Tag Archives: energy/policy

The Predictable Pandemic: Whose Risk, Whose Responsibility?

Post Syndicated from Robert Charette original https://spectrum.ieee.org/riskfactor/energy/policy/the-predictable-pandemic-whose-risk-whose-responsibility

The United States finds itself once more confronting a major public health disaster, albeit this time on a scale not experienced since the flu pandemic of 1918. The obvious lack of preparedness on the part of government in regard to the availability of testing kits, personal protective gear and ventilators, as well as the decision-making process underpinning quarantine protocols and the financial stimulus package, will guarantee fueling Congressional inquiries well into the future. And, if history is any guide, the manufacturing and distribution of any COVID-19 vaccine that is created will be a topic of discussion too. The big question will be why the spending of billions of dollars by the Federal government on pandemic planning over the past 15 years has little to show for it despite previous lessons learned.

Predictably, the inquiries will be framed as they were after the bungled government response to Hurricane Katrina in 2005, which focused on the question, “How could this have happened in America, and what must our government do to make sure to the best of our ability that nothing like this national nightmare ever happens again?” The foregone conclusion will be the same, i.e., “All levels of government failed in their obligations.” The inquiries will fail—again—to probe and answer the more fundamental set of questions that need asking if we are to mitigate future crises: What are the government’s, and the American people’s, respective roles and responsibilities in the face of disaster?

Indeed, so predictable is this turn of events that—with some substitutions to match the current crisis—that what follows below is substantially an identical argument to the one I made in April 2006 for IEEE Spectrum following Katrina, and which warned of future events like pandemics. 

For example, what is the obligation of government—local, state, and federal—to manage its citizens’ risk? Can the government protect its citizens from all their risks, and even if it can, should it? What are U.S. citizens’ expectations regarding personal choice in management of their risk? What is the nation’s risk appetite and risk tolerance? How much risk management is enough? What are the responsibilities of corporations as well as individuals to make preparations? Without addressing these and similar questions, we are likely to end up with more poorly conceived, contradictory and costly strategies that will only increase risk.

A particularly contentious issue has been the lack of intensive care unit (ICU) ventilators available for hospitals. Governors, mayors and other locally elected officials have criticized the Federal government for not having enough ventilators in the Strategic National Stockpile to support the COVID-19 patients in their states’ hospital ICUs. However, the potential lack of ventilators in the event of a national pandemic was fully understood by state health preparedness officials prior to the pandemic.

For instance, in November 2015, New York State Commissioner of Health released its updated ventilator allocation guidelines (PDF) originally released in 2007 which “develop guidance on how to ethically allocate limited resources (i.e., ventilators) during a severe influenza pandemic while saving the most lives.” The guidelines explicitly make it clear that in a severe pandemic, “many more patients will require the use of ventilators than can be accommodated with current supplies.” The guidelines further state that even if New York were to purchase the “vast number” of ventilators needed, a “sufficient number of trained staff would not be available to operate them.”

In the introduction to the guidelines, the Commissioner with obvious pride notes, “The first Guidelines were widely cited and followed by other states. We expect these revised Guidelines to have a similar effect.” Other states who don’t use New York’s guidelines have similar ones of their own.

Given this widespread acknowledgement and acceptance that ICU ventilators and trained personnel would be in short supply in a severe pandemic, state politicians’ feigned surprise and anger over shortages are mere deflections for their own failure to have a robust public discussion about their government’s role, and capability, to manage their state’s citizens’ risk in a pandemic before it occurred. If New York State residents knew, for example, that its public officials were not going to purchase adequate number of ventilators in case of a pandemic, would they have objected and insisted that they should be? Unfortunately, they never were asked.

Similarly, what is the responsibility of the American people to manage their own risks? The Centers for Disease Control and Prevention (CDC) has repeatedly published and widely advertised preparedness guidelines [PDF] for the American people to follow in the case of a severe pandemic. The guidelines recommend that households buy and store two-weeks’ supplies of food, water, medicine, face masks and other essentials. Yet, how many families followed these recommendations? (A related question regards how much thought was given to households without the resources or space to accumulate such a cache, particularly in pandemic-prone high-density cities like New York, where housing costs are burdensome and apartments small.)

