We love large windows, but probably not on a hot summer day when the sun is scorching your room through the big window, especially when your air conditioning is down. Even if everything is working well, it still consumes a lot of energy to cool down your room. Actually, your beautiful windows could be responsible for a staggering 30% of energy loss. The good news is, our team at Berkeley Lab is developing technologies that can reduce this energy loss to zero, and even transform your window into a power generator.

Well, when talking about power generators in buildings, you might first think of the roof-installed solar panels. They are made of opaque solar cells that convert sunlight into electricity. One method to add transparency to the solar cells is placing micro holes. These micro-holes are small enough to be invisible to the human eye, but large enough to avoid diffraction and interference. The solar window with micro holes looks just like the regular window, but it can amazingly transform sunlight into electricity.

But we didn't stop there. My study takes it a step further by integrating micro-shutters into the solar windows. These tiny micro-shutters can open and close just like regular-size window shutters, but by electrostatic force from a voltage difference. Also, the micro-shutters are designed to perfectly cover the micro holes on the solar cells. In this way, the unwanted sunlight is partially blocked by micro-shutters and partially converted to electricity by solar cells. And, the transparency of this window can be controlled pixel by pixel, using the power generated by itself!

When we combine this technology with smart home ecosystem, we can control the window by simply saying:

"Hey Siri, dim the window",  

or "Hey Google, open the shutters at sunrise",

or even "Alexa, display 'Merry Christmas' on my big window."

But, let's take a moment to think bigger. Buildings are not the only place to apply this window technology, we can also use it in cars. Imagine your car is parked in the hot summer sun, but the temperature inside your car automatically stays cool without consuming extra energy. Once this technology becomes mature, you can say goodbye to the ugly sunshade in your car, and say hi to your beautiful, smart, zero-energy windows.

40 BILLION TONS.

That's the amount of carbon dioxide we release in just a single year.

Scientists across the world are trying to capture and remove this excess carbon dioxide, and in fact, some researchers are converting it into carbon black – a stable, solid form that's easier to store.

Now, if we convert billions of tons of carbon dioxide to carbon black, we will have massive mountains of carbon just sitting there.

How do we sequester (i.e., take and store) all this carbon for years to come?

A really good solution is to store it in buildings. Millions of buildings are constructed every year, and they last for over 50 years on average. This is a perfect large-scale, long-term solution.

So, can we develop a building material that can not only sequester carbon but also be strong enough to replace materials like cement and steel that significantly contribute to carbon dioxide emissions?

This is where my research comes in!

I am developing carbon-sequestering composites. Think of a composite as a nicely stuffed chocolate chip cookie, but instead of using flour, butter, and sugar, I'm using Hemp – from agricultural waste streams, Carbon black – from air, and Lignin – a naturally occurring glue found in trees, and it also happens to be a waste product from the paper and pulp industry!

To ensure the composite is strong and robust, I am employing a science-to-system approach, wherein I perform fundamental analyses at a molecular level and connect my findings to the performance of the material at a more realistic scale.

For instance, the basic composition of lignin changes according to which tree it comes from and how it is extracted. To really understand how these differences affect the material's strength, I am performing tensile tests and shear tests, which mimic the modes of failure from an application point of view.

By continuing to establish these structure-property relationships, I believe I can develop a strong material that will fit seamlessly in roofs, walls, and floors of our future buildings, and at the same time, sequester billions of tons of carbon dioxide.

How many of you have used a microwave oven recently? Please raise your hand! Great, that’s pretty much all of you. Did you know that microwaves could help cool down the Earth? Because that’s what I'm working on. We are living in the era of climate change where we have emitted far too much CO2. So, we will have to remove a lot of it directly from the air. We call such a device 'direct air capture.'

Direct air capture is basically an oven. We fill this oven with materials specially designed to capture CO2. We can simply pass air through this device to filter out CO2. Once it's full, we can turn on the oven, and pure CO2 can be released. Now we can store it safely. Sounds great, right? But there’s one problem. This technology would be too expensive to use. Ovens, as we know, are quite slow. This means you would need an oversized system. It will be energy-intensive. And, importantly, this high-temperature operation degrades the precious material, making this process quite inefficient.

So, what do we do? My innovation involves using microwaves. We all know one thing about microwaves – they are really fast. So, we only need a small device to remove the same amount of CO2. And here is what makes it interesting: microwave absorption is a very selective process. For kitchen applications, microwave ovens are designed to efficiently heat water so we can heat up our lunch. For direct air capture, we can apply microwaves in a smart way to release CO2 without really heating anything. This way, direct air capture can now operate near the thermodynamic energy limits, and we can use the precious materials much longer because we are not degrading them. Direct air capture can now be made cheap enough to use against climate change.

At Berkeley Lab, I will be leading a small team to develop this technology into a reality. This includes studying microwave absorption at a tiny molecular level and developing a prototype to demonstrate that this concept works. So, next time you heat up your lunch with microwaves, also remember that we could cool down the Earth using microwaves.