The sun has set in Adjuntas, and the loud mating calls of the coquí frogs reverberate through the town’s narrow streets. In the distance, on the central mountain range that’s earned the town the nickname “the city of the sleeping giant,” its eyes are already indistinguishable.

José Alfaro, on the rooftop of a small building behind Casa Pueblo’s colonial-style headquarters, is having trouble starting a generator. The professor at the University of Michigan School for Environment and Sustainability and his students look worried.

A student feeds pellets made of agricultural waste such as coffee husks into a silver machine made of two big drums connected by a snaking steel pipe. The machine, a biomass reactor, gasifies agricultural waste into a transparent, carbon-neutral gas called ‘syngas’ that in turn should power the generator.

After fiddling around with the older generator, it sputters, springs to life, stalls and rumbles again. The group cheers, relieved.

“Adjuntas will have a microgrid and biomass. That is just one part of what’s happening, but it’s an important part,” Alfaro said. “The goal is to have the whole system running by the end of the summer.”

The stakes are high for this U-M team that traveled 2,000 miles from Ann Arbor to Adjuntas. In collaboration with the local nonprofit Casa Pueblo, they hope to bring energy independence to “The City of the Sleeping Giant.” Retrofitting the generator and setting up the gasifier is one of the key components in a project they will introduce to the community the following day.

The generator was being hooked up to Casa Pueblo’s existing 13kW solar microgrid that already feeds its radio station, movie theater and environmental school. Once it is fully functioning, the generator will add 7-10kW to the microgrid and will serve as a prototype and research and education tool for the community.

It also might be used to test a new massive microgrid Casa Pueblo is installing this summer.

For Adjuntas’ residents—close to 20,000, including neighboring towns—new power sources can’t come fast enough. In September 2017, Hurricane Maria left most of the island in the dark. When a team from U-M visited in 2018, many businesses and homes still had no reliable power. In January, a 6.4-magnitude earthquake severely damaged Costa Sur, one of Puerto Rico’s largest power plants, located on the island’s south side. The disaster left two-thirds of the utility’s clients without power for weeks.

“It is an emergency because of the vulnerability to climate change we have in the mountains in Puerto Rico,” said Arturo Massol-Deyá, Casa Pueblo’s executive director.
“We have an aspiration that the right to clean energy be for everyone. On that route to use our own resources, such as the sun, we also need to diversify the solar microgrid to give it strength. Biomass is an option with a lot of potential.”

Embracing an expanding project

The gasifier installation marks the culmination of the second phase of the project, which launched after Hurricane Maria devastated the island in September 2017. At the time, SEAS professor Ivette Perfecto and John Vandermeer, professor of ecology and evolutionary biology, were looking for ways to help Casa Pueblo. The nonprofit was running several renewable energy projects in the region.

As Perfecto looked for broader solutions, Alfaro came to her with an idea: How about using the biomass—the broken trees and coffee husks left over from the agricultural process—as fuel? And what if the leftover product could in turn be used as fertilizer, closing the agricultural circle?

In 2018, with seed funds from SEAS and a $200,000 grant from U-M’s Graham Sustainability Institute, Alfaro and Perfecto decided to find out. Alfaro oversaw the gasifier and energy production; Perfecto and Vandermeer would lead agricultural research in collaboration with Universidad de Puerto Rico, Utuado. That year, a U-M group traveled to Utuado, 66 miles from San Juan and 13 miles from Adjuntas, to build and test a gasifier prototype, pelletizing biomass and testing soil (check out that story).

Back in Ann Arbor, Alfaro spent the next year building two more gasifiers, including the one destined for Casa Pueblo in Adjuntas in 2020.

Building capacity one gasifier at the time

SEAS graduate student Julia Magee, who has a bachelor’s degree in materials science and engineering from Cornell University, was curious to see how renewable energy projects could work in a decentralized environment. She joined the U-M program after talking to Michelle Farhat, one of the students who built the first prototype in Utuado in 2018.

Magee soon was in charge of getting the gasifier to work as it should and studying the composition of the gas it produced. She worked with Alfaro to modify the gasifier before shipping it to Adjuntas and helped build the second one, which is still in Ann Arbor.

“I had a degree in engineering, but I didn’t feel like I knew how to build anything with my hands,” Magee said. “I had to take classes at Maker Works, a local makerspace, on welding and plasma cutting and angle grinding. I never imagined I’d be gaining those types of skills. It was really exciting to actually fix some things and work on electronics.”

Building the gasifier units from scratch was a logical financial step to ensure they were cost-effective and affordable. A commercial gasifier costs around $70,000, compared to the $20,000 in materials and shipping for the one now sitting atop Casa Pueblo.

“We wanted to make sure that the students learned how to build one. We’re training them to do everything from wire connections to welding to design,” Alfaro said. “This is an opportunity to transfer the knowledge to the community and I know that if I can build a gasifier, I can teach people how to build one as well.”

Mapping a solar town

About a year ago, Casa Pueblo announced it would be working with the Honnold Foundation and the electric car company Rivian to power the entire business district in downtown Adjuntas.

Taking existing data and gathering their own, SEAS graduate students Muzna Raheel and Stephen ‘Simi’ Barr, began energy modeling. They looked at Casa Pueblo’s existing microgrid, modifying and optimizing different scenarios to meet the changing energy demands.For their modeling, the students used HOMER, a software developed by the National Renewable Energy Laboratory in the U.S. that became the commercial standard for microgrid design. HOMER allows researchers to compare and evaluate multiple options. They also used a software called HelioScope to examine solar roof options.

