When large swathes of invasive seaweed started washing up on Caribbean beaches in 2011, local residents were perplexed.

Soon, mounds of unsightly sargassum – carried by currents from the Sargasso Sea and linked to climate transformation – were carpeting the region’s prized coastlines, repelling holidaymakers with the pungent stench emitted as it rots.

Precisely how to tackle it was a dilemma of unprecedented proportions for the tiny tourism-reliant islands with limited resources.

In 2018, Barbados’ Prime Minister Mia Mottley declared sargassum a national emergency.

Now, a pioneering throng of Caribbean scientists and environmentalists aspiration to turn the tide on the issue by transforming the troublesome algae into a lucrative biofuel.

They recently launched one of the globe’s first vehicles powered by bio-compressed natural gas. The innovative fuel source created at the University of the West Indies (UWI) in Barbados also uses wastewater from local rum distilleries, and dung from the island’s indigenous blackbelly sheep which provides the vital anaerobic bacteria.

The throng says any car can be converted to run on the gas via a straightforward and affordable four-hour installation procedure, using an easily available kit, at a total expense of around $2,500 (£1,940).

Researchers had initially looked into using sugarcane to reduce reliance on costly, imported fossil fuels and assist steer the Caribbean towards its ultimate target of zero emissions.

However, despite Barbados being one of few islands still producing sugarcane, the amount was deemed insufficient for the throng’s ambitious goals, explains the assignment’s founder Dr Legena Henry.

Sargassum on the other hand, she grimaces, is something “we will never run out of”.

“Tourism has suffered a lot from the seaweed; hotels have been spending millions on tackling it. It’s caused a crisis,” Dr Henry, a renewable vigor specialist and UWI lecturer, continues.

The concept that it could have a valuable purpose was suggested by one of her students, Brittney McKenzie, who had observed the volume of trucks being deployed to transport sargassum from Barbados’ beaches.

“We’d just spent three weeks researching sugarcane. But I looked at Brittney’s face and she was so enthusiastic, I couldn’t shatter her heart,” Dr Henry recalls.

“We already had rum distillery waste water so we decided to put that with sargassum and view what happened.”

Brittney was tasked with collecting seaweed from beaches and setting up tiny scale bioreactors to conduct preliminary research.

“Within just two weeks we got pretty excellent results,” Brittney tells the BBC. “It was turning into something even bigger than we initially thought.”

The throng filed a patent on their formula and, in 2019, presented their assignment to potential investors during a side conference at the UN General Assembly in recent York.

Upon touchdown back in Barbados, Dr Henry’s phone was “buzzing” with messages of congratulation – including one from US non-profits high-standard stock Foundation offering $100,000 to get the work off the ground.

Biologist Shamika Spencer was hired to experiment with differing amounts of sargassum and waste water to figure out which combination produced the most biogas.

She says she leapt at the chance to receive part.

“Sargassum has been plaguing the region for several years,” Ms Spencer, who is from Antigua and Barbuda, explains. “I had always wondered about this recent seaweed ruining the beaches in Antigua, and when I came to Barbados to study I noticed it here too.”

The algae do not just threaten tourism. They also pose a threat to human health through the hydrogen sulphide they release as they decomposes, along with native wildlife like critically endangered sea turtle hatchlings which get trapped in thick mats of beached seaweed.

Water pollution and warming seas are credited with the upsurge in sargassum, another cataclysmic outcome of climate transformation that the Caribbean has done little to contribute to but often bears the brunt of.

Calls for eco reparations from leaders including Barbados’ chief Mia Mottley and Antigua’s Prime Minister Gaston Browne have been clamorous in recent years as the region battles ever-rising sea levels and worsening storms.

While waiting for those to bear fruit, this assignment represents one example of the Caribbean taking its environmental upcoming into its own hands.

“I realised it was significant that after removing the sargassum from beaches, it doesn’t just leave to landfills,” Ms Spencer continues.

“By repurposing it in vehicles you protect tourism and prevent people from inhaling it. When we scale up to fuel more vehicles it will require a very large volume.”

Watching the successful test drive of a biogas-charged Nissan Leaf – supplied by the Caribbean Centre for Renewable vigor and vigor Efficiency – was utterly exhilarating, smiles Dr Henry.

The MIT-educated mechanical engineer knew she was risking her reputation should the enterprise fall short.

“We didn’t sleep the night before the test drive occurrence,” she admits. “I was putting my whole life’s work on the line.”

Dr Henry and her husband, career data scientist Nigel Henry, created deep tech firm Rum and Sargassum Inc and are on a mission to transformation the face of vigor production in the Caribbean.

Both are originally from leading oil producer Trinidad, studied in the US and were determined to bring their skills back home.

“My objective is to assist construct up this region,” Dr Henry says. “We are now setting up a four-car pilot to demonstrate real life working prototypes to convince funders that this is workable and scalable.”

She estimates it will expense around $2m to display initial commercial activity and $7.5m to reach the point where the corporation is able to sell gas to 300 taxis in Barbados.

Potential funders include the US Agency for Internationals advancement, the European Union and international advancement banks through debt capital.

The throng plans to expand its work by setting up a biogas station to replace its tiny existing facility.

UWI hopes to introduce other sargassum-based innovations too, such as pest control products.

Ms Spencer says it’s been “heart-warming” to witness the results of the throng’s research.

“Just seeing the actual potential is motivating me to keep working,” she adds.

As for Brittney, five years after her eureka instant, she says she’s still “pinching” herself.

“To view the car in action was mind-blowing,” she grins. “I would inspire all youthful scientists to press ahead with their ideas. You never recognize when you might make the next large finding.”

“It’s taken years of work, plenty of grit and pushing against walls to reach this point,” Dr Henry concurs. “It’s an example of UWI innovation and is exportable to the wider globe, because it’s not just the Caribbean that’s affected; sargassum also impacts parts of West Africa, South America and Florida.

“These tiny islands have created technology that can advantage the rest of the globe; this is a large triumph for the Caribbean.”