Why Solar ‘Microgrids’ Are Not a Cure-All for Puerto Rico’s Power Woes
By Peter Fox-Penne
In addition to its many other devastating human consequences, Hurricane Maria left the island of Puerto Rico with its power grid in ruins. Power was knocked out throughout the island, with an estimated 80 percent of its transmission and distribution wires incapacitated. When hospitals and other critical users could not get backup power and water supplies ran low, an extended outage became a humanitarian crisis that has yet to be resolved.
This shameful outcome should have been avoided with strong, swift federal leadership. Yet more than five weeks after the storm, only about 40 percent of the grid has been rebuilt, and service remains unreliable even where power is restored.
As the recovery process inches its way forward, the questions many are asking go like this: Why are we rebuilding the grid to be the same as it was before the storm? Can't we use this as an opportunity to create a more modern, resilient, renewable power system? Isn't this the perfect opportunity for an upgrade?
The answer to these questions, from my perspective having worked with and researched the power industry for four decades, has little to do with technologies and everything to do with some nearly insurmountable financial and governance challenges. There is a path forward, but it will not be easy.
The Power System Before Maria
Prior to Maria, Puerto Rico had one of the largest public power authorities in the U.S., known as PREPA, serving a population of 3.4 million people from 31 power plants, 293 substations and 32,000 miles of wire. Almost half its generation was from old, very expensive oil-fired plants, resulting in prices about 22 cents per kilowatt hour, among the highest in the U.S. The island has several solar photovoltaic farms but gets about 46 percent of its power from oil and only about 3 percent from solar.
At the center of all this is PREPA and its outsized role in Puerto Rico. With US$9 billion of debt, PREPA has been part of the contentious refinancing process that ultimately required congressional action. PREPA is also the largest employer on the island, with strong connections to the island's leadership, so proposals perceived to adversely impact PREPA can be difficult to enact. Recently the island has established a new energy commission called PREC with oversight over PREPA's plans, spending and rates.
The PREC's efforts at reform underscore the enormous challenges the utility faces. In September 2016 the PREC issued an order directing PREPA to convert some of its oil plants to gas, renegotiate some high-priced renewables contracts and purchase more renewable energy.
In April 2017 PREPA issued a new financial plan with starkly grim prospects: a $4 billion maintenance backlog, the loss of fully one-quarter of its sales in the next 10 years, and continued red ink as far as the eye can see. Meanwhile, renewable power developers who have tried to build plants on the island have encountered great difficulties, as chronicled in this blog post.
Then, just before Maria, PREPA declared bankruptcy. Maria therefore destroyed the grid of a system that was already bankrupt, having trouble maintaining its service and paying its bills, resistant to renewable interconnections, and politically difficult to reform.
Proposals for Rebuilding With Microgrids
The challenge, then, is to 1) restore energy access as quickly as possible; 2) begin to build a long-term resilient and operable grid; and 3) reform a broken regulatory system. In the wake of the storm, clean energy experts and businesses saw this as the perfect opportunity to start over.
"Puerto Rico will lead the way for the new generation of clean energy infrastructure," one solar CEO asserted, " and the world will follow." Elon Musk also famously tweeted an offer to solve the island's energy problems with Tesla solar systems and batteries.
With an array of solar panels and batteries, a group of buildings, such as a hospital, or a neighborhood can power itself and operate independently in the case of an outage with the central grid—called "islanding" in industry parlance.
Provided they can be paid for and operated safely, quickly setting up these solar microgrid systems is an excellent measure that is both stopgap and long-term contributor. These systems can be set up in a matter of days, providing enough power to help neighborhoods with critical power needs, such as cellphone charging, powering cash machines and providing electricity service for health care and first responders.
However, these systems cost tens of thousands of dollars, and there is currently no substantial way to pay for them other than the kindness of strangers. Three-and-a-half million people would need perhaps 350,000 of these systems—at a price tag in the billions—to provide only a fraction of most families' power needs.
Even if costs were not a consideration, these distributed systems aren't a substitute for the grid. Many people think that microgrids don't need poles and wires, but if they serve more than one building they use pretty much the same grid as we use today.
Once the grid is rebuilt, the new grid-independent systems should then become part of a series of new community microgrids, or networks of multiple solar panel installations backed up by storage. These interconnected systems would be able to "island" together to keep the whole community running at partial if not complete levels of service. With the necessary planning and approvals, new community power organizations could be set up—perhaps separate from PREPA— to finance the conversion of local grids to a more resilient form.
So there is a path from the current grid to one that is far cleaner and more resilient, but it's not simple or quick. It would require melding complete and rapid restoration of power with a major infusion of capital.
Changing the base of generation from PREPA's aging, inefficient fleet to clean sources is an essential part of this path. However, even at an extremely fast pace, it takes months to plan the economics, financing and engineering of this transition. More commonly, it takes years and careful economic and financial planning to raise the billions of dollars of capital needed and then spend it wisely.
