A team led by Concordia University engineering professor Muthukumaran Packirisamy describe their new invention as a power cell that harnesses electrical energy from the photosynthesis and respiration of blue-green algae.
Packirisamy explains, “Both photosynthesis and respiration, which take place in plant’s cells, involve electron transfer chains. By trapping the electrons released by blue-green algae during photosynthesis and respiration, we can harness the electrical energy they produce naturally.”
You may wonder why plants and blue green algae? Because the algae are already practically everywhere and energy is already there.
Also known as cyanobacteria, blue-green algae are the most prosperous microorganisms on earth, evolutionarily speaking. They occupy a broad range of habitats across all latitudes. And they’ve been here from the start: the planet’s early fauna and flora owe their makeup to cyanobacteria, which produced the oxygen that ultimately allowed higher life forms to flourish.
Packirisamy said, “By taking advantage of a process that is constantly occurring all over the world, we’ve created a new and scalable technology that could lead to cheaper ways of generating carbon-free energy.”
He notes that the invention is still in its early stages. “We have a lot of work to do in terms of scaling the power cell to make the project commercial.”
Currently, the photosynthetic power cell exists on a small scale, and consists of an anode, cathode and proton exchange membrane. The cyanobacteria or blue green algae are placed in the anode chamber.
As they undergo photosynthesis, the cyanobacteria release electrons to the electrode surface. An external load is connected to the device to extract the electrons and harness power.
This photosynthetic power cell of an anode, cathode and proton exchange membrane with an anode chamber filled with of cyanobacteria releases electrons to the electrode surface from a redox agent that is present at the cathode. An external load is connected to extract the electrons. The fabricated cell could produce an open circuit voltage of 993 mV and a power density of 36.23 µW/cm2.
As Packirisamy and his team develop and expand the project, he hopes that the micro photosynthetic power cells will soon be used in various applications, such as powering cell phones and computers. And maybe one day they’ll power the world.
Its an astonishing development. It makes one wonder when another research project will seek the most electron producing plants beyond the abundant algae. How far this concept could go is anyone’s guess at a barely born moment.
While the power output isn’t a huge thing, devices are running on lower and lower voltages using fewer and fewer amps. This is a great idea with legs, albeit really tiny, tiny ones.
Researchers at the Institute for Advanced Sustainability Studies (IASS) in Potsdam and the Karlsruhe Institute of Technology (KIT) are demonstrating a process called ‘methane cracking’. This reaction occurs at high temperatures (750°C and above) and does not release any harmful emissions. The two institutions have been researching an innovative technique to extract hydrogen from methane in a clean and efficient way.
Instead of burning methane (CH4) the main component of natural gas, its molecular components, hydrogen (H2) and carbon (C), are separated, with the hydrogen burned and the carbon stored away.
With two years of intensive experiments using the experimental reactor running reliably and continuously, the proof-of-principle has now been provided and the future potential of this technology is thought to be apparent.
The combustion of fossil fuels to produce electricity, power car engines or generate heat is said to be a major source of harmful carbon dioxide emissions. In particular methane – the main component of natural gas – is a widely used fossil fuel whose worldwide production is forecast to rise dramatically in the coming decades.
The believers say that left unchecked, this continued reliance on conventional fossil fuel technologies will greatly hamper our efforts at mitigating climate change. This is why researchers at the IASS and KIT have decided to investigate an alternative and more sustainable approach: what if we could extract the energy content of methane, in the form of hydrogen, without generating any carbon dioxide in the process?
The researchers propose instead of burning methane its molecular components, hydrogen and carbon, be separated with ‘methane cracking’.
The first product, hydrogen, is an energy vector best known for its clean combustion and high energy density per unit mass. In fact, many view it as an important component of a future, sustainable energy system. Proposed applications include fuel cells, electricity generation and hydrogen-powered vehicles.
But today hydrogen is already an important industrial commodity, used in large quantities for the production of ammonia – a key precursor for the fertilizer industry. Most of the world’s hydrogen production is currently based on conventional technologies like steam methane forming (SMR), which also uses natural gas as feedstock but releases significant amounts of carbon dioxide in the process. Indeed, carbon dioxide emissions from the ammonia industry alone amount to approximately 200 million tons per year – by comparison, the German nation generates around 800 million tons of carbon dioxide per year.
The second product, solid black carbon, is also an increasingly important industrial commodity. It is already widely employed in the production of steel, carbon fibers and many carbon-based structural materials. The black carbon derived from the novel cracking process is of high quality and particularly pure powder. Its value as a marketable product therefore enhances the economic viability of methane cracking. Alternatively, black carbon can be stored away, using procedures that are much simpler, safer and cheaper than the storing of carbon dioxide.
