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Can we harvest energy from plants?

Can we harvest energy from plants?



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This is a cross-cutting question but I think its core is about biology. Our society's need for energy is dramatically growing and we are messing up with our environment to answer them. Maybe another way to proceed would be to use the primary energy source that is the sun in the same way as it has been used throughout the ages: photosynthesis.

I know the energy effiency is not as good as a solar panel's but it could clearly be compensated by volume. I found surprisingly little information about harvesting energy from photosynthesis which is why I began to wonder where we are at today.

Thanks!

Edit I meant transforming the chemical energy generated by photosynthesis into electrical energy. For instance, the first algae powered building was unveiled at the International Building Exhibition hosted in Hamburg. This is a whole different approach. The most basic example of what I would like to talk about seems to be the algae powered lamp that has (apparently) been developped. In other words, it seems that some sort of plant solar panels are under development and I don't understand how it's done.


The most basic example of what I would like to talk about seems to be the algae powered lamp that has (apparently) been developped.

I think you misunderstood the idea. That lamp uses bioluminescence and not electric power. Normally living cells don't like to give you energy. The trick we use is anaerob fermentation. Without the presence of oxygen (good electron acceptor) they cannot extract more energy from compounds like ethanol, etc… so they get rid of them. After that we can "burn" these compounds with oxygen and get a lot of energy. So currently there is no solution which uses sunlight and microbes to produce electricity directly, however it might be possible.

There are many ways to use photosynthesis in order to produce energy.

  • The simplest way to burn the plant itself when it has grown enough. You can burn wood, energy plants (e.g. energy grass), etc… and use a generator.
  • A more sophisticated approach to ferment biomass and produce methane, ethanol, etc… which you can burn. This works very well by starch (e.g. corn bioethanol), and there is active research about cellulose conversion.
  • There is active research about artificial photosynthesis as well.

    • You can feed microbes with electric power coming from a photovoltaic system (solar panel), so they can produce ethanol, methane, etc… This might be better than storing energy in batteries.
    • You can use electric power coming from solar panels to split water. After that microbes can use the hydrogen as electron donor to fix $CO_2$, so they can create ethanol, etc…
    • You can use light to split $CO_2$ into $CO$ and $1/2O_2$. You can use $CO$ in biological systems to create ethanol, etc… You can use $CO$ in shift reaction to create $H_2$. It is a new technology to use copper nanoparticles to convert $CO$ into ethanol in a completely artificial system.

You can use a photovoltaic system instead of photosynthesis if you need electric power instead of chemical compounds.

Related articles:

  • 2011 - Light Absorption Enhancement in Thin-Film Solar Cells Using Whispering Gallery Modes in Dielectric Nanospheres
  • 2010 - Powering microbes with electricity: direct electron transfer from electrodes to microbes
  • 2008 - The microbe electric: conversion of organic matter to electricity
  • 2011 - Electrosynthesis of Organic Compounds from Carbon Dioxide Is Catalyzed by a Diversity of Acetogenic Microorganisms?
  • 2011 - Metal centers in the anaerobic microbial metabolism of CO and CO2
  • 2014 - From Ionizing Radiation to Photosynthesis
  • 2012 - Biological conversion of carbon monoxide to ethanol: effect of pH, gas pressure, reducing agent and yeast extract.
  • 2014 - Electroreduction of carbon monoxide to liquid fuel on oxide-derived nanocrystalline copper
  • 2009 - Molecular Approaches to the Photocatalytic Reduction of Carbon Dioxide for Solar Fuels
  • 2014 - Comparison of CO2 Photoreduction Systems: A Review
  • 2013 - Leaf-architectured 3D Hierarchical Artificial Photosynthetic System of Perovskite Titanates Towards CO2 Photoreduction Into Hydrocarbon Fuels
  • 2009 - Water-Gas Shift Reaction Catalyzed by Redox Enzymes on Conducting Graphite Platelets

It is not possible to do this directly. Indirectly, it is possible, this is actually done by harvesting fruits - they contain the energy of the sunlight conserved in chemical compounds like sugars or starch and their cellular structures. The basic process for this is photosynthesis.

