Technology

The conversion of carbon dioxide (CO2) into fuels and chemicals using renewable energy is a potential pathway to mitigate increasing CO2 concentration in the atmosphere and acidification of the oceans. In a process that is essentially the reverse of combustion and is analogous to photosynthesis, CO2 can be electrochemically reduced to hydrocarbons by using renewable power sources such as wind and solar. This process would not compete with direct use of renewable energy as electricity, as the objective is to store excess energy for later use. On page 783 of this issue, Dinh et al. show that ethylene can be generated selectively via electrochemical CO2 reduction at rates that could yield a technologically feasible process.

The thermodynamics of reducing CO2 are similar to those of splitting water into hydrogen and oxygen, which has been done commercially with an energetic efficiency as high as 80%. However, CO2 reduction is considerably more challenging because of the unreactive nature of the CO2 molecule and the demands of controlling multiple electron and proton transfer events (12, in the case of ethylene) on the surface of the electrocatalyst. Copper catalysts bind carbon monoxide (CO) and other reaction intermediates in such a way as to produce two-carbon products such as ethylene and ethanol. However, it has been difficult to steer the reaction toward any one product. Moreover, most experimental studies provide CO2 to the electrode from aqueous solution, where its finite solubility leads to an upper, diffusion-limited current density of a few tens of milliamperes per square centimeter—far below what would be commercially relevant.

A breakthrough in efficiency can be achieved through intensification of mass transfer within the process. Process intensification is a chemical engineering approach that can achieve manyfold increases in product throughput by eliminating mass and energy transport limitations and exploiting potential synergies, such as combining multiple functions (for example, reaction and separation). Use of a gas diffusion electrode similar to those in fuel cells can greatly reduce the mass-transfer constraint for CO2 and has enabled current densities above 500 mA/cm2 for formation of one-carbon products such as CO. However, careful management of the gas phase CO2, liquid electrolyte, and solid electrocatalyst is required to maintain selectivity and minimize parasitic reactions such as water reduction.

Higher pH conditions can increase the yield of two-carbon products, but CO2 itself is acidic, setting an upper limit to the pH attainable in a conventional experiment. Dinh et al. show that very high hydroxide (OH−) concentrations can be maintained at the catalyst surface, provided that the electrochemical conversion is faster than the homogeneous reaction of CO2 with OH− to form bicarbonate. An optimal balance between these competing processes is attained through the use of very thin (∼25 nm) Cucatalyst layers deposited on the gas diffusion electrode (see the figure). The collocation of the electrocatalyst and high CO2 and OH− concentrations led to about 70% current efficiency to ethylene at current densities up to 750 mA/cm2. When the authors used thicker catalyst layers (for example, 100 nm), a region of lower OH− concentration formed, resulting in lower selectivity for ethylene.

To be economically viable, the process would need to operate continuously. Dinh et al. found that the highly basic conditions required to enhance ethylene yield led to deterioration of the carbon-based electrode material within an hour. As an alternative, they designed and implemented a gas diffusion electrode consisting of base-stable polytetrafluoroethylene (PTFE), with copper nanoparticles as the catalyst and carbon nanoparticles and graphite providing electrical contact. Use of this electrode led to a lower current density (∼300 mA/cm2), but it was stable for 100 hours.

A full electrochemical CO2-reduction system must also oxidize water to oxygen at the anode for sustained operation. Dinh et al. performed such a full-cell experiment, using a nickel iron oxide (NiFeOx) to catalyze the oxygen-evolution reaction at the anode. They measured a full-cell energy conversion efficiency, which captures all losses (overpotentials at the cathode and anode and electrical resistance of the electrolyte), of 34%. This value is lower than the 60 to 80% achieved for water splitting but is comparable to CO2-reduction cells, which make one-carbon products such as CO or formate and have lower cathode overpotentials.

Although the work of Dinh et al. is an important step toward chemical storage of renewable energy, challenges remain. Their reactor, and indeed nearly all CO2-reduction reactors in the literature, makes products which are either entrained in the CO2 stream or dissolved in the electrolyte, leaving product separation as an unsolved challenge.

There is a lively discussion in the literature regarding the prospective economics of electrochemical CO2 reduction . Although there is consensus that a carbon tax would be required to provide an incentive for CO2 conversion, opinions diverge on the economic viability of the conversion targets (such as CO and/or syngas, ethylene, and ethanol). Benchmark demonstrations such as that of Dinh et al. can be used to focus the discussion.

