Microgrids: a Lifeline for Islands

Islands have been deemed the victims of climate change. But they’re now flipping the script and finding solutions that can be scaled globally through microgrids powered by renewable energy.

by Laurie Stone
February 2020

When Hurricanes Irma and Maria tore through the Caribbean in 2017, they left millions without power. This had deadly consequences: critical medical equipment couldn’t operate, hospitals were unable to refrigerate medicine, water treatment plants couldn’t treat water or pump water to homes, and some houses reached unsafe temperatures.

One reason so many people lose power in a natural disaster is due to the centralized grid. Relying on centralized infrastructure means that a power plant failure (as happened during the recent earthquakes in Puerto Rico) or downed transmission lines (as happened during Hurricane Maria in Puerto Rico) can lead to an entire island going dark, including critical services. Even if these critical services have diesel or gasoline generators for back-up power, they can run out of fuel a week or even a few days after a storm.

Another challenge for islands is that they rely on imported fuel, delivered in oil tankers, to supply their centralized power plants. Any disruption in the supply of that fuel can lead to devastating consequences for island residents. Fortunately, there is a solution that more islands are turning to in order to increase the resiliency of their electric systems—microgrids powered by renewable energy.

Renewable energy microgrids—small power systems that use local power such as solar and wind along with battery storage to meet local electricity needs—are often connected to the larger grid, and have an option to disconnect and become an electrical island. Thus, when centralized generation goes down, the microgrid can keep running, providing critical electricity during hurricanes or other disruptions. Other microgrids might not interact with the larger grid at all, but instead operate as completely separate electricity systems.

As more islands around the world turn to microgrids, they’re flipping the script, says Justin Locke, senior director of RMI’s Empowering Clean Economies program. “Islands have been deemed the victims of climate change. But by switching from a dirty imported fuel and centralized generation to clean local resources and distributed energy, they’re finding solutions to the world’s problems and showing the world what is possible.”

“Islands have been deemed the victims of climate change, but they’re flipping the script, finding solutions to the world’s problems and showing the world what is possible.”

Caribbean Microgrids Surviving the Storms

Ragged Island, a small island in the southern Bahamas, was rendered unlivable after Hurricane Irma in 2017. It is now close to commissioning The Bahamas’ first renewable energy microgrid. The 390 kilowatt (kW) solar microgrid with 3,000 kWh of battery storage, which will be completed and operation in April, will displace about 90 percent of the diesel fuel that is used to generate power for the 100 residents of the island. The microgrid is also designed to withstand 180 mph winds. Christopher Burgess, projects director for Rocky Mountain Institute’s (RMI’s) Islands Energy Program, believes this microgrid is extremely important to help eliminate economic reservations and demystify solar-plus-storage microgrids in the Caribbean. “It’s a little scary for utilities and governments who have only known centralized diesel generation to do something completely different,” he said. Operating solar and battery storage as the primary source of generation has a learning curve for utilities, but one that pays off quickly. Bahamas Power and Light (BPL), which operates on 21 islands in The Bahamas, will cut their operational costs by 70 percent on Ragged Island and are assured of their power source immediately after the next storm.

Another renewable microgrid is soon to power the small island of Mayreau in the Grenadines, which bills itself as one of the most pristine and private places on the planet. Yet the approximately 300 residents of the island have been completely dependent on imported diesel for their electricity. The island is now testing and commissioning a 100 kW solar microgrid with 216 kWh of battery storage, which will silence the diesel generators for 6 to 10 hours per day.

And on the Dutch island of St. Eustatius in the northeastern Caribbean, the 4 megawatt (MW) solar microgrid and 5.3 MWh of battery storage kept the island electrified after Hurricane Irma. The microgrid provides power for the 4,000 residents until about 7 p.m. when the diesel-fuel powered plant switches on. Besides making the island more resilient in the face of hurricanes, the microgrid is saving money for the utility, which had previously been losing $2 million each year.

Keeping the Lights on in Puerto Rico

Currently there might be no islands more motivated to switch to microgrids than those in Puerto Rico. In May 2018, the main island’s energy regulator, the Puerto Rico Energy Bureau, issued the world’s first microgrid regulations. The rules establish three classes of microgrids: personal microgrids, which provide power to one or two consumers with the ability to provide excess energy to neighboring customers; cooperative microgrids, serving three or more cooperative members with the ability to sell excess energy to others; and third-party microgrids, which have owners or operators who sell energy to customers under rates approved by the Puerto Rico Energy Bureau.

And Puerto Rico Electric Power Authority’s (PREPA’s) latest Integrated Resource Plan is focused on transitioning away from centralized power to distributed generation, including the installation of 1.4 GW of solar and 920 MW of battery storage by 2022—more than three times the capacity of battery storage deployed in the United States in 2018. This transition has already started, as hundreds of microgrids are now being installed on the island.

It is no surprise that Puerto Rico is turning to renewable energy microgrids, as the islands’ electricity system was devastated by Hurricane Maria in 2017. More than 1.5 million customers lost power, some for almost a year. With the lack of electricity in schools, many children could not go to class for months. In order to help schools and communities become more resilient in the event of future natural disasters, RMI, Save the Children, and the Kinesis Foundation installed solar microgrids on 10 schools located in the mountainous regions of the island.

The systems were designed to run the critical loads at the schools such as the refrigerators and freezers that students rely on for their meals, and computers and internet for essential communications. Besides allowing the more than 3,600 children at these schools to remain in classes during a power outage, the schools can become community resilience hubs and hurricane shelters. “Community members can come to these centers during a power outage and communicate with their loved ones,” says Ana Sophia Mifsud, a senior associate at RMI who provided technical assistance along with partners to the installation of the Puerto Rico microgrids.