The products from the fields are used technically to produce gas by fermentation, which then can be burned to produce electricity. Read reference 1 for more details. What is also done is the use of sugar cane (done widely in Brazil) or corn to produce ethanol which is then used in the fuel of cars. See references 2-4.

Besides these technical processes, there is of course still the possibility to simply burn whole plants or the wood of trees, which is also the result of the fixation of sun energy.

References:

  1. Biogas Production from Maize Grains and Maize Silage
  2. Ethanol Production Using Corn, Switchgrass, and Wood; Biodiesel Production Using Soybean and Sunflower
  3. Ethanol fuel in Brazil
  4. Corn ethanol

I found surprisingly little information about harvesting energy from photosynthesis

Photosynthesis does not produce energy as such, it produces sugars/carbohydrates/chemical energy, which the plant then converts into energy via respiration.


You can burn the sugar to produce heat. But this is basically what your doing when you burn a plant. So no, photosynthesis cannot be used (directly) to produce electrical energy.


In a Standford university research they did successfully harvest electrictity from photosynthesis:

The Stanford research team developed a unique, ultra-sharp nanoelectrode made of gold, specially designed for probing inside cells. They gently pushed it through the algal cell membranes, which sealed around it, and the cell stayed alive. From the photosynthesizing cells, the electrode collected electrons that had been energized by light and the researchers generated a tiny electrical current.

But it goes on to say:

Ryu said they were able to draw from each cell just one picoampere, an amount of electricity so tiny that they would need a trillion cells photosynthesizing for one hour just to equal the amount of energy stored in a AA battery. In addition, the cells die after an hour.

So this is be no means practical at the moment


Another alternative is using plants to generate biomasse using photosynthesis and letting bacteria convert that into electricity.

There is research being done about this method and you can read more about it on the following websites:


I can highly recommend Prof David MacKay's online book http://www.withouthotair.com/ where puts things into perspective. You can find him on YouTube and TED too.

e.g. http://www.withouthotair.com/c18/page_103.shtml "Can we live on renewables"

POWER PER UNIT LAND OR WATER AREA Wind 2 W/m2 Offshore wind 3 W/m2 Tidal pools 3 W/m2 Tidal stream 6 W/m2 Solar PV panels 5-20 W/m2 Plants 0.5 W/m2 Rain-water (highlands) 0.24 W/m2 Hydroelectric facility 11 W/m2 Geothermal 0.017 W/m2

Table 18.10. Renewable facilities have to be country-sized because all renewables are so diffuse.

So it doesn't look good for plants as direct energy source (except for food) (in UK at least)… (or most renewable things for that matter).

Essential reading for anyone interested in energy.


Everyone's looking at photosynthesis for direct energy conversion, but it's not the only approach. Another function of most plants is to pump water up to altitude, to serve its own needs.

Tap into that - picking plants where the sap is watery, not inconveniently sticky like maple syrup, resinous, or likely to congeal into rubber, and you have at least hypothetically, the potential for micro hydro power…

I'm making no claims for energy density or efficiency.


Since gravity is unlimited, can we use it as an infinite energy source?

No, gravity can not be used as an infinite energy source. In fact, strictly speaking, gravity itself can not be used as an energy source at all. You are confusing forces with energy, which are very different things. Energy is a property of objects, such as balls, atoms, light beams, or batteries. In contrast, forces describe the interaction between objects. Forces are the way that energy is transferred from one object to another when they interact, but forces are not the energy itself. Gravity is a force, so it just provides one way for objects to exchange and transform energy to different states.

If I lift a bowling ball to the top of a hill and let it go, the ball falls, speeds up, and seems to gain energy. Isn't this a case of gravity giving energy to the bowling ball? No. Again, gravity is just a force, so it just describes how objects interact. The energy that the ball displays as a falling motion came from my muscles when I hefted the bowling ball to the top of the hill, and not from gravity. Gravity just provides a way to temporarily store energy in an object. We call the energy that an object gains when you lift it against a force "potential energy". The energy comes from the lifting agent and not from the force. The force just provides a way to transfer energy from one object (my muscles) to another object (potential energy in the lifted ball). When I let go of the ball, gravity converts the potential energy of the ball to the kinetic energy (motional energy) of the ball. But the ball can never gain more kinetic energy than the total potential energy that I put into it by lifting it.

