Fuels from the Sea: Micro-Algae and Macro-Algae

Marine ecosystems are an untapped resource that account for over 50% of global biomass and seaweeds themselves are capable of producing more biomass per square metre than fast growing terrestrial plants such as sugar cane. _Daisy Brickhill

On the micro-algae front, scientists from the U. of Western Ontario have discovered a way to increase the growth of algae by almost a factor of 4. They did this using magnetic fields!

Wankei Wan, a professor of biochemical engineering at the University of Western Ontario, thinks he's found a potentially significant way to stimulate algae growth.

Wan and a team of research students built a small raceway pond - a tabletop pond shaped like a racetrack, that is - and began growing a common type of single-celled algae called Chlorella kessleri.

They measured the pace of algae growth and oil production. They then changed the set-up such that the algae in the pond were circulated through an area exposed to static magnetic fields.

What they observed, which is described in an upcoming research paper, surprised them.

The magnetic field exposure “almost quadrupled the biomass and lipid (oil) production rate in raceway ponds,” according to the paper.

Wan's team also noticed the magnetically stimulated algae produced dramatically more antioxidants, such as Astaxanthin - often used as a food supplement.

In an interview, Wan said the algae behaved differently depending on the strength of the magnetic fields and length of exposure to them. The researchers noticed that growth would increased steadily as field strength grew. Then, once peak growth was reached, there would be a steep decline.

This suggested to Wan that there is a “sweet spot,” that might vary depending on the type of algae being grown. _CheckBiotech

On the macro-algae front, scientists at Aberystwyth University have found that kelp contains higher levels of carbohydrate at the peak of summer. They suggest that this may be the best time to harvest kelp for biofuels production.

Collecting monthly samples of kelp from the Welsh coast researchers used chemical analysis to assess the seasonal variability. Their results, which will be presented at the Society for Experimental Biology Annual Conference in Glasgow on the 4th of July, showed that the best month for biofuel harvest was in July when the kelp contained the highest proportions of carbohydrate and the lowest metal content.

Kelp can be converted to biofuels in different ways including fermentation or anaerobic digestion producing ethanol and methane or pyrolysis, (a method of heating the fuel without oxygen) which produces bio-oil. The chemical composition of the seaweed is important to both of these processes.

Research into biofuels has focused on terrestrial plants; however these have the serious drawback of the conflict between using land to grow food or fuel. Marine ecosystems are an untapped resource that account for over 50% of global biomass and seaweeds themselves are capable of producing more biomass per square metre than fast growing terrestrial plants such as sugar cane. _DaisyBrickhill

The assumption of the researchers is that the kelp will be used in the fermentation of ethanol or anaerobic fermentation of methane -- which may not be a wise assumption in the long run. Gasification or pyrolysis of macro-algae depend far less upon the chemical constituents and far more upon absolute biomass. It is those thermochemical approaches which are better positioned to take advantage of the prolific nature of marine aquaculture. Macro-algae can produce up to 6 harvests per year, depending upon local conditions.