The products of electrochemical CO2 reduction are simpler than those of natural photosynthesis, yet they are the most ambitious targets of preparative electrosynthetic chemistry; most work over the past 100 years or more has focused on simpler transformations involving far fewer electron transfers. Demonstrations such as that of Dinh et al., combined with increasing understanding of the mechanism, could lead to a commercially viable electrochemical CO2-reduction process for mitigating rising atmospheric CO2 concentrations and promoting the use of renewable energy.

Imagine a generation of devices that operate not on electricity or batteries, but on light—an energy source that is both portable and abundant. Such technology could eliminate the costs associated with the manufacture of onboard energy systems and storage.

An interdisciplinary group of scientists from several institutions, including UC Santa Barbara’s Javier Read de Alaniz, is embarking on an effort that could result in such next-generation devices. Still in its infancy, the endeavor could change the way we approach the design and manufacture of machines.

Read de Alaniz is co-principal investigator on the new $7.5 million, five-year Multidisciplinary Research Initiative (MURI)-funded project, “Photomechanical materials systems: from molecules to devices.”

“The way that we transport energy today requires you to have a physical contact with the device, such as an electrical cable, to transfer your energy to mechanical work,” said Read de Alaniz, a professor of chemistry. “But if you could envision, for example, the use of lasers to transport light from point A through free space to point B, and upon hitting point B cause the propagating light into mechanical work, all of a sudden you can transport work without having a physical device carrying the energy.”

A relatively new class of molecules called photo switches—molecules that respond to light with some change of their properties—is a key aspect of the technology. One of the most common examples is the material used in eyeglass lenses that causes them to darken in response to UV light exposure when you step outside. Those molecules belong in a type that respond with a change in optical properties, while other types may go from hydrophobic to hydrophilic.

Read de Alaniz and his group are interested in molecules that shapeshift in response to light, essentially becoming a ball when a light shines on them and returning to their original flat state when in the dark.

“So the question becomes: How do you communicate that action of one molecule across a landscape of materials?” he said. “How do you get that small molecule to do this action and in turn make the entire polymer to do some type of function?”

The answer to that and many other questions, will be the work of the MURI researchers. Led by Princeton University polymer scientist (and UCSB alum) Ryan Hayward, the team also includes chemists Christopher Bardeen of UC Riverside and Todd Martinez of Stanford University, physicist Peter Palffy-Muhoray of Kent State University, and mechanical engineer Kaushik Bhattacharya of the California Institute of Technology.

“This whole project is really at the design stage,” Read de Alaniz said of the fundamental understanding that needs to be gained in order to turn light directly into mechanical work. “Each person on the team has a different piece of the road map—there are those who have been studying photo switches on the molecular scale, people who’ve been studying materials that can change shape on the mesoscale, and people who work on quantum mechanical modeling. Together this team is bringing it all together to design and develop the next generation of photomechanical materials.”

Among the early outcomes he predicts of this U.S. Navy-sponsored project could be developments in the field of optics, such as lenses that change or move in response to light. Or, elements that could change the drag of an object—the force that resists its motion through a fluid—allowing one to steer or change the direction of an oceangoing vessel simply by exposing parts of it to light. Other, more terrestrial applications may include soft robotics, in which light could be used to change the shape of an automaton as needed to perform a function.

“These are probably applications we’d be envisioning about 15 years down the road,” he said. “The real challenge is how do we actually make something that can compete with the machines that we have today.”

Read de Alaniz credits the progress thus far to the Challenge Grant awarded to him by the California NanoSystems Institute (CNSI) at UCSB that supports the initiation of new large-scale and high-impact collaborations by CNSI faculty. The funds, he said, enabled him to build a team that was competitive enough to secure the MURI grant.

“It allowed us to go after problems that are much bigger than something each of us could accomplish in just our independent research,” he said.

Among the chief complaints for smartphone, laptop and other battery-operated electronics users is that the battery life is too short and–in some cases–that the devices generate heat. Now, a group of physicists led by Deepak K. Singh, associate professor of physics and astronomy at the University of Missouri, has developed a device material that can address both issues. The team has applied for a patent for a magnetic material that employs a unique structure–a “honeycomb” lattice that exhibits distinctive electronic properties.

