British report: Use kelp to produce energy

By Ryan C. Christiansen
Web exclusive posted Oct. 31, 2008 at 9:55 a.m. CST

The brown seaweed Laminaria hyperborean, more commonly referred to as kelp, could be farmed off the coast of Scotland as biomass for the production of methane and ethanol, according to the Scottish Association for Marine Science in a report that was published for The Crown Estate, the property-holding organization for the British monarchy.

More research is needed, according to SAMS, and the organization is urging the establishment of pilot-scale farms of at least 2.5 acres in size to help scientists learn how to manage kelp farms and see how productive they might be. The estimated cost for setting up a 2.5-acre seaweed farm is $3,800, which might yield an estimated 130 wet metric tons of kelp per year.

Research has shown that chopped or ground seaweed can more effectively be used in anaerobic digesters to produce methane than terrestrial biomass, because seaweed contains no lignin and little cellulose and converts rapidly to methane with high yields, the association said. In addition, kelp contains two main sugars, mannitol and laminarn, which can be relatively easily extracted from milled seaweed for the production of ethanol.

Brown seaweed like kelp degrades more easily than green or red seaweed, according to SAMS, and the most dominant species of brown seaweed along the shores of the United Kingdom is kelp, which grows below the low-tide mark in depths of up to 66 feet of water. An extensive post-World War II survey of Britain's seaweed resources found that the majority of commercially harvestable densities of kelp are found along the coast of Scotland, mainly near the offshore islands Shetland, the Outer Hebrides, and Orkney. By a large margin, the island of Orkney has the most productive kelp forest with more than 1 million metric tons covering 56,000 acres along 500 miles of coastline. There are approximately 386 square miles of kelp forests in the waters around the U.K. that are sufficiently dense to be commercially harvested, the SAMS said.

The main benefits of farming seaweed are that agricultural land doesn't have to be switched from food to fuel production and no freshwater is needed for irrigation, the report said. Seaweed farms might also absorb some of the excess nutrient runoff from agricultural lands.

"Given Scotland's rugged western coastline and island groups, and relatively clean seas, it is sensible to examine the farming of seaweeds… as a source of energy to heat our homes and fuel our vehicles," said Mike Cowling, science and research manager at The Crown Estate. "Extracting energy from seaweed is a particularly efficient and reliable method of producing green energy, and the growing of seaweed could have positive impact on local marine biodiversity. Although more research must be done to establish the practicalities, it seems that seaweed could play an important role in providing a secure and reliable supply of green energy, particularly for coastal and island communities."