Fulbright Scholar explores alternative bioenergy resources for French Guiana

Yixuan Li
April 14, 2016

While generating electricity from bacteria may still be a novelty to many, it is not a new concept to Caroline Rivalland, a doctoral student from France and visiting Fulbright Scholar to Penn State.

In fact, Rivalland has spent the past two years exploring this topic deep in the mangrove forests of French Guiana, an overseas French region in South America that is rich with biodiversity.

“The current electricity production in French Guiana primarily comes from hydraulic power and solar panels,” she said. “But a certain percentage of the production still depends on imported classic fossil fuel.”

Due to its tropical environment, the changes in dry and wet seasons often affect the efficiency of renewable energy production in the region.

Rivalland said that electricity outages in the area she lived in sometimes last for hours. Not only would they cause the food in the fridge to go bad very rapidly, but, on a bigger scale, the inconvenience they bring to people’s everyday work and life is almost immeasurable.

“But bacteria are different,” said Rivalland. “They are there all year round.”

With the growing demand for energy and pressing need for greenhouse gas emission reductions worldwide, scientists now see great potential in bacterial electroactivity to constitute an additional biological resource. 

For Rivalland, French Guiana may even “lead a future of transition” for the world toward more renewable and cleaner energy production. 

“Certain bacteria can transfer electrons directly out of their cells, which can be harvested and used to produce electricity,” said Rivalland. “And they are abundant resources in the mangroves of French Guiana.”

According to Rivalland, extracellular electron transfer is a microbial metabolism that enables efficient electron transfer between microbial cells and extracellular solid materials. For those bacteria, called exoelectrogens, releasing the electrons extracellularly is the final step of the electron transport chain, constituting the only way to produce their own energy.

During her time in French Guiana, Rivalland focused on sampling and characterizing the interactions of microbial populations involved in the production of electricity in bioelectrochemical systems. 

“We provide organic matter for the bacteria to consume and a surface that allows them to grow into a biofilm. They will then produce current spontaneously in the devices they are implemented in, which rely on the simple configuration of a battery,” she said. “We only need to input a little energy when it comes to hydrogen production.”

However, efficiency and cost remain the biggest barriers to bringing these advancements to the real world. And Rivalland hopes to add her piece to solving that puzzle as she continues her research at Penn State in the laboratory of Bruce Logan, Kappe and Evan Pugh Professor of Environmental Engineering.

In Logan’s lab, she concentrates on implementing the electroactive microbes found in the mangrove soil to determine their actual potential for electricity generation and biological production of hydrogen. 

“There are not many labs in the world that focus on this topic, and Dr. Logan’s is one of best out there,” she said. “Even though my colleagues and I are working on different samples, we are often able to share information about similar species and compare results.”

Besides her research, Rivalland also enjoys the comfort and safety State College provides after an adventure moving across the ocean from Europe to South America.

“The weather there was really humid,” she said, laughing. “And there were huge mosquitos everywhere. Even wearing long sleeves and jeans wouldn’t help.”

In the mangrove forests where snakes and spiders commonly resided, she also faced the risk of getting lost with no paths in sight and knee-level water on the ground.

“We had to tie red strips of cloth on the trees to keep our directions,” she said.

Even with many challenges, Rivalland said the opportunity to explore different parts of the world, utilize various labs and share cultures with people from different places makes it all worthwhile.

Caroline Rivalland graduated with her master's degree in biotechnology in 2013 from the University of Southern Brittany in France. She is a doctoral candidate at the University of French Guiana and a member of the research team at the Laboratory of Materials and Molecules in Amazonian Environment (L3MA). She expects to complete her thesis after returning to France at the end of her six-month Fulbright Scholarship appointment in May.

  • Headshot of Rivalland

    Rivalland is a Fulbright Scholar learning how to best generate electricity using bacteria.

    IMAGE: Penn State
  • Sample soil from French Guiana.

    Sample soil from French Guiana.

    IMAGE: Penn State
  • Setup of project.

    The bacteria from Rivalland's soil sample produces current in the devices they are implemented in, which rely on the simple configuration of a battery.

    IMAGE: Penn State
  • Energy balance of FG
    IMAGE: Penn State
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Last Updated April 18, 2016