How to hurricane-proof a solar plant

CODRINGTON, Barbuda — After Hurricane Irma struck Barbuda in 2017, Lyndon Prosper stepped outside to take in the devastation. Only a few utility poles were still standing, and broken pieces of solar panels were strewn far and wide. The hurricane had devastated the Eastern Caribbean island — quite literally shattering its efforts to build a clean energy system.

When Irma made landfall, the Antigua Public Utilities Authority had been building a 1-megawatt solar PV plant, working with the government of Antigua and Barbuda and private company PV Energy. According to Prosper, the superintendent of the island’s power plants, 400 panels had been installed and another 250 were awaiting installation before they were all damaged or washed away.

Prosper had been hopeful that the plant would survive Irma, as it was being built to withstand 160 mph wind. But Irma brought sustained winds of up to 185 mph.

“The [solar modules] didn’t have brackets strong enough to withstand the amount of gale-force winds,” Prosper said.

Now nearly four years later, amid its ongoing recovery from Irma, Barbuda is once again close to completing a solar PV plant — this one built specifically to survive another storm of Irma’s intensity.

Islands across the world are making the switch to solar to save money on expensive imported generator fuel and to play a part in reducing the carbon emissions responsible for climate change.

But if these plants are going to withstand the more frequent and intense hurricanes that are also an outcome of the changing climate, engineers and contractors will have to consider hurricane resiliency throughout the design and construction process.

Green Barbuda aims to do it better

The solar plant now near completion on the island is called the Green Barbuda project. In addition to about 726 kilowatts of solar PV, the project will include a 750 kW/​900 kWh battery system and 800 kW of diesel generation capacity, according to John Caruso, project manager for Masdar, the United Arab Emirates–based renewable energy company overseeing construction.

Construction started in December 2020, and the hybrid plant is expected to begin operating later this year. The project is backed by $4 million from the United Arab Emirates Caribbean Renewable Energy Fund, with additional funding from the government of Antigua and Barbuda, the New Zealand Ministry of Foreign Affairs and Trade’s Aid Programme, and the Caricom Development Fund, which supports a group of economically cooperative Caribbean member states.

Ali Nouri is the managing director and COO of Middle East at Idsud Energies, the engineering and construction contractor on the project. He said his company simulated the high wind load of Hurricane Irma in a lab with the materials it would be using in the hybrid plant to ensure it could withstand a future hurricane of the same strength.

“All components starting from the material of the structure, which is a specific stainless steel with very high resistance to corrosion, to dimensions and number of piles, then the depth into the soil, the concrete formula…were all calculated to withstand the hurricane type of uplift winds,” Nouri said.

Lessons learned will boost the new plant’s resiliency

The Green Barbuda solar project is being built inland at one of the highest points on the island, unlike the first solar plant in the region, which was situated alongside a lagoon. That waterside location rendered the previous plant vulnerable to a saltwater storm surge that damaged equipment, according to Prosper.

The new location is ​“100% more resilient,” said Christopher Burgess, projects director for the Global South at think tank RMI. In an email, he added that ​“the power station with solar and battery is not only the most resilient option. It [is] also the cheapest, [with the] best [levelized cost of energy].”

RMI staff came to Barbuda after Irma to determine why the first plant failed and to recommend potential locations for the new plant. Barbuda wasn’t the only Caribbean island to lose a solar plant to the 2017 hurricane season. Plants in Puerto Rico and the Virgin Islands were also seriously damaged, according to RMI’s 2020 Solar Under Storm report, co-authored by Burgess. (Canary Media is an independent subsidiary of RMI.)

Burgess emphasized that the Caribbean did not experience any Category 5 hurricanes between 2007 and 2016, when the solar industry was taking off. Solar projects in the region were designed to withstand Category 3 hurricanes, which have wind speeds of up to 129 mph.

“Some islands had never even had a Category 5 hit,” Burgess said. ​“But it’s really since 2017 that these Category 5s are now the norm.”

Low tilt helps in high winds

RMI also looked at the solar plants that survived the Caribbean’s stronger recent hurricanes. That helped inform a list of best practices for ground-mounted PV systems in hurricane-prone areas.

Masdar now includes RMI’s list of best practices in its contract specifications, according to Caruso.

Commonalities in the surviving plants included solar modules that were individually bolted to racks instead of clipped and set at a low tilt of between 5 and 10 degrees.

Green Barbuda’s solar panels are being individually bolted down in eight places, rather than attached with clips that have been known to fly off in high winds and start a chain reaction of modules ripping from their frames. The project is being constructed with reinforced frames and double layers of glass. The battery and generators attached to the project are housed in a structure built with doubly reinforced columns.

The modules at the new plant are being installed at a 10-degree tilt. Pull-out tests, which simulate the wind by applying a lifting force to the structure, were performed on the modules already installed to confirm that the structure and foundation can resist the equivalent of 25,000 Newton units of uplifting force.

“Nothing moved at all, even at 35,000 Newtons,” Nouri said of the tests.

Cutting costs, cleaning up the grid and keeping the lights on

Barbuda’s grid currently runs on two diesel generators that replaced the ones damaged by Irma. The 62-square-mile island — which is now home to about 1,500 people, down from 1,800 before Irma — is wholly dependent on frequent shipments of diesel fuel.

