Drone delivery is expected to take off big time in the next few years. Chinese online retailer JD.com has already launched drone delivery in four provinces in China, while DHL and Zipline are delivering medicines with drones in rural and hard-to-reach areas. Amazon, Google, and UPS are all working on getting drone delivery service off the ground.
There are a lot of issues to think about when it comes to package delivery using drones—safety, privacy, and logistics being some of the main concerns. In a new study, researchers tackle two other important aspects: energy use and greenhouse gas emissions.
Drones could use less energy and spew fewer emissions into the air than trucks, researchers say. But that advantage diminishes as drones get bigger and use dirty electricity to recharge.
“If you’re delivering a phone or sunglasses, drones would be a good way to go anywhere in the U.S. or most of world,” says Joshua Stolaroff, an environmental scientist at Lawrence Livermore National Laboratory who led the study published in Nature Communications. “But a larger drone carrying a bag of groceries can lead to higher emissions in a lot of the country with the current electricity grid,” says Stolaroff
To make drone delivery truly green, regulators and retailers will have to limit the size of drones and the number of new warehouses that support them, Stolaroff and his colleagues say.
A simple new recycling process restores old lithium battery cathodes to mint condition using half the energy of current processes. Unlike today’s recycling methods, which break down cathodes into separate elements that have to be put together again, the new technique spits out compounds that are ready to go into a new battery.
The method works on the lithium cobalt oxide batteries used in laptops and smartphones, and also on the complex lithium-nickel-manganese-cobalt batteries found in electric cars.
Renewable energy is rapidly changing the electric grid, and utilities need to adapt or face still greater disruption in their industry, according to a new report. Two directions now appear likely to offer opportunities for growth, the report says.
One is to move toward electric infrastructure as a platform for new applications that other companies can develop, such as renewable energy storage. The other direction is for the utility itself to expand into new growth areas like electric vehicle charging stations.
Either way, says report co-author Dan Cross-Call of the Rocky Mountain Institute, utilities that sit back and continue with business as usual could fall behind. Traditional utility growth models, he says, are not future-proof. “Demand for electricity has become flat or declining in many places,” he says. “So the historical expectation that sales increase is no longer the case.”
Wind-swept fires that killed more than 40 people in California in recent months have also jolted the state's biggest utilities, Pacific Gas & Electric (PG&E) and Southern California Edison (SCE). The utilities have had to work around the clock to keep power flowing to fire-afflicted communities, even as their equipment and policies face scrutiny as potential contributors to the deadly fires. California regulators, politicians and trial lawyers are querying SCE and PG&E's tree trimming and line maintenance — common culprits in prior California fires — but they are also examining a utility device that produces sparks by design: automatic circuit reclosers.
Automatic reclosers are pole-mounted circuit breakers that can quickly restore power after outages, but they can also multiply the fire risk from damaged lines. While SCE is adjusting recloser operations to reduce fire risks, PG&E’s practices are less clear. And only their neighbor to the south — San Diego Gas & Electric (SDG&E) — is tapping advanced recloser technology that is safer by design.
Reclosers make quick work of many line faults, the great majority of which result from temporary insults such as a branch striking a line or the electrocution of an unlucky squirrel. As Australian recloser manufacturer NOJA Power puts it: "Like the success of Vanilla Ice, Dexy’s Midnight Runners and Devo, most network faults are transient.” In such cases the recloser detects a power surge, momentarily interrupts electricity flow, and then automatically re-closes its contacts to restart flow down the affected line.
Reclosers usually try restarting a line 2-3 times before giving up and “locking out” a line. Sometimes multiple attempts are needed to do the job, writes NOJA Power, such as when high-temperature electrical arcing at the site of the fault burns away hung trees or tree limbs.
Under the wrong conditions, however, such arcing and ignition can obviously spark a fire. Reclosers contributed to several of Australia’s deadly Black Saturday bushfires of February 7, 2009, according to the official report of the Victorian Bushfires Royal Commission.
The commission concluded that that Kilmore East fire that killed 119 people “probably would not have started” were it not for a recloser’s three attempts to revive a wind-felled line. Experts testified that the recloser’s attempts delivered 3.4 seconds of 5,000 C° electrical arcing that likely started the fire.
