Sustainable solutions from the sea?

George Guo-Qiang Chen and Shrikumar Suryanarayan look to the planet’s oceans to provide the resources to produce and process the large quantities of biomass that will be needed for a sustainable future

Industrial applications of biotechnology – the new “Bioeconomy” – hold out the promise of being able to produce biofuels and renewable chemicals and provide an alternative for society’s chronic addiction to goods that are produced using the finite supplies of petroleum and fossil fuel feedstocks. “Biorefining” is based on using biomass as its basic feedstock. Biomass is a renewable resource produced by agriculture. However, the scale on which such biomass will need to be produced and used to effectively begin to replace petroleum-based feedstocks will start to rival the current scale of agriculture for food and feed – and therein lies the problem.

There have been impressive demonstrations of the possibilities of “biorefining” technology – whether it is the conversion of a variety of sugars derived from woody biomass to advanced biofuels or production of renewable bioplastics from corn. Some of these products are already commercial. The mantra for the scientists working in this area is “sugar is the “new oil” – the sugar being derived from the breakdown of biomass.

The ingredients to produce biomass are, of course, the same as that for agriculture – i.e. land, fresh water and fertilizer. Some countries have an abundance of land per capita and are also blessed with water for irrigation. Brazil is one such country and has become a leader in biofuels. Other countries are not so lucky. India, for instance, has the lowest amount of land per capita among the large economies (not least because of its huge population, which it has to feed) and it also happens to have a scarcity of fresh water. The United States has adequate land and adequate water and could be a leader in biofuels (though the advent of cheap shale gas has diminished this urgency somewhat).

Fresh water is needed not only to produce the biomass; it is also needed in large quantities during the conversion process of the biomass. When ethanol (a renewable biofuel) is produced by fermentation, typically there are nine litres of water at the end of fermentation for every one litre of ethanol that is produced. This ratio is even more for advanced biofuels, such as butanol, given their lower solubility in water. It is expensive to treat and recycle these waste waters from fermentation processes.

Would it not then make sense to look at the planet’s oceans to provide the resources to produce and process the large quantities of biomass that will be needed for a sustainable future?

It turns out that it is, indeed, scientifically possible. Seaweed (or seaplants or macroalgae) thrive in saltwater. The oceans have an entire ecosystem of micro-organisms well adapted to growing in saltwater and capable of converting the marine biomass into useful products. The techniques of modern biology that have so successfully been applied to terrestrial microbes and plants could easily be applied to marine microbes.

The engineering challenges of operating and carrying out cultivation of seaplants in an ocean environment have already been overcome in other disciplines, such as offshore oil exploration or offshore wind energy generation. Materials are already available that can deal with seawater for extended periods of time with minimal corrosion – one needs to look at the desalination plants that are already in operation in several parts of the world.

All of this can become a reality in the not too distant future, but the urgency with which different countries pursue such solutions will depend on their local imperatives and how they perceive the criticality of their own future energy supplies.

Authors: George Guo-Qiang Chen is Professor of Microbiology and Biomaterials at Tsinghua University Beijing and a member of the World Economic Forum Global Agenda Council on Biotechnology. Shrikumar Suryanarayan is Chairman of Sea6 Energy, India and a member of the World Economic Forum Global Agenda Council on Biotechnology

Image: A family plays on a beach in California REUTERS/Mike Blake