While the human race will always leave its carbon footprint on the Earth, it must continue to find ways to lessen the impact of its fossil fuel consumption.
“Carbon capture” technologies – chemically trapping carbon dioxide before it is released into the atmosphere – is one approach. In a recent study, Cornell University researchers disclose a novel method for capturing the greenhouse gas and converting it to a useful product – while producing electrical energy.
Lynden Archer, the James A. Friend Family Distinguished Professor of Engineering, and doctoral student Wajdi Al Sadat have developed an oxygen-assisted aluminum/carbon dioxide power cell that uses electrochemical reactions to both sequester the carbon dioxide and produce electricity.
Their paper, “The O2-assisted Al/CO2 electrochemical cell: A system for CO2capture/conversion and electric power generation,” was published July 20 in Science Advances.
The group’s proposed cell would use aluminum as the anode and mixed streams of carbon dioxide and oxygen as the active ingredients of the cathode. The electrochemical reactions between the anode and the cathode would sequester the carbon dioxide into carbon-rich compounds while also producing electricity and a valuable oxalate as a byproduct.
In most current carbon-capture models, the carbon is captured in fluids or solids, which are then heated or depressurized to release the carbon dioxide. The concentrated gas must then be compressed and transported to industries able to reuse it, or sequestered underground. The findings in the study represent a possible paradigm shift, Archer said.
“The fact that we’ve designed a carbon capture technology that also generates electricity is, in and of itself, important,” he said. “One of the roadblocks to adopting current carbon dioxide capture technology in electric power plants is that the regeneration of the fluids used for capturing carbon dioxide utilize as much as 25 percent of the energy output of the plant. This seriously limits commercial viability of such technology. Additionally, the captured carbon dioxide must be transported to sites where it can be sequestered or reused, which requires new infrastructure.”
The group reported that their electrochemical cell generated 13 ampere hours per gram of porous carbon (as the cathode) at a discharge potential of around 1.4 volts. The energy produced by the cell is comparable to that produced by the highest energy-density battery systems.
Another key aspect of their findings, Archer says, is in the generation of superoxide intermediates, which are formed when the dioxide is reduced at the cathode. The superoxide reacts with the normally inert carbon dioxide, forming a carbon-carbon oxalate that is widely used in many industries, including pharmaceutical, fiber and metal smelting.
“A process able to convert carbon dioxide into a more reactive molecule such as an oxalate that contains two carbons opens up a cascade of reaction processes that can be used to synthesize a variety of products,” Archer said, noting that the configuration of the electrochemical cell will be dependent on the product one chooses to make from the oxalate.
Al Sadat, who worked on onboard carbon capture vehicles at Saudi Aramco, said this technology in not limited to power-plant applications. “It fits really well with onboard capture in vehicles,” he said, “especially if you think of an internal combustion engine and an auxiliary system that relies on electrical power.”
He said aluminum is the perfect anode for this cell, as it is plentiful, safer than other high-energy density metals and lower in cost than other potential materials (lithium, sodium) while having comparable energy density to lithium. He added that many aluminum plants are already incorporating some sort of power-generation facility into their operations, so this technology could assist in both power generation and reducing carbon emissions.
A current drawback of this technology is that the electrolyte – the liquid connecting the anode to the cathode – is extremely sensitive to water. Ongoing work is addressing the performance of electrochemical systems and the use of electrolytes that are less water-sensitive.
The Materials Project, run by Berkeley Lab, accelerates innovation by enabling computationally driven materials and battery design.
The Materials Project, a Google-like database of material properties aimed at accelerating innovation, has released an enormous trove of data to the public, giving scientists working on fuel cells, photovoltaics, thermoelectrics, and a host of other advanced materials a powerful tool to explore new research avenues. But it has become a particularly important resource for researchers working on batteries.
Co-founded and directed by Lawrence Berkeley National Laboratory (Berkeley Lab) scientist Kristin Persson, the Materials Project uses supercomputers to calculate the properties of materials based on first-principles quantum-mechanical frameworks. It was launched in 2011 by the U.S. Department of Energy’s (DOE) Office of Science.
In 2012, DOE established the Joint Center for Energy Storage Resarch (JCESR), a DOE Energy Innovation Hub, which significantly enhanced the Materials Project with new simulations of next-generation battery electrodes and liquid organic electrolytes.
“This massive amount of precise data released through the Materials Project will have a profound and lasting impact on the battery research community,” said JCESR Director George Crabtree. “This is a great example of the way Berkeley Lab and other JCESR partners share scientific knowledge to advance the scientific frontier.”
The idea behind the Materials Project is that it can save researchers time by predicting material properties without needing to synthesize the materials first in the lab. It can also suggest new candidate materials that experimentalists had not previously dreamed up. With a user-friendly web interface, users can look up the calculated properties, such as voltage, capacity, band gap, and density, for tens of thousands of materials.
Transdisciplinary artist and researcher Ivan Henriques collaborated with scientists from the Vrije Universiteit Amsterdam to create a prototype for an autonomous bio-machine that harvests energy from photosynthetic organisms like algae and uses this energy to search for more of these organisms.
The Symbiotic Machine targets organisms that are found in water bodies like ponds, canals, rivers and the sea. It creates a symbiotic system with its environment as it detects, collects, carries, and processes these organisms. The machine can clean the environment of its location by collecting these organisms for energy and can potentially be used in places with harmful algae bloom.
The machine prototype focuses on detecting a specific algae, Spirogyra, a genus of filamentous green algae. The structure is designed to float in the water among the algae and is transparent in order to catch sunlight at any angle. The machine also has a mouth that takes in and grinds the algae to break down the membrane cells and release micro particles, and a stomach where the energy is harvested. The Symbiotic Machine is programmed to eat, move, sunbathe, rest, search for food, wash itself, and do it all over again on loop.
Meat grown using tissue engineering techniques, so-called ‘cultured meat’, would generate up to 96% lower greenhouse gas emissions than conventionally produced meat, according to a new study.
The analysis, carried out by scientists from Oxford University and the University of Amsterdam, also estimates that cultured meat would require 7-45% less energy to produce than the same volume of pork, sheep or beef. It would require more energy to produce than poultry but only a fraction of the land area and water needed to rear chickens.
A report of the team’s research is published in the journal Environmental Science & Technology.
‘What our study found was that the environmental impacts of cultured meat could be substantially lower than those of meat produced in the conventional way,’ said Hanna Tuomisto of Oxford University’s Wildlife Conservation Research Unit, who led the research. ‘Cultured meat could potentially be produced with up to 96% lower greenhouse gas emissions, 45% less energy, 99% lower land use, and 96% lower water use than conventional meat.’