The Black Saturday commission called for limiting reclosers to one restart attempt on high risk fire days and suggested that some be totally disabled during high risk periods. Not all California utilities are heeding such advice.
PG&E, in a response to questions from California's Public Utilities Commission after the fires north of San Francisco in October, wrote that it could set reclosers on its overhead lines to attempt line restarting 1, 2 or 3 times. It indicated that it could disable that function only on reclosers associated with its underground lines. The San Francisco-based utility did not respond to Spectrum’s requests for comment.
A grid operations manager for Rosemead, Calif-based SCE told Spectrum on background that the utility disables automatic restart capability for all reclosers that its operators can remotely control in areas under "Red Flag" fire warnings. He told Spectrum that SCE tightened its recloser policy shortly before this month’s fires to permanently disable restarting by reclosers that require manual adjustment by field technicians.
SDG&E, SCE’s neighbor to the south, has gone one step further to increase recloser safety. Like SCE it restricts recloser operation on fire days, but it has also deployed advanced technology in its territory's high-risk Fire Threat Zone to reduce the sparking that reclosers generate at faults.
SDG&E uses 172 of S&C Electric Company’s IntelliRupters — so-called pulse reclosers that probe lines after a fault rather than simply restarting power flows. S&C's intelligent breaker recloses its contacts for just 1-2 milliseconds and then evaluates the power that flows back. If the flow looks normal it restarts the line. And if the power signal matches the signature of a permanent fault, it locks the line out.
An IntelliRupter probing a permanent fault generates less than 2 percent as much fault energy as a conventional recloser according to independenttests. Christopher McCarthy, a U.K.-based managing director for S&C who helped commercialize the technology a decade ago, says they developed it as a way to reduce the wear that large fault currents inflict on substation transformers and other utility equipment.
But McCarthy says there is also a clear safety benefit — one that is dramatically evident in the smaller shower of sparks released from faults by its pulse reclosers in side-by-side runs against conventional reclosers [image above]. “We can’t say that it’s not going to cause fires,” he says, “but it’s clearly much safer."
NOJA Power, which says it has no reclosers in service in California, derides some of the growing criticism of reclosers as “unfair.” As the company tells utilities via its website: "There is no need to be ashamed of your arcs and sparks – when it isn’t fire season, use the very power you are charged with delivering to strike the objects that dare get in your way of reliability."
However, California utilities appear to be reevaluating their technology options. SCE tells Spectrum that it is “actively exploring the use of pulse reclosers.
Utilities may have little choice, because they face a potentially existential threat if they can not convince both state officials and the public that they are doing everything possible to prevent fires.
A floating "solar fuels rig" could one day use solar energy to split apart seawater and generate hydrogen fuel. A team of scientists recently described the design for the new rig in the International Journal of Hydrogen Energy. A scaled-up version of their prototype could someday float out on the open sea, they say, producing renewable fuel from sunlight and seawater.
Scientists have long sought ways to harness sunlight to produce storable fuels that could be put to work when the sun doesn't shine. One strategy aims to use solar-generated electricity to drive the electrolysis of water—the splitting of water (H2O) into hydrogen (H2) and oxygen (O2). Hydrogen is a clean fuel, the burning of which generates only water as its byproduct.
When commercial electrolyzers split water, they rely on membranes to separate the resulting hydrogen and oxygen gases, since mixtures of these gases are potentially explosive. But these membranes are expensive, and prone to degradation and failure.
Moreover, solar-powered hydrogen fuel production would ideally make use of cheap, abundant seawater. But commercial electrolyzers require very pure water, because seawater contains impurities and microbes that can easily destroy their membranes.
Today, lithium is the active ingredient in batteries that power smart phones, laptops, and cars. But because of the price of lithium, researchers have been looking for another, more abundant element that could replace it. Several start-ups and established companies have tackled the idea of developing rechargeable batteries in which the active ingredient is sodium, lithium’s neighbor on the periodic table.
