Modifications to Photosynthesis: A Simpler Way to Energy Efficiency and Fine Chemicals

Photosynthesis is a biochemical cycle that produces oxygen and a simple sugar, glucose. In present research, scientists are learning to make photosynthesis a process that can displace commercial chemical production and as a replacement to fossil fuels. It is in photosynthetic processes that research is done to improve the chemical apparatus used by plants and bacteria—making the processes environmentally safer than commercial syntheses or energy production.

What is the Chemistry Behind Photosynthesis?

Many of us in the U.S. learn about photosynthesis in High School science classes as one fundamental chemical process. The process is portrayed by a single equation. Plants and bacteria produce oxygen (O2), water (H2O), and a simple sugar- glucose (C6H12O6) :

                                   6CO+ 12H2O + UV-Light —> C6H12O+ 6O+ 6H2O.

However, the one equation does not tell a complete story. Photosynthesis involves two fundamental processes that include hundreds of individual reactions –light  activated reactions and reactions occurring with no light activation. The two processes with numerous equations are known as biochemical cycles — the cycles of photosynthesis can be represented by the following chart:

Photosynthesis utilizes hundreds of distinct chemical reactions. Diagram of photosynthesis in the chloroplast of a leaf. Image from Brookhaven National Lab https://www.bnl.gov/chemistry/ap/images/Home_01_HR.jpg

How To Modify Photosynthesis?

While the question becomes- what reactions are most conducive towards modification? No plant- nor bacteria-based photosynthetic reaction is modified easily.

As researchers sought ways to modify photosynthesis, they did not find suitable mimicking reactions to take the place of natural photosynthetic reactions. Attempts modifying photosynthesis result with inefficient substitutes that cannot compete with plants, themselves.

One example is to replace biological apparatus of the Calvin cycle with a synthetic catalysts. The Calvin cycle produces a simple sugar- glucose, from carbon dioxide. Thus,

CO2 + H2O  –> C6H12O6.

While the reaction, as written, is not easy to fathom, biology performs the process simply. The plant or bacterium uses molecules called enzymes to push the carbon dioxide molecule to become a glucose molecule.  Enzymes are far larger than the molecules they catalyze. In this particular case, the enzyme surrounds the carbon dioxide molecule while the hydrogens and oxygens are added in one step.

Proposed analogous synthetic reactions use a metal catalyst to add 12 hydrogen atoms and 6 oxygen atoms in separate steps to the carbon dioxide to make the simple sugar- glucose, C6H12O6. While researcher’s results showed the metal catalyst as ineffective, molecules, that can better mimic enzymes, are required.

Quoting from a publication of the American Chemical Society in 2017–researchers from Lawrence Berkeley National Laboratory at the University of California, Berkeley can be quoted “… it would be unreasonably hopeful to imagine we could currently capture all the performance capabilities of biological CO2 reduction…” Chemical processes of photosynthesis adapted to an almost static soil and mostly pure water over the course of billions of years– our current attempts pale in comparison. Knowing that sunlight shining on plants and other organisms is variable as well further confounds the issue.

The following table captures the essence of the argument of the previous three paragraphs:

Photosynthetic organisms with improved light harvesting capacities have light gathering efficiencies greater than 20 percent, are suitable for further alteration. Inorganic materials improve light harvesting. Research continues in this area. Image by John A. Jaksich

Thus, researchers improve light harvesting actions of organisms. Of all aspects related to photosynthesis, organisms efficiently harvest only 3 percent light. The 3 percent number is the biggest reason to approach photosynthesis research to improve light harvesting

Modifications to Photosynthesis Understood from a ‘First Principles Approach’

Cybernetic modifications to photosynthesis is as confusing as black hole physics-- both possessing a sense of a new frontier.
Humanity has entered a new age– learning to alter its larger environment– anthropocene. The age of man (or anthropocene) gives us choices that can save us from potential extinction. Modifications to photosynthesis push the frontiers of science into areas that may prevent our eventual extinction. Image by NASA/JPL-Caltech.

