Energy from Plants

Can we harness energy from plants, rather than harvest  energy from their products?
Dr Abe V Rotor

 Bitaog or palomaria (Calophylum inophylum).  Seeds contain 
oil for lubrication and fuel. UST Botanical Garden

 Stick plant (Euphorbia tirucali).  Extract is 
processed into diesel fuel and oil, UST
 

 Hanga, ripe berries burn bright yellow, 

DENR Loakan, Baguio.

Green charcoal from talahib (Saccharum spontaneum)

Plant residues and farm wastes, as firewood substitute (eg rice hull, coconut coir and sawdust), generation of biogas and composting into organic fertilizer. Landscape supplies, QC

Can we harness energy from plants, rather than harvest energy from their products?

As a simple review, only plants - green plants (those containing chlorophyll which include algae and relatives) - have the ability to capture solar energy and convert it into chemical energy. That is, the light of the sun into sugar (calories), by means of photosynthesis. 

Sugar (CHO) is either transformed into energy for the use of the plant itself, or transferred to animals that feed on the plant.  

Otherwise this primary product is stored into complex sugar like starch, oil, and more importantly protein (CHON) which is used as "building blocks" in growth and development. Post-photosynthetic processes are specific in the production of resin, gum, cork, wood, and many other organic compounds, which when taken by animals are converted into energy, and compounds needed  in their growth and development. Otherwise the unused materials remain at store, or may be lost through oxidation though biological (e.g. fermentation) and physical means (e.g. burning).

Energy is a continuous, incessant  flow in the living system, moving in and out in the process. Biologists explain it in terms of metabolism (catabolism or energy-gain, and anabolism or energy loss or respiration), whereas ecologists draw the lines of interrelationships of participating organisms as food chains forming food webs, and food pyramid to indicate hierarchy in energy utilization. . 

 

 Intricate network in a leaf through which energy and materials flow.

But as a basic principle plants are autotrophs (photosynthesizers), while animals are heterotrophs (consumers in hierarchical order, with man being the ultimate consumer in most cases).    

With this in mind, how can we the harness solar energy in the plant during photosynthesis? 

How can we create a short circuit in directing the electrons before they are used in the final stage of photosynthesis - and instead, convert it directly into electricity?   

We can - theoretically - if we can only develop a method to “interrupt” photosynthesis and redirect the electrons before they are used up to make sugars. So instead of harvesting sugarcane, and make alcohol, and burn it to produce light and heat – or electricity -  we might as well invent a living solar panel and directly "harvest" electricity for our domestic and industrial needs.

Sounds futuristic, isn’t? Well, it is. But remember, no one believed in splitting the atom a century ago and produce nuclear energy. There are now hundreds of nuclear plants all over the world, producing electricity to as much as 50 percent of a country’s electricity need.  Such is the case of France, Germany and Japan.

How about hydrogen fuel? There are cars - thousands of them running on Hydrogen fuel. And the byproduct is not smoke that add to pollution. It is H2O or water.  

Now, hear this. During photosynthesis, the photons that are captured by the plant are used to split water molecules into the component parts of Oxygen andHydrogen. By doing so, they produce electrons. The electrons are then utilized by the plant to create sugars that are then used by the plant (and the animals that eat it) for growth and reproduction.

Architecturally the leaf is like a battery.

"The technology involves separating out structures in the plant cell called thylakoids, which are responsible for capturing and storing energy from sunlight. Researchers manipulate the proteins contained in the thylakoids, interrupting the pathway along which electrons flow. 

These modified thylakoids are then immobilized on a specially designed backing of carbon nanotubes, cylindrical structures that are nearly 50,000 times finer than a human hair. The nanotubes act as an electrical conductor, capturing the electrons from the plant material and sending them along a wire." (Reference: Ramaraja Ramasamy, assistant professor in the University of Georgia and the author of a paper published in the Journal of Energy and Environmental Science.) 

This research is important, because photosynthetic plants function at nearly 100% quantum efficiency. Almost every photon of sunlight captured by the plant is converted into an electron. And what do we get in our solar cells today? A measly fraction - 12 to 17 percent. This huge difference propels us to research towards this direction, away from fossil fuels, and even from the circuitous biomass fuel generation. 

Tree-planting project, Mt Makiling, Laguna

Harvesting electricity directly from plants may be weird and wild an idea as in Jules Verne fiction novels.  But now we can go Around the World in Eighty Days - and even reach the moon and explore outer space. We can now go deeper than Twenty Thousand Leagues Under the Sea and even reach the ocean floor.

And how about coming up a perpetual machine, elusive dream child of science?

The answer may lie in Plant-Based Energy Generation. ~