This concept is true of all forces, and not just gravity. Two magnets attract each other and fly together, speeding up and seeming to gain energy. You may think that the energy has come from the magnetic force. In truth, the energy comes from your hand pulling the two magnets apart against the magnetic force. The magnetic force just provides a way for potential energy to be stored in the magnet (by virtue of you pulling them apart, not just by virtue of them being magnets), and then converted from potential energy to kinetic energy. Any time you push an object to a new location against a force, you are giving it potential energy.

It is true that gravity is "unlimited" in the sense that it never turns off. Earth's gravity will never go away as long as it has mass. But since this is just a force and not an energy, the never-ending nature of gravity cannot be used to extract infinite energy, or any energy at all, for that matter. Think of gravity loosely like a rubber band. Stretch the rubber band and let go and it snaps back into place. You can therefore store potential energy in a rubber band by stretching it, and this potential energy becomes kinetic energy when you let go. But an unstretched rubber band just sitting there won't move at all, and can't create any energy. The energy you see in the rubber band snapping comes from you stretching it and not from the rubber band itself. Neglecting heat losses, the kinetic energy that comes out of the rubber band (how much it snaps) is exactly equal to the potential energy that you put into it using your muscles (how much you stretch it). Lifting an object against gravity is just like stretching the rubber band.

Confusing energy and forces leads to non-sensical ideas such as free energy (perpetual motion) machines. Such machines always fail precisely because forces are not energy, and you can't extract one single bit of energy from a force itself. For instance, a "free energy" machine could consist of a ball that rolls down a hill and hits a paddle, which turns a wheel. The problem with this machine is that the ball has to be returned to the top of the hill for the process to continue, and the amount of energy you have to put into your machine to put the ball back at the top of the hill equals the energy you get out of your machine from the spinning wheel. Actually, the amount of energy you get out of your machines is always less than the energy you put into it because some of the inputted energy is wasted to heat energy through friction. Free energy proponents devise ever cleverer ways to get the ball back to the top of the hill (or the magnets separated again, or the rubber band stretched again, etc.), hoping that just one more extra gear or wheel will somehow magically create energy out of nothing. But they can never get around the fact that forces are not energy and you can never get more energy out of a system than you put in.

What about hydroelectric plants that extract energy from the falling water in rivers? Don't they extract energy from gravity for free? No. The water in the river is no different from the ball that you have to haul up the hill. The water got its energy not from gravity but from some external agent that placed it high up in the mountains against gravity, so it could fall down the river bed. The external agent in this case is sunlight. Sunlight warms the ocean, causing the water to evaporate and float into the sky. The energy contained in the photons of sunlight is converted to the potential energy of the water molecules that are lifted high in the sky. These water molecules then rain down to the ground, form rivers, and flow back down to the ocean, converting their potential energy to kinetic energy, heat, and (in a hydroeletric plant) electricity. Ultimately, therefore, hydroelectric plants extract solar energy from water.


Some organisms can carry out photosynthesis, whereas others cannot. An autotroph is an organism that can produce its own food. The Greek roots of the word autotroph mean “self” (auto) “feeder” (troph). Plants are the best-known autotrophs, but others exist, including certain types of bacteria and algae (Figure 5.2). Oceanic algae contribute enormous quantities of food and oxygen to global food chains. Plants are also photoautotrophs, a type of autotroph that uses sunlight and carbon from carbon dioxide to synthesize chemical energy in the form of carbohydrates. All organisms carrying out photosynthesis require sunlight.

