A team of researchers at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) has now developed a hybrid system that produces renewable molecular hydrogen and uses it to synthesize carbon dioxide into methane, the primary constituent of natural gas.
The team had already cleared quite a milestone with their hybrid system of semiconducting nanowires and bacteria that used electrons to synthesize carbon dioxide into acetate in a bioinorganic hybrid approach to artificial photosynthesis.
Now the team is using the bioinorganic hybrid approach to artificial photosynthesis combining the semiconducting nanowires with select microbes to create a system that produces renewable molecular hydrogen and uses the hydrogen to synthesize carbon dioxide into methane.
Peidong Yang, a chemist with Berkeley Lab’s Materials Sciences Division and one of the leaders of this study give us a performance overview with, “This study represents another key breakthrough in solar-to-chemical energy conversion efficiency and artificial photosynthesis. By generating renewable hydrogen and feeding it to microbes for the production of methane, we can now expect an electrical-to-chemical efficiency of better than 50 percent and a solar-to-chemical energy conversion efficiency of 10-percent if our system is coupled with state-of-art solar panel and electrolyzer.”
Yang, who also holds appointments with UC Berkeley and the Kavli Energy NanoScience Institute at Berkeley, is one of three corresponding authors of the paper published in the Proceedings of the National Academy of Sciences. The other corresponding authors are Michelle Chang and Christopher Chang. Both also hold joint appointments with Berkeley Lab and UC Berkeley. In addition, Chris Chang is a Howard Hughes Medical Institute investigator.
Photosynthesis is the process by which nature harvests the energy in sunlight and uses it to synthesize carbohydrates from carbon dioxide and water. Carbohydrates are biomolecules that store the chemical energy used by living cells.
In the original hybrid artificial photosynthesis system developed by the Berkeley Lab team, an array of silicon and titanium oxide nanowires collected solar energy and delivered electrons to microbes which used them to reduce carbon dioxide into a variety of value-added chemical products. In the new system, solar energy is used to split the water molecule into molecular oxygen and hydrogen. The hydrogen is then transported to microbes that use it to reduce carbon dioxide into one specific chemical product, methane.
Chris Chang explained, “In our latest work, we’ve demonstrated two key advances. First, our use of renewable hydrogen for carbon dioxide fixation opens up the possibility of using hydrogen that comes from any sustainable energy source, including wind, hydrothermal and nuclear. Second, having demonstrated one promising organism for using renewable hydrogen, we can now, through synthetic biology, expand to other organisms and other value-added chemical products.”
The concept in the two studies is essentially the same – a membrane of semiconductor nanowires that can harness solar energy is populated with bacterium that can feed off this energy and use it to produce a targeted carbon-based chemical. In the new study, the membrane consisted of indium phosphide photocathodes and titanium dioxide photoanodes.
In the first study, the team worked with Sporomusa ovata, an anaerobic bacterium that readily accepts electrons from the surrounding environment to reduce carbon dioxide, in the new study the team populated the membrane with Methanosarcina barkeri, an anaerobic archaeon that reduces carbon dioxide using hydrogen rather than electrons.
Michelle Chang explained, “Using hydrogen as the energy carrier rather than electrons makes for a much more efficient process as molecular hydrogen, through its chemical bonds, has a much higher density for storing and transporting energy.”
In the newest membrane reported by the Berkeley team, solar energy is absorbed and used to generate hydrogen from water via the hydrogen evolution reaction (HER). The HER is catalyzed by earth-abundant nickel sulfide nanoparticles that operate effectively under biologically compatible conditions. Hydrogen produced in the HER is directly utilized by the Methanosarcina barkeri archaeons in the membrane to produce methane.
“We selected methane as an initial target owing to the ease of product separation, the potential for integration into existing infrastructures for the delivery and use of natural gas, and the fact that direct conversion of carbon dioxide to methane with synthetic catalysts has proven to be a formidable challenge,” said Chris Chang. “Since we still get the majority of our methane from natural gas, a fossil fuel, often from fracking, the ability to generate methane from a renewable hydrogen source is another important advance.”
Yang added, “While we were inspired by the process of natural photosynthesis and continue to learn from it, by adding nanotechnology to help improve the efficiency of natural systems we are showing that sometimes we can do even better than nature.”
