Companies are building machines to suck carbon from the air and store it underground, but the market isn't there

Elon Musk, Microsoft and oil giants like Occidental and Chevron are investing in technologies to capture carbon. Carbon Engineering and Climeworks are two start-ups that have built machines to suck CO2 straight out of the atmosphere and store it underground. But the industry faces a number of challenges. The dream is to suck carbon from the air and bury it, but the reality is that some captured CO2 helps to make more oil.