Bioelectric future: Harnessing the natural energy of plants

When plants draw water from their roots to nourish their stems and leaves, they produce an electric potential that could be harnessed as a renewable energy source. 

However, like all living things, plants are subject to a circadian rhythm – the biological clock that runs through day and night cycles and influences biological processes. 

Bioelectricity in plants

In plants, this daily cycle includes capturing light energy for photosynthesis and absorbing water and nutrients from the soil during the day and slowing its growth processes at night. 

A recent study led by the Indian Institute of Technology (IIT) Kharagpur has detailed how biological processes produce voltage in plants and the impact of the cyclic day and night changes on this voltage.

Sustainable energy from plants

“This streaming potential, essentially a consequence of the natural energy gathered in the plant, offers a renewable energy source that is continuous and can be sustainable over long periods,” said senior author Suman Chakraborty, a mechanical engineer at IIT. 

“The question we wanted to answer was how much potential it can produce, and how is electric potential influenced by the plant’s biological clock?”

The rhythm of energy flow in plants

To find out, the scientists inserted electrodes into the stems of water hyacinths and attached reservoirs with electrodes to pieces of lucky bamboo to closely examine how electrical potential changes depending on types of ions, ion concentration, and the pH of the fluid flowing through the plants.

“Our eureka moment was when our first experiments showed it is possible to produce electricity in a cyclic rhythm and the precise linkage between this and the plant’s inherent daily rhythm,” Chakraborty said. “We could exactly pinpoint how this is related to water transpiration and the ions the plant carries via the ascent of sap.”

Electric streaming potential 

The study quantified the voltage response originating from the movement of ions through the plant’s pathways that align uniquely with the plant’s daily rhythms. 

The authors discovered plants can actively moderate the flow of fluid or sap in sync with the day and night cycles. They also found the electric streaming potential increases with decreased concentration of ions or increased pH in the fluid.

Plants can help address the energy crisis 

“We not only rediscovered the plant’s electrical rhythm, articulating it in terms of voltages and currents, but we also provided insight into potentially tapping electrical power output from plants in a sustainable manner with no environmental impact and no disruption to the ecosystem,” Chakraborty explained. 

“The findings could help develop biomimetic, nature-inspired systems that can address the global energy crisis with an eco-friendly, sustainable solution in which planting a tree not only relieves the crises of climate change and declining environmental quality, but also provides a way to harness electricity from it,” he concluded.

Electric voltage in plants

Electric voltage in plants refers to the bioelectric potentials that occur naturally within plant tissues. These electrical signals are part of the way plants manage internal processes and respond to their environment. 

The existence of voltage differences in plants is due to ion gradients across cellular membranes, much like the bioelectric processes in animal and human cells.

Stress signals

For instance, when a plant is injured or stressed by environmental factors like cutting or burning, changes in electric potential can be detected. 

These changes often serve as signals that can propagate to other parts of the plant, initiating physiological responses such as the healing of wounds, changes in growth, or defensive mechanisms against pests and diseases.

Plant communication 

Moreover, some research suggests that these electrical signals may help plants communicate distress or physiological states between different parts of themselves, or even with other plants, though this area of study is still quite exploratory.

These bioelectric phenomena are instrumental for understanding how plants interact with their environment and manage their internal functions without a nervous system, highlighting the complexity and adaptability of plant life.

The study is published in the journal Physics of Fluids.

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