Imagine on a hot summer day, you take out your favorite soda from the fridge,  pshhhhh, that is the sound of happiness. In science, that is the sound of CO2  leaving the water. We love CO2 when it’s in our drinks, but we don’t want too  much CO2 in the air. You probably already know this, in less than 200 years,  human activities have raised the CO2 level in the air by 50%, causing a global  temperature on earth to increase by at least 1.1° degree Celsius. To avoid the  negative impacts of global warming, we need to remove a huge amount of CO2  from the air, about half of a trillion tons. How much work are we looking at? Take  the largest carbon capture facility, we need to build a million of such plants to just  offset the CO2 emission from human activities, and even more plants are needed to  reduce atmospheric CO2 to preindustrial level. 

Here at Berkeley Lab, scientists have formed the Carbon Negative Initiative to  work together on removing CO2 from the air. One approach is to find a “sorbent”  that can pick up CO2 from the air. You can think of the sorbent as a special sponge  to absorb CO2. Like every other sponge, CO2 needs to be released before we can  reuse the sorbent. Heat is usually applied to release CO2 and regenerate the  sorbent. In one cycle of absorbing and regenerating, 80% of the energy goes to the  sorbent regeneration by heat. If you recall the scale of carbon capture we just talked  about, that requires a lot of energy and money.  

Our research team is developing an energy-efficient and much cheaper way to  capture CO2 from the air without using heat. It’s a 3-step process. First, we start  with a liquid sorbent, which is a base solution that can selectively react with and  trap CO2 in the solution. In the second step, we zap the water with electricity,  which triggers electrochemical reactions. In this process, the solution becomes  acidic, and CO2 is released. We can collect this concentrated CO2 stream, either  inject it to deep underground for storage or use it to make other products, like soda.  In the third step, we turn the acid solution back to base using the byproduct from  the last step so that it’s ready to use for the next cycle. By only using renewable  electricity instead of heat as the energy input, our process can bring