In both cases, the risk and resources needed to prepare for a pandemic was traded-off against other competing risks, both short-term and long term. While many American households may not have the means to prepare for a pandemic as the CDC recommended, the paucity of ventilators in event of a pandemic was a risk accepted by state government officials with eyes wide-open.

There has been a growing expectation among the American people, as well as state and local governments, that the Federal government be the risk manager of first resort in every crisis. However, there are limits to what any government can realistically accomplish, given the sheer number of disasters possible. Can the government protect all citizens from the effects of pandemics, floods, fires, hurricanes, tornadoes and earthquakes, as well as human follies like oil spills or financial mismanagement?  

If the American people desire the Federal government to be their risk manager of first resort, then there must be an open and honest discussion to decide what its risk management priorities should be. Then allocate tax dollars to mitigate those risks as opposed to others. The government must draw a bright line demarcating which risks it will try to anticipate and act to prevent, and which risks it can only react to. For these latter cases, the government must forcefully convey what it can and cannot reasonably do, and just as forcefully formulate what it expects its citizens to do. Then no one will be under the illusion that the government can control risks that it cannot, nor guarantee a risk-free life where it will make every person “whole” after disasters occur.

A friend of mine who was recovering from his second heart attack remarked to me that his first heart attack got his attention, while the second kept it. Perhaps, after suffering yet another government risk mismanagement heart attack, we can finally have a national debate on the roles, responsibilities, and expectations of government and its citizens in terms of managing risk—and decide which risks and responsibilities are whose. If we don’t, the next heart attack may be the one that kills us.

Energy Research User Handbook

Post Syndicated from IEEE Spectrum Recent Content full text original https://spectrum.ieee.org/whitepaper/energy_research_user_handbook

Energy User Research Handbook

Abstract: This book includes a select set of examples curated to show how researchers and industrial partners are changing the way we produce and consume energy. See what is possible when leveraging the NI platform.

Featured in Handbook:

  • Renewables
  • Nuclear
  • Condition Monitoring
  • Fusion
  • Tidal
  • Wind
  • Photovoltaics

South Sudan Is Building Its Electric Grid Virtually From Scratch

Post Syndicated from Maria Gallucci original https://spectrum.ieee.org/energywise/energy/policy/south-sudan-rebuilding-grid-from-scratch

As South Sudan emerges from the wreckage of civil war, its leaders are beginning to build the nation’s electric sector from the ground up. With only a handful of oil-fired power plants and crumbling poles and wires in place, the country is striving for a system that runs primarily on renewable energy and reaches more homes and businesses. 

Today, only about 1 percent of South Sudan’s 12.5 million people can access the electric grid, according to the state-run utility. Many people use rooftop solar arrays or noisy, polluting diesel generators to keep the lights on; still many more are left in the dark. Those who can access the grid must pay some of the highest electricity rates in the world for a spotty and unreliable service.

Electricity: It’s Wonderfully Affordable, But it’s No Longer Getting Any Cheaper

Post Syndicated from Vaclav Smil original https://spectrum.ieee.org/energy/policy/electricity-its-wonderfully-affordable-but-its-no-longer-getting-any-cheaper

The generations-old trend toward lower electricity prices now appears to have ended. In many affluent countries, prices tilted upward at the turn of the century, and they continue to rise, even after adjusting for inflation.

Even so, the price we pay for electricity is an extraordinary bargain, and that’s why this form of power has become ubiquitous in the modern world. When expressed in constant 2019 dollars, the average price of electricity in the United States fell from $4.79 per kilowatt-hour in 1902 (the first year for which the national mean is available) to 32 cents in 1950. The price had dropped to 10 cents by 2000, and in late 2019 it was just marginally higher, at about 11 cents per kilowatt-hour. This represents a relative decline of more than 97 percent. A dollar now buys nearly 44 times as much electricity as it did in 1902.

Because average inflation-adjusted manufacturing wages have quadrupled since 1902, blue-collar households now find electricity about 175 times as affordable as it was nearly 120 years ago. And it gets better: We buy electricity in order to convert it into light, kinetic energy, or heat, and the improved efficiency of such conversions have made the end uses of electricity an even greater bargain.