In addition to the corresponding authors, other co-authors of the PNAS paper describing this research were Eva Nichols, Joseph Gallagher, Chong Liu, Yude Su, Joaquin Resasco, Yi Yu and Yujie Sung.
Coming out with a 10 percent starting figure for the solar to hydrogen step is impressive alone. Combined with the 50 percent hydrogen plus CO2 to methane step just begs field trials to be performed. If the team can improve on this state to even higher production efficiencies, and the process can scale up there would be no doubt that an endless supply of methane is in store as long as the sun shines down on earth.
The Chalmers team developed a new optimization algorithm that optimizes the robot’s movements reducing acceleration and deceleration, as well as the time the robot is at a standstill since being at a standstill also consumes energy.
Professor Bengt Lennartson initiated the research together with, among others, General Motors. Industrial robots are counted in the millions worldwide now and consume a substantial amount of electrical power. They range in size from huge assembly, press and weldment machines to tiny little actuators types that perform simple repetitive motions on to exacting robots that operate where humans simply cannot be such as contaminant free computer processor building.
Lennartson explained, “We simply let the robot move slower instead of waiting for other robots and machines to catch up before carrying out the next sequence. The optimization also determines the order in which the various operations are carried out to minimize energy consumption – without reducing the total execution time.”
The optimization never changes the robot’s operation path, only the speed and sequence.
“Thus, we can go into an existing robot cell and perform a quick optimization without impacting production or the current cycle,” he said.
To achieve safe optimization, several robots moving in the same area need to be coordinated. The optimization tool will therefore initially identify where robots may collide, and the entry and exit positions for each collision zone, and for each robot path.
Kristofer Bengtsson, who is responsible for the implementation of the new optimization strategy explains the next step, “The first test results have shown a significant improvement, such as a 15 to 40 percent energy reduction, but the results are still preliminary. In order to estimate the actual energy savings, further testing in industry is required.”
In robot-intensive manufacturing industries, such as bodywork factories in the automotive industry, robots consume about half of the total energy used for production.
The optimization program starts by logging the movements of each robot during an operations cycle, as well as any collision zones. This information is processed by the optimizer, which generates new control instructions that can be directly executed by the robots.
Bengtsson sums up with, “The goal is to make this kind of optimization standard, and included in robots from the start. At each adjustment of the operating sequences, a new optimization is conducted by default. But as we all know, it takes time to bring a development product into a robust production process, with several years of engineering work,”
The research group at the Department of Signals and Systems also includes PhD students Oskar Wigström and Sarmad Riazi. The optimization tool is being developed in the EU research project Areus.
Readers may have seen assembly line robot systems, they have been becoming more widespread with each passing year. They do work that is dirty, dangerous, nasty and quite unpleasant that is getting very hard to find employees to do or employ safely without huge costs.
Even if the industrial application comes in midway say at 25 to 30% the savings would be huge for what sounds like is mostly a software upgrade. One does wonder why it has taken so long for the research to have gotten underway.
Professor Ian Kinloch, Professor of Material Science at the University of Manchester added a small amount of graphene to strontium titanium oxide. The resulting composite thermoelectric material was able to convert heat which would otherwise be lost as waste into an electric current over a broad temperature range, all the way down to room temperature.
Graphene’s range of superlative properties and small size causes the transfer of heat through the material to slow leading to the desired lower operating temperatures. Of particular interest would be automobile heat.
Harvesting heat produced by a car’s engine that would otherwise be wasted and using it to recharge the car’s batteries or powering the air-conditioning system could be a significant feature in the next generation of hybrid cars.
The average car currently loses around 70% of energy generated through fuel consumption to heat. Utilizing that lost energy requires a thermoelectric material which can generate an electrical current from the application of heat.
Thermoelectric materials convert heat to electricity or vice-versa, such as with refrigerators. The challenge with these devices is to use a material that is a good conductor of electricity but also dissipates heat well.
Currently, materials which exhibit these properties are often toxic and operate at very high temperatures – higher than that produced by car engines. By adding graphene, a new generation of composite materials could reduce carbon emissions globally from car use.
