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Author Topic: Plant Based Products for a Sustainable civilization  (Read 5657 times)

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The Ugly Duckling: Can Duckweed Find Its Way to Bioenergy Commercialization?  

 Bruce Dorminey, Correspondent 
 June 23, 2014 

Greater Duckweed (Spirodela polyrhiza) — one of the smallest and simplest freshwater plants known — generally gets a bad rap. That’s because the millimeter-sized floating plant thrives on the worst sort of livestock and human wastewater, basically garden-variety sewage. In fact, in the South Pacific, New Zealand and Australia, it’s frequently used to clean such wastewater.

For years, researchers have been trying to commercialize duckweed as a viable source of bioenergy for the production of ethanol, biodiesel, natural gas and steam-generated electricity.

But even now, there’s little agreement on whether duckweed is best suited as a natural option for turning so-called municipal graywater into something clean enough to drink from the tap, or as a renewable biomass.  In pelletized form, it can also be used to feed tilapia, shrimp or poultry, and is even co-fired with coal.

Duckweed to bioenergy conversion may ultimately work best when done in tandem with some sort of ongoing wastewater cleanup.

The plant itself is composed of only a single kidney-shaped leaf, connected to the water on, which it floats by only a few thin underwater roots.  However, duckweed advocates point to the fact that, in warm climates, it can basically grow anywhere and at all altitudes.

A shallow big pond full of effluent from secondary treatment is just like liquid duckweed fertilizer, says Anne Marie Stomp, a retired North Carolina State University plant molecular biologist.

“You dump duckweed on top and every three days you take half of it away and the rest keeps growing,” says Stomp.

Multi-use Resource

Duckweed also has an advantage over algae biomass;/ it is large enough that it can be easily separated from water, it is very easy to air dry and, like hay, is also easy to store.  

It may soon become more prevalent in the U.S. if the Environmental Protection Agency (EPA) places more stringent requirements on wastewater discharge permits, and small towns could be forced to comply with tertiary wastewater treatment options.

“Small towns could be forced to put in $100 million chemical tertiary treatment plants which they can’t afford,” said Stomp.  “However, duckweed is fantastically good at tertiary wastewater treatment.”

Duckweed bio-engineering could also make it even more attractive as a bioenenergy feedstock.

A paper published earlier this year in the journal Nature Communications provides new and comprehensive details of the duckweed’s genome.

“If used for ethanol or electricity, any improvement in its BTU [output] would require that you improve the carbon allocation of the organism,” said Joachim Messing, Director of the Waksman Institute of Microbiology at Rutgers University in New Jersey.

Messing, the paper’s senior author, says that, it requires knowing the duckweed’s gene content. 

“We can bio-engineer the organism so that it has a better carbon output — in some form of carbon, either sugar, protein or oil — to potentially make kerosene, gasoline or diesel,” said Messing.

Commercial Applications

Duckweed, however, is already capable of doubling its population in as little as 48 hours, a fact that hasn’t eluded police officer Sam Licciardello, CEO of Biomass Alternative Power in Mantua Township, New Jersey. He  is heading up a group that is investing $40 to $60 million to use duckweed to generate both electricity and natural gas by late 2015

“I will be growing duckweed in a 15-acre, gutter-connected greenhouse site,” said Licciardello.  “It will accumulate steam from the gasifiers that will run two turbines which will create electricity and supply the grid with 12 MW.  While making steam, it will also create natural gas from the duckweed which will be stored, then tested processed and released in a metered [grid] system.”

But Stomp remains skeptical.

“No one wants to fund research to figure out a high-value product from duckweed because there is no mass source or cropping system for the plant,” said Stomp.  “So, nothing but futile attempts at commercialization get started, usually by people who are passionate but have limited business sense.”

Yet Licciardello couldn’t disagree more.  ;D

Biogas Potential

For his own operation, Licciardello explains that the duckweed will be automatically harvested from six separate greenhouse sections before being screened and dried in a process that removes 75 percent of its water.  From there, it will move into a patented convection system that will use a furnace-like closed loop process to heat and burn the duckweed to create both natural gas and steam.

Duckweed is dried down to 25 percent moisture before being put into three rows of 11 gasifiers that are fired up to 1,600 degrees Fahrenheit.  The gasifiers will be automatically fed with duckweed.  The steam created from the process will travel back to the turbines.

Licciardello says a component inside the gasifiers actually separates the natural gas from the steam.  The natural gas component is then pumped into a holding tank before being fed into the natural gas grid.

Steam from the process will be fed into one of the two Siemens-built turbines at 12 MW of capacity.  Biomass Alternative Power plans on selling its electricity to Florida’s NextEra Energy.  The New Jersey start-up’s natural gas is to be purchased by British Petroleum (BP) for possible transport to California via cross-country pipeline.

When up and running, Licciardello says Biomass Alternative Power will become the only commercial duckweed-to-bioenergy conversion operator in North America.

“The production of ethanol and biogas from duckweed still cannot compete against petroleum products (gasoline and natural gas) economically,” said Jay Cheng, an agricultural and biological engineer at North Carolina State University.

It’s a view again not shared by Licciardello, however, who claims that his own start-up’s natural gas production from duckweed can already easily compete with natural gas garnered via fracking.

Once up to speed, Biomass Alternative Power will process about a million sq. ft. of duckweed per day says Licciardello.  But he remains undecided about whether his greenhouse lagoons will be filled with wastewater or whether the company will fertilize their ponds with phosphorous, nitrogen and potash.

