Renewable Gas : Scenes From The Very Near Future

The Future Phycological

A future system of near-shore, open water seaweed colonies are developed for the supply of biofuels, foods and human vitamins and minerals.

Scene : The North Sea

Season : Autumn

Scale : 5 to 10 years from now

The sun is melting and dropping slowly towards the horizon. The colours of day and the open sea are darkening; but there are globes of lime and peachy yellow light still visible on the surface of the water, all around, bobbing slightly up and down. They mark the gradually mutating locations of the seaweed balloon nets, billowing just underneath the metallic surface of the gently rocking slight ocean waves.

Little boats are still clustered around the field of lights, where workers in flotation jackets are still mending, monitoring, seeding seaweed spores and harvesting; but will soon be chugging towards the coast, powered by macro-algal oil, a very low carbon biofuel, made mostly from seaweed.

We are quite far north, and the days are short here, but the sea is rich in nutrients, so that algae, microalgae and macroalgae grow well. Since the early days of the mega-phycofarm project, a massive stock of a rich variety of well-adapted lifeforms has accumulated in and around the balloon nets, and it is more-or-less self-sustaining, given the regimes of nutrient distribution and net maintenance.

This style of alga-dominated biome is not entirely novel on planet Earth, and, relatively early in their development, with the full lifecycle of the macroalgae established, a net flow of carbon was shown to be transferring to the seabed, for permanent sequestration into submarine rock-forming systems.

A portion of the carbon dioxide that is fixed by the algal communities and the hosted co-species in their mixed communities is harvested and recycled into fuels, but this is compensated for by the other services that the seaweed-and-friends biosystems offer : seawater is filtered of dangerous environmental metals; excess agricultural run-off becomes macroalgal nutrition, reducing dangerous microalgal blooms and algal infestation of waterways; more fish and other seafood species – including seaweed – are supported and then farmed for human food, vitamins and minerals; and top waters are more well-oxygenated, meaning that other kinds of aquaculture are enhanced besides the seaweed.

From a vantage point beneath the water line, the permanent balloon nets look a lot like hot air balloons in shape, huge inverted baskets, especially when fully seeded with macroalgae and hosting other species, rising and bulging out from the mooring ropes that stretch down into the deep dark, and weighed down at regular intervals around the edge by anchors on the seabed that stabilise them.

As a rule, the balloon nets do not drift far, and only migrate significantly when violent storms cause currents that can shift the anchors laterally, carving channels in the floor of the ocean. On average, the balloon nets do not relocate into the deep sea, or get stranded close to shore. At times, the nets need to be pulled mechanically to better locations, and this is done by submersibles that haul the anchors.

The churning of the anchors dredges up debris from the seabed, and re-circulates nutrients up to the seaweed-supported biocommunity in the balloon net. Many species of coral that were becoming heat-stressed elsewhere in the world have been introduced to the drifting zones of the seaweed nets; the occasional scraping of the sea floor creates areas suitable for colonisation, and supplies of nutrients, and reefs have become well-established. Even though the Great Barrier Reef was not saved, it has been reborn here between Scotland and Norway.

Baby seaweeds are cultivated in carefully-controlled warehouses onshore in bio farms near the coast, at ports or jetties where boats can moor. The machines feed and nurture the seaweed all day and all night, and when the phycobabies are ready, they are encouraged to attach themselves to specially-designed twine, which is slowly pulled through the warm baby baths. The twine ropes are made of extraordinary industrially-manufactured seawater-resistant polymers, with embedded slow-release nutrients, which can deliver just the right levels and kinds of nutrition to growing macroalgae. The cables need to be supple enough to be knotted and tied, but strong enough to be storm-resistant.

All of these polymers are made from biomass, but they are novel in the environment, and will remain undegraded for decades. Eventually, bacteria will evolve that can eat through this twine, so new polymers will need to be developed in time.

Although this part of the process for raising new seaweed and implanting them into cables is entirely automated, bedding and replacing of impregnated twines in the balloon nets is largely a manual operation done in situ by seaweed farmers. Harvesting, in particular, requires a lot of manual labour. It would be difficult to crop these dynamic, living systems efficiently and non-destructively using sea tractors. The work is not intensive, but takes commitment and knowledge. Seaweed farmers normally work out at sea for around six months of the year, especially in the peak and optimum months for seeding baby seaweed. During the more unproductive months, they will be involved in biofuel and biogas manufacture and distribution; and the production of seaweed-based food and nutrient products.

Because some of the mega seaweed farms are close to major shipping lanes, the project development managers needed to build in a design for lighting for the balloon nets that would enable passive proximity warning and support collision avoidance. The top of the balloon nets have solar lighting bars and poles that reach above the water. This has had a quadruple benefit : the lights with in-built GPS beacons indicate to the seaweed farmers where the balloon nets have migrated to; the lights and beacons prevent destruction of nets and deter boats; the surface lights enable workers to extend their productive hours; and the extra light after dark enables increased growth of target species. The lights have to be sealed against that salt water and so the solar system is entirely isolated, and is an integral part of the balloon net ocean replenishment system.

Down in the blue-green depths, under the protection of the balloon nets, and around its edges, there rises a tall forestscape of kelp, and other seaweed species, and hiding and grazing amongst their fronds, extending up and down, is a range of sea creatures, in a diverse community. Besides feeders on the seaweed, there are some ruinous predators, and there is a delicate balance to be maintained between the growth of the alga and the elimination of such things as molluscs.

The density of the seaweed helps to extend the oxygen-rich zone, which permits communities of oxygen-loving plants and fish to extend further down into the water column than would normally be possible. There is a certain lack of energy at depth, because the sunlight does not reach this far down, but the high oxygen levels, and the artificial light reaching through from the surface, compensate for this in some respects.

The development of the balloon nets took many decades, including the time taken to perfect the design and the twine, and the time it took for algal communities to physically establish themselves. But looking at these systems of sea community closely you can see that they have a strong resilience, as they are patterned on evolved Nature.