Besides its availability, sodium has several other important properties—not the least of which is its resistance to catching on fire. What’s more, “It was a good candidate because it could store a similar amount of energy as compared to lithium,” remembers Minah Lee, who does research on sodium batteries at Stanford University.
Today a number of companies are working on developing sodium batteries with the ultimate aim of replacing lithium as the key ingredient. The CNRS, The National Center for Scientific Research in France, recently announced the creation of Tiamat, a start-up company based in Amiens, France, that will develop and bring to the market a sodium rechargeable battery by 2020. CNRS says the battery will be designed in the widespread industrial 18650 format.
In the United States, Aquion, a startup whose focus is the production of high-capacity saltwater batteries for energy storage, escaped bankruptcy by a hair’s breadth. Initially funded with $190 million mainly by Bill Gates and Kleiner Perkins, Aquion was acquired in July by Juline Titans LCC for $9.16 million.
Also, researchers at several universities are now focusing on swapping sodium for lithium in batteries. The advantage these scientists have is that they can use large instruments, such as accelerators, to investigate the anode materials and how they function. “We can get great insight into where the sodium actually goes—both at a detailed atomic level (how it bonds with other atoms) and at much larger scales—as well as how the electrode particles change when they take up sodium,” says Michael Toney, a researcher at the SLAC National Accelerator Laboratory, operated by Stanford University.
However, reception for sodium batteries by power utilities and by manufacturers of electrical power systems for cars has remained cool. For the moment, they’d prefer to stick with lithium. “The cost of today’s lithium-ion battery technology is very competitive across a variety of markets,” says David Snydacker, a battery expert at Dosima Research. “So for these new sodium batteries to succeed, they not only have to compete against conventional technologies, but have to compete against lithium batteries—currently a tall order.”
One problem that has not yet been resolved is finding or creating a high capacity anode, the negative side of the battery. A favored material is hard carbon, a form of the element with a peculiar structure that allows the storage of sodium ions in spaces in-between atoms. "Lithium-ion batteries use graphite, but this does not work for sodium ions,” says Toney. “Instead we use hard carbon. This is not optimal and nobody really understands what this material is."
Also, scalability is an important factor, says Lee. “We can rescale on different sizes of battery. The point of my electrode material is its sustainability. It is based on biomass, so for larger amounts you have a better benefit of the material,” says Lee. Another important factor for finding a receptive market is a battery that can be produced with current industrial production lines. “[Sodium batteries’] processing should be very similar [to that of their lithium-ion counterparts],” says Lee.
So, sodium batteries might roll off existing production lines, but the question is when? The answer to that question assumes that the sodium batteries are actually economical, and we don’t know this yet.
Though the researchers associated with Tiamat have given themselves that tight 2020 deadline to start production, it remains to be seen whether they’ll hit their target. “There is still a lot of work, we did not get there yet,” admits Mathieu Morcrette of the University of Picardie “Jules Verne” in France.
The price of sodium as a raw material is much lower than lithium because of its relative abundance. Sodium sells at about $150 a ton compared to $15,000 a ton for lithium. After refinement, a battery made from sodium would be 5 to 10 percent cheaper than an identical battery made of lithium, estimates Snydacker. But because sodium has a lower charge capacity than lithium, sodium batteries are heavier and require more materials to manufacture, which adds far more to the overall cost than is saved by replacing lithium with sodium. Also, Snydacker thinks sodium batteries will be inferior in performance, and ultimately can’t compete with a lithium-based technology that has been perfected over the last few decades.
Editor’s note: This story was updated on 19 December to accurately represent the viewpoints of David Snydacker in the final paragraph.
North America’s electric transmission may be an engineering marvel, but that doesn’t make it immune to failure, sometimes in spectacular fashion. For proof, just mention some dates and names to Nicholas Abi-Samra and wait for his reply.
Abi-Samra has more than 35 years of experience in power generation, transmission, distribution, retail, and end-use energy applications. He is president of Electric Power & Energy Consulting and an adjunct professor with UC San Diego. He also is the author of a new book Power Grid Resiliency for Adverse Conditions (Artech House, 2017).