Figure 5.2 (a) Plants, (b) algae, and (c) certain bacteria, called cyanobacteria, are photoautotrophs that can carry out photosynthesis. Algae can grow over enormous areas in water, at times completely covering the surface. (credit a: Steve Hillebrand, U.S. Fish and Wildlife Service credit b: “eutrophication&hypoxia”/Flickr credit c: NASA scale-bar data from Matt Russell)

Heterotrophs are organisms incapable of photosynthesis that must therefore obtain energy and carbon from food by consuming other organisms. The Greek roots of the word heterotroph mean “other” (hetero) “feeder” (troph), meaning that their food comes from other organisms. Even if the food organism is another animal, this food traces its origins back to autotrophs and the process of photosynthesis. Humans are heterotrophs, as are all animals. Heterotrophs depend on autotrophs, either directly or indirectly. Deer and wolves are heterotrophs. A deer obtains energy by eating plants. A wolf eating a deer obtains energy that originally came from the plants eaten by that deer. The energy in the plant came from photosynthesis, and therefore it is the only autotroph in this example (Figure 5.3). Using this reasoning, all food eaten by humans also links back to autotrophs that carry out photosynthesis.

Figure 5.3 The energy stored in carbohydrate molecules from photosynthesis passes through the food chain. The predator that eats these deer is getting energy that originated in the photosynthetic vegetation that the deer consumed. (credit: Steve VanRiper, U.S. Fish and Wildlife Service)


Can we harvest energy from plants? - Biology

Humans have to grow, hunt, and gather food, but many living things aren’t so constrained. Plants, algae and many species of bacteria can make their own sustenance through the process of photosynthesis. They harness sunlight to drive the chemical reactions in their bodies that produce sugars. Could humans ever do something similar? Could our bodies ever be altered to feed off the Sun’s energy in the same way as a plant?

As a rule, animals cannot photosynthesise, but all rules have exceptions. The latest potential deviant is the pea aphid, a foe to farmers and a friend to geneticists. Last month, Alain Robichon at the Sophia Agrobiotech Institute in France reported that the aphids use pigments called carotenoids to harvest the sun’s energy and make ATP, a molecule that acts as a store of chemical energy. The aphids are among the very few animals that can make these pigments for themselves, using genes that they stole from fungi. Green aphids (with lots of carotenoids) produced more ATP than white aphids (with almost none), and orange aphids (with intermediate levels) made more ATP in sunlight than in darkness.

Another insect, the Oriental hornet, might have a similar trick, using a different pigment called xanthopterin to convert light to electrical energy. Both insects could be using their ability as a back-up generator, to provide energy when supplies are low or demand is high. But both cases are controversial, and the details of what the pigments are actually doing are unclear. And neither example is true photosynthesis, which also involves transforming carbon dioxide into sugars and other such compounds. Using solar energy is just part of the full conversion process.

There are, however, animals that photosynthesise in the fullest sense of the word. All of them do so by forming partnerships. Corals are the classic example. They’re a collection of hundreds and thousands of soft-bodied animals that resemble sea anemones, living in huge rocky reefs of their own making. They depend upon microscopic algae called dinoflagellates that live in special compartments within their cells. These residents, or endosymbionts, can photosynthesise and they provide the corals with nutrients.

Some sea anemones, clams, sponges, and worms also have photosynthetic endosymbionts, and they’re joined by at least one back-boned example: the spotted salamander. Its green-tinged eggs are loaded with algae, which actually invade the cells of the embryos within, turning them into solar-powered animals. The algae die as the salamanders turn into adults, but not before providing them with a useful source of energy in the earliest parts of their lives.

Sun buddies

Despite these varied examples, photosynthetic symbionts are again the exception rather than the rule. In a classic paper, botanist David Smith and entomologist Elizabeth Bernays explain why: such partnerships are more complicated than they seem. The host needs to “pay” its symbionts in nutrients. They need ways of persuading the symbionts to release their manufactured nutrients, rather than hoarding it for themselves. They need to control the symbionts’ growth, so their populations don’t run amok. They need to transfer their partners to the next generation (corals do it by releasing the symbionts into the surrounding water).

But maybe the seeds of such relationships aren’t as difficult to plant as they might seem. In 2011, Christina Agapakis, a synthetic biologist from the University of California, Los Angeles got baby zebrafish to accept photosynthetic bacteria, simply by injecting them into the fish when they were embryos. As she wrote on her blog, “The biggest surprise was that nothing happened.” The fish cannot photosynthesise, but they didn’t reject the bacteria either. Agapakis’ experiment showed that back-boned animals can, at the very least, tolerate the presence of photosynthetic microbes, or the type that fuels the baby salamanders. And with a little tweak, she even persuaded the bacteria to invade mammalian cells.