Most small island grids run on diesel generators, Burgess said. ​“Every island is addicted to diesel and heavy fuel oil for transportation, heavy industries, cruise ships and electricity.”

The cost of shipping fuel to supply these generators makes island electricity some of the most expensive in the world. Hawaii, which has long relied on imported oil and coal for its central generators, has the highest electricity costs of any U.S. state. These cost dynamics even hold true for a grid at the much smaller scale of Barbuda’s.

Anything that enables islands to offset some of those fuel costs can dramatically improve the economics of island grids. Solar PV, which over the past decade has fallen in price to be able to compete with mainland coal and natural-gas-fired power plants on cost, certainly fits that bill.

Once Green Barbuda is up and running, it will save an estimated 92,000 gallons of diesel a year, preventing around 1,000 tons of carbon dioxide emissions annually, according to Caruso. In good weather conditions, the solar PV at Green Barbuda is expected to provide between 50% and 60% of the electricity needed to power the island in a 24-hour period, so the diesel generators will only be used for a few hours each night, Caruso said.

“It’s a moving target,” Caruso said of the percentage of power that will be supplied by solar, ​“because by the time we actually install this plant…the load for the island will have increased even further. [The load profile] is changing pretty rapidly…as more people come to the island.”

Room for growth

A plant that provides a more stable energy supply will open up opportunities for more infrastructure on the island, which in turn will likely draw more people, Caruso predicted.

Construction is already happening all over the island. Barbudans’ homes are still being rebuilt, while some residents continue living in tents. Major luxury developments are also being built, garnering a mixed response from locals, some of whom see the projects as disaster capitalism, while others see the construction projects as a way to make a living.

The new power plant’s location could accommodate an expansion in the number of solar modules if there is an increase in the electric load. There’s also room to add additional diesel generators.

Ragged Island in the Bahamas also took a direct hit from Irma, and like Barbuda, it faces logistical challenges obtaining fuels and supplies. RMI studied Ragged Island and found that a grid powered 93% by solar would be the most economical, allowing utility Bahamas Power and Light to fire up its diesel generators around 7% of the time, or just a few hundred hours a year, Burgess said.

Solar power can’t completely replace some sort of dispatchable generation, at least not with the current level of technical sophistication available to island grid operators, Burgess said. There will always be ​“cloud-covered days” with ​“too much risk and too much cost” involved in trying to rely on 100 percent solar and battery-powered microgrids, he said.

But even if fossil fuels cannot be eliminated yet, solar and batteries can play a big role in cutting costs, reducing emissions and making island grids more resilient.

A model for storm-hardened microgrids across the Caribbean

The government of Antigua and Barbuda has been interested in expanding renewable energy in Barbuda since 2016, according to Brian Challenger, chief technical adviser for the country’s Ministry of Public Utilities, Civil Aviation and Energy.

Under the Paris Agreement, Antigua and Barbuda set a goal of having 50 MW of renewable energy by 2030, conditional on funding assistance. Challenger calls the country’s renewable energy goals ​“very ambitious.”

Solar currently provides about 13% of the power on Antigua, Barbuda’s sister island, which has a much larger population of around 80,000 people, Challenger said.

Gaston Browne, the prime minister of Antigua and Barbuda, has often called on wealthier nations to assist Caribbean islands in their transition to renewable energy, pointing out that the islands are bearing the brunt of a climate crisis they are not responsible for creating. Browne told Reuters in March that the country’s transition to clean energy has been further delayed by the economic woes brought on by a pandemic that gutted its chief industry: tourism.

Island PV projects bolstered by international aid

The country applied for and received funding for the Barbuda solar facility from the United Arab Emirates Caribbean Renewable Energy Fund (UAE-CREF), which has $50 million to disperse and a goal of deploying renewable energy projects in 16 Caribbean countries. The fund was established under a partnership between the UAE Ministry of Foreign Affairs and International Cooperation, Masdar and the Abu Dhabi Fund for Development.

Projects that have benefited from the fund have been undertaken in the Bahamas, Barbados, and St. Vincent and the Grenadines. On Union Island in the Grenadines, Masdar has built a 600 kW solar PV plant connected to a 637 kWh lithium battery, which together meet 100% of the island’s daytime power needs. It’s Masdar’s first fully implemented grid-connected battery energy storage system, according to the company’s website.

UAE-CREF is also funding a project with similarities to Green Barbuda in Belize: a hybrid solar PV-diesel plant equipped with energy storage.

Challenger sees the plant on Barbuda as a model for other small islands and communities as they look to transition to renewable energy.

But to be a successful model in the long term, the facility will have to withstand the more destructive hurricanes of the future. The plant has been designed and tested to weather another Irma, but as hurricanes get stronger, ​“at a certain point we cannot expect [and design for] something that has never happened,” Nouri said.

Ultimately, a hurricane-proof plant ​“is not designable,” according to Masdar’s Caruso. ​“But within the limits that are reachable, we have put a lot of measures into the design of the plant itself and the selection of the site” to make the plant hurricane-resilient.

(Lead image courtesy of Masdar)