Out of all the clean energy options in development, it is algae-based biofuel that most closely resembles
the composition of the crude oil that gets pumped out from beneath the
sea bed. Much of what we know as petroleum was, after all, formed from these very microorganisms, through a natural heat-facilitated conversion that played out over the course of millions of years.
Now, researchers at the U.S. Department of Energy’s Pacific Northwest
National Laboratory in Richland, Washington, have discovered a way to
not only replicate, but speed up this “cooking” process to the point
where a small mixture of algae and water can be turned into a kind of
crude oil in less than an hour. Besides being readily able to be refined
into burnable gases like jet fuel, gasoline or diesel, the proprietary
technology also generates, as a byproduct, chemical elements and
minerals that can be used to produce electricity, natural gas and even
fertilizer to, perhaps, grow even more algae. It could also help usher
in algae as a viable alternative; an analysis has shown that
implementing this technique on a wider scale may allow companies to sell
biofuel commercially for as low as two dollars a gallon.
“When it comes down to it, Americans aren’t like Europeans who tend
to care more about reducing their carbon footprint,” says lead
investigator Douglas C. Elliott, who’s researched alternative fuels
for 40 years. “The driving force for adopting any kind of fuel is
ultimately whether it’s as cheap as the gasoline we’re using now.”
Scientists have long been intrigued by the laundry list of inherent
advantages algae boasts over other energy sources. The U.S. Department
of Energy, for instance, estimates that scaling up algae fuel production to
meet the country’s day-to-day oil consumption would take up about
15,000 square miles of land, roughly the size of a small state like
Maryland. In comparison, replacing just the supply of diesel produced
with bio-diesel from soybeans would require setting aside half of the
nation’s land mass.
Besides the potential for much higher yields, algae fuel is still
cleaner than petroleum, as the marine plants devour carbon dioxide from
the atmosphere. Agriculturally, algae flourishes in a a wide range of
habitats, from ocean territories to wastewater environment. It isn’t
hazardous like nuclear fuel, and it is biodegradable, unlike solar
panels and other mechanical interventions. It also doesn’t compete with
food supplies and, again, is similar enough to petrol that it can be
refined just the same using existing facilities.
“Ethanol from corn needs to be blended with gas and modified
vegetable oil for use with diesel,” says Elliott. “But what we’re making
here in converting algae is more of a direct route that doesn’t need
special handling or blending.”
Or, as algae researcher Juergen Polle of Brooklyn College puts it: “We cannot fly planes with ethanol. We need oil,” he tells CBS News.
But while the infrastructure for corn-based ethanol production has
expanded to the extent that most cars on the road run on gasoline blends
comprised of 10 percent biofuel, the ongoing development of algae fuel
has progressed ever-so glacially since the initial spark of interest in
the 1980s. Industry experts attribute this languishing to the lack of a
feasible method for producing algae fuel running as high as 10 dollars a gallon, according to a report in the New York Times.
However, the promise of oil from algae was tantalizing enough that
ExxonMobil, in 2009, enlisted the expertise of world renowned
bioengineer Craig Venter’s Synthetic Genomics lab to fabricate a genetic
strain of lipid-rich algae, as a means to offset the expense of
cultivating and processing the substance into a commercially attractive
resource. Yet, despite investing $600 million into a considerably
ambitious endeavor, the project was beset with “technical limitations,”
forcing the company to concede earlier this year that algae fuel is “probably further” than 25 years away from becoming mainstream.
The hydrothermal liquefaction
system that Elliott’s team developed isn’t anything new. In fact,
scientists tinkered with the technology amid an energy crisis during the
1970s as a way to gasify various forms of biomass
like wood, eventually abandoning it a decade later as the price of
gasoline returned to more reasonable levels. PNNL’s lab-built version
is, however, “relatively newer,” and designed simply to demonstrate how
replacing cost-intensive practices like drying the algae before mixing in chemicals
with a streamlined approach makes the entire process much more
cost-effective across all phases. Elliott explains, for example, that
the bulk of the expenditures are spent on raising algae,
which is either grown in what’s called an open-pond system, similar to
natural environments, or in well-controlled conditions found in
closed-loop systems. The open-pond system isn’t too expensive to run,
but it tends to yield more contaminated and unusable crops while
artificial settings, where algae is farmed inside clear closed
containers and fed sugar, are pricey to maintain.
“People have this slightly inaccurate idea that you can grow algae
anywhere just because they’ll find it growing in places like their
swimming pool, but harvesting fuel-grade algae on a massive scale is
actually very challenging,” Elliott says. “The beauty of our system is
you can put in just about any kind of algae into it, even mixed
strains. You can grow as much as you can, any strain, even lower lipid
types and we can turn it into crude.”
Forbes energy reporter Christopher Helman has a good description of how this particular hydrothermal liquefaction technique works:
“You start with a source of algae mixed up with water. The ideal solution is 20% algae by weight. Then you send it, continuously, down a long tube that holds the algae at 660 degrees Fahrenheit and 3,000 psi for 30 minutes while stirring it. The time in this pressure cooker breaks down the algae (or other feedstock) and reforms it into oil.
Given 100 pounds of algae feedstock, the system will yield 53 pounds of ‘bio-oil’ according to the PNNL studies. The oil is chemically very similar to light, sweet crude, with a complex mixture of light and heavy compounds, aromatics, phenolics, heterocyclics and alkanes in the C15 to C22 range.”
Operating what’s essentially an extreme pressure cooker at such a
constant high temperature and stress does require a fair amount of
power, though Elliott points out that they’ve built their system with
heat recovery features to maximize the heat by cycling it back into the
process, which should result in a significant net energy gain overall.
As a bonus, the ensuing chemical reaction leaves behind a litany of
compounds, such as hydrogen, oxygen and carbon dioxide, which can be
used to form natural gas, while leftover minerals like nitrogen,
phosphorus and potassium work well as fertilizer.
“It’s a way of mimicking what happens naturally over an unfathomable
length of time,” he adds. “We’re just doing it much, much faster.”
Elliott’s team has licensed the technology to the Utah-based startup Genifuel Corporation,
which hopes to build upon the research and eventually implement it in a
larger commercialized framework. He suggests that the technology would
need to be scaled to convert roughly 608 metric tons of dry algae to
crude per day to be financially sustainable.
“It’s a formidable challenge, to make a biofuel that is
cost-competitive with established petroleum-based fuels,” Genifuel
president James Oyler said in a statement. “This is a huge step in the right direction.”
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