In Adjuntas last week, they measured rooftops and inventoried solar panels with the help of drone footage.

“We had to come up with an [energy] mix to make the model feasible and for it to meet the commercial demand in Adjuntas,” Raheel said. “We included that software with solar panels, with the wiring, inverters, shadow analysis. And we ran a few scenarios which included full-sized bio gasifiers, solar panels, the solar panel on top of Casa Pueblo and batteries.”

They presented their findings to Massol-Deyá, who will work with Alfaro and community business owners to determine the appropriate final scenario.

Barr had always been interested in climate modeling since starting his degree in climate and space sciences and engineering at U-M’s College of Engineering. But he realized he wanted not only to model but to find solutions to sustainability and climate change issues.

“Informing the problem by gathering more data and making our climate models better is important and necessary and interesting, but it just wasn’t exactly what I wanted to do,” Barr said. “So I added on the dual degree at SEAS and started working a lot more on the sustainability side of things.”

“I found it interesting and technically challenging and it allowed me to grow. At SEAS, you can have a direct impact in a community like this. We get to work on all these models that are sort of the background of what’s being done. And it was really great getting that face time and meeting the stakeholders here.”

For Raheel, an international student from Pakistan, studying in Michigan but being able to work in Puerto Rico helped with her interest in working with different communities and cultures.

In addition to the cold, studying in Ann Arbor meant learning to navigate cultural norms, language issues and even basic things like those from colder climates take for granted: What kind of clothes to buy for Michigan weather? After spending a week in Puerto Rico, Raheel said she looks forward to looking at working opportunities in the U.S. and abroad, and called for new students to get out of their comfort zones.

“I think the most experience in renewable energy I would get is in the United States, but if I get a job in Africa or Asia, I would definitely go just for the experience of the culture,” she said. “As for Puerto Rico … the culture, I really enjoyed it. It reminded me of home.

“And to other students: Don’t restrict yourselves to Ann Arbor or the United States. There’s a whole lot of opportunities all over the world and a whole lot of interactions with different cultures, languages and foods. Do not restrict yourselves. Take your chance. You can do it.”

Closing the circular economy

Casa Pueblo’s research coffee farm is a 15-minute uphill drive into the mountains. It’s also where the solar-powered radio station antenna is located. The five-acre plot is where master’s student Juan Jhong Chung and research lab associate Koralis Reyes started an experiment last summer to study whether the biochar, the gasifier byproduct, can help improve plant productivity. Jhong Chung also spent last summer measuring how much biomass—all agricultural waste such as tree branches and coffee husks—could be available to feed the gasifier.

The farm is one of two locations where biochar experiments are taking place, Jhong Chung said. Originally from Ica, Peru, he spent seven years in Boston as a software engineer before joining the SEAS program.

“I decided to come to SEAS to change careers because I really wanted to put together my passion for technology with my passion for the environment,” he said. “This project definitely helped me a lot, to grow not only as a student but as a person.

I had to meet with community members, farmers, University of Puerto Rico students, basically with a whole ecosystem of collaborators trying to have an impact in their community. This experience taught me a lot as a student and helped me grow as a leader. I was in Utuado for three months having to figure out things on my own whenever something needed to get done for the project.”

At the farm, the team has set up six stations, each with coffee saplings planted with different mixes of soil, compost and biochar. Every two weeks, they measure the plant’s height, the thickness of its stem and the number of its leaves. So far, the plants that have been fed biochar are growing faster than the ones without the biochar.

“We’re trying to use the agricultural waste to produce energy, and then use that biochar to improve farming,” said Reyes, the research assistant who works in Puerto Rico. “This closes the circular economy and helps us take advantage of the natural resources we have at hand.”

Sharing progress with the Adjuntas community

The morning after their successful trial, the U-M team heads to elementary school Escuela Domingo Massol in the Vacas Saltillo neighborhood, about four miles from Adjuntas. Casa Pueblo representatives, school officials, parents and neighbors have gathered to introduce the school’s new solar panels and refrigerators for its cafeteria.

The Casa Pueblo choir sings “En mi Viejo San Juan” (In my Old San Juan), one of the island’s most popular songs, composed by Puerto Rican singer Noel Estrada. Sitting on the ground, about 50 students wearing blue tops sing the revised lyrics “in my solar school.”

“We are very thankful for this project,” said school director Ángel Ortiz Marrero. “We’re very happy we’re Casa Pueblo’s first solar school.”

School cafeteria worker Sandra Ortiz agreed.

“We are always losing power, and sometimes spend up to two weeks without electricity,” she said. “Now, we’ll be able to have the food refrigerated, and with this system we’ll be able to have all the energy we need in the school.”

After the event, which included a performance by the New York City Labor Chorus, media and Casa Pueblo officials return to downtown Adjuntas, where Alfaro shows off the gasifier, explaining how it works and what researchers hope it will accomplish in the community.

“This type of project is why I left industry and returned to academia. We are impacting communities directly and in the areas where they need it,” Alfaro said. “In the process, we are training our students to do the same when they graduate and they get engaged learning they can’t get anywhere on campus.

“Most importantly, we didn’t come and ‘parachute’ in with solutions. We came in alongside what Casa Pueblo is doing and together we worked out how to support each other. I love the idea of supporting Casa Pueblo’s energy insurrection.”

In the background, the sun hits Adjuntas’ sleeping giant, which now sparkles with life.

Note from the editor: As with many other University of Michigan projects, this project has been put on hold due to coronavirus. Any updates will be posted.