The glorious beaches of the Caribbean are losing their appeal as fertilizer runoff fuels a seaweed explosion. A cheap way of turning this material to biofuel could restore the tourism industry, help power the islands in a carbon-neutral manner, save some rainforests on the other side of the world, and slightly reduce the ocean's build-up of plastic.
So many biofuels either destroy forests or contribute to world hunger that their reputation has gone sour. Nevertheless, fuels made from algae, whether macroalgae (seaweed) or the microscopic version, don't face these problems and could fill niches other renewable forms of energy can't.
Professor Mike Allen of the University of Exeter has announced a method for processing seaweed to facilitate biofuel production in the Journal of Chemical Technology and Biotechnology. The technique could be applied to farmed algae, but Allen sees a chance to solve other environmental problems at the same time.
Allen has found a set of catalysts that release the seaweed's sugars, while also preparing what is left for subsequent processing. When fed to yeast, the sugars produce a substitute for palm oil (meaning less rainforest clearance), while the remaining algae can be turned into fuel and a fertilizer that won't produce as much of the run-off that causes the problem in the first place.
Excess fertilizer washed into rivers and eventually the sea is fueling algal growth. As well as posing one more threat to coral reefs, this leads to more seaweed washing up on beaches. Besides spoiling the view and swimming experience, there is the rotting smell after high tides. The Caribbean, with an economy built on tourism and fertilizer-bearing rivers on three sides, is particularly affected by the foul-smelling Sargassum seaweed.
Although not a panacea, the project is about turning a problem into a resource, and the team found they could do the same thing with the salt that has previously needed to be removed at great expense lest the containers where the processing is done corrode. “For the first time this study demonstrates that, rather than a hindrance, the presence of saltwater can be helpful,” said University of Bath PhD student and first author Ed Jones.
“Ultimately, for this to work it has to make financial sense,” Allen said in a statement. “Processing marine biomass like seaweed usually requires removing it from the salt water, washing it in fresh water and drying it. The costs of these processes can be prohibitively high.”
Allen enrolled his children in the research by having them collect seaweed for his studies. Allen's 12-year-old daughter Rosie noticed increasing quantities of plastic caught up in the collection. Frustrated by removing it, she asked: “Dad, can't you just convert the plastics alongside the seaweed?” The comment inspired Allen to prove this is possible last year, and he is now expanding the range of plastics that can be converted to fuel without requiring separation from the organic material.