African Rift Valley. The latter runs from Ethiopia to Mozambique, with Kenya right at its center.
New Territory for Carbon Storage
Kenya is the eighth-largest producer of geothermal energy in the world, and gets almost 40 percent of its power from geothermal sources. The country’s geology means there’s a massive amount of heat relatively close to the Earth’s surface. The movement of tectonic plates creates fissures in the Earth’s crust that bring underground water into contact with ultra-hot rock, creating steam. This phenomenon exists all over the world, but in most places you’d have to drill much deeper into the ground to find temperatures like those in Kenya.
Besides this bottomless source of energy, the country’s geology also means there’s a huge amount of volcanic rock—like basalt—underground (including the Mega Basalt Field along the Kenya-Ethiopia border). Combine abundant geothermal power with easy access to volcanic rock, and you’ve got an ideal site for direct air capture and carbon sequestration.
The scope of Cella’s work in Kenya will initially be limited to carbon sequestration via mineralization; the company will buy CO2 from outside sources to use as a proof of concept. Eventually, the startup will partner with another company that will build a carbon capture plant, bringing the capture-and-store process full circle. Kenya’s biggest geothermal power plant, Olkaria, is set to open its newest unit later this year. Cella will start its pilot around the same time.
In Kenya, proponents of carbon storage—from the country’s president, William Ruto, to the cofounder of Climate Action Platform-Africa, James Mwangi—are endorsing the idea of their country as an ideal location for the technology, speaking of building a “Great Carbon Valley” and exporting carbon credits.
Reality Check
But how realistic is this? There are major gaps to bridge from an infrastructure and business standpoint before carbon capture could truly become a viable industry in Kenya—not to mention the viability of carbon capture in general. Even if we build thousands of direct air capture plants, we can’t hope to capture more than a fraction of the CO2 that’s already in the atmosphere. Using geothermal energy helps by ensuring the capture process itself doesn’t emit CO2, but it remains debatable whether these plants will make enough of a difference to be worth the cost of building and running them.
Finally, we should pause to consider the ethics of using a large amount of power to store carbon in a country that hasn’t created much carbon, and could use said power to grow its economy. Kenya’s grid has the capacity to produce more electricity from renewable sources than the country uses, yet more than a quarter of its population doesn’t have reliable access to electricity. It’s something of a chicken-before-the-egg problem; there’s not enough industry to build out the grid, but as long as the grid remains limited, there’s no power for industry.
On the one hand, then, you may as well put the surplus of renewable power to good use, like by capturing and storing CO2. But how might these projects impact the likelihood of the country’s economy growing and diversifying, and the cost of and access to energy for the average Kenyan?
Cella believes its activities will have a net positive impact on Kenya and its people, and this could certainly end up being the case. But it will be a while before we find out, since the pilot is just the first step of many.
In our continued quest to repair the damage done to Earth, carbon capture in Kenya and elsewhere will continue to be explored as options; time and economics will tell whether the technology persists.
Image Credit: Roma Neus/Wikimedia Commons