Lighting offers the most impressive gain: In 1902, a lightbulb with a tantalum filament produced 7 lumens per watt; in 2019 a dimmable LED light delivered 89 lm/W (see “Luminous Efficacy,” IEEE Spectrum, April 2019). That means a lumen of electric light is now three orders of magnitude (approximately 2,220 times) more affordable for a working-class household than it was in the early 20th century. Lower but still impressive reductions in end-use costs apply in the case of electric motors that run kitchen appliances and force hot air into the ducts to heat houses using natural-gas furnaces.

An international perspective shows some surprising differences. The United States has cheaper residential electricity than other affluent nations, with the exception of Canada and Norway, which derive high shares of their power from hydroelectric generation (60 percent and 95 percent, respectively).

When using prevailing exchange rates, the U.S. residential price is about 45 percent of the European Union’s mean, about half the Japanese average, and about a third of the German rate. Electricity prices in India, Mexico, Turkey, and South Africa are lower than in the United States in terms of the official exchange rates, but they are considerably higher in terms of purchasing power parity—more than twice the U.S. level in India and nearly three times as much in Turkey.

A naive observer, reading the reports of falling prices for photovoltaic cells and wind turbines, might conclude that the rising shares of solar and wind power will bring a new era of falling electricity prices. Just the opposite has been true.

Before the year 2000, when Germany embarked on its large-scale and expensive Energiewende (energy transition), that country’s residential electricity prices were low and declining, bottoming at less than €0.14/kWh ($.13/kWh, using the prevailing exchange rate) in 2000.

By 2015, Germany’s combined solar and wind capacity of nearly 84 gigawatts had surpassed the total installed in fossil-fueled plants, and by March 2019 more than 20 percent of all electricity came from the new renewables. However, over an 18-year period (2000 to 2018) electricity prices more than doubled, to €0.31/ kWh. The E.U.’s largest economy thus has the continent’s highest electricity prices, followed by heavily wind-dependent Denmark, at €0.3/kWh.

A similar contrast can be seen in the United States. In California, where the new renewables have taken an increasing share, electricity prices have been rising five times as fast as the national mean and are now nearly 60 percent higher than the countrywide average.

This article appears in the February 2020 print issue as “Electricity Prices: A Changing Bargain.”

How to Harden Puerto Rico’s Grid Against Hurricanes

Post Syndicated from Efraín O’Neill-Carrillo original https://spectrum.ieee.org/energy/policy/how-to-harden-puerto-ricos-grid-against-hurricanes

Another devastating hurricane season winds down in the Caribbean. As in previous years, we are left with haunting images of entire neighborhoods flattened, flooded streets, and ruined communities. This time it was the Bahamas, where damage was estimated at US $7 billion and at least 50 people were confirmed dead, with the possibility of many more fatalities yet to be discovered.

A little over two years ago, even greater devastation was wreaked upon Puerto Rico. The back-to-back calamity of Hurricanes Irma and Maria killed nearly 3,000 people and triggered the longest blackout in U.S. history. All 1.5 million customers of the Puerto Rico Electric Power Authority lost power. Thanks to heroic efforts by emergency utility crews, about 95 percent of customers had their service restored after about 6 months. But the remaining 5 percent—representing some 250,000 people—had to wait nearly a year.

After the hurricanes, many observers were stunned by the ravages to Puerto Rico’s centralized power grid: Twenty-five percent of the island’s electric transmission towers were severely damaged, as were 40 percent of the 334 substations. Power lines all over the island were downed, including the critical north-south transmission lines that cross the island’s mountainous interior and move electricity generated by large power plants on Puerto Rico’s south shore to the more populated north.

In the weeks and months following the hurricane, many of the 3.3 million inhabitants of Puerto Rico, who are all U.S. citizens, were forced to rely on noisy, noxious diesel- or gasoline-fired generators. The generators were expensive to operate, and people had to wait in long lines just to get enough fuel to last a few hours. Government emergency services were slow to reach people, and many residents found assistance instead from within their own communities, from family and friends.

The two of us weren’t surprised that the hurricane caused such intense and long-lasting havoc. For more than 20 years, our group at the University of Puerto Rico Mayagüez has studied Puerto Rico’s vulnerable electricity network and considered alternatives that would better serve the island’s communities.

Hurricanes are a fact of life in the Caribbean. Preparing for natural disaster is what any responsible government should do. And yet, even before the storm, we had become increasingly concerned at how the Puerto Rico Electric Power Authority, or PREPA, had bowed to partisan politics and allowed the island’s electrical infrastructure to fall into disrepair. Worse, PREPA, a once well-regarded public power company, chose not to invest in new technology and organizational innovations that would have made the grid more durable, efficient, and sustainable.