The book is part technical reference guide and part history lesson. In it, Abi-Samra describes the impacts of heat waves, ice storms, and hurricanes on grid operations through case studies from North America, Europe, and Asia.
Start with the 1965 Northeast Blackout. It cascaded from Ontario and upper New York State through Manhattan, leaving millions of New Yorkers in the dark. That incident offered the first large-scale evidence of the vulnerability of North America’s interconnected grid. It also led to the creation of the Electric Power Research Institute (EPRI), Abi-Samra says, and its mission to enhance grid reliability through research and cooperation across the industry.
Mention the 2003 Northeast blackout and Abi-Samra links it to a realization that the grid’s operating conditions were not visible enough. Remedies included technologies like synchophasors and operational strategies like load shedding.
Synchophasors measure the instantaneous voltage, current, and frequency at specific locations on the grid, offering operators a near-real-time picture of what’s happening on the system, which lets them take action to prevent power outages.
Load shedding involves the short-term interruption of power to one or more end users to allow the grid to rebalance itself. Many industrial-scale power users trade off the occasional loss of power for lower power prices, known as “interruptible rates.”
The early 2000s were also marked by hurricanes that hit Florida and Louisiana particularly hard. Widespread loss of transmission and distribution poles led to efforts to replace wooden poles with steel and concrete. Further hardening came after Hurricane Katrina devastated substations, leading to investments to elevate them above storm surge levels.
Superstorm Sandy in 2012 exposed storm vulnerabilities in the Northeast, particularly the near-impossibility of insulating a system from damage in the face of fearsome winds and flooding.
The idea that resulted from Sandy was to “allow the system to fail, but in such a way that it could quickly recover,” Abi-Samra says. This illustrates another lesson: Efforts intended merely to harden infrastructure are not enough—the grid also needs to be resilient.
Hardening and resiliency are different concepts, Abi-Samra says. Resiliency refers to characteristics of the infrastructure and operations such as strength and the ability to make a fast recovery, which help utilities minimize or altogether avoid disruptions during and after an extreme weather event.
Abi-Samra says that making the power distribution system more resilient starts with design changes. It may be advantageous, for example, to split up a large network into smaller circuits, and to reexamine circuit arrangements to enhance the speed of repair.
Greater deployment of smart grid technology can also help. With it, when an outage occurs, intelligent switches can detect a short circuit, block power flows to the affected area, communicate with nearby switches to reroute power around the problem and keep as many users energized as possible.
And because these intelligent switches do this automatically, they can reduce the time it takes to restore power to just a few minutes, Abi-Samra says.
For example, when Hurricane Harvey hit Texas in August, local utility CenterPoint operated more than 250 intelligent switches on its network. The effort saved more than 40 million outage minutes, Abi-Samra says. The utility also used smart meters to remotely disconnect customers. Both measures helped to minimize the storm’s impact and speed up restoration efforts.
Abi-Samra is a proponent of distributed generation resources and microgrids. Indeed, microgrids are part of a 10-year, $17 billion plan to rebuild and modernize Puerto Rico’s electric system, which was largely destroyed by Hurricane Maria in September. The combination of distributed energy resources like rooftop solar, battery energy storage, and microgrids could better protect hospitals and government buildings, large employers, and vulnerable communities.
“This duet between renewables and batteries is a perfect element of a resilient grid,” Abi-Samra says.
But such approaches are not a panacea to preventing grid failures, he says, and the interconnected grid still has a lot to offer.
When an area is hit by severe weather, adjoining utilities can offer support by supplying power and ancillary services. That value may be best demonstrated during summer heat waves, when generating resources from across a region are summoned to meet soaring demand for air conditioning in businesses and homes.
But when it comes to the massive destruction suffered by Puerto Rico, Abi-Samra says the biggest lessons may involve nothing more technical than a chainsaw and a bucket truck.
In part, he says, Puerto Rico’s grid disaster is the story of a financially struggling utility that deferred maintenance, limped along with a shortage of maintenance workers, and let slide seemingly mundane tasks like tree trimming.
Because as much as 45 percent of reliability incidents are due to vegetation, efforts to harden Puerto Rico’s electric system could benefit from simply revisiting its vegetation management strategy, Abi-Samra says.