However, revenue streams from processing wastewater treatment for counties and municipalities could arguably aid fledgling duckweed bioenergy start-ups’ bottom lines.

Duckweed in Argentina

There may even be room for more socially-conscious entities, such as Argentina’s Mamagrande, a Buenos Aires-based biotech concern that has a stated goal of “regenerating ecosystems” by using duckweed to cleanup wastewater.  It may also eventually ferment the duckweed’s starch into lactic acid to manufacture biodegradable plastic and/or bioethanol.

Funded with only several hundred thousand dollars, Mamagrande currently is working with a 4 hectare (9.88 acre) pilot plant in the small Argentinean town of Totoras.

Eduardo Mercovich, one of Mamagrande’s co-founders, says the initial cost of the duckweed needed to get such projects going is almost negligible.  That’s in part because, as he notes, usually within a month’s time, the plant can grow to cover a hectare (2.47 acres) of a lagoon’s surface area.

“In our pilot plant,” said Mercovich, “we should have ten fresh wet tons of duckweed per day; or about a quarter ton of starch per day; half of which would produce 100 liters of ethanol daily.”

Mercovich says that once Mamagrande’s duckweed process is proven in Argentina, its technology will be made publicly available.  He notes that in both Brazil and Argentina, ethanol is currently made from either corn or sugar cane.  But unlike cane or corn, as Mercovich points out, duckweed needs less energy to process.

Bioengineering Starch for Ethanol

If future duckweed bioenergy entrepreneurs can find some sort of revenue-generating synchronicity with global municipalities interested in cleaning up wastewater — either to be reused as graywater for agricultural irrigation or for drinking water — then duckweed may find a viable bioenergy conversion niche.  And as Stomp points out, it also compares favorably with corn, as it is likely easier to isolate starch from duckweed. 

After over 15 years of duckweed research in the laboratory, Stomp explains that she and Cheng proved that once loaded into a fermentation vessel, more than 95 percent of its starch could be converted into ethanol.

“By growing duckweed on wastewater from hog production,” said Stomp, “we harvested duckweed biomass at the rate of 20 grams of dry weight per sq. meter a day, which is equivalent to 54,000 kg of dry weight on 2.5 acres a year.”

Stomp notes that if this 54,000 kg of dry weight duckweed were only 50 percent starch then it would yield something like 27,000 kg of starch for every 2.5 acres, or roughly four times the starch that could be expected from 2.5 acres of corn.

Stomp, however, says that by using enzymatic degradation of corn stover, the traditionally unused portion of a corn plant for ethanol conversion itself, then that “drastically” increases dry weight biomass that can harvested from an acre of corn.

But with bioengineering, duckweed would likely still have an edge on corn.

“You could probably trick this plant into accumulating starch to as much as 75 percent; [roughly] the same starch percentage as corn,” said Stomp. *


* Agelbert NOTE: Not mentioned is the fact that it takes MUCH longer to get that "high percentage of starch" in corn than the 40% or so in Duckweed. Also, ALL of the duckweed has that starch content whereas corn only has it in the seed with LOTS of wasted energy (from a starch production standpoint) used to make the rest of the plant with a huge stalk and root system. Duckweed is ALL usable product. Duckweed has much less lignin content that corn. Lignin is the THE biggest chemical bugaboo obstacle because it is expensive to rid the feed stock of it in preparation for making biofuel. So yeah, duckweed beats the living daylights out of corn and even switchgrass, never mind that corn and switchgrass have short growing seasons and Duckweed can be grown ALL YEAR.   


My comment posted on the article web site:

A. G. Gelbert   
 June 24, 2014 

Great Article! I just want to add the tiniest flowering plant known to science (Lemna minor - Duckweed), also has great promise as a source of nutrition and bioremediation of the environment at the same time.

This wonder plant grows almost everywhere on earth, can be fertilized with pig feces, thereby avoiding chemical fertilizers and nitrogen waste farm runoff, grows in shallow ponds with no need of continual water resupply once the initial pond is set up, does not replace crop land because ponds can be placed over non arable land all over the world to help sequester carbon, can be used as feed for animal and nutrient supplements for humans to prevent malnutrition, have even been used as environmental markers to detect heavy metal pollutants in water and, last but not least, is a known natural water purifier (lower the fecal coliform count to acceptable levels).

The Chinese have actually proposed Duckweed refineries because, as long as crude oil costs more that $80 a barrel, biofuel hydrocarbons form the Duckweed carbohydrates are profitable. Duckweed, unlike many cellulose biofuel plant sources is extremely low in lignin . This makes the extraction process far simpler, cheaper and more environmentally friendly that making biofuel out corn (a horrible choice only a fossil fuel lover could like) or even sugar can, which is eight times more efficient as a biofuel source than corn. Even switchgrass varieties have more lignin than Duckweed.

I am firmly convinced this humble plant is part of a human future in a viable biosphere. I have video and research data as well as links below.

Duckweed, The Little Green Plant that Could.


We need to transition to 100% renewable Energy sources. Duckweed is part of the answer to how we can accomplish this herculean task quickly.

If you agree, please sign this petition to President Obama:

Demand Liberty From Fossil Fuels Through 100% Renewable Energy WWII Style Effort

Here's a link to the petition: http://www.care2.com/go/z/e/Ai3Tb

We did it with the Liberty Ship massive building effort in WWII; we can do it again with Renewable energy technology and infrastructure.

Thank you

Anthony G. Gelbert
Green Leaf Star American in the Service of Future Generations


He that loveth father or mother more than me is not worthy of me: and he that loveth son or daughter more than me is not worthy of me. Matt 10:37


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