In our research, we’ve tried to answer such questions as these: What would it take to make the island’s electricity network more resilient in the face of a natural disaster? Would a more decentralized system provide better service than the single central grid and large fossil-fuel power plants that Puerto Rico now relies on? Hurricane Maria turned our academic questions into a huge, open-air experiment that included millions of unwilling subjects—ourselves included. [For more on our experiences during the storm, see “For Two Power Grid Experts, Hurricane Maria Became a Huge Experiment.”]

As Puerto Rico rebuilds, there is an extraordinary opportunity to rethink the island’s power grid and move toward a flexible, robust system capable of withstanding punishing storms. Based on our years of study and analysis, we have devised a comprehensive plan for such a grid, one that would be much better suited to the conditions and risks faced by island populations. This grid would rely heavily on microgrids, distributed solar photovoltaics, and battery storage to give utilities and residents much greater resilience than could ever be achieved with a conventional grid. We are confident our ideas could benefit island communities in any part of the world marked by powerful storms and other unpredictable threats.

As is typical throughout the world, Puerto Rico designed its electricity infrastructure around large power plants that feed into an interconnected network of high-voltage transmission lines and lower-voltage distribution lines. When this system was built, large-scale energy storage was very limited. So then, as now, the grid’s control systems had to constantly match generation with demand at all times while maintaining a desired voltage and frequency across the network. About 70 percent of Puerto Rico’s fossil-fuel generation is located along the island’s south coast, while 70 percent of the demand is concentrated in the north, which necessitated building transmission lines across the tropical mountainous interior.

The hurricane vividly exposed the system’s vulnerability. Officials finally acknowledged that it made no sense for a heavily populated island sitting squarely in the Caribbean’s hurricane zone to rely on a centralized infrastructure that was developed for continent-wide systems, and based on technology, assumptions, and economics from the last century. After Maria, many electricity experts called for Puerto Rico to move toward a more decentralized grid.

It was a bittersweet moment for us, because we’d been saying the same thing for more than a decade. Back in 2008, for instance, our group at the university assessed the potential for renewable energy [PDF] on the island. We looked at biomass, microhydropower, ocean, photovoltaics (PV), solar thermal, wind, and fuel cells. Of these, rooftop PV stood out. We estimated that equipping about two-thirds of residential roofs with photovoltaics would be enough to meet the total daytime peak demand—about 3 gigawatts—for the entire island.

To be sure, interconnecting so much distributed energy generation to the power grid would be an enormous challenge, as we stated in the report. However, in the 11 years since that study, PV technology—as well as energy storage, PV inverters, and control software—has gotten much better and less costly. Now, more than ever, distributed-solar PV is the way to go for Puerto Rico.

Sadly, though, renewable energy did not take off in Puerto Rico. Right before Maria, renewable sources were supplying just 2.4 percent of the island’s electricity, from a combination of rooftop PV, several onshore wind and solar-power farms, and a few small outdated hydropower plants.

Progress has been hamstrung by PREPA. The utility was founded as a government corporation in 1941 to interconnect the existing isolated electric systems and achieve islandwide electrification at a reasonable cost. By the early 1970s, it had succeeded.

Meanwhile, generous tax incentives had induced many large companies to locate their factories and other facilities in Puerto Rico. The utility relied heavily on those large customers, which paid on time and helped finance PREPA’s infrastructure improvements. But in the late 1990s, a change in U.S. tax code led to the departure of nearly 60 percent of PREPA’s industrial clients. To close the gap between its revenues and operating costs, PREPA periodically issued new municipal bonds. It wasn’t enough. The utility’s operating and management practices failed to adapt to the new reality of more environmental controls, the rise of renewable energy, and demands for better customer service. Having accumulated $9 billion in debt, PREPA filed for bankruptcy in July 2017.