“Flying debris such as roofs and road signs and vegetation such as falling trees and limbs are the primary causes of distribution-pole damage during a storm, not strong winds themselves,” he says.
What’s more, the risk of airborne debris coming from trees outside of the right-of-way can exceed the risk from trees inside the right-of-way by a factor of as much as four to one. “Vegetation management on the right-of-way only is not enough,” he says.
Hurricane Maria in September and Superstorm Sandy in 2012 both showed that no amount of reinforcement and preparation can completely eliminate damage.
Abi-Samra says that structurally hardening the distribution system should focus on two objectives: hardening circuits that feed critical loads and load centers, and designing systems to allow for quick restoration.
“A cost-effective hardening approach should start with substations, feeders, and circuits which serve critical infrastructure such as hospitals,” he says. Once that is complete, the remaining feeders can then be prioritized.
The most common hardening practices include replacing wooden utility poles with poles made of steel, concrete, or a composite material; upgrading transmission towers from aluminum to galvanized-steel lattice or concrete and installing guy wires and other structural supports.
In the end, Abi-Samra says it’s unrealistic to think that damage to the grid can be avoided when severe storms or other events occur. Instead, he says the goal should be to minimize any adverse impacts. Microgrids, distributed generation resources, smart grid technologies, and operational analytics all can enhance resiliency.
“Put intelligence on top of that,” he says, “and you can make life better for the public.”
A $17.6 billion plan to rebuild and modernize Puerto Rico’s electric power system was released on 11 December.
Prepared by more than a dozen entities, including the island’s electric power authority (PREPA), the 63-page plan calls for a decade-long series of projects and operational improvements. The plan is aimed at building an electric power system capable of surviving an “upper Category 4 event” (250-kilometer-per-hour winds) and heavy flood waters.
Hurricane Maria largely destroyed the island’s electric infrastructure in September. Work continues to restore electric power service knocked out by high winds and flooding.
Key elements of the plan were earlier shared with the Energywise blog in an interview with New York Power Authority President and CEO Gil Quiniones. He was one of seven industry leaders who made up a steering committee to oversee the plan’s creation.
In broad terms, the plan is modeled on work under way on Long Island, New York, in response to the destruction caused by Hurricane Sandy, Quiniones told IEEE Spectrum. Sandy hit Long Island and the Northeast in 2012, causing widespread damage to the grid.
From Microgrids to Tree Trimming
Among the projects included in the newly released Puerto Rico recovery and enhancement plan are:
1. Reinforcing existing direct-embedded poles with perimeter-injected concrete grout or other soil stabilization
2. Upgrading damaged poles and structures to a higher wind loading standard
3. Strengthening poles with guy wires
4. Installing underground power lines in areas prone to high wind damage
5. Modernizing the T&D system through smart grid investments to make the system less prone to extended outages
6. Installing automated distribution feeder fault sectionalizing switches to enable fault isolation and reduce outage impact
7. Deploying control systems to enable distributed energy resource integration and encourage their development
8. Adopting asset management strategies, such as the targeted inventory of critical spares
9. Instituting consistent vegetation management practices that take into consideration the island’s tropical conditions
10. Applying enhanced design standards for equipment and facilities damaged in the recent storms.
The price tag for all of the work is pegged at around $17.6 billion through 2027. That includes $5.3 billion for overhead and underground distribution lines; $4.9 billion for overhead and underground transmission lines; $1.7 billion for substation upgrades; $3.1 billion for generating assets; and nearly $1.5 billion for distributed energy resources.
A Costly Recovery
In addition to the grid plan, Puerto Rico’s Governor Ricardo Rosselló, members of the New York congressional delegation, and New York Governor Andrew Cuomo called on Congress to approve $94.4 billion in funds to aid in the island’s recovery.
A report released in November found that more than 472,000 housing units were destroyed and severely impacted by the storm. In addition, the island’s agricultural sector was almost entirely destroyed, including the loss of almost 80 percent of planted crops. Nearly all of the island’s water and wastewater assets also were disabled.
