Tackling climate change with bugs and batteries

Of the many global challenges facing humanity, few are as urgent as mitigating climate change. Achieving carbon neutrality is a critical milestone in the fight against climate change, one that will only be met if diverse disciplines, from engineering to economics, work closely together.

To bring some of Japan’s best minds to bear on this complex issue, the Waseda Center for a Carbon Neutral Society at Waseda University was established in Tokyo, on 1 December 2022. Aiming to go beyond the boundaries of traditional disciplines, the centre will build an ecosystem that not only promotes innovative research, but cultivates the next generation of scientific talent.

One of the centre’s stars is Masashi Okubo, a researcher in the Department of Electrical Engineering and Bioscience, who is leading the search for new types of batteries that are safe, efficient and environmentally friendly.

Although lithium-ion batteries are now ubiquitous — powering everything from phones to electric vehicles — they are not suitable for certain applications. Their high cost makes it prohibitive to integrate them into energy grids, hindering adoption of renewable energy. Moreover, lithium is a finite resource, raising concerns about long-term sustainability.

AQUEOUS BATTERIES

As an alternative, Okubo and his team are pursuing aqueous batteries. All batteries have three main components: a positive electrode, a negative electrode and an electrolyte. Unlike lithium-ion batteries which use organic solvents as the electrolyte, aqueous batteries use electrolytes that are primarily made of water.

Aqueous batteries were the first type of battery to be invented. The lead-acid batteries in cars, for example, use sulfuric acid diluted in water as the electrolyte. However, the low energy-density and toxicity of lead in these batteries have limited widespread use.

Okubo is searching for alternative materials to make each of the three components of an aqueous battery. With his collaborators, he recently tested an alternative cathode material called anhydrous molybdenum trioxide that uses protons as a charge carrier.

“This material can address the high cost of lithium but we still need the other two components. Further work on all three components is needed to fabricate a battery system that does not use lithium,” says Okubo.

Despite recent progress, the puzzle is far from complete. The quest for the ideal materials is compounded by the intricate interplay of two critical interfaces within battery systems: one between the cathode and the electrolyte and the other between the anode and the electrolyte. These complex reactions demand sophisticated tools and facilities, such as synchrotrons and supercomputers, to unravel the intricacies of the aqueous battery system.

Even though a commercially viable aqueous battery is at least a decade away, Okubo is already considering the social impact they could have, particularly on the Sustainable Development Goal to provide affordable, clean energy. “From the viewpoint of sustainability, batteries help to provide electricity for everyone,” says Okubo “I strongly believe aqueous batteries can outperform lithium-ion batteries in terms of cost, safety and power.”

SECRETS OF THE SOIL

Apart from renewable energy, another major focus of the centre is regenerative agriculture. Leading the charge is Haruko Takeyama, a microbiologist in the Department of Life Science and Medical Bioscience, who currently heads a consortium of five research groups under the Japanese government’s Moonshot Research and Development Program.

Building on her extensive experience in the microbiology of marine environments, Takeyama is now tackling what may be her most ambitious project to date: creating a soil microbe atlas. The challenge is considerable, as a single teaspoon of soil can contain more microbes than there are people on Earth.

Studying the soil microbiome comes with a host of additional complications. Firstly, there is the diversity of types of microorganisms found in the soil, encompassing not only bacteria but also archaea, fungi and viruses.

The dynamic interactions between these different determinants of soil health adds layers of complexity to the task. Moreover, a significant proportion of these soil microbes stubbornly defy cultivation in laboratory settings, making them difficult to study.

“Metagenomics has been used to study other complex microbial systems such as those found in the gut or seawater, but soil is much more difficult to understand because of the diversity,” says Takeyama. “Even if you manage to get sequencing data from a soil sample, it can be difficult to assemble a genome.”

To overcome these limitations, Takeyama dips into a toolkit of techniques she has honed over the years, including 16S ribosomal RNA sequencing, single-cell genomics and Raman spectroscopy. Combining these approaches, she hopes to be able not only to understand which microbes make for healthy soil, but also promote the chemical fertilizer-free production of crops, and even store carbon in the soil by tweaking microbial composition.

As part of the project, Takeyama will focus on how microbes interact with soybeans, particularly at root structures known as rhizospheres where the plants are known to interact with nitrogen-fixing bacteria.

For her, the goal is not solely food security and reducing the carbon footprint of agriculture, but something even broader.

“Microbes can fix atmospheric carbon and convert it to useful materials, certainly. But as key players in the carbon cycle, they have a critical role in planetary health that extends beyond carbon,” she says. “Agriculture is just the start — when we talk about carbon capture, we also have to think about the ocean environment which stores 20 times more carbon than environments on land.”

MAKING AN IMPACT

Reflecting the global impact of their work, Okubo and Takeyama are both part of Waseda’s Top Global University Project, which has just celebrated its 10th anniversary. Their research exemplifies the multidisciplinary research necessary to accelerate progress on climate change. To foster such innovative research, the Waseda Center for a Carbon Neutral Society brings researchers together across the different faculties, and connects them to the wider Waseda network of more than 670,000 researchers all over the world.

Ultimately, the goal is to make not just scientific but social impact. The research will be measured not only in terms of publications but also policy proposals to government agencies and technology transfers to private companies. As universities apply their significant strengths to solve global challenges, there is growing hope we can build a better future.