Methane cracking itself is not an entirely new idea: in the last two decades, many experiments in different institutions have been carried out that have proven its technical feasibility. But these past attempts were limited by issues such as carbon clogging and low conversion rates.
The IASS and KIT researchers decided to build on this knowledge base and go one step further, setting up an experimental reactor that could demonstrate the potential of methane cracking and overcome previous obstacles. The starting point is a novel reactor design, as proposed by Nobel Laureate and former IASS Scientific Director Carlo Rubbia and based on liquid metal technology.
Fine methane bubbles are injected at the bottom of a column filled with molten tin. The cracking reaction happens when these bubbles rise to the surface of the liquid metal. Carbon separates on the surface of the bubbles and is deposited as a powder at the top end of the reactor when they disintegrate.
This idea was put to the test during a series of experimental campaigns that ran from late 2012 to the spring of 2015 in KIT’s KALLA (KArlsruhe Liquid Metal LAboratory). Researchers were able to evaluate different parameters and options, such as temperature, construction materials and residence time. The final design is a 1.2 meter high device made of a combination of quartz and stainless steel, which uses both pure tin and a packed bed structure consisting of pieces of quartz.
Professor Thomas Wetzel, head of the KALLA laboratory at KIT said, “In the most recent experiments in April 2015, our reactor operated without interruptions for two weeks, producing hydrogen with a 78% conversion rate at temperatures of 1200°C. In particular the continuous operation is a decisive component of the kind of reliability that would be needed for an industrial-scale reactor.”
The innovative reactor is resistant to corrosion, and clogging is avoided because the microgranular carbon powder produced can be easily separated. The reactor thus guarantees the technical preconditions that would be needed for the continuous operation of an industrial-scale reactor.
While these remain laboratory-scale experiments, researchers can extrapolate from them to gain insights into how methane cracking could be integrated into the energy system and, more specifically, what its contribution to sustainability could be. To this end, the IASS is collaborating with RWTH Aachen University to conduct a life cycle assessment (LCA) of a hypothetical commercial methane cracking device based on a scaling-up of the prototype.
Notably, the researchers assume that some of the produced hydrogen is used to generate the required process heat. The compared hydrogen production technologies were steam methane reforming (SMR) and water electrolysis coupled with renewable electricity. With respect to emissions of carbon dioxide equivalent per unit of hydrogen, the LCA showed that methane cracking is comparable to water electrolysis and more than 50% cleaner than SMR.
Beyond that IASS researchers have also analyzed the economic aspects of methane cracking. At this stage, cost estimates are uncertain, since methane cracking is not yet a fully mature technology. However, preliminary calculations show that it could achieve costs of 1.9 to 3.3 euro per kilogram of hydrogen at German natural gas prices, and without taking the market value of carbon into consideration.
Professor Rubbia said, “Our experimental results as well as the environmental and economic assessments all point to methane cracking as a clear candidate option in our portfolio of measures to transform the energy system. This could be a gap-bridging technology, making it possible to tap into the energy potential of natural gas while safeguarding the climate and facilitating the integration of a clean energy carrier like hydrogen.”
In the next phase of the process, the IASS and KIT will focus on optimizing some aspects of the reactor design, such as the carbon removal process, and progressively scaling it up to accommodate higher flow rates.
There are some glaring omissions in the press release.
The researchers have not provided a published paper, a link or even a mention. This not is not meant to impinge the credibility, rather raise our attention that perhaps the researchers have more information that they don’t want shared for replication before a patent proceeding is underway or simply that as a Nobel Laureate the need “to publish or perish concept” does not have such imperative power.
The next matter is the value of the carbon. A particularly pure high quality powder will have value. No mention is made of the structure, other than pure, and in a world of increasing uses for graphene, other carbon nano products and synthetic diamonds, a very pure carbon source might have a significant value.
Lastly is overlooking the heat unit production. The combustion of natural gas produces heat from both the oxidation of the hydrogen and the carbon. Removing the carbon is going to take carbon combustion heat units out of the end product. The net energy release for work is going to be significantly reduced.
The likely factually correct and politically incorrect note is the most interested folks are going to be process engineers in the anhydrous ammonia and oil refining industries, which will become good for consumers if efficiencies and cost savings are found in the technology.
November 19, 2015 | Leave a Comment
Scientists from the Department of Technical Electrochemistry and the Research Neutron Source FRM II at the Technical University of Munich (TUM) have come a step closer to identifying the causes of lithium ion battery aging in their latest experiments. Lithium ion battery aging significantly reduces their potential storage capacity. To date, very little is known about what causes the aging effects. The economic impact to consumers for lithium ion battery life extension would be significant.
