Turn­ing Ex­cess CO2 Into a Rock

Trillions - - From The Publisher -

There are only two ap­proaches to deal­ing with cli­mate-dam­ag­ing Car­bon Diox­ide emis­sions: don’t emit them at all or trap them be­fore they es­cape.

Be­com­ing more en­ergy-ef­fi­cient and de­ploy­ing clean re­new­able en­ergy sources like so­lar, wind, tidal, and hy­dro­elec­tric power cov­ers the first one. But do­ing safe and ef­fi­cient CO2 trap­ping seemed im­pos­si­ble un­til now.

The lat­est cli­mate change in­no­va­tion to hit the planet comes from of all places, Ice­land, where 85% of all en­ergy use there is pro­duced by geo­ther­mal heat, hy­dropower, and a few other re­new­able op­tions. But even in Ice­land, where hot vol­canic rocks pro­vide the raw en­ergy be­hind the coun­try’s geo­ther­mal power, there have been car­bon diox­ide emis­sions com­ing out in the steam and es­cap­ing into the air.

The new in­no­va­tion to deal with those emis­sions grew out of pro­ject called Carb­fix. It was launched in 2007 by Ice­land’s Reyk­javik En­ergy, the owner-op­er­a­tors of the 303 MW Hel­lisheidi plant, one of the largest geo­ther­mal plants any­where.

The goal was straight­for­ward, the idea of pulling the car­bon diox­ide and also dan­ger­ous hy­dro­gen sul­fide emis­sions out of the ex­haust chain, and then shov­ing the dan­ger­ous ma­te­ri­als back into the ground. The prob­lem is that al­though push­ing the gases back down is not that hard, keep­ing them there is a chal­lenge.

What the sci­en­tists did to han­dle that was first to dis­solve the dan­ger­ous gases into large quan­ti­ties of wa­ter, fol­lowed by sec­ond to in­ject that wa­tery mix­ture into por­ous basalt, a vol­canic rock that forms nat­u­rally when lava cools. With the help of the basalt and the mas­sive amounts of wa­ter, a chem­i­cal re­ac­tion en­sues that con­verts the po­ten­tially leaky car­bon diox­ide emis­sions into a solid car­bon­ate by bind­ing it with either cal­cium, iron, or mag­ne­sium, all ma­te­ri­als that nat­u­rally show up in basalt com­pounds through­out the world.

The end re­sult is the orig­i­nally dan­ger­ous car­bon diox­ide emis­sions have been lit­er­ally turned into rock. These were gases that even if they were pushed back in the ground would have likely mi­grated back out in the fu­ture, adding once again to global warm­ing.

The car­bon-trap­ping process hap­pens very quickly and with re­mark­able ef­fi­ciency. In the Ice­land re­search site where the process is un­der eval­u­a­tion, the car­bon diox­ide be­comes min­er­al­ized quickly and at an over 95% con­ver­sion rate. And these rocks, when formed, stay in that form for a very long time.

Hav­ing al­ready achieved suc­cess in test runs, Rey­javik En­ergy is now gear­ing up to han­dle as much as 10,000 tons of CO2 con­ver­sion into basalt per year soon. The plant cur­rently pro­duces 40,000 tons of emis­sions per year, which puts it on a path to 100% con­ver­sion not too long from now.

It is not yet clear all this could mean to the rest of the world. The U.S., for ex­am­ple, spits out more than 5 bil­lion tons of car­bon diox­ide per year, and the sys­tems to in­te­grate basalt-based car­bon cap­ture may not work so well be­cause of lo­gis­tics, among other things. But the so­lu­tion is still a ma­jor and pos­i­tive devel­op­ment in a world hop­ing for new an­swers to the cli­mate change dilem­mas fac­ing us all.

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