Benjamin Franklin harnessed electricity by sending a kite with a metal key into a sky full of lightning. We know how electricity is produced today –from electric power plants that use a turbine to drive electricity generators with a moving fluid –water, steam, combustion gases or air – that pushes a series of blades mounted on a rotor shaft.

Researchers at the Technion-Israel Institute of Technology in Haifa, however, how found a simpler way They developed a new method that harvests an electrical current directly from seaweed in an environmentally friendly and efficient way. 

The idea, which came to the doctoral student Yaniv Shlosberg while swimming at the beach, has been developed by a consortium of researchers from three Technion faculties who are members of the Grand Technion Energy Program (GTEP), along with a researcher from the Israel Oceanographic and Limnological Research Institute (IOLR).

The researchers presented their new method for collecting an electrical current directly from macroalgae (seaweed) in the journal Biosensors and Bioelectronics under the title “Bioelectricity generation from live marine photosynthetic macroalgae.:” The paper describes results obtained from researchers from the Technion’s Faculty of Chemistry, Faculty of Biology, Faculty of Biotechnology and Food Engineering, GTEP and IOLR. 

The use of fossil fuels results in the emission into the air of greenhouse gases and other polluting compounds. These have been found to be linked to climate change, as seen by a variety of terrestrial phenomena that have brought climate change to the forefront of global concerns. Pollution due to use of these fuels starts from their extraction and transportation around the globe to be used in centralized power plants and refineries. 

These problematic issues are the driving force behind research into methods of alternative, clean and renewable energy sources. One of these is the use of living organisms as the source of electrical currents in microbial fuel cells (MFC). Certain bacteria have the ability to transfer electrons to electrochemical cells to produce electrical current. The bacteria need to be constantly fed and some of them cause disease.

A similar technology is bio-photoelectrochemical cells (BPEC). As for the MFC, the source of electrons can be from photosynthetic bacteria, especially cyanobacteria (also known as blue-green algae).  These organisms make their own food from carbon dioxide, water and sunlight, and in most cases, they are cause no harm. In fact, there are cyanobacteria such as Spirulina that are considered “super foods” and are grown in large quantities. 

Prof. Noam Adir and Schuster’s research groups at the Faculty of Chemistry e previously developed technologies that used cyanobacteria to obtain electrical current and hydrogen fuel, as published in the journals Nature Communications and Science. Cyanobacteria do have some drawbacks, however, as they produce less current in the dark, as no photosynthesis is performed. Also, the amount of current obtained is still less than that gained from solar cell technologies, so that while more environmentally benign, the BPEC is less attractive commercially.

In the present study, the two researchers decided to try to solve this issue using a new photosynthetic source for the current – seaweed. They collaborated with additional researchers from the Technion – Dr. Tunde Toth, Prof. Gadi Schuster, Dr. David Meiri, Nimrod Krupnik, Benjamin Eichenbaum, Dr. Omer Yehezkeli, Matan Meirovich and Dr. Alvaro Israel. Many different species of seaweed grow naturally on the Mediterranean shore of Israel, especially Ulva (also known as sea lettuce) that is grown in large quantities at IOLR for research purposes.

After developing new methods to connect between the Ulva and the BPEC, currents 1000 times greater than those from cyanobacteria were obtained – currents that are on the level of those obtained from standard solar cells. 

Adir noted that these increased currents are due to the high rate of seaweed photosynthesis and the ability to use the seaweed in their natural seawater as the BPEC electrolyte – the solution that promotes electron transfer in the BPEC. In addition, the seaweed provides currents in the dark, about half of that obtained in light. The source of the dark current is from respiration – where sugars made by the photosynthetic process are used as an internal source of nutrients. In a fashion similar to the cyanobacterial BOEC, no additional chemicals are needed to obtain the current. The Ulva produce mediating electron transfer molecules that are secreted from the cells and transfer the electrons to the BPEC electrode.

Fossil fuel-based energy producing technologies are known as “carbon positive,” meaning that the process releases carbon to the atmosphere during the fuel combustion. Solar cell technologies are known as “carbon-neutral” in which no carbon is released to the atmosphere. 

But the production of solar cells and their transportation to the site of use is many times more “carbon positive.” The new technology presented here is “carbon negative.” The seaweed absorbs carbon from the atmosphere during the day while growing and releasing oxygen. While harvesting of the currents during the day, no carbon is released. At night, the seaweed releases the normal amount of carbon from respiration. In addition, seaweed, especially sea lettuce, are grown for a variety of industries: food, cosmetics and pharma.

“It is a wonder where scientific ideas come from,” concluded Shlosberg, who dreamed up the idea. “The famous philosopher Archimedes had a brilliant idea in the bathtub, leading to the “Archimedes’ Principle.’ I had the idea one day when I went to the beach. At the time I was studying the cyanobacterial BPEC, when I noticed seaweed on a rock that looked like electrical cords. I said to myself: Since they also perform photosynthesis, maybe we can use them to produce currents. From this idea came the collaboration that led to our most recent paper. I believe that our idea can lead to a real revolution in clean energy production.”

The Technion/IOLR researchers built a prototype device that collects the current directly in the Ulva growth vat. “By presenting our prototype device, we show that significant currents can be harvested from the seaweed,” commented Adir. We believe that the technology can be further improved leading to future green energy technologies.”