Sea lettuce could make an ideal future biofuel
THEY have tried raking it away, dumping it, throwing it on crops and in some cases even eating it...
But now experts are claiming that the annual ‘plague’ of slimy green sea lettuce in St Aubin’s Bay could actually become a blessing in disguise – in the form of a source of renewable energy for Jersey.
A government report published today on seaweed harvesting and aquaculture has highlighted that the ulva species, which is usually abundant in Jersey each summer, is one of the best candidates for producing renewable biofuels that are developed from plants.
Research across different countries has assessed the potential use of different seaweeds for the purpose because they would have the advantage of providing eco-friendly biofuel, without taking up agricultural land that is used to grow food.
‘This form of fuel production is still in its research phase. Significant investments are being made into the development of this technology in the UK, Ireland and Norway as well as in Japan, China and the USA,’ the report says.
‘This is driven by international climate and emissions targets as well as by a desire to avoid putting agricultural land into fuel production and therefore reducing food output.’
It adds that several species that grow in Jersey could be used to develop biofuels, most notably the now infamous sea lettuce, which, due to its high levels of sugar, could be used to produce both liquid bioethanol and biogas.
‘Commercial bioenergy production is not yet close to deployment at a scale and price suitable for Jersey,’ the report adds, however.
‘Research is ongoing and while, under laboratory conditions, good yields have been achieved the challenge of replicating these on a continuing basis in an industrial setting is significant.
‘Considering also the costs of farming, collection, drying and mixing with terrestrial waste as a purely financial proposal there are significant challenges to overcome.
‘However, if the clearing of Ulva from St Aubin’s Bay is seen as a requirement for Jersey in the future then the feed costs of an anaerobic digestion or bioethanol plant are reduced to some degree.’
The report says that trials in Japan have discovered that sea lettuce is one of the easiest seaweeds to break down to produce biofuels, and this can be done by storing it at a temperature of 4°C for a month.
And it adds that mixing bio-digested Ulva with cattle slurry in a 25% to 75% ratio could produce an ‘optimum mix’ for producing methane biogas.
The report says that the timeframe for this would probably be at least ten years from now, with the first biofuel usage in larger jurisdictions – such as Scotland, Ireland and Norway – at least more than four years away.
Recently, Environment Minister John Young lodged proposals to update Jersey’s seaweed-harvesting regulations, which at present technically restrict collection to between February and April.
The new regime, which, subject to States approval, should come into force this autumn, would provide a bag limit for personal and commercial harvesting and allow year-round collection.
Francis Binney, of the Marine Resources Department, said that it was hoped that the new regime would allow seaweed-harvesting businesses to flourish.
‘There are businesses that were uncomfortable about operating outside the law, so having this in place will hopefully now make them grow and develop,’ he said.
He added that sea lettuce and storm-cast weed, which is used to fertilise potato crops, would be exempt from the regulations due to their abundance in the Island.
Getting rid of the sea lettuce – what has been tried so far?
- Composting it. This year the Growth, Infrastructure and Environment Department has been trialling converting it into compost by mixing it with other green waste at its La Collette facility. The lettuce has been collected using lorries with specialised rakes.
- Dumping it. Last year about 70 tonnes of sea lettuce was collected and dumped four miles offshore by the Normandy Trader – a freight boat owned by the Jersey Oyster Company – in time for the Battle of Flowers.
- Eating it. In 2015 Joe Baugh, head chef at the Hampshire Hotel, suggested an innovative way of addressing the sea lettuce issue – human consumption. Mr Baugh created a series of dishes using the highly abundant weed.