Then the hurricane struck. After the debris was cleared came the recognition—finally—that the technological options for supplying electricity have multiplied. For starters, distributed energy resources like rooftop PV and battery storage are now economically competitive with grid power in Puerto Rico. Over the last 10 years, the residential retail price of electricity has fluctuated between 20 and 27 U.S. cents per kilowatt-hour; for comparison, the average price in the rest of the United States is about 13 cents per kWh. When you factor in the additional rate increases that will be needed to service PREPA’s debt, the price will eventually exceed 30 cents per kWh. That’s more than the levelized cost of electricity (LCOE) from a rooftop PV system plus battery storage, at 24 to 29 cents per kWh, depending on financing and battery type. And if these solar-plus-storage systems were purchased in bulk, the LCOE would be even less.

Also, the technology now exists to match supply and demand locally, by using energy storage and by selectively lowering demand through improved efficiency, conservation, and demand-response actions. We have new control and communications systems that allow these distributed energy resources to be interconnected into a community network capable of meeting the electricity needs of a village or neighborhood.

Such a system is called a community microgrid. It is basically a small electrical network that connects electricity consumers—for example, dozens or hundreds of homes—with one or more sources of electricity, such as solar panels, along with inverters, control electronics, and some energy storage. In the event of an outage, disconnect switches enable this small grid to be quickly isolated from the larger grid that surrounds it or from neighboring microgrids, as the case may be.

Here’s how Puerto Rico’s grid could be refashioned from the bottom up. In each community microgrid, users would collectively install enough solar panels to satisfy local demand. These distributed resources and the related loads would be connected to one another and also tied to the main grid.

Over time, community microgrids could interconnect to form a regional grid. Eventually, Puerto Rico’s single centralized power grid could even be replaced by interconnecting regional grids and community microgrids. If a storm or some other calamity threatens one or more microgrids, neighboring ones could disconnect and operate independently. Studies of how grids are affected by storms have repeatedly shown that a large percentage of power outages are caused by relatively tiny areas of grid damage. So the ability to quickly isolate the areas of damage, as a system of microgrids is able to do, can be enormously beneficial in coping with storms. The upshot is that an interconnection of microgrids would be far more resilient and reliable than Puerto Rico’s current grid and also more sustainable and economical.

Could such a model actually work in Puerto Rico? It certainly could. Starting in 2009, our research group developed a model for a microgrid that would serve a typical community in Puerto Rico. In the latest version, the overall microgrid serves 700 houses, divided into 70 groups of 10 houses. Each of these groups is connected to its own distribution transformer, which serves as the connection point to the rest of the community microgrid. All of the transformers are connected by 4.16-kilovolt lines in a radial network. [See diagram, “A Grid of Microgrids.”]

Each group within the community microgrid would be equipped with solar panels, inverters, batteries, control and communications systems, and protective devices. For the 10 homes in each group, there would be an aggregate PV supply of 10 to 20 kW, or 1 to 2 kW per house. The aggregate battery storage per group is 128 kWh, which is enough to get the homes through most nights without requiring power from the larger grid. (The amounts of storage and supply in our model are based on measurements of energy demand and variations in solar irradiance in an actual Puerto Rican town; obviously, they could be scaled up or down, according to local needs.)

In our tests, we assume that each community microgrid remains connected to the central grid (or rather, a new and improved version of Puerto Rico’s central grid) under normal conditions but also manages its own energy resources. We also assume that individual households and businesses have taken significant steps to improve their energy conservation and efficiency—through the use of higher-efficiency appliances, for instance. Electricity demand must still be balanced with generation, but that balancing is made easier due to the presence of battery storage.

That capability means the microgrids in our model can make use of demand response, a technique that enables customers to cut their electricity consumption by a predefined amount during times of peak usage or crisis. In exchange for cutting demand, the customer receives preferential rates, and the central grid benefits by limiting its peak demand. Many utilities around the world now use some form of demand response to reduce their reliance on fast-starting generating facilities, typically fired by natural gas, that provide additional capacity at times of peak demand. PREPA’s antiquated grid, however, isn’t yet set up for demand response.

During any disruption that knocks out all or part of the central grid, our model’s community microgrids would disconnect from the main grid. In this “islanded” mode, the local community would continue to receive electricity from the batteries and solar panels for essential loads, such as refrigeration. Like demand response, this capability would be built into and managed by the communications and control systems. Such technology exists, but not yet in Puerto Rico.

Besides the modeling and simulation, our research group has been working with several communities in Puerto Rico that are interested in developing local microgrids and distributed-energy resources. We have helped one community secure funding to install ten 2-kW rooftop PV systems, which they eventually hope to connect into a community microgrid based on our design.