There is another option to adding entire symbionts: steal their factories instead. Within the cells of plants and algae, photosynthesis takes place within tiny structures called chloroplasts. Chloroplasts are the remnants of a free-living photosynthetic bacterium that was swallowed by a larger microbe billions of years ago. Unlike many such events, this fateful encounter didn’t end with the engulfed bacterium being digested. Instead, the two cells formed a permanent partnership that fuels the cells of plants and algae to this day. So rather than teaming up with a symbiont, why not cut out the middle-man and take its chloroplasts for yourself?

At least one group of animals has done this – the Elysia sea slugs. These beautiful green creatures graze on algae, and co-opt their chloroplasts for themselves. The pilfered chloroplasts line the slug’s digestive tract, provide it with energy, and allow it to “live as a plant”, as Elysia expert Mary Rumpho describes it. This association is vital to the slug, which cannot reach adulthood without it.

Taking a leaf

It’s still unclear how the slugs maintain and use their chloroplasts. These structures aren’t green USB sticks. You cannot plug them into a fresh host cell and expect them to work normally, because many of the proteins that they use are encoded within the genome of their host cell. These proteins, which number in their hundreds, are made in the cell’s nucleus, and transported into the chloroplast. Elysia’s genome contains at least one algal gene, and while more could lie in wait, it’s unlikely to contain the hundreds necessary to sustain a functional chloroplast.

That’s a mystery for another time. For now, Chris Howe from the University of Cambridge says, “If you wanted to set up a relationship between a chloroplast and a new animal host, you’d need all that extra support machinery. You’d have to put those genes in the host’s genome.” And with hundreds of such genes, turning a human cell into a compatible home for chloroplasts would involve genetic engineering on a vast scale.

And to what end? Even if the symbionts took, even if the controlling genes were successfully added, would this make a difference to us? Probably not. Photosynthesis is a useless ability without some way of exposing yourself to as much of the Sun’s energy as possible. That requires a large surface area, relative to their volume. Plants achieve that with large, horizontal, light-capturing surfaces – leaves. Elysia, the sea slug, being flat and green, looks like a living leaf. It’s also translucent, so light can pass through its tissues to the chloroplasts within.

Humans, on the other hand, are pretty much opaque columns. Even if our skin was riddled with working chloroplasts, they would only manufacture a fraction of the nutrients we need to survive. “Animals need a lot of energy, and moving at all doesn’t really jive well with photosynthesis,” says Agapakis. “If you imagine a person who had to get all of their energy from the sun, they’d have to be very still. Then, they’d need a high surface area, with leafy protrusions. At that point, the person’s a tree.”

And why would be bother? Agapakis points out that by domesticating wild plants, and growing them for food, we have effectively outsourced the process of photosynthesis on a massive scale. Agriculture is a global symbiosis – our version of what the pea aphid does, without the faff of maintaining symbionts in our own bodies. We just plant them in fields.

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Harvesting Light Like Nature Does: Synthesizing a New Class of Bio-Inspired, Light-Capturing Nanomaterials

Inspired by nature, researchers at Pacific Northwest National Laboratory (PNNL), along with collaborators from Washington State University, created a novel material capable of capturing light energy. This material provides a highly efficient artificial light-harvesting system with potential applications in photovoltaics and bioimaging.

The research provides a foundation for overcoming the difficult challenges involved in the creation of hierarchical functional organic-inorganic hybrid materials. Nature provides beautiful examples of hierarchically structured hybrid materials such as bones and teeth. These materials typically showcase a precise atomic arrangement that allows them to achieve many exceptional properties, such as increased strength and toughness.

PNNL materials scientist Chun-Long Chen, corresponding author of this study, and his collaborators created a new material that reflects the structural and functional complexity of natural hybrid materials. This material combines the programmability of a protein-like synthetic molecule with the complexity of a silicate-based nanocluster to create a new class of highly robust nanocrystals. They then programmed this 2D hybrid material to create a highly efficient artificial light-harvesting system.