A Sustainable, Resilient Path Forward
Puerto Rico's citizens have endured great hardship and tragedy. We as a society certainly owe it to them to do whatever we can to lessen the damage from the next hurricane and speed power restoration. However, the path to a sustainable and resilient grid for the island is not as simple as air-dropping solar panels and other equipment onto the island and assuming all will be well. The suggestion that restoring power by replanting the current poles and wires will foreclose a more distributed solution isn't correct, nor is it the most equitable way to restore power to everyone as quickly as possible.
This isn't to say that the installation of fully independent solar systems and microgrids should be discouraged in any way. With the important provision that the hardware is maintained properly, the more solar and storage we can get onto the island sooner the better.
At this point, Puerto Rico's grid is being rebuilt essentially as it was before.
But even as the grid is rebuilt as quickly as possible, the planning and engineering should begin on how to migrate the grid to smaller sections that self-island. This must include all the main aspects of power system development and operation, including financing, ownership, operation and maintenance of the systems.
The only logical way for Puerto Rico—and every other storm-prone electric system—to become a series of resilient and clean microgrids is to first get the entire grid functioning and then to create sections that can separate themselves and operate independently when trouble hits.
Dr. Peter Fox-Penner is a Professor of Practice in the Questrom School of business and the Director of Boston University's Institute for Sustainable Energy. He thanks Scott Sklar, Phil Hanser, Sameer Reddy, Thomas McAndrew and Jennie Hatch for input. All errors are his own.
Reposted with permission from our media associate The Conversation.
The ghoulishly named ogre-faced spider can "hear" with its legs and use that ability to catch insects flying behind it, the study published in Current Biology Thursday concluded.
"Spiders are sensitive to airborne sound," Cornell professor emeritus Dr. Charles Walcott, who was not involved with the study, told the Cornell Chronicle. "That's the big message really."
The net-casting, ogre-faced spider (Deinopis spinosa) has a unique hunting strategy, as study coauthor Cornell University postdoctoral researcher Jay Stafstrom explained in a video.
They hunt only at night using a special kind of web: an A-shaped frame made from non-sticky silk that supports a fuzzy rectangle that they hold with their front forelegs and use to trap prey.
They do this in two ways. In a maneuver called a "forward strike," they pounce down on prey moving beneath them on the ground. This is enabled by their large eyes — the biggest of any spider. These eyes give them 2,000 times the night vision that we have, Science explained.
But the spiders can also perform a move called the "backward strike," Stafstrom explained, in which they reach their legs behind them and catch insects flying through the air.
"So here comes a flying bug and somehow the spider gets information on the sound direction and its distance. The spiders time the 200-millisecond leap if the fly is within its capture zone – much like an over-the-shoulder catch. The spider gets its prey. They're accurate," coauthor Ronald Hoy, the D & D Joslovitz Merksamer Professor in the Department of Neurobiology and Behavior in the College of Arts and Sciences, told the Cornell Chronicle.
What the researchers wanted to understand was how the spiders could tell what was moving behind them when they have no ears.
It isn't a question of peripheral vision. In a 2016 study, the same team blindfolded the spiders and sent them out to hunt, Science explained. This prevented the spiders from making their forward strikes, but they were still able to catch prey using the backwards strike. The researchers thought the spiders were "hearing" their prey with the sensors on the tips of their legs. All spiders have these sensors, but scientists had previously thought they were only able to detect vibrations through surfaces, not sounds in the air.
To test how well the ogre-faced spiders could actually hear, the researchers conducted a two-part experiment.
First, they inserted electrodes into removed spider legs and into the brains of intact spiders. They put the spiders and the legs into a vibration-proof booth and played sounds from two meters (approximately 6.5 feet) away. The spiders and the legs responded to sounds from 100 hertz to 10,000 hertz.
Next, they played the five sounds that had triggered the biggest response to 25 spiders in the wild and 51 spiders in the lab. More than half the spiders did the "backward strike" move when they heard sounds that have a lower frequency similar to insect wing beats. When the higher frequency sounds were played, the spiders did not move. This suggests the higher frequencies may mimic the sounds of predators like birds.
University of Cincinnati spider behavioral ecologist George Uetz told Science that the results were a "surprise" that indicated science has much to learn about spiders as a whole. Because all spiders have these receptors on their legs, it is possible that all spiders can hear. This theory was first put forward by Walcott 60 years ago, but was dismissed at the time, according to the Cornell Chronicle. But studies of other spiders have turned up further evidence since. A 2016 study found that a kind of jumping spider can pick up sonic vibrations in the air.
"We don't know diddly about spiders," Uetz told Science. "They are much more complex than people ever thought they were."
Learning more provides scientists with an opportunity to study their sensory abilities in order to improve technology like bio-sensors, directional microphones and visual processing algorithms, Stafstrom told CNN.
"The point is any understudied, underappreciated group has fascinating lives, even a yucky spider, and we can learn something from it," he told CNN.
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