Growing lots and lots of algae not that easy
By Harry Eagar
The Maui News
By Harry Eagar
Growing microalgae is no problem, Barry Raleigh, the former dean of the School of Earth Sciences and Ocean Technology at the University of Hawai'i, told The Maui News.
Growing it day after day in industrial quantities has been.
Raleigh is a co-founder and scientific leader of HR BioPetroleum, which is heavily seeded with ocean scientists from the UH and the Scripps Institute of Oceanography in La Jolla, Calif. Here is how they propose to grow algae by the megaton on Maui:
First, select the critter. Microalgae are one-celled plants that live in fresh or salt water. They are not macroalgae, multicelled plants, such as limu.
For the past two years, HR has experimented with a number of microalgae species at the Natural Energy Laboratory of Hawaii in Kona. Some were collected (by UH researchers) locally, and all are commonplace marine species. The final commercial candidate has not been picked.
HR proposes to pump brackish water at Ma'alaea, which will be put into long, clear plastic tubes along with a starter batch of algae.
Algae grow with sunlight, water and carbon dioxide and a small admixture of nutrients, primarily nitrogen and phosphorous.
HR will get carbon dioxide from the stacks of MECO's diesel-fired generators at Ma'alaea. That is why the farm must be close to the power plant. The gases "are pretty well scrubbed," said Raleigh, but they will contain some nitrogen and sulfur oxides.
The nitrogen will probably suit the algae well, and the sulfur is something they tolerate in the wild.
After multiplying for a short while in closed reactors, the inoculation of algae soup will be poured into long shallow growing ponds. These will be about 100 feet long by 30 feet wide and 8 inches deep.
This differs from Bioreal (also known as Micro-gaia) in Kihei, which grows algae in hemispherical reactors; and Cyanotech in Kona, which uses deep ponds.
The ponds will multiply the algae quickly and, to keep them from being infected from things in the air, they will be harvested every day.
Raleigh says the algae are not genetically modified with recombinant techniques and pose no threat to native limu in the ocean at Ma'alaea.
Harvesting involves filtering and pumping the green matter into tanks and wiping down and cleaning the ponds. Most of the water is reclaimed and used again, although some will be pumped into injection wells.
With food, light and warmth, the algae produce proteins. By putting them under stress (by limiting nutrients), the algae can be induced to shift production to lipids - vegetable oils.
The oils are equivalent to oils from seed crops and are converted into biodiesel by the same process.
Depending on the refining process, they can be made into diesel, jet fuel or feedstock for other industrial products, like plastics.
Other products can be recovered, like astaxanthins for use in pharmaceuticals and feed additives.
At best, the algae produce about 35 percent lipids.
The remainder is largely protein, which can be processed into animal feed, and some carbohydrates, which could be made into ethanol.
The farm site is next to a bird refuge. Raleigh says he doubts the birds, some of them endangered Hawaiian coots and stilts, would be attracted to the algal water since they are filter feeders looking for small crustaceans. Because the ponds are drained each day, he says they would not breed mosquitoes.
For more information, visit the Web site www.hrbp.com.
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