“The sun is the most important energy source we have,” said Chen. “We wanted to see if we could program our hybrid nanocrystals to harvest light energy—much like natural plants and photosynthetic bacteria can—while achieving a high robustness and processibility seen in synthetic systems.” The results of this study were published May 14, 2021, in Science Advances.

Materials scientist Chun-Long Chen finds inspiration for new materials in natural structures. Credit: Photo by Andrea Starr | Pacific Northwest National Laboratory

Big dreams, tiny crystals

Though these types of hierarchically structured materials are exceptionally difficult to create, Chen’s multidisciplinary team of scientists combined their expert knowledge to synthesize a sequence-defined molecule capable of forming such an arrangement. The researchers created an altered protein-like structure, called a peptoid, and attached a precise silicate-based cage-like structure (abbreviated POSS) to one end of it. They then found that, under the right conditions, they could induce these molecules to self-assemble into perfectly shaped crystals of 2D nanosheets. This created another layer of cell-membrane-like complexity similar to that seen in natural hierarchical structures while retaining the high stability and enhanced mechanical properties of the individual molecules.

“As a materials scientist, nature provides me with a lot of inspiration” said Chen. “Whenever I want to design a molecule to do something specific, such as act as a drug delivery vehicle, I can almost always find a natural example to model my designs after.”

POSS-peptoid nanocrystals form a highly efficient light-harvesting system that absorbs exciting light and emits a fluorescent signal. This system can be used for live cell imaging. Credit: Illustration by Chun-Long Chen and Yang Song | Pacific Northwest National Laboratory

Designing bio-inspired materials

Once the team successfully created these POSS-peptoid nanocrystals and demonstrated their unique properties including high programmability, they then set out to exploit these properties. They programmed the material to include special functional groups at specific locations and intermolecular distances. Because these nanocrystals combine the strength and stability of POSS with the variability of the peptoid building block, the programming possibilities were endless.

Once again looking to nature for inspiration, the scientists created a system that could capture light energy much in the way pigments found in plants do. They added pairs of special “donor” molecules and cage-like structures that could bind an “acceptor” molecule at precise locations within the nanocrystal. The donor molecules absorb light at a specific wavelength and transfer the light energy to the acceptor molecules. The acceptor molecules then emit light at a different wavelength. This newly created system displayed an energy transfer efficiency of over 96%, making it one of the most efficient aqueous light-harvesting systems of its kind reported thus far.

Demonstrating the uses of POSS-peptoids for light harvesting

To showcase the use of this system, the researchers then inserted the nanocrystals into live human cells as a biocompatible probe for live cell imaging. When light of a certain color shines on the cells and the acceptor molecules are present, the cells emit a light of a different color. When the acceptor molecules are absent, the color change is not observed. Though the team only demonstrated the usefulness of this system for live cell imaging so far, the enhanced properties and high programmability of this 2D hybrid material leads them to believe this is one of many applications.

“Though this research is still in its early stages, the unique structural features and high energy transfer of POSS-peptoid 2D nanocrystals have the potential to be applied to many different systems, from photovoltaics to photocatalysis,” said Chen. He and his colleagues will continue to explore avenues for application of this new hybrid material.


Ask An Engineer

Stand next to the entrance ramp of a busy freeway at rush hour or walk into an American Eagle clothing store and the first thing you’ll notice is the noise. The din can seem deafening, and it’s tempting to imagine channeling that sound energy into a way to power streetlights and electric cars — or at least to charge your smartphone.

“There is definitely energy contained in that sound,” says David Cohen-Tanugi, vice president of the MIT Energy Club and a John S. Hennessy Fellow in MIT’s Department of Materials Science and Engineering. “But the density of the energy is very low, and there is no way to capture it all. You’d have to have obscenely loud, continuous noise for harvesting to be worthwhile.”

What the human ear perceives as clanging cacophony — the roar of a train engine or the whine of a pneumatic drill — only translates to about a hundredth of a watt per square meter. In contrast, the amount of sunlight hitting a given spot on the earth is about 680 watts per meter squared. “That’s many orders of magnitude more,” explains Cohen-Tanugi. “That’s why it’s more efficient to collect and store sunlight using solar panels than to harvest energy from sound. And the energy density in oil and gas is orders and orders of magnitude higher, making generating power from those sources, even more, cost effective.”