Lithium ion batteries with graphite anodes are a relatively new development. They were patented only in 1989 and have been deployed in electrical devices since 1991. Since then, they have been a success worldwide and do their service not only in small electrical devices but also in electric cars, airplanes and even locomotives. In the future they could also serve as intermediate storage with up to megawatt capacities.
Lithium ion batteries with graphite anodes suffer their first significant loss of capacity during the initial charging cycle, the formation step. A battery loses up to ten percent of its capacity in the process. Each additional charge-discharge cycle reduces storage capacity further, if only insignificantly. Capacity is also lost through the mere storage of batteries – especially above room temperature.
Physics has come up with a number of ideas about the nature of these aging effects, but no one has yet found the definitive explanation for them. The TUM scientists have now come a good deal closer to closing this knowledge gap in their latest experiments.
In order to understand the aging mechanism and to uncover the reasons behind them the TUM scientists combined electrochemical investigations with measurement methodologies as diverse as X-ray diffraction, impedance measurements and prompt gamma activation analysis (PGAA).
They deployed these methodologies to analyze the behavior of batteries with graphite anodes and nickel-manganese-cobalt cathodes, so-called NMC cells, at various temperatures. NMC cells are popular in electromobility since they have a large capacity and can theoretically handle charging voltages up to just under five volts. However, above 4.4 volts aging effects increase strongly.
Using X-ray diffraction, the scientists investigated the loss of active lithium over multiple charging cycles. They used impedance measurements to register the increasing resistance in the battery cells. Neutron activation analysis ultimately facilitated the accurate determination of extremely minute quantities of transition metals on the graphite electrodes.
The significant capacity loss in the formation step is caused by the build-up of a pacifying layer on the anode. This consumes active lithium, but also protects the electrolyte from decomposition at the anode.
The scientists determined two key mechanisms for the loss of capacity during operation: The active lithium in the cell is slowly used up in various side reactions and is thus no longer available. The process is very temperature dependent: At 25°C the effect is relatively weak but becomes quite strong at 60°C.
When charging and discharging cells with a higher upper cut off potential (4.6 V), cell resistance increases rapidly. The transition metals deposited on the anode may increase the conductivity of the pacifying layer and thereby speed up the decomposition of the electrolyte.
So far, by way of trial and error, battery manufacturers have determined the optimal relationship between the electrode material and lithium. “Using our insights, now individual processes can be improved,” says Irmgard Buchberger, PhD student at the Department of Electrochemistry at TU Munich. “Possibilities include additives that improve the build-up of the pacifying layer, for example, or modifications of the cathode surface.”
A great deal of research gas been poured into alternative anodes and cathodes. So far there hasn’t been a market significant change offered, even with a huge array of promising ideas. The production facilities are still wedded to the graphite.
The German’s work here offers others a good baseline to rethink and experiment with methods, processes and materials to extend lithium ion battery life. Meanwhile, don’t let your lithium ion battery get hot!
November 18, 2015 | Leave a Comment
Researchers from Empa and ETH Zurich have discovered an alternative to the lithium ion battery chemistry with the “fool’s gold battery”. They believe the prime potential lies in giant storage batteries that could be built at low cost and used for stationary storage in buildings or next to power plants. Maybe not for electric vehicles or portable electronics just yet.
A fool’s gold battery consists of iron, sulfur, sodium and magnesium – all elements that are low cost and in plentiful supply. Lithium will eventually start to price even higher as batteries are deployed in electric cars and stationary storage units. For high performance lithium ion batteries basic supply issues are a major cost problem.
There is an urgent need to find and develop low-priced batteries to store electricity. The intermittency of wind and solar electricity is affecting the power grid, a situation calling for stationary storage units to be connected into a smart grid. Electric cars are of increasing popularity, but are still to expensive. Today’s efficient lithium ion batteries are not suitable for large-scale stationary storage of electricity, they are just too expensive because precious lithium is too scarce. A cheap alternative is called for – a battery made of inexpensive ingredients that are available in abundance. But electrochemistry is a tricky business: Not everything that’s cheap can be used to make a battery.
Maksym Kovalenko, Marc Walter and their colleagues at Empa’s Laboratory for Thin Films and Photovoltaics have now managed to pull off the unthinkable. By combining a magnesium anode with an electrolyte made of magnesium and sodium ions with nanocrystals made of pyrite – more commonly known as fool’s gold – to serve as the cathode, they have a working battery.
Pyrite is crystalline iron sulfide. The sodium ions from the electrolyte migrate to the cathode during discharging. When the battery is recharged, the pyrite re-releases the sodium ions. This so-called sodium-magnesium hybrid battery already works in the lab and has several advantages: The magnesium as the anode is far safer than highly flammable lithium. And the test battery in the lab already withstood 40 charging and discharging cycles without compromising its performance, suggesting further optimization would be useful.
