Hard questions, soft materials

My research interests trace back to my time growing up in Costa Rica. In high school, I particularly liked math and physics, and then in college I double-majored in mechanical engineering and physics. My favorite classes in mechanical engineering were the heat transfer classes, like thermodynamics, where I could also see their value for energy systems.

I moved to Boston to do my PhD at MIT, where I began working with hydrogels for producing water from the air. Initially, the materials we used were fairly expensive, so I got interested in more common hydrogels and salts – basically the material found in diapers and the same salt we throw on the streets when it snows. We started from fairly simple and inexpensive chemistry and began engineering materials to push the performance higher and higher. We eventually developed the best materials for capturing water from the air, proving them successful as part of a device we tested in the Atacama Desert in Chile, the driest desert in the world.

My lab’s work is at the intersection of soft materials and transport. To mention one idea, we want to do carbon capture powered by heat from data centers. A data center is like a toaster because all the electricity that a data center consumes ends up being rejected as heat – except a data center is not making any toast. It’s just wasting that heat to the ambient.

Soon, about 10% of all U.S. electricity use could go to data centers. That means 10% is wasted as heat. We’ve done some analysis that shows that if you use that heat to power carbon capture from the air, we can create a data center that’s carbon negative, meaning it pulls more CO2 from the air than it produces in powering that data center.

These carbon capture systems also produce water, so we’re talking about flipping the paradigm – we can have a data center that’s carbon negative and water positive. That’s essentially addressing two of the biggest environmental burdens of these data centers.

Another direction that I’m very excited about is exploring the concept of an electrochemical heat pump. Heat is one of the largest energy consumers. We heat our homes and businesses, use it to dry our clothes, heat up water, and so on. We typically do this one of two ways: either you burn gas, and that’s very inexpensive, or you use vapor compression heat pumps, which are similar to AC systems.

Both of those have limitations. These heat pumps are barely cost competitive with natural gas, so there’s not a strong incentive to innovate or deploy them. We are starting to develop a concept that I call a moisture and electrochemical heat pump, which captures moisture from the air, regenerates it electrochemically, and produces water. We’ve done some calculations showing that this technology can be something between 3 to 30 times more efficient than a current vapor compression heat pump.

For me, this is exciting because we are starting to reach the plateau for these vapor compression systems. If we look at a radically different paradigm to produce heat, you can really go to the next step in bringing new ideas and new tools to an old problem.

Related: Carlos Diaz-Marin, Assistant Professor of Energy Science and Engineering