Scientists from The University of Manchester led by Kinloch, include Professor Robert Freer and Yue Lin. Working with European Thermodynamics Ltd they have increased the potential for low cost thermoelectric materials to be used more widely in the automotive industry.
The new composite thermoelectric material works all the way to room temperature.
Professor Freer said: “Current oxide thermoelectric materials are limited by their operating temperatures which can be around 700º C (1292º F). This has been a problem which has hampered efforts to improve efficiency by utilizing heat energy waste for some time.”
“Our findings show that by introducing a small amount of graphene to the base material can reduce the thermal operating window to room temperature which offers a huge range of potential for applications,” he said. “The new material will convert 3-5% of the heat into electricity. That is not much but, given that the average vehicle loses roughly 70% of the energy supplied to it by its fuel to waste heat and friction, recovering even a small percentage of this with thermoelectric technology would be worthwhile.”
The findings were published in the American Chemical Society’s journal ACS Applied Materials and Interfaces. Graphene’s range of superlative properties and small size causes the transfer of heat through the material to slow leading to the desired lower operating temperatures.
Improving fuel efficiency, whilst retaining performance, has long been a driving force for car manufacturers. Graphene could also aid fuel economy and safety when used as a composite material in the chassis or bodywork to reduce weight compared to traditional materials used.
The University of Manchester folks have long experience with graphene. Graphene was first isolated there in 2004 by Sir Andre Geim and Sir Kostya Novoselov, earning them the Nobel Prize for Physics in 2010. The University is the home of graphene research with over 40 industrial partners working on graphene-related projects through the £61m National Graphene Institute.
Now that the basic formula for the composite is out its only a matter of some more innovation and intuition to take that 3 to 5% and improve on it. Meanwhile, those operating temperatures are major news in their own right. The applications where this technology could be used are awe inspiring.
Distinguished Fellow Ali Erdemir and his team at the U.S. Department of Energy’s Argonne National Laboratory have developed a newly patented technology that greatly extends the lifetime of mechanical parts.
From bearings and shafts to cutting tools metal parts that wear out quickly consume a great deal of time, manpower, money and the energy used to make them is a serious cost to an economy.
Several methods of surface hardening protect machinery and increase longevity have been developed over the centuries including of late, pack-boriding, which lays down a boride layer on metal pieces through the diffusion of boron.
Erdemir’s work is a departure from this conventional boriding technique, which is both time-consuming and energy-intensive. Instead, his team came up with a process for ultra-fast boriding, a process that saves time, money and energy, and even alleviates environmental concerns.
During three years of study and research Erdemir and his team took an abstract concept and turned it into an industrial-scale furnace that can deposit a boride layer 100 micrometers thick in half an hour. Pack-boriding would need approximately 10 hours to achieve the same thickness.
Erdemir’s group has recently been awarded a utility patent covering the ultra-fast nature of the technology, the range of materials that can be treated and several specific steps in the process of ultra-fast boriding.
Erdemir described the new technology as “clean and green, cost-effective and energy-efficient.”
Conventional pack-boriding involves baking parts in a complex mix of powders – at 1,800°F, often for 10 hours or more – but Erdemir’s ultra-fast method uses a battery-like design to channel a reactive boron into metal surfaces. Like a battery, the furnace relies on the attraction between positive and negative charges to get boron flowing swiftly toward its destination.
Because boron is supplied so quickly, the layers produced by ultra-fast boriding are more uniform and dense than the results of conventional pack-boriding.
Not only is ultra-fast boriding faster, but it creates tougher layers than any existing option for surface hardening, including the use of carbon or nitrogen in place of boron.
A thicker protective layer is unlikely to crack or come loose, so it increases the lifetime of metal pieces, making them more reliable in the long term. Machines that last longer and that require less maintenance for their parts could ultimately be much more profitable.
According to Erdemir, the heating process alone makes pack-boriding extremely energy-intensive. Ultra-fast boriding can do a better job while using 80 to 90 percent less energy.
And while the powder mix-based traditional boriding releases carbon dioxide and other hazardous emissions, the ultra-fast alternative releases almost none, he said.
Few people would look at a car, an airplane or a farming tool and appreciate the durable layers protecting its parts. But depositing this covering is an essential manufacturing step that allows machines to function with repeated use.