When discerning ways to modify photosynthesis, scientists are left with one easy option. The improvement of light-gathering efficiency is addressed because the photosynthetic apparatus shuts out more light that it can handle. Given that plants and bacteria respond to increased light through the slow evolutionary processes that spawned their genesis, we proceed with evolution in mind. When increased light normally coincides with growth and carbon dioxide uptake, we take it one step at a time. Once light gathering efficiency is improved, scientists can take the next step: the discernment of plant photo-biochemistry and chemistry.

The present course of climate change has made research in this area a major concern. Of late, average yearly temperature changes appear to increase exponentially. When the year 2050 arrives, we may not possess the luxury of accepting fossil fuels as our source chemistry dependence–if we are still around to do so.

ADDITIONAL READING & REFERENCES

GARY F. MOORE and GARY W. BRUDVIG. Annual Reviews in Condensed Matter Physics. 2010, Energy Conversion in Photosynthesis: A Paradigm for Solar Fuel Production.

ICHIRO TERASHIMA, et. al. Plant Physiology. 2011,Leaf Functional Anatomy in Relation to Photosynthesis.

PEIDONG YANG and JEAN-MARIE TARASCON. Nature Materials, 2012, Towards Systems Materials Engineering.

CHONG LIU, et. al. Science. 2016, Water splitting–biosynthetic system with CO2 reduction efficiencies exceeding photosynthesis.

NIKOLAY KORNIENKO, et. al. Proceedings of the National Academy of Sciences. 2016, Spectroscopic elucidation of energy transfer in hybrid inorganic–biological organisms for solar-to chemical production.

J. BLOEMEN, et. al. Acta Horticulturae. 2013, Understanding Plant Responses to Drought: How Important is Woody Tissue Photosynthesis?

C. LIU, et. al. Science. 2016, Water Splitting-Biosynthetic System with CO2 Reduction Efficiencies Exceeding Photosynthesis.

STUART A. WEST, et. al. Proceedings of the Royal Society, B. 2002, Sanctions and mutualism stability: why do rhizobia fix nitrogen?

KELSEY K. SAKIMOTO, et. al. Accounts of Chemical Research. 2017, Cyborgian Material Design for Solar Fuel Production: The Emerging Photosynthetic Biohybrid Systems.

Cold Fusion Revisited?

This is a modified version of the original Cold Fusion setup of Pons and Fleischmann. The modified setup reproduced findings of Pons and Fleischmann and addressed the temperature fluctuations originally found by Pons and Fleischmann. StevenBKrivit [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0)%5D

While chemistry is the science that explains matter’s transformation; on occasion, chemists puzzle and misinterpret their own results. It is an understanding of transformations that allows chemists to attempt to improve our lives. While the topic of cold fusion is one that elucidates incredulity among those who heard it, the story of cold fusion is one that opened opportunities in different areas of research.

While the reaction is one that is still being studied – albeit it is a process that elucidates how heavy water produces hydrogen gas. The reaction, seemingly simple, reveals misunderstandings that researchers fall into when their personal biases interfere with their research. The physical chemists who discovered cold-fusion never saw their efforts become golden –instead the reaction now bears their name. Cold fusion goes by the name– the Pons-Fleischmann effect.

What is Nuclear Fusion?

Nuclear fusion is known as a hot, energetic process that powers the Sun and creates the chemical elements. Paraphrasing and expanding the entry from Encyclopedia Britannica–

(fusion is a) process by which nuclear reactions between light elements form heavier elements (up to iron) – The vast energy potential of nuclear fusion was first exploited in thermonuclear weapons, or hydrogen bombs, which were developed in the decade immediately following WWII

The process of hot, nuclear fusion is yet to be harnessed as a true energy source.

What is Cold Fusion?

While hot fusion takes place at millions of degrees Fahrenheit, cold fusion took place at room temperature. Moreover, according to the Encyclopedia Britannica–

In 1989 two chemists, Martin Fleishmann of the University of Utah and Stanley Pons of the University of Southampton in England, announced that they had produced fusion reactions at essentially room temperature. Their system consisted of electrolytic cells containing heavy water (deuterium oxide, D2O) and palladium rods that absorbed the deuterium from the heavy water. Efforts to give a theoretical explanation of the results failed, as did worldwide efforts to reproduce the claimed cold fusion.

What is Immediately True from the Event?