That’s not to say researchers aren’t examining ways to transfer environmental noise into electrical energy. Passing trains and subways aren’t only loud, but their surroundings rattle and vibrate as they pass, and part of the thrill of a rock concert is feeling the whole auditorium shake. “There’s a strong interplay between vibrations through the medium that you hear through — air or water — and the physical objects around you,” says Cohen-Tanugi. “It’s perfectly conceivable to absorb that movement and glean useable energy. You’re not going to power a city with it, but you can power small devices.”

He cites the work of London-based Facility: Innovate, an architectural research firm investigating ways to convert environmental vibrations into electricity. As crowds walk through malls, sports arenas, and other high-traffic areas, small hydraulic generators beneath the company’s floor tiles capture the vibrations of their steps — and generate enough electricity to power nearby phone-charging stations and illuminate electronic signage and advertising.

Though still in the research phase, such technology could mean a new era in energy generation and conservation. “Harvesting acoustic noise is more about mechanical vibrations than sound itself,” says Cohen-Tanugi. “The idea is definitely there, and it’s quite promising.”

Thanks to Sateesh Smart, a 20-year-old from India, for this question.


Mary Beth O'Leary is Press Officer and Associate Media Relations Manager for Cell Press (@CellPressNews), based in Cambridge, Massachusetts. She began her career at Cell Press as an Senior Editorial Assistant for the journal Cell before transitioning into a role as Marketing/Publicity Coordinator. In December, she moved into her position as Press Officer for Cell Press's 29 journals. A graduate of the College of the Holy Cross in Worcester, Massachusetts, she studied literature and art history.


Jade Boyd is Associate Director and Science Editor in the Office of Public Affairs at Rice University (@RiceUniversity) in Houston, Texas. He began his science writing career at Rice in 2002 and spent more than a decade reporting for a daily newspaper, an international wire service and a technology trade magazine. He earned a degree in journalism from Texas A&M University.

4 Archived Comments

Great study. As a plant biologist, I always knew that vegetables and fruit were alive. But your research shows that vegetables are still responding in complex ways to their environment. I will try to incorporate this information into a new botany teaching lab. experiments.

I *did* share on Facebook. Nicely written cool research exciting implications. :)

Thank you, April. I agree, and I'm looking forward to seeing what practical applications come out of this research. Yesterday, I actually decided to leave my fresh peach on the counter instead of sticking it in the fridge.

Thanks April- this research has certainly garnered a lot of people's attention on social media and in the press!


The case for cold plasma pyrolysis

Cold plasma pyrolysis makes it possible to convert waste plastics into hydrogen, methane and ethylene. Both hydrogen and methane can be used as clean fuels, since they only produce minimal amounts of harmful compounds such as soot, unburnt hydrocarbons and carbon dioxide (CO₂). And ethylene is the basic building block of most plastics used around the world today.

As it stands, 40% of waste plastic products in the US and 31% in the EU are sent to landfill. Plastic waste also makes up 10% to 13% of municipal solid waste. This wastage has huge detrimental impacts on oceans and other ecosystems.

Of course, burning plastics to generate energy is normally far better than wasting them. But burning does not recover materials for reuse, and if the conditions are not tightly controlled, it can have detrimental effects on the environment such as air pollution.

In a circular economy – where waste is recycled into new products, rather than being thrown away – technologies that give new life to waste plastics could transform the problem of mounting waste plastic. Rather than wasting plastics, cold plasma pyrolysis can be used to recover valuable materials, which can be sent directly back into industry.


Contents

Light-harvesting complex I is permanently bound to photosystem I via the plant-specific subunit PsaG. It is made up of four proteins: Lhca1, Lhca2, Lhca3, and Lhca4, all of which belong to the LHC or chlorophyll a/b-binding family. The LHC wraps around the PS1 reaction core. [4]

The LH 2 is usually bound to photosystem II, but it can undock and bind PS I instead depending on light conditions. [4] This behavior is controlled by reversible phosphorylation. This reaction represents a system for balancing the excitation energy between the two photosystems. [5]