“Besides allowing the more than 3,600 children at these schools to remain in classes during a power outage, the schools can become community resilience hubs.”

The average size of the school systems is 27 kW of solar and 32 kWh of battery storage, and they all have remote monitoring systems. During last month’s earthquakes, the monitoring systems showed the power going off when the first earthquake hit, and then the batteries kicking in, ensuring the lights stayed on and no food was wasted during the grid outages.

These microgrids can also be used as more than just back-up power. “Right now, because of regulatory constraints and the way the utility is being restructured, the batteries are fancy back-up generators,” adds Mifsud. “But they don’t have to be. There is a future in which the utility leverages the assets that are already stored in their grid before they start procuring more assets and duplicate what they already have.” In other words, the batteries and excess solar energy become a utility asset simultaneously.

For example, the utility can use the batteries in the microgrid systems to shave down peak demand. And schools are just the beginning. Although the school systems were grant funded, the RMI team is looking to expand this initiative to support many of the 23,000 identified critical facilities in Puerto Rico through innovative financing mechanisms.

Battery Storage and Sophisticated Controls Are Game Changers

The 2017 hurricane season may have put a spotlight on microgrids, but it’s not the only reason that so many island nations are now turning to microgrids. “The least-cost approach to generating electricity on islands has historically been scale, which meant a large centralized power plant with transmission lines to distribute that electricity over long distances,” says Burgess. That’s no longer the case. “You can now get solar power at the same cost or cheaper than business as usual,” he adds. “Add in distribution costs and rebuilding transmission lines every five years or so due to hurricanes, and solar plus storage comes in a lot cheaper.”

“Lithium-ion battery storage has dropped in price over 60 percent over the last two years,” says Justin Locke, senior director of RMI’s Empowering Clean Economies program. “This makes the combination of renewable energy and battery storage much more competitive with traditional fossil fuel generation. And islands are where these technologies are being tested and deployed today.”

Another reason microgrids make so much sense today are the sophisticated controls available. These can make microgrids more than just back-up power in case the grid goes down. “Throughout the Caribbean there are millions of dollars in diesel gensets that sit behind hospitals, cell towers, and schools, collecting dust waiting for the grid to go down,” explains Burgess. “If we couple those diesel gensets with solar-plus-storage microgrids, they can be everyday resources for the grid.”

That means, the microgrid can be both a power battery and an energy source. During normal operation it is a power battery for the utility, storing and supplying electricity in nanoseconds when needed. Then when the grid goes down, it becomes an energy source providing critical electricity locally (to schools, hospitals, water treatment plants, airports, seaports, communications facilities, etc.). And with the controls available today, that transition can be completely seamless.

Beyond Resilience

While keeping the lights on and the water pumps running after a natural disaster are important reasons to install microgrids powered by renewables, they are not the only reasons. Keeping customers on-line means revenue. “When the electric grid went down after Hurricane Maria, PREPA didn’t get a dollar in the door for months and didn’t get close to its normal revenue for a year,” says Burgess. Solar microgrids could have kept the meters spinning and the utility from losing millions of dollars in revenue.

Other islands are taking note. For example, a 3 MW solar farm installed in 2018 in Saint Lucia is providing power at US$0.10/kWh, which made a lot of sense for the bottom line of the Saint Lucia utility, St. Lucia Electricity Services Limited (LUCELEC). However, that utility is now adding battery storage to turn it into a microgrid, so that when high winds take the transmission lines down, the customers in that area, which include the Hewanorra International airport, won’t lose power and LUCELEC won’t lose critical revenue.

In some island nations, installing a microgrid powered by renewables makes economic sense from the very beginning. One of the major factors for the microgrid on Ragged Island in The Bahamas was operating cost. The island is so isolated that getting fuel there comes with an exorbitant price tag. Providing more than 90 percent of the island’s electricity with renewables (only 7 percent of the electricity demand will be supplied by diesel) turned out to be the least-cost option.

Microgrids are also often locally controlled, which can potentially decrease the cost of providing electricity and reduce the amount of time to restore power after an outage. They also lower operating costs by displacing high-cost grid power, particularly when the sun is shining. But perhaps more importantly, they can be a benefit to economic development. “Resiliency has many dimensions,” says Agustín Irizarry Rivera, a professor of electrical engineering at the University of Puerto Rico Mayagüez who has extensively studied Puerto Rico’s electricity network and microgrid alternatives. He argues that having solar microgrids power grocery stores, bakeries, and other businesses that serve the community is extremely important. “A move toward community microgrids would be more than a technical solution—it would be a socioeconomic development strategy,” he says. “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.”

“A move toward community microgrids would be more than a technical solution—it would be a socioeconomic development strategy.”

Irizarry Rivera’s team at the university installed five small microgrids in mountainous regions of Puerto Rico where the electrical grid was down for more than five months. These systems provided resiliency in the form of hope. “People told us they were brought some hope seeing a place where they could store their medicine and charge their phones,” Irizarry Rivera explains. “While some forms of resiliency you can measure very well, others are not as measurable, but very human.”

A Model for the World

While it’s true that islands have found themselves at ground zero for climate change, they are also at ground zero to help move forward the global energy transition. Although new technologies and other innovations have often come from large industrialized countries, island nations now have a chance to lead and advance crucial solutions. Islands are demonstrating that an economy can go from a centralized electricity system based on dirty polluting fuel, to a distributed system based on clean local sources. And that it is not only technically possible, but economically feasible as well.

As Locke puts it, “Islands, whether they like it or not, will provide the blueprint for how an economy transitions from an economic, regulatory, financial, and technical perspective, and provide insights for what a global energy transition will look like at scale.”