Imagine if there was basically 0 cost carbon capture device that ran completely off of solar power and didn't just store CO2 but also expelled oxygen and miraculously created useful usable materials...
Where will you put them? A recent study showed that just to offset _the yearly increase_ in CO2 emissions we would need to plant an entire continent of trees every year. And then ensure that they get adequate quantities of water.
Human CO2 emissions are so far off the scale of anything that has ever happened naturally that nature as she evolved on Earth has no way coping.
The best developed idea for CO2 disposal today is to compress to 1500 psi and inject into a saline aquifer. It isn't that hard to do, people have been doing injection into oil formations since the 1980s for "Enhanced Oil Recovery".
There are some questions about how long it stays there, induced seismicity, etc. but the way you're going to find out about this is by doing.
My educated environmentalist friends are complaining loudly about forest-planting programs the way they are implemented being pad for CO2 absorption (because they replace healthier ecologies) on top of being terrible for the local ecosystems. Ecology is _complex_.
I ran some numbers on running an algae bioreactor for carbon capture last year. Totally easy to do, but there's two problems for home use.
First, the typical American carbon footprint is like 15 tons. Which means that a successful backyard bioreactor will have many tons per year of captured carbon to move and dispose of.
Second, the amount of air that needs to be pulled through the system to even have access to 15 tons of carbon is /enormous/. Because CO2 concentrations in air are still very tiny. So a working system pulling a significant portion of one person's carbon footprint will require a really large fan and air management system.