“Semiconductor diodes and amplifiers, which often are made of silicon or germanium, are key elements in modern electronic devices,” said Singh, who also serves as the principal investigator of the Magnetism and Superconductivity Research Laboratory at MU. “A diode normally conducts current and voltage through the device along only one biasing direction, but when the voltage is reversed, the current stops. This switching process costs significant energy due to dissipation, or the depletion of the power source, thus affecting battery life. By substituting the semiconductor with a magnetic system, we believed we could create an energetically effective device that consumes much less power with enhanced functionalities.”

Singh’s team developed a two-dimensional, nanostructured material created by depositing a magnetic alloy, or permalloy, on the honeycomb structured template of a silicon surface. The new material conducts unidirectional current, or currents that only flow one way. The material also has significantly less dissipative power compared to a semiconducting diode, which is normally included in electronic devices.

The magnetic diode paves the way for new magnetic transistors and amplifiers that dissipate very little power, thus increasing the efficiency of the power source. This could mean that designers could increase the life of batteries by more than a hundred-fold. Less dissipative power in computer processors could also reduce the heat generated in laptop or desktop CPUs.

“Although more works need to be done to develop the end product, the device could mean that a normal 5-hour charge could increase to more than a 500-hour charge,” Singh said. “The device could also act as an ‘on/off switch’ for other periphery components such as closed-circuit cameras or radio frequency attenuators, which reduces power flowing through a device. We have applied for a U.S. patent and have begun the process of incorporating a spin-off company to help us take the device to market.”

The proposed startup company associated with this research, highlights the university’s impact on the state’s economic development efforts, including commercialization of research conducted at Mizzou, workforce development and job growth, quality of life improvements for residents, and attracting corporations and businesses to the state. Companies commercializing MU technologies have secured hundreds of millions of dollars in investments and grants to advance their commercialization efforts. In 2017, the Office of Technology Management and Industry Relations reported that 31 U.S. patents were issued to members of the MU community.

The studies, “Magnetic Diode Behavior at Room Temperature in 2D Honeycombs” and “Spin Solid versus Magnetic Charge Ordered State in Artificial Honeycomb Lattice of Connected Elements,” were published in Advanced Electronic Materials and Advanced Science, respectively. The U.S. Department of Energy, Office of Basic Energy Sciences (DE-SC0014461) provided funding for this research. The content is solely the responsibility of the authors and does not necessarily represent the official views of the funding agencies.

When dozens of utilities received stimulus funds for distribution automation projects in 2009, solar was barely a gigawatt-scale market in the U.S. Sandy was simply a lead character in Grease, not a superstorm that would prompt cities and states to reassess the future-readiness of their electricity systems.

Much has changed in America’s power sector in the past decade. Powerful storms have made resiliency a focus for the industry. In the past two years alone, 25 gigawatts of solar have been installed. Renewable portfolio standards have intensified in many states, and are increasingly being backed up by regulatory innovation that encourages utilities to rethink their business models.

The need for more flexible, resilient grids in the face of extreme weather and increasing distributed energy resources has made distribution automation all the more critical. DA brings together digital sensors and switches with advanced communication and software to automate activities on the distribution grid, thus providing increased visibility across the system.

As utilities are increasingly faced with requirements for hosting capacity analyses for distributed resources, DA has become a fundamental building block for the utility of the future.

“Getting the right information is key to generate the business case,” said Makary Tarnoff, senior director of strategic marketing at Aclara.

There are a multitude of lessons learned for utilities that want to leverage DA to mitigate impacts of distributed resources on their systems. “There isn’t a utility I talk to that doesn’t see that impact,” said Tarnoff. “Even the smallest ones are seeing it.”

Build in layers

Although DA applications have been around a long time, most utilities are still starting with point solutions. While that is not a problem by itself, it can create challenges as applications are layered onto the system in the future.

Some utilities have run into this problem when using their smart meter network for DA applications, but the communications network doesn’t have the latency requirements or the ability to prioritize messages to effectively run DA applications. For DA applications, network architecture and security are paramount, especially as more and more devices are added.

A roadmap is critical for making the right investment the first time. “Lay the foundation, but then modulate the approach based on the budget that you have,” said Kumi Premathilake, SVP of AMI at Aclara. “And keep planning for the future.”

Tackle resiliency first

When it comes to prioritizing investment, one of the first DA applications that can provide the best return is fault location isolation and service restoration. FLISR can be particularly attractive for utilities with more aggressive performance metrics. Hawaii, for instance, just became the first state to have performance-based ratemaking mechanisms in statute, and other states could follow.

