Green Expectations

A Florida algae-to-ethanol operation is poised to go commercial scale with a project colocated with a natural-gas-fired power plant.
By Holly Jessen | March 09, 2015

By harnessing CO2, sunlight, saltwater and algae, Algenol’s technology takes only 25 days to produce maximum concentrations of ethanol. Imagine trying to replicate that timeline in the corn-ethanol industry, including planting, harvest and ethanol production. “It’s not possible,” says Paul Woods, founder and CEO of the company. “But it is possible with algae, because it grows so fast.”

How fast does algae grow? Woods likes to tell people in Florida that all they need to do is turn off their pool pumps to witness the power of algae. 

The technology also uses significantly fewer acres of land than corn-ethanol production. At a yield of 170 bushels per acre and 2.8 gallons per bushel, a corn ethanol plant produces 476 gallons of ethanol per acre of corn. A corn stover cellulosic facility will be able to sustainably remove 2 or more tons of corn stover per acre, which will yield 140 gallons of ethanol, according to an industry expert. Algenol’s technology, on the other hand, can produce, on average, 8,000 gallons of ethanol per acre in a year, Woods says, adding that at peak production in the sunny summer months, Algenol produced more than 10,000 gallons of ethanol. 

How It Works  
The clear plastic bags used in the direct-to-ethanol technology look like giant hanging file folders, Woods says. Each bag is 10 feet by four feet, 2 inches deep and has capacity of 50 liters. The bag is filled with saltwater, which is inoculated with algae culture. All green plants, including algae, take in water and CO2 from the atmosphere, and combine those elements as a precursor to sugar, which, with Algenol’s two-step direct-to-ethanol process, is immediately converted to ethanol. In the end, approximately 85 percent of the carbon consumed produces ethanol and other fuels.

When that process is complete, a simple centrifuge is used for separation, Woods says. Spent algae goes one way and liquid goes another. Next comes a two-step ethanol purification process, the first of which is patented by Algenol and the second is no different than the method used by the corn-ethanol industry, he adds. The remaining biomass, or spent algae, is turned into green crude in a six-minute process, which can potentially be sent to a refinery to produce mostly gasoline or diesel and some jet fuel. The four fuels can be produced for about $1.30 a gallon each, the company says.

At Algenol’s demonstration facility near Fort Meyers, Florida, the CO2 feedstock arrives in tanks. The company is focusing first on colocation with carbon dioxide emitters in Florida and Arizona. “We are going to take CO2 that is about to be emitted into the atmosphere and instead we’re going to capture that carbon and recycle it or reuse it,” Woods says, adding that the CO2 is collected by a giant straw at the stack, transported by fans and blowers and injected into the algae-inoculated bags. “We’re actually going to turn these emissions into something that is a very useful and valuable product.”

The company has already demonstrated that CO2 collection works, by building a machine to gather and compress it. The next step was to see if there was anything in the flue gas that would be detrimental. Although there were concerns, four tests show the algae actually performed 3 to 5 percent better on flue gas than bottled compressed CO2. It turns out that post-combustion gas is significantly depleted in oxygen, resulting in faster and more efficient photosynthesis.

In Florida, there are three types of CO2 sources, the first two of which are natural gas- or coal-fired power plants. Algenol has already signed a 24-year supply agreement with a natural gas-fired power plant in which it agreed to pay the company $1 per ton. Compared to the approximately $40 a ton charge for pure CO2 from a pipeline, Algenol is scoring a cheap feedstock, Woods says. Plus, that $1 flows back to the power plant’s electric customers.

The goal is to announce the name of the facility this spring and break ground this year. Algenol wants to eventually expand to 8,000 acres of algae-producing modules, with a target production of 8,000 gallons of ethanol per acre, per year, or about 64 MMgy. “We’re not there yet,” he says, adding that the project is currently in the planning and engineering phase. “We’re really evaluating all of the costs and making sure that it really can be done on this land. There’s a lot of moving parts.”

The third CO2 source in Florida, is the DOE-funded carbon capture program, which Woods is very interested in having access to someday. Underground carbon storage is very expensive, adding up to somewhere between $40 and $100 per ton and most likely on the higher end of the scale. “That is ugly,” he says, adding that Algenol offers a very different approach to carbon mitigation or reduction strategies.

Complement Vs Competition
In case there’s any confusion, Woods clarifies that he sees Algenol’s second-generation technology as a complement to the first-generation industry. “I get asked all the time, ‘Are you guys competitors to corn and are you going to destroy the corn ethanol market?’” he says, the day after returning from a trip to the White House to talk policy needs, including a functioning renewable fuel standard. “I’ve got to tell you, I think that is disappointing that people think that. In my opinion, there wouldn’t be an ethanol market without corn producers.”

So what about a partnership with corn-ethanol plants? Could Algenol colocate with a first-generation facility and capture CO2 to produce more ethanol? The idea does have limitations, particularly in the Midwest. “The problem is, of course, you can’t freeze algae cultures,” he says, adding that algae grows best in areas where it is hot and the sun shines year-round. Woods also doesn’t believe it makes sense to build on valuable and viable farmers’ fields. “I’ve got to say, I think algae is really suited for the lowest-quality land,” he says.

Still, there are some places, such as California, where colocation with an ethanol plant could work, depending on available land. “The CO2 that comes off fermentation is damn near pure, so the thought is really fantastic,” he says, adding he believes that there will be a time when Algenol’s feedstock could be captured at ethanol plants and transported by pipeline or rail for conversion at an Algenol facility.

Author: Holly Jessen
Managing Editor, Ethanol Producer Magazine