Monday, April 22, 2013

Algae: The Fuel of the Future, Forever

Meaning it always seems to be in the future, sort of like fusion:

Last year, Preznit Obama was  touting algae as the fuel of the future, but has it come any closer to reality?

Algae at a Pump Near You?
The promise of using algal biofuels as a substitute for petroleum has been bandied about for several decades. During that time, the political and commercial appetite for achieving it has waxed and waned with the price of oil and the demands of national security. But today, calls for oil independence and alternative energy sources have placed renewed focus on algae.

Many species of algae are rich in lipids—fat molecules that are easily processed into biodiesel. Others are rich in carbohydrates, which can be fermented into alcohol-based biofuels such as ethanol and butanol. Theoretically, an algae farm could yield as much as 10,000 gallons of oil per acre annually; palm oil offers the next-highest yield at 650 gallons per acre per year. And algae thrive on waste, consuming the carbon dioxide, nitrates, and phosphates thrown off by agriculture, power generation, and other commercial endeavors.
Once upon a time, I used to work primarily with algae, including some of the species being bandied about as potential producers of voluminous, low carbon footprint fuel.  There's an important word embedded in the paragraph above "thoeretically."  While algae are simple plants, and just want clean water, nutrients, light and some micronutrients, growing them on a large scale has always been dicey.  One reason is that it's hard to keep the pure cultures pure, and free of bacteria (which kill the algae and eat the product, kind of like mice in a grain field), and the larger the size of the culture, the more difficult that is.
So why isn’t algal oil flowing from gas pumps everywhere? Because despite algae’s many benefits, neither scientists nor entrepreneurs have found an efficient way to cultivate and harvest algae, or to convert it into oil at scale, and at a price that matches conventional oil. These challenges—and the powerful potential benefits of algal biofuels—captured the attention of William Cooke, a physics professor at the College of William & Mary and co-leader of the Chesapeake Algae Project. As Cooke sees it, algae are already a primary source of oil. Before the evolutionary emergence of bacteria that cause decay, algae sank and their oils were preserved. Thus, much of the conventional oil that we pump out of the ground today comes from very old algae.
And therefore algae farts are the primary source of natural gas, too.  But still, after all this time, why aren't algae carrying their share of the load now?
What is the main obstacle to the industry’s growth? Is it processing?
COOKE: No. Processing is really important, but it’s fairly straightforward, even though it’s not clear exactly how it will be done at scale. You squeeze algae, or dry it and crush it, or condense it. It’s the cultivation that’s tough. The National Research Council [NRC] recently released a techno-economic analysis [TEA] that nails the problems. The trouble with farming algae is that you need sunlight. You need flat land and water to grow it in—saltwater or brackish water provides a more robust environment. You need nutrients—nitrates and phosphates. You need carbon dioxide.

It seems laughable, but obtaining carbon dioxide is a major constraint for the industry. C.J. Warner said that you have to think about carbon dioxide as the feedstock for algae. As soon as you start isolating algae into circulating ponds and bioreactors, you’ve got to put in the carbon dioxide. If you have to truck your carbon dioxide more than 20 kilometers or so, it’s a losing proposition. The idea that we have to import carbon dioxide to make a biofuel that’s supposed to reduce carbon dioxide is a little mind-numbing.
Yep, when algae are happy, they make organics, (in this case the planned fuel) from light and CO2.  And when algae grow really fast, they run out of CO2 in the water, which makes the algae unhappy again, and the water extremely basic (on reason the algae are unhappy).  CO2 is a limiting resource for plants, algae included, maybe even especially.  And to make fuel cheap competitive the price of that CO2 has to be literally dirt cheap.

One thing might be to couple the algae growing plant to coal or gas burning power plant, which produce ample CO2 as waste products.  Hopefully, CO2 could be diverted from the exhaust to feed the algae.  Moreover, power plants tend to be huge sites with lots of ponds for waste handling anyway, so it shouldn't be hard to squeeze in some room for specialized algae growing systems.  You can use those to cover the old fly ash dumps.

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