We have chemical reactivity that needed further investigation with no publicizing. It was an instance of poor professionalism.

  1. Fusion energy – the energy that powers the Sun, takes place at thousands of degrees Fahrenheit. Cold fusion took place at room temperature. While the two processes seem disparate in terms of temperature, both processes formed hydrogen gas. However, neither process has been successfully replaced fossil fuels.
  2. Another issue dealt with the scale of the experiment – the cold fusion could fit on top of a lab bench. Present attempts to produce hot fusion energy take place in specialized nuclear reactors. The fusion reactors are housed in buildings that can fit tens of dozens (if not hundreds) of “lab bench sized” cold fusion reactors.

Some have labeled cold fusion as bad science. It has also been labeled as completely irreproducible. However, the result is not evidence of no reaction–just poorly investigated science.

What Exactly Happened?

When Pons and Fleischmann passed an electric current through radioactive water, they produced an excess of hydrogen gas and a seemingly anomalous rise of temperature. Fleischmann and Pons also believed they had observed gamma ray production from their reaction vessel. Gamma rays are a by-product of hot nuclear fusion.

They elected to report the reaction results via News Conference; this turned an anomalous but interesting result into a ‘public relations disaster’ for them and their home university. They believed they found a ‘holy grail’ – result that could replace fossil fuels and other ways to produce energy.

However, researchers from around the world could not repeat their results. In fact, Fleischmann and Pons could not reproduce their own results in many instances.

An Incorrect Interpretation of Fusion leads to LENR- (Low Energy Nuclear Reactions).

It took nearly twenty years until researchers understood that Fleischmann and Pons made an interesting discovery. It was a real chemical reaction that took place. It ultimately became known as the Fleischmann-Pons effect. It produced hydrogen gas and small amount of Helium. The production of helium lent some credence to original being one of fusion:

H +H –> He (helium)

However, the reaction is not the same as occurs in sun to produce He and other elements.

Scientists discovered the Fleischmann-Pons effect to be one in which -the passage of electric current along with the mechanical agitation of the reaction vessel disrupted the deuterium-oxygen bonds in radioactive water.

However, they were not producing fusion reactions like the sun; rather, they produced low energy bond rearrangements with a small but anomalous temperature rise.

Further experimentation showed the anomalous temperature rise to be the production of helium from heavy water– also lending credence to a fusion interpretation.

The helium production results from deuterium (from heavy water) embedded in the palladium electrode (thus converting to helium). While the helium production is proven as accurate, its exact mechanism is not certain.

However, the reaction for cold fusion became:

D2O + electricity –> D2 + He + heat (in the presence of palladium metal).

While the reaction is not suitable for producing great amounts of hydrogen gas nor helium, it may lead to hydrogen fuel cell technology in the distant future.

Will LENR lead to Energy Self-Sufficiency?

This purported Holy Grail is one of illusion – not an immediate discovery that could alleviate fossil fuel dependence. Presently, cold fusion is a research topic that is pursued by various research groups. Its chemistry is not hot fusion—  but it is re-termed. It is known as the Pons-Fleischmann effect. The production of helium is still under investigation–however, it is a low energy and a low temperature fusion product, nonetheless. Thus, the possibility for energy self-sufficiency from this reaction is many years in the future.

 

 

ADDITIONAL READING & REFERENCES

MARK DAVIDSON. Journal of Physics Conferences Series. 2015, Variable Mass theories in Relativistic Quantum Mechanics as an Explanation for Anomalous Low Energy Nuclear Phenomena.

MELVIN H. MILES. Chemical and Chemical Engineering News. 2017, More on Cold Fusion.

S. SPVZK. ICCF-14 International Conference on Condensed Matter Nuclear Science. 2008, SPAWAR Systems Center-Pacific Pd:D Co-Deposition Research:Overview of Refereed LENR Publications.

MARTIN FLEISCHMANN and STANLEY PONS. Journal of Electroanalytical Chemistry. 1989, Electrochemically induced nuclear fusion of deuterium.

P. L. HAGELSTEIN. et. al. Proceedings of the 11th international conference on cold fusion. 2006, Physical Effects in Metal Deuterides, in Condensed matter Nuclear Science.