ANOTHER LIFE:
GALES DELIVERED fresh sea-rods to
the tide-line, the long, toffee-coloured furls of Laminaria torn up
from mini-forests offshore, writes
Michael Viney.
Once a random harvest gathered by hand for distant factories, most of this slippery flotsam is now left to disintegrate into shingle or sand, food for the organisms of low-nutrient shores and their winter flocks of wading birds. It is also a reminder that about 10 million tonnes of kelp seaweeds flourish as an unseen fringe to Ireland's rocky coasts and reefs - to some minds, a rich potential source of biofuel.
The stems and long blades or fingers of kelp are high in carbohydrates - chemical energy conjured through photosynthesis, drawing in carbon from ocean and atmosphere. It supports the seaweed's structural growth, like the cellulose in plants ashore. And like sugar cane, corn stalks, wheat or miscanthus grass, kelp can be processed into bio-ethanol for engine fuel. So also could other brown seaweeds, such as the bladderwrack Ascophyllum nodosum, long harvested in bulk for alginates from the rocky shores of Connemara.
"Considering the negative stories surrounding the use of food crops to produce these green fuels," wrote Dr Stefan Kraan in Inshore Ireland last month, "algae might be an excellent green sustainable alternative." As manager of the Irish Seaweed Centre at NUI Galway, he was promoting the first International Conference on Applied Phycology to be held in Ireland (in June), and its keynote address by an Australian expert, Prof Michael Borowitzka: Algae and biofuels: Quo vadis? Algae, in this context, can be microscopic, but it was Dr Kraan who mentioned the 10 million tonnes of kelp. Exploiting kelp for energy is by no means a new idea. During the oil crisis of the 1970s, the US government supported a $20 million project to develop ocean farms of California's giant kelp, Macrocystis, as biomass for generating natural gas.
The first farm, of about three hectares, was anchored some 12m below the surface with stainless steel cables and concrete blocks. It had an artificial bottom of polypropylene ropes into which the claw-like holdfasts of the kelp were sown (seaweed doesn't have roots). The idea was to feed the plants with nutrient-rich water pumped up from the depths and contained by a curtain around each farm.
Three pilot farms were torn apart by winds and waves before oil got cheap again and funding dried up. The biggest lesson, apart from those for marine engineers, was the need to study kelp's adaptation to particular wave regimes and temperatures.
Laminaria farming inshore, on ropes suspended from rafts, to supply industrial chemicals and food supplements, is long established in China and Japan.
There are new Japanese proposals for giant nets, 10sq km, growing more modest seaweeds - the Zostera seagrass and fast-growing Sargassum muticum (this now an invasive alien in Ireland) - as moppers-up of carbon and a source of biomass energy. Other farming ideas include genetic modification of giant kelp to grow bigger and stronger in the open ocean.
How much harvesting of Ireland's resident kelp would be sustainable? The plant grows a whole new blade each year, while the old one fragments into particles that help nourish the ocean food chain. Up to 60 per cent of the carbon in coastal invertebrates - molluscs, worms, and so on - can be traced to kelp photosynthesis. Kelp "forests" are shelters and nursery grounds for a host of ocean species and a vital brake on the power of storm waves as they surge in to sandy shores.
Highly regulated mechanical harvesting for alginates is already part of the Marine Institute's big ambitions for the seaweed industry. But its own review of kelp has urged "a precautionary approach" that respects the seaweed's ecological importance, and the institute is pledging to work with the National Parks and Wildlife Service in shaping harvesting management plans. Some 90 or so Irish bays and coasts already protected as Special Areas of Conservation include many rich in kelp that will certainly need to be left alone.
Meanwhile, algae does not have to be big to offer a potential biofuel. The microscopic single cells of some ocean plant-plankton species and others among the green micro-algae of freshwater ponds store carbon as natural oil as well as in carbohydrates. In the right conditions of sunshine and nourishment, they can produce 30 times the amount of oil per square metre yielded by terrestrial oilseed crops. Their potential for producing biodiesel, perhaps subsidised by carbon credits, is attracting intense research and investment.
Artificially-nourished freshwater ponds are currently the favourite idea. One elegant notion is to feed CO2 from the flue-stacks of coal-fired power stations into the pondwater. Peat-fired power stations feeding their carbon to ponds in the neighbouring cutaway bogs might prompt a comparable line of inquiry.