Better Bug for Algae Fuels Likes Salt

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To most, it's mere bio-gunk; the stuff that fouls fishing lines and destroys deck shoes.

For many bio-researchers algae smells more like our energy future. As part of its natural process of photosynthesis, algae thrives on carbon dioxide and efficiently converts CO2 into energy-rich natural oils known as triacylglycerols (TAGs). From there, via a process known as transesterification, researchers can chemically convert TAGs into a green-energy substitute for fossil diesel.

Researchers acknowledge that the quest for a cost-effective, carbon-neutral diesel fuel is just a small slice of the bio-energy pie. And at the moment, biodiesel made from micro-algae represents only the smallest of slivers.

Now, Tom Beer, an Australian national environmental researcher, has co-authored a new paper that claims under ideal conditions, algal biodiesel can be produced at a competitive cost with fossil diesel and and with less greenhouse gas emissions than the more convetional diesel.

The paper “Greenhouse gas sequestration by algae — energy and greenhouse gas life cycle studies” is to appear in Proceedings of the Australian Life Cycle Assessment Society.

Beer, head of transport biofuels research at the Commonwealth Scientific and Industrial Research Organisation in Australia, says that biodiesel production from micro-algae grown in saltwater ponds could facilitate algal diesel production for transport fuel or even for electricity generation. (It also produces so much bio-gas in one design that Beer writes: “Given the amount of electricity produced by the algae farm with the above design, it is perhaps more accurate to think of it as a biogas power plant that produces biodiesel as a by-product, rather than the other way around.”)

Beer and his team specifically studied Dunaliella salina, an extremophile micro-algae that thrives in a high-saline environment. As a result of this new study, Beer now feels comfortable with the claim that algal diesel should be able to be produced at a competitive price with fossil diesel. However, he refuses to speculate on just how competitive the pricing would be.

But the key to using algae effectively for bio-diesel production remains the efficient extraction of oil from the algae. And among those attempting such extractions, their methods remain proprietary, as does much about this burgeoning field of algal diesel.

Beer says his own team’s next step, however, is to get algal ponds growing next to the mouth of the River Torrens in South Australia. There, they plan to test their ideas on a larger scale.

They expect to have algal harvesting in place within 6 to 9 months of setting up the ponds, but commercial algal diesel production is expected to take “several” years, said Beer.

Even so, the current trend back toward greener-burning diesel actually brings Rudolph Diesel’s legacy full circle.
In 1900, Diesel first demonstrated his patented engine using peanut oil. But cheap petroleum soon made fossil diesel king, and the industry never looked back. That is, not until the oil embargo of the 1970s.

Partly as a result of such uncertainty, Europe has been using rapeseed oil to manufacture bio-diesel for years and now China has moved to join in.

And now advances in nanotechnology are making existing bio-diesel producers take note of algae. Beer foresees new molecular sieves enabling micro-algae harvesters to maximize their per-liter yields.

“But if you insist on using some really energy-intensive way of harvesting and drying your algae,” said Beer, “then you’re just going to shoot yourself in the foot.”

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