FLISR also has the advantage of providing measurable impacts to customers, particularly in regions that have been battered by severe storms in recent years. Hours-long outages can be cut to minutes or eliminated entirely, delivering significant value to C&I customers looking for an even higher level of reliability.

Seek out true visibility

Now that more than half the meters in the U.S. are digital, utilities have more visibility than ever down their distribution lines. But just seeing voltage at the end of the line isn’t enough, especially as DERs such as solar proliferate on distribution circuits. Now utilities need more granular information to feed into control systems like SCADA.

“The meter only tells the direction of current flow through the single meter,” said Tarnoff. “You need direction of flow at key locations on the electric grid. Tying that visibility into SCADA is critical.”

Along with visibility, communications with those devices can help control the power flows. The ability to see and then control distribution circuits allows for more accurate planning of DERs and surgical use of load control to manage intermittency of DERs connected to the grid.

Leverage pinpoint accuracy

With more distributed resources on the system, DA applications can allow for load control in new ways. For example, if electric vehicles create localized capacity constraints, distribution automation can moderate that impact. Tarnoff said some utilities are using DA to trade on locational marginal pricing to reduce the need to buy capacity when it is most expensive.

One utility in the Southeast has more than 2 gigawatts of capacity under load control, said Tarnoff, and now it can manage that capacity in tailored ways, and far more often.

“It’s entirely different than how they were doing load control before,” he noted. “And they can do it in less than 15 seconds.”

Nissan has built a battery remanufacturing facility that will disassemble used battery packs, discard any of the 48 modules that have lost 20% or more of their original capacity, and replace them with modules from other batteries that are still serviceable. The clusters that are no longer adequate for automotive use can be repurposed for use in energy storage products or batteries for electric fork lifts and other heavy equipment.

The price of a remanufactured 24 kWh battery for a Nissan LEAF is $2,855 in Japan. The price in the US is unknown at this time, but Craig Van Batenburg of the Automotive Career Development Center in Worcester, Massachusetts, tells Green Car Reports the replacement batteries can be installed by your local Nissan dealer or properly trained independent.

The new factory only began operations this month, so it may be a while before remanufactured batteries are available outside of Japan. Eventually, however, it will begin rebuilding the 30 kWh and 40 kWh batteries found in later LEAF models.

Recycling and repurposing lithium ion batteries is vitally important as the world transitions to electric cars. Sumitomo has come up with a way to analyze all 48 modules in each 24 kWh battery pack in four hours, a huge time savings from the 16 days Nissan engineers previously used for similar measurements, says Reuters. The factory has a capacity of 2,250 battery packs a year, but initial plans are to start with only “a few hundred” units in the first year.

As the factory gains experience, it will explore ways of disassembling modules and individual cells to reclaim the raw materials inside. One of those materials is cobalt, which is becoming more expensive and is often derived from child labor. China has recently enacted new policies putting the burden on manufacturers to recycle and dispose of lithium batteries in a sustainable manner, setting an example for other nations to follow. Japan is now part of that trend.

Most Icelanders oppose transfer of power over Iceland’s energy sector to European institutions according to a fresh opinion poll produced for the organisation Heimssýn which opposes the idea that the country should seek membership of the European Union.

Based on the results of the poll some 80.5% of Icelanders do not want further power over Icelandic energy matters to be transferred to European institutions, such as those of the EU or the European Free Trade Association (EFTA), while 8.3% are in favour.

The majority of the supporters of all the political parties represented in the Icelandic parliament, Alþingi, are opposed to giving away such powers to European institutions according to the poll, including those parties calling for an Icelandic membership of the EU.

The poll, which was produced by the polling company Maskína, was commissioned following an ongoing debate whether Iceland should accept the EU’s Third Energy Package through the country’s membership of the European Economic Area (EEA) Agreement.

Two of the political parties who form the current coalition government in Iceland have the policy of opposing transferring power over the country’s energy sector to foreign institutions through the EEA Agreement, the Independence Party and the Progressive Party.

Iceland’s Finance Minister and leader of the Independence Party Bjarni Benediktsson expressed his opinion in a parliamentary debate earlier this year on the matter that the country’s energy sector should not be an area where Brussels had a say.

Benediktsson also said to the Daily Telegraph last month that repeated attempts by the EU to get Iceland to accept direct rule from Brussels through the EEA Agreement left the country “struggling to assert its independence even though it is not an EU member state.”