Microgrids for Resiliency
The electric modernization plan recommends that microgrids be deployed to make the system more resilient in the event of power outages and interruptions. It outlines a two-pronged approach.
In the first, hospitals, police and fire stations, emergency shelters, communications infrastructure, water treatment plants, airports, sea ports, and commercial and industrial centers would operate in isolation as microgrids and be ready to provide vital services immediately after a natural disaster. Technologies such as onsite backup generation, combined heat and power systems, rooftop solar, battery storage, and building energy management systems would be capable of creating centers that can help in post-storm recovery.
The second approach calls for microgrids located in remote communities to remain disconnected from the larger grid and continue to provide electricity to critical infrastructure as well as grocery stores, gas stations, and community centers. The installation of solar, battery storage, feeder automation control systems, load control equipment, and similar technologies could allow these communities to more quickly recover from natural disasters.
Substation and Transmission Automation
The plan also recommends that substations be enhanced by upgrading relay protection equipment and SCADA systems. Doing so would enable improved system control, reinforced and hardened substation facilities through defense-in-depth flood protection, and additional security access and monitoring systems.
In its 2015 integrated resource planning document, PREPA laid out its intent to pursue more flexible generating capacity to handle the intermittency of renewable resources. The modernization plan now says that the grid can be rebuilt with smaller distributed generating units that provide more flexibility and redundancy, and that help maintain operating and spinning reserve margins.
“The PREPA power system could also serve as a model for the future development of advanced power generation, transmission, and distribution systems and the use of renewable resources throughout the Caribbean or other similar global locations,” the plan says.
Widespread use of substation and distribution automation is recommended to better enable the system to respond to real-time events and enable deployment of distributed energy resources.
The plan also envisions that technologies such as centralized energy management systems, automated mapping and facilities management, and geographic information systems will become integral to day-to-day operations.
Turning to operations and maintenance, the plan says that PREPA should adopt a “robust asset management approach” that includes “aggressive vegetation management and optimized maintenance programs with adequate staffing.” Because of the tropical growth in Puerto Rico, PREPA will likely need to adopt vegetation management programs that are more aggressive than the industry norm.
The Puerto Rico Energy Resiliency Working Group developed the plan with help from Navigant Consulting. Group members include PREPA, the Puerto Rico Energy Commission, the U.S. Department of Energy, the Electric Power Research Institute, NYPA, Consolidated Edison, Edison International, the Long Island Power Authority, the Smart Electric Power Alliance, Brookhaven National Laboratory, the National Renewable Energy Laboratory, the Grid Modernization Lab Consortium, and Pacific Northwest National Laboratory.
If electric vehicles are ever going to outcompete gas-powered ones, batteries must improve. Conventional lithium-ion batteries, the most energy-dense for their weight, can only be charged to about 50 percent of their theoretical capacity. When researchers have tried to pack more lithium into a battery’s electrodes, it hasn’t helped. The electrodes begin to quickly degrade after the first discharge/recharge cycle, and nobody has been able to figure out how to prevent it.
Now there’s a clue. Using a combination of theoretical computer modeling and sophisticated X-ray methods, researchers have for the first time found a relationship between the way atoms rearrange themselves in the electrode when it’s being charged and how electrons are stored in the battery’s atomic and chemical structures. This insight should give battery-makers a blueprint for building lithium-rich electrodes that could dramatically improve battery performance.
Plans to modernize Puerto Rico’s power grid likely will include an array of fixes such as stronger electric poles, microgrids, and more renewable energy. The plan, expected to be released later this month, will also focus on reducing the island’s reliance on transmission lines that cross its mountainous interior. These proved to be a weak link when Hurricane Maria struck in September.
Puerto Rico’s electric power authority, PREPA, is writing the plan along with the New York Power Authority (NYPA), the Long Island Power Authority, ConEd, Edison International, the Electric Power Research Institute, and the Smart Electric Power Alliance.
The plan will offer details based on a request made by Gov. Ricardo Rosselló in November for $94 billion in federal aid to rebuild the island. Around $17 billion of that would be earmarked for the electric power system, which was largely destroyed by the storm.