“The application conditions for all kinds of machinery are getting harsher,” Erdemir said. “The conventional approach to surface hardening is just not enough to sustain these machines.”
This includes automobiles, with parts that bear the burden of heavy loads, erosion and corrosion. In the aerospace industry, many components are made of titanium, which would be more resilient if treated with ultra-fast boriding.
Tools used in mining, farming and even oil and gas exploration are highly vulnerable to wear and tear, Erdemir said. His new technology could help preserve all this equipment.
“It feels great to get this patent,” Erdemir said, “because it’s very exciting to see something start at the demonstration level and reach the full production level. We have real fruits to show for our labor, and we’re proud of this rapidly-growing technology that will hopefully be up and ready for commercial practice by the end of this year, if not by this fall.”
The Argonne Lab scientists are collaborating with a private industry partner to get the large-scale furnace into commercial operation.
Erdemir plans to continue exploring ways to improve surface hardening. For now, he said he’s thrilled that the ultra-fast boriding technique is close to its first real-world applications.
There isn’t much info on now basic machining, tooling, farm and construction implements and other harsh condition metal use would save or reduce costs to consumers. Its a large set of fields, even larger situation sets and an incredible list of potential items.
For certain though, as near invisible as the effect will be, the results will soak through the whole of the world’s economy to everyone’s benefit.
Challa V. Kumar, Ph.D working at the University of Connecticut reported today the development of a unique, “green” antenna that could potentially double the efficiencies of certain kinds of solar cells and make them more affordable. The report was presented at the 250th National Meeting & Exposition of the American Chemical Society held in Boston.
Kumar offered a background with, “Most of the light from the sun is emitted over a very broad window of wavelengths. If you want to use solar energy to produce electric current, you want to harvest as much of that spectrum as possible.”
For now solar energy in the U.S. is growing, but panels on rooftops are still a rare sight. They cost thousands of dollars, and homeowners don’t recoup costs for years even in the sunniest or best-subsidized locales. Where wind and hail are common insurance alone can exceed the cost of grid electrical service.
Kumar is on to something. The silicon solar cells people buy today are not very efficient in the blue part of the light spectrum. So Kumar’s team at the University of Connecticut built an antenna that collects those unused blue photons and then converts them to lower energy photons that the silicon can then turn into current.
Kumar added, “Many groups around the world are working hard to make this kind of antenna, and ours is the first of its kind in the whole world.”
Commercial solar cells do a good job of converting light from about 600 to 1,000 nanometers (nm) into electric current but not from the 350 to 600 nm range. That’s part of the reason solar cells on the market today are only about 11 to 15 percent efficient. High-end panels can reach 25 percent efficiency but are unaffordable for most customers. Lab prototypes can reach even higher efficiencies but are difficult to scale up.
Converting the mostly unused portion of the light spectrum to wavelengths solar cells can use in an affordable way is far from a simple task. To tackle this problem, Kumar turned to organic dyes. Photons in light excite dye molecules, which can then, under the right circumstances, relax and emit less energetic but more silicon-friendly photons.
But to get dye molecules to work together, they need to be wrapped individually and densely, while satisfying certain quantum mechanical requirements. To address this issue, they embed the dyes inside a protein-lipid hydrogel by mixing them together, warming them up and then cooling them to room temperature. With this simple process, the material wraps around individual dye molecules, keeping them separated while packing them densely. Rather than creating a radio-like antenna, however, the procedure results in a thin, pinkish film that can be coated on top of a solar cell.
“It’s very simple chemistry,” Kumar said. “It can be done in the kitchen or in a remote village. That makes it inexpensive to produce.”
The new antennas are made with biological and non-toxic materials that are edible in theory, Kumar said, “Not that you would want to eat your solar cells, but they should be compostable so they won’t accumulate in the environment.”
Now his team is working with a Connecticut company to figure out how to apply the artificial antenna to commercial solar cells. In other projects, they also are figuring out ways to use the versatile hydrogel for drug delivery and white light-emitting diodes.
Kumar’s team deserves recognition for innovation and serendipity. This simple solution could go far in electrifying a lot more folks at affordable prices. Let hope the scale up works smoothly and quickly and finds a welcome in the solar cell industry. Double the output is no small feat. Congratulations!