The biggest advantage, however, is the fact that all the ingredients for this kind of battery are easily affordable and in plentiful supply. Iron sulfide nanocrystals, for instance, can be produced by grinding dry metallic iron with sulfur in conventional ball-mills. Iron, magnesium, sodium, and sulfur hold the 4th, 6th, 7th and 15th places by the abundance in the Earth’s crust (by mass). One kilogram of magnesium costs at most four Swiss francs, which makes it 15 times cheaper than lithium. There are also savings to be made when it comes to constructing the cheap batteries. Lithium ion batteries require relatively expensive copper foil to collect and conduct away the electricity. For the fool’s gold battery, however, inexpensive aluminum foil is perfectly sufficient.
Today the researchers primarily see potential in their development for large network storage batteries. The fool’s gold battery is not suitable for electric cars – its output is too low. But wherever it boils down to costs, safety and environmental friendliness, the technology is a plus.
In their paper published in the journal Chemistry of Materials, the Empa researchers propose batteries with terawatts of storage capacity. Such a battery might be used to temporarily store the annual production from the Swiss nuclear power station in Leibstadt, for instance.
Kovalenko, who teaches as a professor at ETH Zurich’s Department of Chemistry and Applied Biosciences alongside his research at Empa said, “The battery’s full potential has not been exhausted yet. If we refine the electrolytes, we’re bound to be able to increase the electric voltage of the sodium-magnesium hybrid cell even further and to extend its cycling life. We also look for investors willing to support research into such post-Li-ion technologies and bring them to the market.”
The Swiss folks may be exploring a little understatement, too. The technology is already closing in on lead acid, carbon and alkaline technology and half way to lithium ion cell voltages, in the first working lab sample. The technology might not seem real exciting, but the materials costs are going to set off a revolution if the commercial scale step works out well.
Old enough to remember how fast alkaline batteries eclipsed carbon batteries? Duracell and Energizer might want to be checking in with these Swiss folks. A “Gold Rechargeable” at a low price might be a battery sales gold mine.
November 17, 2015 | Leave a Comment
Professor Seigo Tarucha’s research group at the Department of Applied Physics at the Graduate School of Engineering has created an electrically controllable valley current device that converts conventional electrical current to valley current, passes it through a long (3.5 micron) channel, then converts the valley current back into charge current that can be detected by a measurable voltage.
Tarucha’s research group used a graphene bilayer sandwiched between two insulator layers, with the whole device sandwiched between two conducting layers or ‘gates’, allowing for the control of valley. The group’s paper has been published in Nature Physics.
They transferred valley current over a distance large enough to exclude other possible competing explanations for their results and were able to control the efficiency of valley current conversion over a wide range. The device also operated at temperatures far higher than expected. “We usually measure our devices at temperatures lower than the liquefaction point of Helium (-268.95 C, just 4.2 K above absolute zero) to detect this type of phenomena,” says Dr. Yamamoto, a member of the research group. “We were surprised that the signal could be detected even at -203.15 C (70 K). In the future, it may be possible to develop devices that can operate at room temperature.”
“Valley current, unlike charge current is non dissipative. This means that no energy is lost during the transfer of information,” says Professor Tarucha. He continues, “With power consumption becoming a major issue in modern electronics, valley current based devices open up a new direction for future ultra-low-power consumption computing devices.”
Experimental studies on valley current have only recently started. Control of valley current in a graphene monolayer has been demonstrated, but only under very specific conditions and with limited control of conversion from charge current to valley current. In order for valley current to be a viable alternative to charge current-based modern electronics, it is necessary to control the conversion between charge current and valley current over a wide range at high temperatures.
At the atomic scale, matter behaves as both a particle and a wave. Electrons, therefore, have an associated wavelength that usually can have many different values. In crystalline systems however, certain wavelengths may be favored. Graphene, for example, has two favored wavelengths known as K and K’ (K prime). This means that two electrons in graphene can have the same energy but different wavelengths – or, to put it another way, different “valley.”
Electronics use charge states to represent information, but when charge flows through a material, some energy is dissipated as heat, a problem for all electronic devices in use today. However, if the same quantity of electrons in a channel flow in opposite directions, no net charge is transferred and no heat is dissipated – but in a normal electronic device this would mean that no information was passed either. A valleytronics device transmitting information using pure valley current, where electrons with the same valley flow in one direction, would not have this limitation, and offers a route to realizing extremely low power devices.
Very cool, er, low power. When devices with this technology become practical is still quite away off. Yet the incentives are powerful, tablets and cell phones and other devices that use battery power can still use a reduction in energy use with an increase in power. Two intense motivators. Next up is more and better technological progress and some idea of how the technology might go to commercial scale.