Other communities in central Puerto Rico have installed similar systems since the hurricane. The largest of these consists of 28 small PV systems in Toro Negro, a town in the municipality of Ciales. Most are rooftop PV systems serving a single household, but a few serve two or three houses, which share the resources.

Another project at the University of Puerto Rico Mayagüez built five stand-alone PV kiosks, which were deployed in rural locations that had no electricity for months after Maria. University staff, students, and faculty all contributed to this effort. The kiosks address the simple fact that rural and otherwise isolated communities are usually the last to be reconnected to the power grid after blackouts caused by natural disasters.

Taking this idea one step further, a member of our group, Marcel J. Castro-Sitiriche, recently proposed that the 200,000 households that were the last to be reconnected to the grid following the hurricane should receive rooftop PV and battery storage systems, to be paid for out of grid-reconstruction funds. If those households had had such systems and thus been able to weather the storm with no interruption in service, the blackout would have lasted for 6 months instead of a year. The cost of materials and installation for a 2-kW PV system with 10 kWh of batteries comes to about $7,000, assuming $3 per watt for the PV systems and $100/kWh for lead-acid batteries. Many households and small businesses spent nearly that much on diesel fuel to power generators during the months they had no grid connection.

To outfit all 200,000 of those households would come to $1.4 billion, a sizable sum. But it’s just a fraction of what the Puerto Rico government has proposed spending on an enhanced central grid. Rather than merely rebuilding PREPA’s grid, Castro-Sitiriche argues, the government should focus its attention on protecting those most vulnerable to any future natural disaster.

As engineers, we’re of course interested in the details of distributed-energy resources and microgrid technology. But our fieldwork has taught us the importance of considering the social implications and the end users.

One big advantage of the distributed-microgrid approach is that it’s centered on Puerto Rico’s most reliable social structures: families, friends, and local community. When all else failed after Hurricane Maria, those were the networks that rose to the many challenges Puerto Ricans faced. We think it makes sense to build a resilient electricity grid around this key resource. With proper training, local residents and businesspeople could learn to operate and maintain their community microgrid.

A move toward community microgrids would be more than a technical solution—it would be a socioeconomic development strategy. That’s because a greater reliance on distributed energy would favor small and medium-size businesses, which tend to invest in their communities, pay taxes locally, and generate jobs.

There is a precedent for this model: Over 200 communities in Puerto Rico extract and treat their own potable water, through arrangements known as acueductos comunitarios, or community aqueducts. A key component to this arrangement is having a solid governance agreement among community members. Our social-science colleagues at the university have studied how community aqueducts are managed, and from them we have learned some best practices that have influenced the design of our community microgrid concept. Perhaps most important is that the community agrees to manage electricity demand in a flexible way. This can help minimize the amount of battery storage needed and therefore the overall cost of the microgrid.

During outages and emergencies, for instance, when the microgrid is running in islanded mode, users would be expected to be conservative and flexible about their electricity usage. They might have to agree to run their washing machines only on sunny days. For less conscientious users, sensors monitoring their energy usage could trigger a signal to their cellphones, reminding them to curtail their consumption. That strategy has already been successfully implemented as part of demand-response programs elsewhere in the world.

Readers living in the mainland United States or Western Europe, accustomed to reliable, round-the-clock electricity, might consider such measures highly inconvenient. But the residents of Puerto Rico, we believe, would be more accepting. Overnight, we went from being a fully electrified, modern society to having no electricity at all. The memory is still raw. A community microgrid that compels people to occasionally cut their electricity consumption and to take greater responsibility over the local electricity infrastructure would be far more preferable.

This model is applicable beyond Puerto Rico—it could benefit other islands in the tropics and subtropics, as well as polar regions and other areas that have weak or no grid connections. For those locales, it no longer makes sense to invest millions or billions of dollars to extend and maintain a centralized electric system. Thanks to the advance of solar, power electronics, control, and energy-storage technologies, community-based, distributed-energy initiatives are already challenging the dominant centralized energy model in many parts of the world. More than two years after Hurricane Maria, it’s finally time for Puerto Rico to see the light.

About the Authors

Efraín O’Neill-Carrillo and Agustín Irizarry-Rivera are professors of electrical engineering at the University of Puerto Rico Mayagüez.